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    CHLOROTHALONIL

    EXPLANATION

         Chlorothalonil was evaluated for acceptable intake by the Joint
    Meeting in 1974 and further reviewed in 1977, 1979, 1981, 1983 and
    1985 (Annex 1, FAO/WHO, 1975a, 1978a, 1980a, 1982a, 1984 and 1986a).
    In 1974 a temporary ADI of 0.03 mg/kg bw was estimated. In 1981 the
    Meeting reduced the temporary ADI to 0.005 mg/kg bw due to the absence
    of adequate metabolic data and assuming total conversion of the parent
    compound to a more toxic metabolite, the 4-hydroxy derivative. This
    value was further reduced by the 1985 JMPR to 0.0005 mg/kg bw because
    of concern for oncogenicity. The 1985 Meeting recommended that any
    available data on the on-going carcinogenicity studies in rats and
    mice be submitted for evaluation when available, and required further
    metabolism data to identify the change in metabolic pattern with
    increasing dose, as well as further characterization of the GSH
    conjugation occurring in the G.I. tract and kidney. The oncogenicity
    study in mice and the metabolism studies required by the 1985 JMPR,
    plus several additional studies, including two 90-day studies in rