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    PESTICIDE RESIDUES IN FOOD - 1983


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    EVALUATIONS 1983





    Data and recommendations of the joint meeting
    of the FAO Panel of Experts on Pesticide Residues
    in Food and the Environment and the
    WHO Expert Group on Pesticide Residues
    Geneva, 5 - 14 December 1983

    Food and Agriculture Organization of the United Nations
    Rome 1985


    CHLOROTHALONIL

    TOXICOLOGY

    Explanation

         Chlorothalonil was evaluated by the Joint Meetings of 1974, 1977,
    1979 and 1981 (FAO/WHO, 1975, 1978, 1980 and 1982). The 1981 Meeting
    reduced the temporary acceptable daily intake (ADI) from 0.03 to
    0.005 mg/kg b.w. inadequate metabolism data and a low no-effect level
    (NOEL) in a rat reproduction study with the 4-hydroxy-2, 5,
    6-trichloro-isophthalonitrile metabolite. Additional data were
    required by 1983 in order to clarify the metabolism, nephrotoxicity
    and mutagenicity of the parent compound and the 4-hydroxy metabolite.
    These data are reviewed in this monograph addendum.

         Temporary maximum residue limits (MRLs) were estimated during
    previous meetings for a variety of commodities. Certain studies on
    residues were required by 1983 and others considered desirable.
    Desirable data and information have been provided in response to
    several questions raised at the 1981 Meeting. One such question
    concerned the efficiency of tumble extraction for field-incurred
    residues of chlorothalonil, hexachlorobenzene (HCB) and
    pentachlorobenzonitrile (PCBN). Another concerned apparent
    discrepancies between two studies on residues resulting from the
    cooking of chlorothalonil-treated foods. A revised report has been
    provided, based on the original data.

         In response to the suggestion of the 13th Session of the Codex
    Committee on Pesticide Residues (CCPR) that the recommended limit for
    clorothalonil on grapes did not represent good agricultural practice
    (GAP), information on GAP and additional residue data were provided to
    the 1981 Meeting, but were received too late for evaluation. These
    data are also reviewed in this addendum, together with new or
    additional residue data on other commodities, information on national
    tolerances, and monitoring data on selected commodities from one
    country.

         The Meeting re-examined the definition of the residue in response
    to a request of the 14th Session of the Codex Committee on Pesticide
    Residues (CCPR).

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    BIOCHEMICAL ASPECTS

    Absorption, Distribution and Excretion

         Chlorothalonil (2, 4, 5, 6-tetrachloroisophthalonitrile,
    DS-2787), labelled in the benzene ring, was orally administered as a

    water suspension to male Sprague-Dawley rats (five per group) housed
    in metabolism cages. Urine and faeces from rats administered a single
    dose of 0, 5 or 200 mg/kg were analysed by high performance liquid
    chromatography (HPLC) to determine the extent to which chlorothalonil
    was metabolized to 4-hydroxy- 2 3, 5-trichloroisophthalonitrile
    (DS-3701) and/or other metabolites, at 2, 9, 24, 36, 48, 60, 72, 84
    and 96 hours after dosing. Blood and other tissue samples were
    collected at necropsy, but not analysed.

         HPLC analyses of high dose faecal extracts showed that 28 percent
    of the administered dose was eliminated as DS-2787 and 5 percent as
    DS-3701. A third peak of radioactivity eluted from the HPLC in the
    same time frame as the trichloroacid amide (DS-46851) and accounted
    for 1.4 percent of the administered dose. Analyses of faecal extracts
    from the low dose level showed that chlorothalonil, DS-3701 and
    DS-46851 (tentative) accounted for 1.6, 6.2 and 2.6 percent of the
    administered dose, respectively.

         HPLC analyses of urine samples showed that, at the 200 mg/kg dose
    level, chlorothalonil, DS-3701 and DS-46851 represented 0.05, 0.29 and
    3.53 percent, respectively, of the administered dose. At the 5 mg/kg
    dose level, DS-2787, DS-3701 and DS-46851 accounted for 0.08, 0.58 and
    4.48 percent, respectively, of the administered dose (Ignatoski et
    al 1983a).

         Chlorothalonil, labelled in the benzene ring, was orally
    administered to male Sprague-Dawley rats at dose levels of 0, 5, 50
    and 200 mg/kg b.w. to determine the distribution of radioactivity in
    rats at 2, 9 and 24 hours after dosing. Approximately 80 percent of
    the administered dose was found in the contents of the small intestine
    at 2 hours, 90 percent in the large intestine at 9 hours and 95
    percent in the large intestine at 24 hours after dosing. Accumulation
    of radioactivity in all tissues except the gastro-intestinal tract was
    less than 1 percent of the dose. The total g equivalents (expressed
    as chlorothalonil) found in the gastro-intestinal tract contents were
    directly proportional to the dose administered.

         Profiles of the concentration of labelled material in blood and
    other tissues as a function of time showed that only at the 5 mg/kg
    dose was the concentration essentially zero 24 hours after dosing. At
    the 50 and 200 mg/kg doses, blood and tissue concentrations of the
    labelled material (s) were persistent in significant quantities 24
    hours after dosing when compared to the 5 mg/kg dose (Ignatoski et
    al 1982).

         14C-Chlorothalonil was administered orally as a microparticulate
    suspension in 0.5 percent methylcellulose to male Charles River CD-1
    mice (16 per group) at dose levels of 0, 1.5, 15 or 105 mg/kg b.w.

    Urine, faeces, blood and other selected tissues were assayed for
    radioactivity. The total recoveries of radioactivity ranged from 93 to
    99 percent for the low dose, 78 to 85 percent for the mid dose and 73
    to 77 percent for the high dose.

         The major route of elimination of radiolabelled material was via
    the faeces. Faecal elimination was complete by 24 hours for the low
    and mid doses and by 96 hours for the high dose. Delayed faecal
    elimination at the high dose resulted from large amounts of
    radioactivity remaining in the stomach contents at 9 and 24 hours.
    Approximately 20 percent and 9 percent of the high dose was found in
    the stomach contents at 9 and 24 hours, respectively.

         There was also a high amount of radio activity in the large
    intestine (13 percent) at 9 hours. The high dose of chlorothalonil may
    have had an effect on stomach emptying time, which delayed faecal
    elimination of radioactivity. Furthermore, the soft consistency of the
    faeces suggested that there was increased motility or water retention
    in the lower gastro-intestinal tract but no increased faecal
    elimination at the high dose.

         Urinary excretion at all doses generally varied between 5 and 10
    percent of the administered dose. The total amount of radioactivity
    found in nine tissues and blood was less than 3 percent of the
    administered dose (Ignatoski et al 1983b).

         14C-Chlorothalonil was administered intraduodenally to male rats
    (donor animals) at a dose level of 5 mg/kg b.w. and bile was collected
    for 24 hours after dosing. The bile collected during the first 6 hours
    post-dosing was pooled from individual animals and administered
    intraduodenally to recipient rats. The recipient rats received 0.2
    percent to 2.4 percent of the total radioactivity administered to the
    donor rats. Bile from the recipient animals was also collected for 24
    hours after dosing.

         Data from the donor animals indicated that 1 to 6 percent of the
    administered radioactivity was excreted in bile within 24 hours
    after dosing. Approximately 19 percent of the radioactivity
    administered to recipient rats was excreted within 24 hours after
    dosing. Characterization of the radioactivity with respect to the
    parent compound or metabolites was not performed (Ignatoski et al
    1983c).

         14C-chlorothalonil was administered intraduodenally in maize oil
    to Sprague-Dawley rats (six per group) at dose levels of 0.5, 5 or
    50 mg/kg b.w. or in methyl-cellulose at a dose level of 5 mg/kg b.w.
    The percent of the administered dose excreted in bile from animals
    receiving 5 mg/kg b.w. in maize oil (31.2 percent) was essentially
    identical to those animals receiving 0.5 mg/kg b.w. in maize oil (35.8
    percent). At 50 mg/kg b.w. in maize oil, only about 11 percent of the
    administered dose was excreted in bile.

         When methylcellulose was the vehicle at 5 mg/kg b.w., about
    7 percent of the administered dose was absorbed and excreted in bile
    within 24 hours, suggesting that absorption was facilitated by maize
    oil as compared with methylcellulose (Ignatoski et al 1983d).

         14C-Chlorothalonil was administered intraduodenally in maize oil
    to male Sprague-Dawley rats (five per dose) at six dose levels (0.5,
    5, 10, 50, 100 and 200 mg per kg). Data suggested that when
    chlorothalonil is administered intraduodenally to rats, the excretion
    profile in bile is dependent upon the dose and further that there is
    possibly a pharmacokinetic overload in response to increasing doses of
    chlorothalonil (Ignatoski et al 1981).

         Two male Sprague-Dawley rats were administered orally 5 mg
    14C-chlorothalonil/kg b.w. as a microparticulate suspension in 0.5
    percent methylcellulose. Blood samples, obtained at periodic intervals
    by orbital sinus puncture, showed peak blood levels between 4 and 7
    hours post-dosing, which rapidly declined thereafter. The total amount
    of radioactivity in the blood never exceeded one percent (1 percent)
    of the administered dose, with the majority of the activity in plasma
    (70 percent) and the remainder in the red blood cells (packed cell
    volume) (Ignatoski et al 1983e).

         In a separate study there were dose related changes in the mean
    blood concentrations (ng equivalents/ml), versus time. The kinetics
    were non-linear at 200 mg/kg with a shift in the time of peak
    concentration at 50 and 200 mg/kg caused possibly by affecting stomach
    emptying and a resultant lag in absorption (Ignatoski et al
    1983f).

    TOXICOLOGICAL STUDIES

    Short-Term Studies

    Mouse

         Groups of CD-1 Charles River mice (15 males and 15 females/group)
    were administered chlorothalonil (98.9 percent pure, containing 0.03
    percent HCB or less) in the diet at dosage levels of 0, 7.5, 15, 50,
    275 and 750 ppm for 13 weeks. Five males and five females/group were
    subjected to interim necropsies after six weeks of compound
    administration. Routine examinations were performed for gross signs of
    toxicity, physical examinations, body weight changes, food consumption
    and selected clinical chemistry parameters. At terminal sacrifice all
    surviving animals were subjected to complete gross necropsy, brain and
    kidneys were weighed and a histological evaluation made of stomach and
    kidneys.

         There were no compound-related deaths during the study or any
    other untoward signs of toxicity, mood consumption and body weight
    gains were comparable among groups. Mean compound consumption ranged

    between 1.2 and 141.2 mg/kg/day for the respective doses. There were
    no compound related effects on the clinical chemistry parameters,
    including blood urea nitrogen (BUN) and creatinine. Alkaline
    phosphatase levels were increased in high-dose females. There were no
    significant differences in brain weight; however, absolute and
    relative kidney weights were increased in females, but not in males,
    at 275 and 750 ppm. Gross necropsy was unremarkable except for
    proteinaceous plugs in the lumen of the bladder in males, generally
    distributed among all groups, with slight increased incidence in high-
    dose males. Microscopic examination of the stomach revealed an
    increased finding of hyperplasia and hyperkeratosis of the squamous
    epithelial cells in both sexes at 50, 275 and 750 ppm. Histologic
    evaluation of the kidney did not reveal any compound-related changes.
    Generalized vacuolation of the cortical tubular epithelial cells and
    hyperplasia of the epithelial cells of the proximal convoluted tubules
    in high-dose males at the interim sacrifice were not evident at
    terminal sacrifice. Other changes were sporadic and not considered
    compound-related.

         Chlorothalonil was demonstrated to be without adverse effects on
    mice at levels up to and including 15 ppm (2.5-3.0 mg/kg/day) when
    incorporated in the diet for 90 days (Shults 1983).

    Rat

         Groups of Charles River CD rats (20 sex/dose) were administered
    chlorothalonil (98 percent pure, with 0.03 percent HCB) in the diet at
    dosage levels of 0, 40, 80, 175, 375, 750 and 1 500 mg/kg b.w./day for
    90 days.  Animals were examined routinely for mortality and gross
    signs of toxicity; body weights and food consumption were measured
    periodically and haematological, clinical chemistry and urinalysis
    parameters examined pre-test, at 30 days and at the termination of the
    study. All surviving animals were necropsied, selected organs weighed
    and a complete list of tissues/organs examined microscopically.

         Survival was comparable among all groups. Indication of cathartic
    action related to compound ingestion was evident in both sexes at 750
    and 1 500 mg/kg/day. Evidence of soft stools, reduced faecal output,
    mucus in stools, swelling and irritation of the anus occurred with
    greater frequency and severity in the two highest dose groups. There
    were significant dose-related body weight reductions in both sexes at
    dose levels of 375 mg/kg/day end greater. Food consumption comparisons
    indicated compound-related increases throughout the study. There were
    significant but spurious increases in haemoglobin, haematocrit and
    erythrocyte counts in males, which are not considered to be compound-
    related. Mean corpuscular volume, mean corpuscular haemoglobin and
    mean corpuscular haemoglobin concentration were unaffected by
    treatment. Red blood cell morphology was normal in all groups. There
    were compound-related decreases in glucose levels at > 375 and

    > 750 mg/kg in males and females, respectively. There were similar
    reductions in BUN at > 80 and > 375 for males and females,
    respectively. All other clinical chemistry determinations were normal
    except for depressed SGPT activity, present in both sexes in all
    treatment groups. This effect was generally dose-related. A special
    evaluation of serum thyroxine (T-4) and triiodothyronine (T-3)
    demonstrated depressed T-4 levels at > 175 and 1 500 mg/kg in males
    and females, respectively. This depression correlates with the
    decreased rate of body weight gain at those levels.

         There were dose-related increases in specific gravity and
    decreased urine volume for males given > 375 mg/kg of
    chlorothalonil. There was also an increased incidence of dark urine as
    the dose was increased from 375 to 1 500 mg/kg. There were no similar
    findings in females.

         Although several absolute and relative organ weight changes were
    determined, only the kidney weight changes are considered to be
    compound-related. Relative kidney weights were increased in both sexes
    at all treatment levels, but gross and histopathological evaluations
    revealed no correlative compound-related effects. Gross necropsy
    findings were unremarkable among all groups. The only dose-related
    histologic effect of treatment, which was inversely related to dose,
    was a finding of acute gastritis in the non-glandular portion of the
    stomach in all treatment groups.

         Based on the relative kidney weight changes at all levels, with
    compound-related effects on specific gravity and urine volume at
    > 375 mg/kg, a clear no-adverse-effect level has not been
    demonstrated. The depressed SGPT activity at all treatment levels in
    both sexes, considered to be compound-related, is difficult to
    interpret, particularly since relative liver weights were increased at
    > 750 mg/kg for both sexes (Wilson et al 1981).

         Technical grade chlorothalonil (98.2 percent pure) was
    administered in the diet to groups of Sprague-Dawley rats
    (25/sex/dose) at dose levels of 0, 1.5, 3, 10 and 40 mg/kg for 13
    weeks. Selected animals from each group were continued on a control
    diet for an additional 13-week recovery period. Serial sacrifices were
    conducted at 6 weeks (5/sex/group), 13 weeks (10/sex/group) and 26
    weeks (all remaining animals). Mortality was monitored daily and
    physical examinations conducted periodically. Body weight gain and
    food/water consumption were recorded weekly. Haematological, clinical
    chemistry and urinalysis parameters were determined throughout the
    study. Complete necropsies were performed and selected organs weighed;
    microscopic examination was done on all animals. In addition, EM
    examination of kidneys was also performed.

         There was no mortality associated with treatment. Physical
    examinations were unremarkable as were body weight, food consumption,
    urinalysis and haematological determinations. The only differences
    between control and treatment groups regarding clinical chemistry
    evaluations were reduced alkaline phosphatase and glutamic pyruvic
    transaminase activities in both sexes at 10 and 40 mg/kg. The
    differences were more pronounced in males and remained depressed thru
    week 13, while females tended to recover by week 13.

         Gross necropsies did not reflect treatment-related effects,
    except for increased kidney weights in males and females at 3, 10 and
    40 mg/kg/day and increased liver weights in males at 40 mg/kg/day.

         Microscopic examination revealed an increased incidence of
    epithelial hyperplasia and hyperkeratosis in the non-glandular portion
    of the stomach in both sexes given 10 and 40 mg chlorothalonil/kg
    b.w./day. Examination of the kidney revealed marginal increases in the
    incidence of dilated medullary tubules but no effects on cortical
    tubules at 10 and 40 mg/kg/day. There were no other adverse effects
    noted in other organs/tissues. After the 13-week recovery period,
    these apparent compound-related effects had reversed. Microscopic
    examinations did not provide evidence for the cause of organ weight
    changes observed in the liver and kidneys.

         Chlorothalonil was without adverse effects on the Sprague-Dawley
    rat at doses up to and including 3 mg/kg/day (Wilson et al 1983a,
    b).

         Groups of Sprague-Dawley CD rats (10 males and 10 females/group)
    were fed 4-hydroxy-2, 5, 6-trichloroisophthalonitrile (99.6 percent
    pure) in the diet at dosage levels of 0, 10, 20, 40, 75, 125, 150,
    500 and 750 mg/kg b.w./day for 61 to 69 days. Complete physical
    examinations were conducted routinely and body weight and food
    consumption measured throughout the study. Haematology, clinical
    chemistry and urinalysis parameters were routinely determined. Gross
    necropsy, organ weights and histologic examinations were performed at
    the termination of the study.

         Mortality was significantly increased in males at > 125 mg/kg
    and in females at > 75 mg/kg. There were no mortalities in dose
    groups of 0 to 40 mg/kg. Gross observation included dose-related
    occurrence of piloerection in all dose groups and pale skin and eyes
    in males and females at > 20 and > 75 mg/kg respectively. Body
    weights were depressed by treatment at levels > 40 mg/kg in both
    sexes. Food consumption was similarly decreased at the same dietary
    levels.

         Haematological evaluations presented evidence of anaemia in
    treated groups. There were significant decreases in the red blood cell
    count, haematocrit, haemoglobin, mean corpuscular volume and mean

    corpuscular haemoglobin at > 75 and > 40 mg/kg in males and
    females, respectively. Reticulocytes were similarly increased in males
    and females at > 75 and > 40 mg/kg, respectively. Nucleated red
    blood cells were increased in both males and females at > 40 mg/kg.

         Clinical chemistry parameters demonstrated similar compound-
    related effects with increases in alkaline phosphatase, BUN, SGPT and
    SGOT at > 125 and > 75 mg/kg in males and females, respectively.
    Both males and females at > 75 mg/kg had reduced total protein,
    albumin and globulin levels, with an increased albumin globulin (A/G)
    ratio at the same dosage level.

         Urinalyses were unremarkable at doses up to and including
    75 mg/kg. There were no evaluations conducted at higher doses.

         Gross necropsies presented occurrences of pale liver,
    pale/discoloured kidney, gastric ulceration, distended urinary bladder
    and flaccid heart at 75 mg/kg in both sexes. Since body weight
    decreased at 40 mg/kg, brain weight was used for comparison of
    relative organ weights. Accordingly, males and females at 40 mg/kg had
    reduced heart and kidney-to-brain weights. Females at that level also
    had reduced ovarian weights. At 75 mg/kg males, had reduced liver,
    spleen and testes weights, while females had reduced liver weights.

         Histopathological examination demonstrated compound-related
    effects in males and females at > 40 mg/kg in the form of erythroid
    hyperplasia and depressed granulopoiesis in bone marrow and spleen.
    There were also increased incidences of ovarian follicular
    degeneration and necrosis and renal cortical atrophy in females (the
    latter evident in males at > 75 mg/kg). At > 75 mg/kg, males and
    females had increases of hepatic haemosiderosis, toxic centrilobular
    hepatitis and myocardial degeneration. In females, there was also
    evidence of increased focal adrenal cortical necrosis, vacuolative
    degeneration and renal cortical tubular degeneration. These became
    evident in males at > 125 mg/kg, along with an increased incidence
    of testicular degeneration. Females were more sensitive to the toxic
    effects of the metabolite than were males. There were no adverse
    effects demonstrated at dose levels up to and including 20 mg/kg
    (Murchison et al 1979).

    Special Studies on Reproduction

    Rat

         A one-generation reproduction study was performed using Charles
    River CD rats, wherein 4-hydroxy-2, 5, 6-trichloroisophthalonitrile
    was administered in the diet. Five groups containing 12 males and 24
    females each were given dosage levels of 0, 10, 20, 30, 60 and 120 ppm
    for 18 weeks before mating and continuously through two successive

    reproduction cycles. F1a and F1b offspring were necropsied at weaning
    with tissues preserved from 5 males and 5 females in each group from
    the Flb pups. These tissues were not examined microscopically.
    Litters were culled at day 4 to 10 per litter (sexes equal) and the
    litter weights were determined at days 0, 4, 7, 10, 14 and 21. Indices
    of reproductive performance were determined.

         Mortality, body weight and food consumption of F0 parents were
    unaffected by treatment, with the exception of increased food
    consumption in high-dose males. The overall mating index in F1a and
    F1b litters was poor, being 62.5 percent and 54.2 percent,
    respectively. Gestation index for both control litters was similarly
    reduced, being 73.3 percent and 69.2 percent, respectively. Overall
    mating and gestation indices in the dose groups were greater than
    control values and, therefore, unaffected by treatment. There were no
    compound-related effects on maternal body weights during gestation and
    lactation. There were no compound-related effects observed on the mean
    number of live pups in either F1a or F1b litters from birth through
    lactation. Live born and stillborn indices were comparable among all
    groups in both litters. Pup viability in the high dose group at day
    4 was significantly lower than controls in the F1a and F1b litters.
    There were no compound-related effects on the lactation or litter
    viability indices, although slightly reduced litter viability indices
    were reported for both litters (86.7 and 84.6 percent, respectively)
    at the high dose.

         No statistically significant differences in mean live pup weights
    between control and treatment groups were reported at birth or day 4,
    although there was a negative trend in the F1a high dose group at day
    4. This was not evident in the F1b litter. There were, however,
    statistically significant differences for the high dose group in both
    litters at days 7, 10, 14 and 21 and at 60 ppm on days 10, 14 and 21
    in the F1b litter. There were no compound-related gross findings in
    any of the animals necropsied. The no-effect level in this study was
    demonstrated at 30 ppm (Ford 1982).

    Special Studies on Teratogenicity

    Rat

         Groups of Sprague-Dawley rats (25 females/groups) were
    administered chlorothalonil orally, via gavage, doses of 0, 25, 100
    and 400 mg/kg/day from day 6 through 15 of gestation. Surviving
    females were necropsied on day 20 and foetuses delivered by
    hysterotomy. The number and position of viable/non-viable foetuses,
    early/later resorptions, mean number of corpora lutea and total
    number of implantations were recorded. External, internal and skeletal
    examinations of foetuses were performed for evidence of abnormalities
    and anomalies. Half of the foetuses were evaluated for soft tissue
    anomalies and the other half for skeletal effects.

         There was no dose related mortality in the 25 and 100 mg/kg/day
    groups. However, the deaths during treatment of three dams in the
    400 mg/kg group were considered related to compound ingestion. There
    were no abortions in any group. General appearance and behaviour were
    unremarkable, except for evidence of cathartic action at 400 mg/kg
    (e.g. loose faeces, matting of urogenital fur). Mean maternal body
    weights were significantly different (less) than control at the high
    dose level. Food consumption was significantly reduced in all
    treatment groups initially (days 6 to 9) and in the high-dose group
    throughout the dosing period (days 6 to 15). There were no differences
    compared to controls for mean number of viable foetuses, implantation
    sites, corpora lutea or foetal weights. There was a significant
    increase in the number of early resorptions in the high-dose group, as
    well as post-implantation losses, when compared to controls. There
    were no reported effects on number or percentage of foetuses/litters
    with external, internal or skeletal malformations or developmental
    variations at any dose level administered.

         Chlorothalonil was considered maternally toxic to rats at
    400 mg/kg but there was no evidence of teratogenicity at any level
    tested (Rodwell et al 1983).

    Rabbit

         Groups of pregnant Japanese White rabbits (9/group) were
    administered orally, via gastric intubation, doses of 0, 5 and
    50 mg/kg of chlorothalonil from day 6 through 18 of gestation. All
    does were sacrificed on day 29, pups delivered by caesarean section,
    and the number of implants, live and dead foetuses recorded. Pups were
    examined for gross malformation, visceral organs removed and examined,
    and carcases stained with Alizarin Red S for skeletal evaluation.

         Body weights were reduced in high-dose females and 4/9 does
    aborted. Foetal resorptions were increased at 5 and 50 mg/kg compared
    to controls. The number of implants and number of live foetuses were
    reduced in the high-dose group when compared to controls. External
    examination revealed 1/74 foetuses at 5 mg/kg with hydrocephaly and
    1/36 foetuses at 50 mg/kg with cleft palate. There were no visceral or
    skeletal anomalies reported. Chlorothalonil is considered maternally
    toxic at 5 and 50 mg/kg, but there was no evidence presented of
    teratogenic effects (Shirasu & Teramoto 1975).

         In a pilot teratology study, groups of rabbits were orally dosed
    with 4-hydroxy-2, 5, 6-trichloroisophthalonitrile at 1, 5, 10, 25 and
    50 mg/kg/day from day 6 through 18 of gestation. Maternal death and
    toxicity occurred at doses of 10, 25 and 50 mg/kg with no adverse
    effects observed at 1 mg/kg. In the 5 mg/kg dose group, one female
    aborted, one was not pregnant and one female presented a litter of
    runts. The other females in this group had normal pregnancies and pups
    (Wazeter & Goldenthal 1976).

         Groups of Dutch Belted rabbits (10 per/group) were orally
    intubated with 4-hydroxy-2, 5, 6-trichloroisophthalonitrile at dose
    levels of 0, 1, 2.5 and 5 mg/kg/day from day 6 through 18 of
    gestation. Pups were delivered by Caesarean section on day 28 and the
    number, location and distribution of live/dead foetuses, corpora
    lutea, implantations and early/late resorptions recorded. All
    foetuses  were examined grossly, sectioned for visceral anomalies and
    stained for skeletal anomalies.

         There were three deaths, one at 2.5 and two at 5 mg/kg. There
    were no other gross signs of toxicity reported and body weight gains
    were uniform among all groups. There were no compound-related effects
    on the number of implantation sites, foetal weights, sex ratios or
    foetal anomalies. The number of females with early resorbed foetuses
    and number of females aborting was increased compared to controls at
    the high dose. However, most of these early resorptions in the high-
    dose group occurred in one female which had 10 implantation sites and
    10 resorptions. Otherwise, resorptions were comparable among treatment
    and control groups. There were no visceral or skeletal anomalies or
    abnormalities directly attributable to compound ingestion at doses up
    to and including 5 mg/kg/day. However, this dose did present marginal
    effects of maternal toxicity, which were not apparent at 2.5 mg/kg
    (Wazeter & Goldenthal 1976).

    Special Studies on Carcinogenicity

    Mouse

         Groups of CD-1 mice (60 males and 60 females/group) were
    administered technical chlorothalonil in the diet at dosage levels of
    0, 750, 1 500 and 3 000 ppm for 24 months. Mice were six weeks old at
    the initiation of the study. Animals were observed daily for mortality
    along, with other cage-side observations for signs of toxicity.
    Individual body weights, food consumption, physical examinations and
    haematological parameters were evaluated regularly throughout the
    study. All animals were necropsied, organ weights determined and
    selected tissues/organs examined histologically.

         There were no apparent compound-related effects on body weight
    gain, food consumption or general toxic response. Mortality was
    increased in high-dose males (40/60) compared to control males
    (29/60). Mortality in control females was 42/60. There was abdominal
    swelling in mid-and high-dose males, which was evident for the first
    six months, but no differences between control and treatment groups
    after six months. Distended abdomens were noted generally among all
    groups. Compound consumption resulted in 0, 119, 251 and 517 mg
    chlorothalonil/kg b.w./day for males; and 0, 134, 278, and 585 mg
    chlorothalonil/kg b.w./day for females in the 0, 750, 1 500 and
    3 000 ppm dose groups, respectively.

         Haematology measurements revealed an increased incidence of
    abnormal erythrocyte morphology, which was unrelated to other normal
    findings and not considered significant. Decreased haemoglobin,
    haematocrit and red blood cell values were evident in high-dose males
    at 24 months and in high-dose females at 18 and 24 months. There was
    an increase of hyperplastic bone marrow (sternum) for males and
    females of all treatment groups, in relation to corresponding
    controls, as well as hyperplasia of the red pulp in the spleen of
    treated males. The spleens of all female groups were comparable with
    control females, which had the most significant increase in
    hyperplastic red pulp. Haemosiderosis was unremarkable or not evident.

         Examination of organ weights demonstrated an increase in absolute
    and relative spleen weights for high-dose females but no significant
    pathological changes. Gross necropsy indicated the spleen was enlarged
    for mid- and high-dose males. Absolute and relative ovary weights in
    all females were decreased, with no significant dose-related or
    histopathologic changes. Absolute and relative testes weights for
    high-dose males were decreased but no compound related histomorphic
    changes were observed. Absolute and relative liver weights were
    increased in mid- and high-dose males and all females but were not
    statistically significant and were not accompanied by histopathologic
    changes. Absolute and relative kidney weights were increased in all
    treatment groups (p < 0.01) and were considered dose-related.

         Gross necropsy of all organs revealed compound-related effects in
    the kidney, described as renal enlargement, discolouration, surface
    irregularities, pelvic dilation, cysts, nodules and masses in treated
    groups only. There were no other significant compound-related effects
    on other organs or tissues reported.

         Histopathological data demonstrated compound-related effects on
    the stomach, esophagus and kidneys. The incidence and severity of
    hyperplasia and hyperkeratosis of the squamous mucosa in the
    oesophagus of treated males and females was significantly increased in
    a dose- and compound-related manner. Microscopic examination of the
    stomach demonstrated a more significant dose-related increase in the
    incidences of hyperplasia and hyperkeratosis of the squamous mucosa in
    male and female mice in the treated groups. This finding was virtually
    non-existent in control groups. There was a significant increase in
    squamous cell tumours in the 1 500 ppm females but the incidence was
    not dose-related. The incidence of squamous cell tumours in males was
    0/60, 1/60, 5/60 and 2/60 in control, 750, 1 500 and 3 000 ppm groups,
    respectively. In females the incidence was 0/60, 2/60, 6/60 and 5/59
    in control, 750, 1 500 and 3 000 ppm groups, respectively. Glandular
    epithelial tumours were increased in the treated groups but were not
    significant or dose-related. The incidence of glandular epithelial
    tumours in males was 0/60, 1/60, 2/60 and 0/60 in control, 750, 1 500
    and 3 000 ppm groups, respectively. In females the incidence was 0/60,
    1/60, 1/60 and 2/59 in control, 750, 1 500 and 3 000 ppm groups,
    respectively.

         Microscopic examination of the kidney revealed a significant
    finding of chronic glomerulonephritis present in all control and
    treatment groups, which was increased predominantly in males at
    3 000 ppm. Tubular degeneration was increased in males at 750 and
    1 500 ppm and in females at 1 500 ppm. The incidence of cortical cysts
    was increased in all treated males and in high-dose females. The
    neoplastic changes, reported as adenomas and carcinomas of the renal
    cortical tubules, were increased in the males in all treated groups
    but not in females. The incidence was 0/60, 6/60, 4/60 and 4/60 for
    control, 750, 1 500 and 3 000 ppm male groups, respectively. There
    were no neoplastic changes in the female groups, except for one
    low-dose female with a kidney haemangiosarcoma.

         Chlorothalonil has presented evidence of causing nephrotoxicity
    in earlier studies in rats, mice and dogs, predominantly in males. In
    an NCI rat study there was presumptive evidence of adenomas and
    carcinomas of the renal tubular epithelium. The NCI mouse study was
    negative for evidence of kidney tumours. Although primary renal
    tumours in rodents are rare, there was no positive trend for adenomas
    and carcinomas in the renal cortical tubules of male mice in this
    study, and therefore the evidence for tumourigenicity of
    chlorothalonil in the kidney remains elusive. The effects on the
    kidney, in this study, are nonetheless considered compound-related
    (Wilson et al 1983a; Tierney 1983).

         Groups of six-week old CD-1 mice (60 males and 60 females per
    group) were administered the chlorothalonil metabolite 4-hydroxy-2, 5,
    6-trichloroisophthalonitrile in the diet at dosage levels of 0, 375,
    750 and 1 500 ppm for 105 consecutive weeks. Animals were observed
    daily for mortality and other gross signs of toxicity. Individual body
    weights, food consumption, physical examinations and haematological
    parameters were evaluated regularly throughout the study. All animals
    dying or sacrificed during and at the termination of the study were
    necropsied; organ weights were determined, and selected tissues/organs
    were examined histologically.

         The mortality in the low- and mid-dose females reached 75 percent
    during month 20 and, therefore, all surviving low- and mid-dose
    females, as well as 10 control females (to serve as concurrent
    controls) were terminated at month 20. Mortality in the high-dose
    females reached 75 percent at month 22 at which time all females in
    that group and in the control group were sacrificed. Survival of the
    male mice was comparable between control and treated groups.

         There were no significant differences between control and
    treatment group animals on the basis of cage-side observations for
    signs of toxicity. Body weights were significantly reduced in both
    males and females given 1 500 ppm throughout the study. There were
    also sporadic decreases in males and females at 750 ppm that were
    evident during the first year of study and were comparable to controls

    during the second year. There were significant increases in food
    consumption for high-dose females compared to controls throughout the
    study and for high-dose males during the first year.

         Average compound intake throughout the study, on a mg/kg/day
    basis, for males was 50-88 (at 375 ppm), 90-180 (at 750 ppm) and
    190-425 (at 1 500 ppm); for females it was 58-103 (at 375 ppm),
    100-275 (at 750 ppm) and 232-624 (at 1 500 ppm).

         Haematological examinations conducted at 12, 18 and 20-24 months
    revealed compound-related effects on red blood cells with decreases in
    all treatment groups at 12 months, decreases in males at 750 ppm and
    females at 750 and 1 500 ppm at 18 months, and decreases in males
    given 1 500 ppm at 24 months. Reticulocyte counts were increased in
    males given 1 500 ppm at 24 months and in females given 750 and
    1 500 ppm at 20 months.

         Evaluation of differential leukocyte counts demonstrated moderate
    to marked increases in morphological changes in erythrocytes and
    leukocytes at 18 months in all treated females and 750 ppm males. At
    terminal sacrifice, all treatment and control groups presented
    evidence of changes, but they were more noticeable in the high-dose
    groups. Changes included anisocytosis, poikilocytosis, polychromic red
    cells, target cells, large platelets, crenated red cells and nucleated
    red cells.

         Bone marrow differential counts, including M/E ratios,
    demonstrated a decreasing trend of 2:1 for control females to
    approximately 1:1 for treatment groups. Similarly, a ratio of 1:2 for
    control males was approximately 0.9:1 for treated males.

         Organ weights and organ-to-body weight measurements demonstrated
    significant increases in spleen and liver weights and respective
    organ-to-body weight increases at 20 months in 750 ppm females.
    Absolute liver weights and liver-to-body weight ratios were also
    increased in 1 500 ppm females at 22 months. Absolute kidney weights
    and heart weights were also decreased at 22 months in the 1 500 ppm
    females. Male mice given 375-1 500 ppm revealed significant increases
    in liver weight and liver-to-body weight ratios and a positive trend
    in the spleen-to-body weight ratio. Absolute kidney weights were
    reduced in males at 1 500 ppm but were not considered significant,
    based on decreased body weight.

         Histopathological evaluations revealed an increase in
    bronchioalveolar adenomas in treated males. However, the differences
    between the control incidences were not dose-related or significant
    and, therefore, were not considered compound-related. The reported
    incidence in males was 2/59 (0 ppm), 6/57 (375 ppm), 6/57 (750 ppm)
    and 4/59 (1 500 ppm). The incidence of benign hepatocellular neoplasms
    and hepatocellular carcinomas was higher in control mice, with a

    negative trend in the treatment groups. There was one tubular adenoma
    and one tubular carcinoma of the kidney in the low-dose males but no
    incidences in any other groups.

         Non-neoplastic changes consisted of a dose-related increase of
    amyloidosis in the thyroid of both males and females. There was an
    overall marginal dose-related increase in the incidences of
    amyloidosis in treated males and females reported for the stomach,
    duodenum, ilex, liver, adrenal and urinary bladder. There was also an
    overall increase in amyloidosis reported for all female groups with
    respect to the spleen, kidney, jejunum and ovary. There was an
    increase in pigmentation (haemosiderin) of the spleen, which was
    compound-related and evident at all doses in both sexes. Chronic
    interstitial nephritis of the kidney was also considered compound-
    related and was increased in all treated females compared to controls.

         The test material was not oncogenic in CD-1 mice under the
    conditions of this study at doses up to and including 1 500 ppm.
    However, marginal and significant non-neoplastic changes, including
    amyloidosis, haemosiderin in the spleen, morphological changes in
    leukocytes and erythrocytes, increase in reticulocyte count as well as
    evidence of red cell haemolysis, failed to demonstrate a clear no-
    effect level for these effects (Hozan & Auletta 1981).

    Rat

         Groups of Sprague-Dawley CD rats (75 males and 75 females/group)
    were administered 4-hydroxy-2, 5, 6-trichloroisophthalonitrile in the
    diet at dosage levels of 0, 0.5 and 3 mg/kg/day for 104 weeks.
    Original dosage levels of 15 and 30 mg/kg/day were reduced at week 30
    to 10 and 20 mg/kg/day, respectively, because of poor survival and
    anaemia. Animals were observed daily for mortality, gross signs of
    toxicity and general appearance. Individual body weights and food
    consumption were measured regularly during the study. Clinical
    laboratory studies were performed periodically throughout the study on
    10 rats/sex/group at six-month intervals. Ophthalmological
    examinations and urinalyses were performed routinely, and faeces were
    collected and examined to evaluate the observed anaemia. Interim
    sacrifices were performed after one year on 10 rats/sex in all groups,
    except for the high-dose animals, which were all necropsied. Terminal
    necropsies were performed on all surviving animals after two years,
    selected organs weighed and complete histopathological examinations
    conducted.

         Pale skin and eyes were evident for the first 30 weeks in high-
    dose males and females, with similar but less marked findings observed
    in the 15 mg/kg group. Mortality was significantly increased in the
    30 mg/kg males and females and in the 15 mg/kg females. The high-dose
    group was sacrificed at 12 months after the dose level had been

    reduced to 20 mg/kg at week 30. Decreasing the 15 mg/kg/day dose level
    at week 30 to 10 mg/kg similarly improved the survival, which was
    comparable to controls for the remainder of the study. Body weight was
    reduced in the 10/15 and 20/30 mg/kg males and females throughout the
    study, even after reduction of doses. Food consumption was
    unremarkable except for decreases in 10/15 and 20/30 mg/kg females and
    20/30 mg/kg males, which was consistent with decreased body weights
    and increased mortality during the first 30 weeks. There were similar
    decreases in total serum protein, albumin, globulin and cholesterol in
    20/30 mg/kg males and females and 10/15 mg/kg females after six
    months. These returned to control levels for the remainder of the
    study after doses were reduced to 20 and 10 mg/kg, respectively.

         There were significant haemopoietic effects in the 10/15 and
    20/30 mg/kg animals, particularly females, during the first six
    months. Evidence of microcytic anaemia was provided by reduced red
    cell counts, haematocrit, haemoglobin, MCV and MCH, with accompanying
    increases in MCHC, reticulocytes and metarubricytes. Segmented
    neutrophiles were increased with a corresponding decrease in the
    percentage of lymphocytes. Specially stained bone marrow presented
    evidence of hypocellularity. Mallory's stain of liver tissue revealed
    an increased iron content (haemosiderin). After 18 and 24 months
    exposure, the 10/15 mg/kg group females continued to present evidence
    of anaemia (decreased Hct, Hgb, MCV, MCH and increased MCHC) with a
    positive bone marrow response (increased cellularity with a shift to
    increasing number of immature erythyroid cell types and increased
    number of animals with 1:1 M/E ratio). Prussian Blue staining
    demonstrated the presence of haemosiderin in the 10 mg/kg males and
    females which was not considered significant at 3 mg/kg. After 24
    months exposure, there were decreased serum potassium levels in all
    treated females. Urinalyses, and examination for faecal occult blood
    were unremarkable, except for increased urine volume at six months in
    the high-dose animals.

         Ophthalmological examination at six months revealed increased
    pale ocular structures and spontaneous hemorrhage in high-dose males
    and females. At 24 months there were increased numbers of dilated
    pupils (not responding to light) and increased bilateral cataract
    disease in high-dose males.

         Comparison of selected organ weights demonstrated decreased
    absolute organ weights for kidney, heart and brain in high-dose males
    with no significant relative organ-to-body weight changes. High-dose
    females had decreased absolute kidney and heart weights with no
    relative weight changes, except for spleen and brain. Microscopic
    examination failed to confirm any compound-related effects on these
    organs. There were no significant compound-related non-neoplastic
    organ changes, except for haemosiderin in the liver of high-dose
    females and haemorrhage in CNS tissues, hypocellular bone marrow and
    post-mortem congestion of lymph in high-dose males and females.

         Examination of tissues/organs for neoplastic changes did not
    indicate any compound-related effects at any level tested. Data
    presented in this study demonstrate that the metabolite 4-hydroxy-2,
    5, 6-trichloroisophthalonitrile is without adverse effects on male and
    female rats at levels up to and including 3 mg/kg/day for two years
    (McGee et al 1983).

    Special Studies on Mutagenicity

    Bacteria

         Chlorothalonil, dissolved in DMSO, was tested for mutagenic
    activity in Salmonella typhimurium strains TA98, TA100, TA1535,
    TA1537 and TA1538 according to the plate incorporation procedure of
    Ames, at concentrations between 0.33 and 6.6 g/plate with and without
    metabolic activation. Under the test conditions reported
    chlorothalonil (97.8 percent pure) did net induce point mutations in
    the five histidine-requiring strains of S. typhimurium at the
    concentrations tested (Banzer 1977a).

         Chlorothalonil was examined for mutagenic activity in
    S. typhimurium strains G-46, TA1530, C207, TA1531, C3076, TA1700,
    D3056 and TA1724 implanted in male albino mice. Host mediated assay at
    the dose level of 4 mg/kg (single IP administration) was carried out.
    No increase in mutation frequency of chlorothalonil treated group over
    the control was observed and the test compound (99 percent pure) was
    not mutagenic in the host mediated assay at the dose level tested
    (Legator 1974a).

         Chlorothalonil was tested for its mutagenic activity in
    S. typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538,
    according to the plate incorporation procedure of Ames et al.
    (1975), at concentration between 1 and 10 g/plate without metabolic
    activation and between 2 and 20 g/plate with metabolic activation. In
    addition, Escherichia coli B/r WP2 hcr+4 and its uv-sensitive
    derivative WP2 hcr -5 were also employed in the plate incorporation
    procedure with specific selective medium at concentrations between 10
    and 500-g/plate without metabolic activation and between 10 and
    100 g/plate with metabolic activation. Under the given experimental
    test conditions, chlorothalonil (99.3 percent pure) failed to induce
    any increase in the number of revertant colonies above that of the
    control and, thus, was not mutagenic at the concentrations tested
    (Shirasu et al 1977).

    Cultured mammalian cells

         Chinese hamster cells (V-79) and mouse fibroblast cells
    (Balb/3T3) in culture, with and without metabolic activation, were
    exposed to chlorothalonil at a concentration of 0.3 g/ml and
    0.03 g/ml, respectively, to detect mutations at the Ouabain resistant

    gene locus, according to the method of Schechtman. Acetone was the
    vehicle control without activation. S-9 alone was the negative control
    with activation. No evidence of mutagenic effect of chlorothalonil was
    observed in these two in vitro mammalian cell mutagenesis assay
    systems. The test compound (97.8 percent pure) was not mutagenic under
    the experimental conditions tested (Banzer 1977b).

    Cytogenic assay

         Chlorothalonil, suspended in 0.5% (w/v) Methocel E 15 premium
    (hydroxy-propyl methyl cellulose), was tested in rats, mice and
    Chinese hamsters for its ability to induce chromosomal aberrations in
    bone marrow cells. Prior to the chromosomal aberration test, a
    preliminary study was conducted in animals to determine appropriate
    dosage levels. In the cytogenetic assay, animals were orally dosed
    with the test compound with a 24-hour interval between doses. Six
    hours after the second dose, animals were killed, bone marrow removed
    from the femurs and slides prepared for the cells. One hundred
    metaphase cells per animal were evaluated for chromosomal aberrations.

         Ten male rats (Wistar) per group were orally dosed with 0, 8, 40,
    200, 1 000 and 5 000 mg/kg chlorothalonil twice, with a 24-hour
    interval between doses.

         Ten male mice (Swiss C.F.L.P>) per group were orally dosed with
    0, 4, 20, 100, 500 and 2 500 mg/kg chlorothalonil twice, with a
    24-hour interval between doses.

         Ten male Chinese hamsters, per group were orally dosed with 0, 8,
    40, 200, 1 000 and 5 000 mg/kg chlorothalonil twice, with a 24-hour
    interval between doses.

         No significant differences in the induced chromosomal aberrations
    were observed for the test animals between the treated and control
    groups at the dose levels tested. Under the given experimental test
    conditions, chlorothalonil (98.2 percent pure) was not considered to
    be a clastogenic agent (Siou et al 1981a).

    Micronucleus test

         Chlorothalonil, suspended in 0.5 percent (w/v) Methocel E 15
    premium (hydroxy-propyl methyl cellulose), was tested in rats, mice
    and Chinese hamsters for its ability to induce the formation of
    micronuclei in polychromatic erythrocytes. Prior to the micronucleus
    test, a preliminary study was conducted in animals to determine
    appropriate dosage levels. In the micronucleus test, animals were
    orally dosed with the test compound, with a 24-hour interval between
    doses. Six hours after the second dose, animals were killed, bone
    marrow removed from the femurs and slides prepared from the cells. Two
    thousand polychromatic cells per treatment were examined for the
    presence of micronuclei.

         The number of rats and mice per group and the dosage levels of
    test compound used in this study were identical with that used in the
    previous cytogenetic assay (Siou et al 1981b).

         Ten male Chinese hamsters per group were orally dosed with 0, 4,
    20, 100, 500 and 2 500 mg/kg chlorothalonil twice, with a 24-hour
    interval between doses.

         No significant differences in the mean value of polychromatic
    erythrocytes with micronuclei were observed between the treated and
    control groups at the dose levels tested. Under the test conditions
    reported, chlorothalonil (98.2 percentage pure) exhibited no
    clastogenic activity in the polychromatic stem cells of treated
    animals (Siou et al 1981b).

         Chlorothalonil was tested for its ability to induce clastogenic
    activity in the polychromatic erythrocytes of treated animals. Swiss
    albino male mice were given an oral dose of 6.5 mg/kg/day for five
    consecutive days. Three hours after the final administration, animals
    were killed, bone marrow removed from the femurs and slides prepared
    from cells. Two thousand polychromatic cells were examined for the
    presence of micronuclei. No significant differences in the frequency
    of micronuclei from the polychromatic erythrocytes were noted between
    the treated and control groups at the dose level tested. Under the
    test conditions of this experiment, chlorothalonil (98 percent pure)
    was not a clastogenic agent in the micronucleus test (Legator 1974a).

    Dominant lethal test

         Ten male mice were orally gavaged with 6.5 mg/kg/day
    chlorothalonil for 5 days. Following the treatment, the males were
    sequentially mated to two females per week for 8 weeks. The number of
    corpora lutea, total implantations and resorptions were counted for
    each pregnant female. The same number of untreated mice served as
    controls. No increase in the resorptions in the treated group was
    observed when compared to the control group. Chlorothalonil was not
    considered to induce dominant lethals in treated male mice at the dose
    level tested (Legator 1974a).

    DNA damage and repair

         The DNA damaging capacity of chlorothalonil was investigated by
    the bacterial system (PolA-/PolA+) using S. typhimurium strains
    TA1538 (repair deficient) and TA1978 (repair competent) in a spot
    test. The test compound was tested with and without metabolic
    activation at concentrations of 2, 10, and 20 l of a 1.0 mg/ml stock
    solution. Chlorothalonil (97.8 percent pure) exhibited significantly
    different preferential cell killing between the two strains of
    S. typhimurium, with and without metabolic activation, at the
    concentrations tested. The test compound appears to have reacted with

    the DNA molecules in a manner causing preferential cell killing of
    strains, which lack an excision repair enzyme system. It is considered
    a DNA-modifying agent in this test (Banzer 1977c).

         Chlorothalonil was tested in Rec Assay using Bacillus subtilis
    H17 (recombination wild) and M44 (repair deficient) in a spot test.
    The compound was tested at concentrations of 2, 5, 10, 20, 100 and
    200 g/disc without metabolic activation. Chlorothalonil (99.3 percent
    pure) exhibited no marked difference in the growth inhibition zones of
    the strain H17 and M44. It is not considered a DNA-modifying agent at
    the concentrations tested (Shirasu et al 1977).

    Cell transformation

         Chlorothalonil, diluted in acetone and saline, was tested to
    determine its ability to induce malignant transformation of Fischer
    rat embryo (F1706 and H4536) cells in culture. Prior to the
    transformation assay, a preliminary cytotoxicity test was conducted to
    determine the maximum non-toxic dose level of the test compound. In
    the transformation assay, three concentrations of the test compound
    (0.001, 0.0001 and 0.00001 g/ml) were incubated with each of the
    described cell lines for seven days. At the end of incubation, each
    culture was washed, refed with a complete medium and held for two
    additional weeks to look for foci of transformed cells. The cell
    cultures treated with the test compound were inoculated subcutaneously
    in the back of a newborn Fischer rat and examined for the development
    of tumours within three months. There was no increased number of
    transformed foci over the control in either of the treated cell
    cultures. The cultures that had been exposed to the test compound were
    not tumourigenic when injected into newborn Fischer rats.
    Chlorothalonil (96 percent pure) is not considered a transforming
    agent in the Fischer rat embryo cell lines at the concentrations
    tested (Price 1978a).

         The results of mutagenicity assays carried out with
    chlorothalonil are summarized in Table 1.

    Special Studies on Mutagenicity of Metabolites

    Bacteria

         4-hydroxy-2, 5, 6-trichloroisophthalonitrils (DS-3701), dissolved
    in DMSO, was tested for mutagenic activity in S. typhimurium strains
    TA98, TA100, TA1535, TA1537 and TA1538 according to the plate
    incorporation procedure of Ames et al. (1975) at concentrations
    between 1 and 100 g/plate, with and without metabolic activation.
    Under the conditions of this test, DS-3701 (99 percent pure) did not
    induce point mutations in the five histidine-requiring strains of
    S. typhimurium at the concentrations tested (Banzer 1977d).

        Table 1.  Results of Mutagenicity Assays of Chlorothalonil
                                                                                                                      

    Test Organism                 Test Substance      Results                                           Reference
                                  (% purity)
                                                                                                                      

    GENE MUTATION STUDIES

    Bacteria

    S. typhimurium                97.8                No mutagenic activity was                         Banzer 1977a
                                                      reported in TA98, TA100, TA1535,
                                                      TA1537 and TA1538 with or without
                                                      metabolic activation.

                                  99.0                Negative response in G46, C207,                   Legator 1974a
                                                      TA1530, TA1531, C 3076, TA1700,
                                                      D3056 and TA1724 according to
                                                      host mediated assay.

                                  99.3                No mutagenic activity was                         Shirasu et al
                                                      reported in TA98,TA100, TA1535,                   1977
                                                      TA1537 and TA1538 without
                                                      metabolic activation.

    E. coli                       99.3                No mutagenic activity was                         Shirasu et al
                                                      reported in WP2 hcr+4 and WP2                     1977
                                                      hcr-5 with or without metabolic
                                                      activation.

    Cultured Mammalian
    Cells
                                                                                                                      

    Table 1.  (con't)
                                                                                                                      

    Test Organism                 Test Substance      Results                                           Reference
                                  (% purity)
                                                                                                                      

    Chinese hamster cells         97.8                No mutagenic effect was reported                  Banzer 1977b
    (V79) and Mouse Fibroblast                        in these two mammalian cell lines
    Cells (Balb/3T3)                                  with or without metabolic activation.

    CHROMOSOMAL EFFECTS

    Cytogenetics - In Vivo        98.2                No induced chromosomal aberrations                Siou et al
    Rat, Mouse, Chinese                               were reported in bone                             1981a
    hamster                                           marrow cells of rat, mouse and
                                                      Chinese hamster.

    Micronucleus - In Vivo        98.0                Negative responses were reported                  Legator 1974a
    Rat, Mouse, Chinese                               in the polychromatic erythrocytes                 & Siou et al
    hamster                                           of treated animals.                               1981b

    Dominant Lethal - Mice                            No mutagenic activity to induce                   Legator 1974a
                                                      dominant lethals in male mice
                                                      were reported.

    DNA DAMAGE AND REPAIR -
    Bacteria

    S. typhimurium                97.8                Positive response in demonstrating                Banzer 1977c
                                                      significantly preferential
                                                      cell killing between the
                                                      TA1538 and TA1978 with or
                                                      without metabolic activation.
                                                                                                                      

    Table 1.  (con't)
                                                                                                                      

    Test Organism                 Test Substance      Results                                           Reference
                                  (% purity)
                                                                                                                      

    S. subtilis                   99.3                Negative response. No marked                      Shirasu et al
                                                      difference in the inhibition zones                1977
                                                      of the strain H17 and M44 was
                                                      reported.

    Cell Transformation -         96.0                Negative responses were reported                  Price 1978a
    In Vitro                                          in both treated cell lines.
    Fischer Rat Embryo Cell
    Lines (F1706 and H4536)
                                                                                                                      
             4-hydroxy-2, 5, 6-trichloroisophthalonitrile was examined for
    mutagenic activity in S. typhimurium strains G46, TA1530, C207,
    TA1531, C3706, TA1700, D3056 and TA1724 which was implanted in male
    Swiss albino mice according to the method of host mediated assay at
    the dose level of 6.5 mg/kg (single IP administration). No increase in
    mutation frequency of the treated group over the control was observed
    and the metabolite (99 percent pure) was not mutagenic in the host
    mediated assay at the dose level tested (Legator 1974b).

    Mammalian cells

         Chinese hamster cells (V-79) and mouse fibroblast cells
    (Balb/3T3) in culture were exposed to 4-hydroxy-2, 5,
    6-trichloroisophthalonitrile (DS-3701) at a concentration of 30 g/ml,
    with and without metabolic activation, to detect mutations at the
    Ouabain-resistant gene locus, according to the method of Schechtman
    et al. Acetone was the vehicle control. No evidence of mutagenic
    effect of DS-3701 was observed in these two in vitro mammalian
    cell mutagenesis assay systems. The test compound (99 percent pure)
    did not induce Ouabain-resistant mutations at the concentration tested
    (Banzer 1977e).

    Micronucleus test

         4-hydroxy-2, 5, 6-trichloroisophthalonitrile (DS-3701) was tested
    in Swiss albino male mice at 6.5 mg/kg/day for five days for its
    ability to induce the formation of micronuclei in polychromatic
    erythrocytes. At the concentration tested, this compound (99 percent
    pure) did not increase the number of polychromatic cells with
    micronuclei (Legator 1974b).

    Dominant lethal test

         Ten male albino rats per group received a single oral
    dose or five daily doses of 0, 2, 4 or 8 mg/kg 4-hydroxy-2, 5,
    6-trichloroisophthalonitrile (DS-3701). Following treatment, the male
    rats were sequentially mated with two virgin female rats per week for
    eight weeks. After 12 days, the females were sacrificed and their
    uteri were removed, implantation sites examined, resorption sites and
    total foetuses counted and foetal deaths noted. No significant
    differences in body weights of males, percent fertility, foetal deaths
    or resorptions were observed between the treated and the respective
    untreated groups either on a weekly or total basis. The test compound,
    DS-3701 (99 percent pure), did not induce dominant lethals at the dose
    levels tested (Hastings & Clifford 1975).

         4-hydroxy-2, 5, 6-trichloroisophthalonitrile was tested for its
    ability to induce dominant lethals in treated male mice at 1, 3 and
    6.5 mg/kg/day for five days. The compound (99 percent pure) was not
    considered as a mutagenic agent and did not induce dominant lethals at
    the dose tested (Legator 1974b, 1975).

    DNA damage and repair

         DNA damaging capacity of 4-hydroxy-2, 5,
    6-trichloroisophthalonitrile (DS-3701) was evaluated by the bacterial
    system (PolA-/PolA+) using S. typhimurium strains TA1538 (repair
    deficient) and TA1978 (repair competent) in a spot test. The compound
    was tested with and without metabolic activation at concentrations of
    2, 10 and 20 l of a 1.0 mg/ml stock solution. Under these test
    conditions, DS-3701 (99 percent pure) did not interfere with the DNA
    mechanisms of S. typhimurium and, thus, was not considered a
    DNA-modifying agent (Banzer 1977f).

    Cell transformation

         4-hydroxy-2, 5, 6-trichloroisophthalonitrile (DS-3701), diluted
    in acetone and saline, was tested to determine its ability to induce
    malignant transformation of Fischer rat embryo (F1706 and H4536) cells
    in culture. Prior to the transformation assay, a preliminary
    cytotoxicity test was conducted to determine the maximum nontoxic dose
    level. The test compound (0.1, 1 and 10 g/ml) was incubated with each
    of the described cell lines for seven days. There was no increased
    number of transformed foci over control in either of the treated cell
    cultures. The cultures exposed to the test compound were not
    tumourigenic when injected into newborn Fischer rats. However, the
    F1706 cells exposed to DS-3701 did produce late tumours in the rats.
    The production of these late tumours was considered to be due to
    spontaneous transformation and not due to transformation by the test
    compound. DS-3701 (99 percent pure) is not considered a transforming
    agent in the Fischer rat embryo cell lines at the concentrations
    tested (Price 1978b).

         The results of mutagenicity assays of 4-hydroxy-2, 5,
    6-trichloroisophthalonitrile are summarized in Table 2.

    COMMENTS

         Excretion and elimination studies in rats demonstrated that
    chlorothalonil is preferentially excreted in the faeces, with minor
    elimination of the parent compound or its metabolites in the urine.
    4-hydoxy-2, 3,5-trichloroisophthalonitrile was identified as a major
    metabolite. Faecal elimination was complete (95 percent) within 24
    hours on low doses, but was noticeably delayed (96 hours) at high
    doses. The total amount of radioactivity in the blood following the
    oral administration of labelled chlorothalonil was less than one
    percent of the administered dose, with most of the activity being
    found in the plasma. This information failed to clarify the general
    metabolism of chlorothalonil, particularly regarding the 4-hydroxy
    metabolite.

        Table 2.  Results of Mutagenicity Assays of 4-hydroxy-2,5,6-trichloroisophthalonitrile
                                                                                                                      

    Test Organism                 Test Substance      Results                                           Reference
                                  (% purity)
                                                                                                                      

    GENE MUTATION STUDIES

    Bacteria

    Salmonella                    99.0                No mutagenic activity was reported                Banzer 1977d
    typhimurium                                       in TA98, TA100, TA1535,TA1536 and
                                                      TA1538 with or without metabolic
                                                      activation.

    S. typhimurium                99.0                Negative response in G46, TA1530,                 Legator 1974b
                                                      C270, TA1531, C3076, TA1700, D3056
                                                      and TA1724 according to host
                                                      mediated assay.

    Cultured Mammalian
    Cells

    Chinese hamster Cells         99.0                No mutagenic activity was reported                Banzer 1977e
    (V79) and Mouse Fibroblast                        in TA98,TA100, TA1535, TA1537 and
    Cells (Balb/3T3)                                  TA1538 without metabolic activation.

    CHROMOSOME EFFECTS

    Micronucleus - In Vivo        99.0                Negative response was reported in                 Legator 1974b
    Mouse                                             the polychromatic erythrocytes of
                                                      treated mice.
                                                                                                                      

    Table 2 (con't)
                                                                                                                      

    Test Organism                 Test Substance      Results                                           Reference
                                  (% purity)
                                                                                                                      

    Dominant Lethal - Rodent

    Rat                           99.0                No induced dominant lethals were                  Hastings et
                                                      reported in treated rats.                         al 1975

    Mouse                         99.0                No induced dominant lethals were                  Legator 1974b,
                                                      reported in treated mice.                         1975

    DNA DAMAGE AND REPAIR -
    Bacteria

    S. typhimurium                99.0                Negative response. No marked                      Banzer 1977f
                                                      difference in the inhibition
                                                      zones of the strains TA1538 and
                                                      TA1978 were reported.

    CELL TRANSFORMATION -
    IN VITRO

    Fischer Rat Embryo Cell       99.0                Negative responses were reported                  Price 1978b
    Lines (P1706 and H4536)                           in both treated cell lines.
                                                                                                                      
             Short-term dietary studies in rats and mice exposed to
    chlorothalonil demonstrated increased incidences of hyperplasia and
    hyperkeratosis in the non-glandular portion of the stomach and
    hyperplasia of the epithelial cells of the proximal convoluted tubules
    in the kidney. Kidney and liver weights were also increased, but there
    was no microscopic evidence of morphological change. The no-observed-
    effect level (NOEL) was 3 mg/kg b.w. in both rats and mice.

         A short-term dietary study in rats using the 4-hydroxy metabolite
    at levels of 10-750 mg/kg presented evidence of anaemia and compound-
    related liver effects at dietary levels greater than 20 mg/kg b.w.

         A one-generation study in rats using the 4-hydroxy metabolite
    demonstrated adverse reproductive effects at doses greater than
    30 ppm. These included poor pup viability and reduced mean live pup
    weights.

         Teratology studies with rabbits and rats gavaged with
    chlorothalonil produced no teratogenic responses; however, maternal
    toxicity was evident at >5 mg/kg and 400 mg/kg in rabbits and rats,
    respectively. Teratogenicity studies by gavage in the rabbit at
    maternally toxic doses of 5 mg 4-hydroxy metabolite/kg failed to
    induce terata. A wide range of mutagenicity studies, using both
    chlorothalonil and the 4-hydroxy metabolite, did not indicate
    mutagenic activity for either compound.

         A carcinogenicity study in mice exposed to chlorothalonil at
    dietary levels of 150-3 000 ppm produced glandular epithelial tumours
    in treated groups, which were compound-related but not dose-related.
    The neoplastic changes in the kidney, including adenomas and
    carcinomas of the renal cortical tubules were increased in males in
    all treated groups, but not in females. There was no positive trend
    for these kidney adenomas and carcinomas and, therefore, the evidence
    for the tumourigenicity of chlorothalonil in the kidney remains
    elusive. A NOEL was not determined.

         Carcinogenicity studies in rats and mice using the 4-hydroxy
    metabolite did not demonstrate oncogenic potential at doses up to and
    including 1 500 ppm in the diet (22.5 mg/kg b.w.) and 20 mg/kg b.w. in
    mice and rats, respectively. There was, however, clear evidence of
    anaemia at doses greater than 3 mg/kg b.w. in rats. A NOEL for non-
    oncogenic effects was not demonstrated in the mouse study.

         The Meeting expressed concern about the lack of adequate
    metabolism data for chlorothalonil and the 4-hydroxy metabolite and
    the need to clarify the incidence of kidney adenomas and carcinomas in
    rodents. The Meeting was informed that a long-term oncogenicity
    feeding study with chlorothalonil in the rat is currently being
    conducted, but the results will not be available until 1985. The

    Meeting, therefore, agreed that the temporary ADI should remain at the
    present level until further data are made available to clarify
    remaining questions on metabolism and carcinogenicity of
    chlorothalonil.

    TOXICOLOGICAL EVALUATION

    Level Causing no Toxicological Effect

    Rat: 10 ppm in the diet, equivalent to 0.5 mg/kg b.w.

    Dog: 120 ppm in the diet, equivalent to 3 mg/kg b.w.

    Estimate of Temporary Acceptable Daily Intake for Man

    0-0.005 mg/kg b.w.

    FURTHER WORK OR INFORMATION

    Required (by 1985)

    1.   Further work to elucidate the metabolism of chlorothalonil and
         the 4-hydroxy metabolite.

    2.   Submission of the on-going long-term oncogenicity feeding study
         in the rat.

    Desirable

         Information on data which may clarify the type of anemia which
         has been demonstrated in mammals exposed to the 4-hydroxy
         metabolite.

    REFERENCES - TOXICOLOGY

    Ames, B.N., McCann, J. & Yamasake, E. Methods for detecting
    1975      carcinogens and mutagens with the Salmonella mammalian-
              microsome mutagenicity test. Mutat. Res., 31: 347-364.

    Banzer, C.B. Activity of DTX-77-0035 in the Salmonella/microsomal
    1977a     assay for bacterial mutagenicity. Report from
              Microbiological Associates submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Banzer, C.B. Activity of DTX-77-0034 in an in vitro mammalian cell
    1977b     point mutation assay. Report from Microbiological Associates
              submitted to WHO by Diamond Shamrock Corp. (Unpublished)

    Banzer, C.B. Activity of DTX-77-0033 in a test for differential
    1977c     inhibition of repair deficient and repair competent strains
              of Salmonella typhimurium: repair test. Report from
              Microbiological Associates submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Banzer, C.B. Activity of DTX-0038 in the Salmonella/microsomal assay
    1977d     for bacterial mutagenicity. Report from Microbiological
              Associates submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    Banzer, C.B. Activity of DTX-77-0040 in an in vitro mammalian cell
    1977e     point mututation assay. Report from Microbiological
              Associates submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    Banzer, C.B. Activity of DTX-77-0039 in a test for differential
    1977f     inhibition of repair deficient and repair competent strains
              of Salmonella typhimurium: repair test. Report from
              Microbiological Associates submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Ford, W.H. A one-generation reproduction study in rats with DS-3701.
    1982      Report submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    Hastings, T.F, & Clifford, D. 8-week dominant lethal study of DAC-3701
    1975      in rats. Report from Bio/tox Research Lab. Inc. submitted to
              WHO by Diamond Shamrock Corp. (Unpublished)

    Hozan, G.K. & Auletta, C.S. A chronic dietary study in mice with T-114
    1981      (DS-3701). Report from Bio/dynamics, Inc. submitted to WHO
              by Diamond Shamrock Corp. (unpublished)

    Ignatoski et al. Dose-response determination of the excretion of
    1981      radioactivity in rat bile following intraduodenal
              administration of 14C-chlorothalonil (14C-DS-2787). Report
              submitted to WHO by Diamond Shamrock Corp. (Unpublished)

    Ignatoski et al. Balance study of the distribution of radioactivity
    1982      following oral administration of 14C-chlorothalonil
              (14C-DS-2787) to rats. Report submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Ignatoski et al. Distribution of radioactivity following oral
    1983a     administration of 14C-chlorothalonil to rats: extraction
              and analysis of 14C-materials in excreta. Report submitted
              to WHO by Diamond Shamrock Corp. (Unpublished)

    Ignatoski et al. Balance study of the distribution of radioactivity
    1983b     following oral administration of 14C-chlorothalonil to male
              mice. Report submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    Ignatoski et al. Recirculation of radioactivity in rat bile following
    1983c     intraduodenal administration of bile containing
              14C-chlorothalonil label. Report submitted to WHO by
              Diamond Shamrock Corp. (Unpublished)

    Ignatoski et al. Dose-response determination of the excretion of
    1983d     radioactivity in rat bile following intraduodenal
              administration of 14C-chlorothalonil. Report submitted to
              WHO by Diamond Shamrock Corp. (Unpublished)

    Ignatoski et al. Method development for the determination of 14C-DS-
    1983e     2787 in blood. Report submitted to WHO by Diamond Shamrock
              Corp. (Unpublished)

    Ignatoski et al. Levels of radioactivity in blood following oral
    1983f     administration of 14C-chlorothalonil to male rats. Report
              submitted to WHO by Diamond Shamrock Corp. (Unpublished)

    Legator, M.S. Mutagenic testing with DAC 2787. Report submitted to
    1974a     WHO by Diamond Shamrock Corp. (Unpublished)

    Legator, M.S. Mutagenic testing with DAC 3701. Report submitted to WHO
    1974b     from Diamond Shamrock Corp. (Unpublished)

    Legator, M.S. Dominant lethal evaluation of DAC 3701 at 1.0 and 3.0
    1975      mg/kg for five days. Report submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    McGee, D.H. et al. A two-year toxicity and tumourigenicity study of
    1983      T-114 in rats. Report from International Research and
              Development Corp. submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    Murchison, T.E. et al. A short-term dietary study in rats with
    1979      T-114-2 (DS-3701). Report from Dawson Research Corp.
              submitted to WHO by Diamond Shamrock Corp. (Unpublished)

    Price, P. The activity of compound DTX-77-0037 in the Fischer rat
    1978a     embryo transformation assay system. Report from
              Microbiological Associates submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Price, P. The activity of compound DTX-77-0041 in the Fischer rat
    1978b     embryo transformation assay system. Report from
              Microbiological Associates submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Rodwell, D.E. et al. A teratology study in rats with T-117-11. Report
    1983      from Wil Research Labs. Inc. submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Shirasu, Y. & Teramoto, S. Teratogenicity study of Daconil in rabbits.
    1975      Report from Institute of Environmental Toxicology submitted
              to WHO by Diamond Shamrock Corp. (Unpublished)

    Shirasu, Y. et al.  Mutagenicity testing on Daconil in microbial
    1977      systems. Report from the Institute of Environmental
              Toxicology submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    Shults, K. A 90-day feeding study in mice with technical
    1983      chlorothalonil. Report from SDS Biotech Corp. submitted to
              WHO by Diamond Shamrock Corp. (Unpublished)

    Siou, et al. The chromosomal aberration test in the rat, mouse and
    1981      hamster using chlorothalonil. Report from C.E.R.T.I.
              submitted to WHO by Diamond Shamrock Corp. (Unpublished)

    Siou, G. et al. The micronucleus test in the rat, mouse and hamster
    1981b     using chlorothalonil. Report from C.E.R.T.I. submitted to
              WHO by Diamond Shamrock Corp. (Unpublished)

    Tierney, W.J. A chronic dietary study in mice with technical
    1983      chlorothalonil. Report from Bio/dynamics, Inc. submitted to
              WHO by Diamond Shamrock Corp. (Unpublished)

    Wazeter, F.X. & Goldenthal, E.I. Teratology study in rabbits. Report
    1976      from International Research and Development Corp. submitted
              to WHO by Diamond Shamrock Corp. (Unpublished)

    Wilson, N. H. et al. A 90-day toxicity study of technical
    1981      chlorothalonil in rats. Report submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Wilson, N.H. et al. A subchronic toxicity study of technical
    1983a     chlorothalonil in rats. Report submitted to WHO by Diamond
              Shamrock Corp. (Unpublished)

    Wilson, N.H. et al. Progress report for the electron microscopic
    1983b     evaluation of renal tissue from a subchronic toxicity study
              of technical chlorothalonil in rats. Report from Huntingdon
              Research Centre submitted to WHO by Diamond Shamrock Corp.
              (Unpublished)

    RESIDUES

    USE PATTERN

         Use patterns have been reviewed previously. Additional summary
    information indicated that uses on grapes are registered or
    recommended in Argentina, Australia (confirmed at the 13th Session of
    the CCPR), Austria, Brazil, Greece, Italy, Spain, The Philippines, Sri
    Lanka and Yugoslavia. Studies on the potential for chlorothalonil use
    on grapes are or have been in progress in Canada, Chile, Colombia,
    South Africa and the United States.

         The most common good agricultural practice is said to be three to
    six applications of either a 75 percent WP or a 500 g a.i./1 flowable
    (water dispersible) formulation at 1.5-2.0 kg a.i./ha in a spray
    volume up to 4 000 l/ha. The most common last-treatment-to-harvest
    interval is said to be 7 to 14 days, but occasionally it is 21 to
    28 days.

         Diseases for which chlorothalonil is used are Plasmopara (downy
    mildew), Uncinula necator (powdery mildew) and Botrytis cinerea
    (grey mould). Good agricultural practice information from individual
    countries was not provided except for Spain, in which the following
    formulations and doses are recommended for fruit tree seeds, potatoes,
    vines, strawberries and winter cereals:

              Type of formulation    Application rate
                                                       

              LC 75%                   0.15 - 0.2%
              LC 50%                   0.25 - 0.3%
              P 5%                     20 kg/ha
                                                       

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         Residue trials have been conducted in The Netherlands on onions
    and strawberries (Netherlands 1983) and on grapes in Australia,
    Canada, The Federal Republic of Germany and South Africa (Tables 1-5;
    Diamond Shamrock 1981).

    Grapes

         The current temporary maximum residue limit (MRL) of 5 mg/kg is
    based on a 46-day last-treatment-to-harvest interval and on residue
    trials in Canada, where the Meeting is informed that there are no
    recognized uses reflecting good agricultural practices (GAP). The only
    country in which the use of chlorothalonil on grapes is regarded as
    good agricultural practice and for which residue trials data are

        Table 1.  Residues of chlorothalonil in grapes treated with
              Chlorothalonil-Australia 1973-741
                                                                                   

                                Application
                                                   
    Location            Rate                Number    Pre-harvest         Residue
                        (a,i.)                        interval (days)     (mg/kg)
                                                                                   

    Hunter Valley       113 g/100 l2        7         -1 last spray       3.9
                                                      0-post-spray        6.1, 7.1
                                                      10                  5.6 (8.6)4

                        225g/100 l3         7         -1 last spray       6.8
                                                      0-post-spray        10.7
                                                      10                  8.7 (13.4)4

    South Australia     0.5 kg/378 l2       6         1                   1.4
                                                      7                   0.6
                                                      18                  1.6 (2.9)4
                                                      26                  0.6, 0.3

                        1 kg/378 13         6         1                   2.3
                                                      7                   3.1
                                                      18                  2.7 (4.9)4
                                                      26                  0.8
                                                                                   

    1    BRAVO 75W wettable powder containing 75 percent active
         ingredient was used for treatment. Information on spray volume
         was not available.
    2    Recommended rate.
    3    2X recommended rate.
    4    Figures in parentheses are corrected for recovery (64 percent
         Hunter Valley; 55 percent South Australia).
    
        Table 2.  Residues of Chlorothalonil and D-3701 (4-hydroxy-2, 5,6-trichloroisophthalonitrile)
              in Grapes Treated With Chlorothalonil - Canada 1979
                                                                                                       

                               Application1                                     Residues (mg/kg)2
                                                      Pre-Harvest                                      
    Location            Rate              Number      Interval         Chlorothalonil         DS-3701
                        (kg a.i./ha)                  (days)
                                                                                                       

    Vineland, Ont.      1.65              5           40               0.28                   0.02
                                                                       0.26                   0.01
                                                                       <0.01, <0.01           0.01, 01
                        -                 -           -                ND                     0.02

    St. Catherines,     1.65              4           30               1.94                   0.13
    Ont.                                                               1.62                   0.03
                        -                 -           -                <0.01                  0.01

    Jordan, Ont.        1.65              3           30               3.80                   0.04
                                                                       4.07                   0.06
                        -                 -           -                ND(<0.005)             0.01

                        1.65              2           30               0.54                   0.01
                        1.65              1           30               0.63                   0.01
                                                                       1.04, 1.21             0.03, 0.1
                        -                 -           -                ND                     0.01
                                                                                                       

    1    BRAVO 75W wettable powder containing 75 percent active ingredient was used for treatment.
         Information spray volume was not available.
    2    Uncorrected for 76 and 80 percent recoveries of chlorothalonil and DS-3701, respectively.

    Table 3.  Residues of Chlorothalonil in Grapes Treated With Chlorothalonil - Federal Republic of Germany
                                                                                                                           

                                                           Application
                                                                                    Pre-               Residues (mg/kg)
                                                      Spray                         Harvest                                
    Location            Year      Rate                Volume         Number         Interval       Treated        Untreated
                                  (kg a.i.ha)         (l/ha)                        (days)
                                                                                                                           

    Bad Mnster         1972      4.5                 3 000          6              1              12.0           0.5
    (Trial 129)                   (0.2% DaconilR                                    15             6.2
                                  2787, 75% WP)                                     22             6.0
                                                                                    29             7.0
                                                                                    71             3 4

    Welhausen           1972      4.5                 3 000          6              0              13.0           0.05
    (Trial 128)                   (0.2% DaconilR                                    14             8.0
                                  2787, 75% WP)                                     21             6.8
                                                                                    28             8.0
                                                                                    70             5.8            0.06

    Rhodt               1972      1.5-3.75            1 000-         7              1              26.2           0.05
    (Trial 47)                    (0.2% DaconilR      2 5001                        14             12.4           0.03
                                  2787)                                             21             5.0            0.02
                                                                                    28             5.8
                                                                                    68             2.0

    Volkach/Main        1973      1.46/spray          1 000          8              2              2.71           0.03
                                                                                    51             0.38           0.04

    Grossbottwar        1974      2.19  6;           1 000          8              0              26.5           0.06
                                  2.92  2                                          21             17.13          0.22
                                  (60.3% soln                                      28             8.0            0.06
                                  20.4% soln)                                      35             7.0            0.06
                                                                                    42             4.25           0.03
                                                                                                                           

    Table 3.  (con't)
                                                                                                                           

                                                           Application
                                                                                    Pre-               Residues (mg/kg)
                                                      Spray                         Harvest                                
    Location            Year      Rate                Volume         Number         Interval       Treated        Untreated
                                  (kg a.i.ha)         (l/ha)                        (days)
                                                                                                                           

                                  2.92/spray          1 000          8              0              28.0
                                  (0.4% soln)                                       21             13.5
                                                                                    28             8.0
                                                                                    35             4.75
                                                                                    42             6.7

    Mettenheim          1974      1.75/spray          800            6              0              1.45           0.05
                                  (0.3% soln)                                       21             0.23           0.01
                                                                                    28             0.64           0.01
                                                                                    35             0.16           <0.01
                                                                                    42             0.13           <0.01

                                  2.33/spray          800            6              0              1.9
                                  (0.4% soln)                                       21             0.45
                                                                                    28             0.82
                                                                                    35             0.59
                                                                                    42             0.39

    Deidesheim          1974      1.75/spray          800            6              0              3.7            <0.01
                                  (0.3% soln)                                       21             1.07           0.02
                                                                                    28             0.55           <0.01
                                                                                    35             0.4            <0.01
                                                                                    42             0.23           <0.01
                                                                                                                           

    Table 3.  (con't)
                                                                                                                           

                                                           Application
                                                                                    Pre-               Residues (mg/kg)
                                                      Spray                         Harvest                                
    Location            Year      Rate                Volume         Number         Interval       Treated        Untreated
                                  (kg a.i.ha)         (l/ha)                        (days)
                                                                                                                           

                                  2.33/spray          800            6              0              5.15
                                  (0.4% soln)                                       21             2.15
                                                                                    28             1.07
                                                                                    35             0.72
                                                                                    42             0.21

    Wrzburg            1975      24.4 total          1/800          10             0              3.83           0.01
                                  (8  0.15%          1/1 000                       21             0.27           0.02
                                  2  0.2%)           1/1 300                       28             0.62           <0.01
                                                      1/2 000                       35             0.63           0.01
                                                      2/1 600                       42             0.59           0.01
                                                      4/2 500

    Ebernburg           1975      28 total            2/1 500        10             0              1.87           <0.01
                                  (80.15% soln)      8/2 500                       21             0.49           <0.01
                                  20.18% sola)                                     27             0.76           0.26
                                                                                    35             0.52           0.01
                                                                                    42             0.76           <0.01

    Deidesheim          1975      31.9 total          2 500          10             0              2.38           <0.01
                                  (60.15% soln                                     21             1.14           0.04
                                  40.2% soln)                                      35             1.85           0.04
                                                                     43             2.0            0.09
                                                                                                                           

    1    Spray volume varied from 1 000 to 2 500 l/ha, apparently increasing during the season from early to mature growth stages.

    Table 4.  Residues of Chlorothalonil in Wine From Grapes Treated With Chlorothalonil Federal Republic of Germany
                                                                                                                          

                                                            Application
                                                                                    Pre-             Residues (mg/kg)
                                                      Spray                         Harvest                               
    Location            Year      Rate                Volume         Number         Interval       Treated    Untreated
                                  (kg a.i./ha)        (1/ha)                        (days)
                                                                                                                          

    Hattenheim          1973      2.92                1 000          4              98             <0.01          <0.01
                                  (0.4% DaconilR                                                   <0.01          <0.01
                                  75% WP)

    Hattenheim          1972      NA1                 NA             NA             NA             0.003          0.00
                                                                                                   0.004          0.003
                                                                                                                          

    1    NA = Information not available.
        Table 5.  Residues of Chlorothalonil and DS-3701
              (4-hydroxy-2,5,6-trichloroisophthalonitrile) in Grapes
              Treated With Chlorothalonil - South Africa 1979-80
                                                                        

          Application1
                          
                               Pre-         Residues (mg/kg)2
    Rate            Number     Harvest                                  
    (kg a.i./ha)               Interval     Chlorothalonil DS-3701
                               (days)
                                                                        

    1.5/spray       8          1            18.4; 20.9     0.14; 0.14
                               2            12.4; 13.4     0.10; 0.11
                               4            3.6; 3.5       <0.05; <0.05
                               16           2.7; 2.5       0.06; 0.06
                               32           2.6; 2.3       0.07; 0.07
                                                                        

    1    BRAVO 500, a water dispersible flowable formulation containing
         500 g chlorothalonil/1, was used for treatment. Information on
         spray volume was not available.

    2    Limit of determination for both chlorothalonil and DS-3701 was
         0.05 mg/kg. Uncorrected for recoveries of 89 percent and 94
         percent respectively.

    available is Australia (see Table 1), although specific information on
    use patterns was not available. Data from residue trials were however
    provided from The Federal Republic of Germany and South Africa
    together with additional data from Canada. The trials conducted in
    Australia therefore, warrant special consideration. Data were
    available from recommended and twice the recommended application
    rates, although the approved Australian pre-harvest interval (PHI) was
    not known. At the recommended rate and 7-18 days, the most common PHI,
    maximum residues were 5.6 mg/kg (or 8.6 mg/kg when corrected for 65
    percent recoveries). These data represent chlorothalonil only, whereas
    previously recommended limits also include the 4-hydroxy metabolite,
    which can contribute approximately 5 percent of the total residue in
    grapes.

         Previously reviewed Canadian data at a 46-day PHI support the
    current 5 mg/kg limit based on that PHI. So do Canadian data at 30-40
    day PHI submitted to the Meeting (Table 2), although neither PHI is
    commonly used.

         In Table 3, data from The Federal Republic of Germany include
    residues of 5-12-4 mg/kg at recommended pre-harvest intervals which
    significantly exceed the current 5 mg/kg limit, but result from
    exaggerated (twice the common recommended) application rates. Residues
    at commonly recommended application rates and pre-harvest intervals
    range from 4 to 17 mg/kg. Although these residues result from eight
    applications as opposed to the six recommended, the data appear to be
    atypically high when compared to other West German trials with six to
    ten applications in which residues do not exceed the current limit.
    Table 4 shows residues of 0.01 mg/kg in wine from grapes harvested 98
    days after treatment. South African data (Table 5) are consistent with
    the current limit.

    Onions

         Additional residue data provided to the Meeting (Netherlands
    1983) reflect good agricultural practices of the Netherlands. In eight
    trials conducted in 1981 represented by over 60 samples, residues in
    mature silver onions and set onions ranged from <0.05 to 0.34 mg/kg
    (0.57 mg/kg unwashed) at the 7-day last-application-to-harvest
    interval that is the basis of the current 5 mg/kg limit, and were
    <0.05 mg/kg (0.28 ppm unwashed) at the 28-day interval, which is
    regarded as good agricultural practice in The Netherlands.

    Strawberries

         In a 1981 trial (Netherlands 1983) understood to represent good
    agricultural practice in The Netherlands. residues in four samples of
    mature berries ranged from 1.5 to 3 mg/kg (2.1 mg/kg mean) 14 days
    after the last of five applications of a 75 percent WP formulation at
    1.5 kg a.i./ha.

    Residues of 4-hydroxy-2,5,6-trichloroisophthalonitrile (DAC 3701)

         At the request of the 14th session of the Codex Committee on
    Pesticide Residues (CCPR), the Meeting re-examined the definition of
    the residue for chlorothalonil. Past evaluations of chlorothalonil by
    the Meeting as well as new data were considered in order to estimate
    the proportion of the major metabolite DAC 3701, in the total residue.
    The results of supervised trials carried out at various locations in
    the United States between 1965 and 1973 are summarized in FAO/WHO
    1975, p.126-128. The concentration of DAC 3701 was lower than the
    0.1 mg/kg limit of determination in all crops for which it was
    analysed except lima beans (in pod) where it accounted for 10 percent
    of the total residue, cantaloupe and grapes (5 percent) peaches and
    onions (2 percent), celery (1 percent) and peanuts (0.1 percent). No
    DAC 3701 was detected in crops grown in glasshouses. Similarly low
    residues were reported in peaches and no residues of DAC 3701 in whole
    banana or banana pulp, regardless of the rate of application (FAO/WHO
    1978). DAC 3701 residues of less than 2 percent and 5 percent,

    respectively, in onions and grapes were reported in later supervised
    trials (FAO/WHO 1980). Data submitted to the Meeting more or less
    confirm the estimate for grapes and indicate that DAC 3701 does not
    exceed 5 percent of the parent compound residue in oranges.

    Lima beans

         In conducting the above review, the Meeting observed that the
    current 0.5 mg/kg limit for lima beans was based on data for beans
    without pod. The temporary MRL should be amended accordingly.

    FATE OF RESIDUES

    In Storage and Processing

         The 1981 Meeting listed as desirable an explanation of apparent
    inconsistencies between studies carried out in 1979 and 1980 on the
    nature of residues resulting from the cooking of chlorothalonil-
    treated foods. The main point of concern was the statement in the 1979
    study that 14C-chlorothalonil was largely lost by volatilization
    during cooking under open conditions while of the 14C in the organic
    phase approximately 57 percent was characterized as the 4-hydroxy
    metabolite whereas 43 percent was unidentified and was near the thin-
    layer chromatography (TLC) origin. This was confirmed by a TLC
    autoradiogram in the 1979 study.

         In apparent conflict was the statement in the 1980 study that
    chlorothalonil was the major residue in organic extracts of
    chlorothalonil-fortified tomatoes after cooking with and without a pot
    cover and that there were negligible quantities of the metabolite.
    Again this was confirmed by an autoradiogram. It was further stated
    that the effect of cooking chlorothalonil with green beans was similar
    and this was again confirmed by a TLC autoradiogram.

         In response to the questions raised by the 1981 Meeting, the
    manufacturer submitted a redrafted report to present the data from the
    1979 and 1980 studies in a more consistent manner (SDS 1983a). No
    additional studies were provided. The new report confirms previous
    conclusions that 85-98 percent of added chlorothalonil is lost through
    cooking under open conditions. It emphasizes that the residue of the
    hydroxy metabolite formed is only 2.4 percent of the chlorothalonil
    originally present and that the percentages of degradation products
    identified after cooking refer to the composition of the small residue
    remaining.

    EVIDENCE OF RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION

         Data were provided from Sweden on chlorothalonil residues found
    in domestic and imported commodities for the period 1981 - 30 April
    1983 (Sweden 1983). Of 1 085 samples analysed, residues in 1 070 were
    below 0.21 mg/kg. Maximum residues with the number of samples having
    residues over 0.21 mg/kg/total analysed in brackets were: cauliflower
    0.41 mg/kg (1/165), celery 1.9 mg/kg (7/50), cucumbers 0.23 mg/kg
    (1/580), gherkins 0.66 mg/kg (2/49, melons 0.71 mg/kg (2/98) and
    strawberries 2.9 mg/kg (2/143). The highest levels found are well
    below current Codex temporary MRLs except gherkins and strawberries
    for which there are no Codex limits.

    METHODS OF RESIDUE ANALYSIS

         To compare the relative extraction efficiencies of tumble
    extraction and maceration techniques, Bravo 500R was field-applied
    to oranges at 12.9 l/ha and sampled at 0, 14 and 28 days after the
    last of three applications (SDS 1983b). The formulation contained
    40.6 percent chlorothalonil, 0.33 percent pentachlorobenzonitrile
    (PCBN) and 0.21 percent hexachlorobenzene (HCB).

         For surface extraction, residues were extracted with methylene
    chloride by rotating the sample at 22 rpm for 2 h. One portion was
    analysed for chlorothalonil by electron capture gas chromatography
    after elution from a florisil column with a 50 percent methylene
    chloride:48.5 percent hexane: 1.5 percent acetonitrile eluant after a
    pre-wash with 20 percent methylene chloride:80 percent hexane. A
    separate portion was analysed for HCB and PCBN after separation
    from a florisil column by eluting successively with 20 percent
    methylene chloride:80 percent hexane and 0.05 percent acetonitrile
    in 1:1 hexane:methylene chloride.

         For maceration extraction, samples were blended with 385 ml
    acetone and 15 ml 1:1 (w/w) H2SO4:water, filtered, concentrated and
    after pH adjustment in aqueous solvent, partitioned with hexane.
    Clean-up and analysis for chlorothalonil, HCB and PCBN was as
    described above. The DS-3701 metabolite was extracted from the aqueous
    phase with 1:1 petroleum ether:diethyl ether after pH adjustment and
    methylated for gas chromatographic analysis.

         Analyses of samples extracted by both procedures were validated
    by fortifying oranges in the extraction vessel with organic solutions
    of chlorothalonil, HCB, PCBN and DS-3701 before analysis.
    Fortification levels and mean recoveries are given in Table 6.

         Determinations of field-incurred residues by surface extraction
    and maceration techniques are summarized in Table 7.

         Table 7 demonstrates that surface and maceration extraction
    techniques give comparable results for chlorothalonil, HCB.

        Table 6.  Validation of Analytical Procedures for Determining Residues of Chlorothalonil and its Metabolites in Oranges.
                                                                                                                                

                         Chlorothalonil                   HCB                           PCBN                     DS-3701
                                                                                                                                

                   Added             Mean        Added          Mean           Added          Mean           Added     Mean
                   mg/kg             %           mg/kg          %              mg/kg          %              mg/kg     %
                                     Recovery                   Recovery                      Recovery                 Recovery
                                                                                                                                

    Surface
    extraction     0.5-2.1           103         0.01           88             0.01-0.02      95             -         -

    Maceration     0.5-2             85          0.01           77             0.01-0.02      82             0.03-0.05 69
                                                                                                                                

    Table 7.  Comparison of Maceration and Surface Extraction Techniques for Measuring Field-lncurred Residues of Chlorothalonil
              and Metabolites in Oranges.
                                                                                                                     

                                                    Residue (mg/kg)1
                                                                                                                     

                         Chlorothalonil          D S-3701               HCB                            PCBN
    Days after                                                                                                       
    Last Treatment    Surface     Macerated      Macerated      Surface      Macerated        Surface      Macerated
                                                                                                                     

    0                 11.2        10.1           0.04           0.006        0.004            0.1          0.07
                      (0.03)      (0.05)         (ND)           (ND)         (ND)             (ND)         (ND)

    14                4.7         6.1            0.3            0.006        0.003            0.06         0.05
                      (0.03)      (0.06)         (ND)           (ND)         (ND)             (ND)         (ND)

    28                5.3         4.1            0.014          0.003        ND               0.04         0.04
                      (ND)        (0.13)         (ND)           (ND)         (ND)             (ND)         (ND)
                                                                                                                     

    1    Each value is the mean of three replicates, each of which consists of four samples.  Numbers in parentheses are
         the means of two untreated controls where ND = <0.01 mg/kg chlorothalonil and DS-3701, <0.003 mg/kg HCB and
         (0.005 mg/kg PCBN.
        NATIONAL MAXIMUM RESIDUE LIMITS REPORTED TO THE MEETING

                                                           

    Country             Commodity                MRL (mg/kg)
                                                           

    The Netherlands     banana                   0.2
                        tomato                   1

    Sweden              fruit and vegetables     1
                        potatoes                 0.1
                        banana (without peel)    0.05
                                                           

    APPRAISAL

         Limited information on good agricultural practice in the use of
    chlorothalonil on grapes was made available to the Meeting. Data on
    residue trials from several countries were also provided but from only
    one country in which uses on grapes are known to be approved or
    registered. The limited data reflecting approved uses, and some of the
    other data suggest that the 5 mg/kg limit may be too low. In the
    absence of data from residue trials and information on registered or
    approved uses from other countries, there is no firm basis on which to
    change the current limit. However, it should remain temporary
    irrespective of the ADI status until this information is provided.

         Additional residue data for onions do not warrant a revision in
    the current limit, and data provided for strawberries were not
    adequate to estimate a maximum residue level. Monitoring data from
    Sweden indicated that previous estimates for cauliflower, celery,
    cucumbers and melons are adequate.

         The meeting reviewed a revised report on the effects of cooking
    on chlorothalonil residues in food. In one of two previously reviewed
    reports, the major residue remaining in beans after cooking under open
    conditions was said to be unchanged chlorothalonil with little
    degradation. In the other report, the major residue under similar
    conditions was said to be the 4-hydroxy metabolite and unidentified
    material (57 percent and 43 percent of the remaining residue,
    respectively) with no chlorothalonil remaining. The redrafted report,
    based on the original two reports, still does not fully clarify the
    apparent inconsistencies noted by the 1981 Meeting, although the
    results are more clearly presented. Whether the residue is
    chlorothalonil, its hydroxy metabolite, a combination of those, or
    57:43 hydroxy metabolite: unknown, the total residues remaining after
    cooking chlorothalonil-fortified green beans under open conditions in
    both studies are <7 percent of fortification levels. The 57:43

    percent hydroxy metabolite: unknown is shown in the 1983 submission to
    represent 2.4 and 1.8 percent, respectively of the originally added
    chlorothalonil. For this reason, the Meeting concluded that the matter
    had been adequately considered.

         The Meeting also reviewed a study comparing surface and
    maceration extraction techniques for determining field-incurred
    residues of chlorothalonil, HCB and PCBN in oranges and data on levels
    of the hydroxy metabolite (DS-3701) by the maceration technique. The
    study showed the two techniques to give comparable results for field-
    incurred residues. A similar conclusion had been reached for bananas
    by the 1979 Meeting. Both procedures were validated by fortifying just
    prior to extraction, but the study does not provide information on the
    efficiency of extraction of field-incurred residues by either
    technique. However, since the maceration extraction conditions are
    similar to those used in earlier evaluations (FAO/WHO 1975), the
    efficiency for the surface extraction technique is as high as that
    considered adequate previously. Residues of chlorothalonil, HCB, PCBN
    and DS-3701 are shown to decrease with time from application.

         The Meeting reviewed the definition of the residue for
    chlorothalonil. The results of supervised trials conducted in
    different parts of the world between 1965 and 1983, which had been
    reviewed by the Meeting, showed that levels of the major metabolite,
    DAC 3701, were lower than the 0.1 mg/kg limit of determination in most
    of the crops for which it was analysed. DAC 3701 accounted for
    approximately 10 percent of the total residue in lima beans (in pod);
    5 percent in cantaloupes, oranges and grapes; 2 percent in peaches and
    onions; 1 percent in celery and 0.1 percent in peanuts.

         The Meeting noted that the current 0.5 mg/kg limit for lime beans
    is based on data for beans without pods and concluded that this should
    be reflected in the commodity description.

    RECOMMENDATIONS

         Additional data reviewed by the Meeting do not warrant a revision
    of current limits or support the estimation of new limits. The Meeting
    concludes that the current 5 mg/kg temporary MRL for grapes should
    remain temporary, irrespective of the status of the ADI, pending the
    receipt of additional information on good agricultural practice and
    data on residue trials, preferably from countries providing
    information on good agricultural practices.

         The Meeting recommends that the definition of the residue be
    revised to include chlorothalonil only and concludes that no changes
    in the numerical values of the maximum residue limits are necessary as
    a result. The current 0.5 mg/kg limit for lima beans should be
    expressed as applying to lima beans (without pod) to reflect the data
    on which it was based.

    FURTHER WORK OR INFORMATION

    Required (by 1985)

    1.   Additional and more specific information on good agricultural
         practice in the use of chlorothalonil on grapes, as well as
         residue data from field trials in countries where uses on grapes
         are known to be good agricultural practice.

    2.   Information, if it exists, on good agricultural practice for
         those countries in which residue trials for data provided to the
         1983 Meeting were conducted.

    Desirable

    1.   Analyses of chlorothalonil-treated animal feed items (for
         example, bean and peanut vines), processed and unprocessed, for
         residues of PCBN (from the 1981 Meeting).

    2.   Information on possible PCBN residues in tissues and milk of
         dairy cattle fed a diet containing chlorothalonil (from the 1981
         Meeting).

    REFERENCES-RESIDUES

    Diamond Shamrock. (2, 4, 5, 6-tetrachloroisophthalonitrile),
    1981      Compilation of Residue Data and Registration/Recommendation
              Information on Use of Chlorothalonil on Grapes. Submitted to
              FAO by Diamond Shamrock Corporation.

    Netherlands. Information submitted to FAO by the government of The
    1983      Netherlands, September 1983, MVD, Ref.: CL1983/22-Fr.

    SDS. The effects of cooking 2,4,5,6-tetrachloroisophthalonitrile
    1983a     (chlorothalonil, DS-2787) with vegetables. Document No.
              372-3EF-83-0004-001 submitted to FAO by SDS Biotech
              Corporation.

    SDS. Validation of analytical procedures for determining residues of
    1983b     2,4,5,6-tetrachloroisophthalonitrile (chlorothalonil,
              DS-2787), 4-hydroxy 2,5,6-trichloroisophthalonitrile
              (DS-3701), hexachlorobenzene (HCB) and
              pentachlorobenzonitrile (PCBN) on oranges. Document
              No. 506-3CR-81-0182-001 submitted to FAO by SDS Biotech
              Corporation.

    Sweden. Chlorothalonil residues in imported and domestic commodities -
    1983      1981 to 1983. Data submitted to FAO from The Government of
              Sweden.


    See Also:
       Toxicological Abbreviations
       Chlorothalonil (EHC 183, 1996)
       Chlorothalonil (HSG 98, 1995)
       Chlorothalonil (ICSC)
       Chlorothalonil (WHO Pesticide Residues Series 4)
       Chlorothalonil (Pesticide residues in food: 1977 evaluations)
       Chlorothalonil (Pesticide residues in food: 1981 evaluations)
       Chlorothalonil (Pesticide residues in food: 1985 evaluations Part II Toxicology)
       Chlorothalonil (Pesticide residues in food: 1987 evaluations Part II Toxicology)
       Chlorothalonil (Pesticide residues in food: 1990 evaluations Toxicology)
       Chlorothalonil (Pesticide residues in food: 1992 evaluations Part II Toxicology)
       Chlorothalonil  (IARC Summary & Evaluation, Volume 30, 1983)
       Chlorothalonil  (IARC Summary & Evaluation, Volume 73, 1999)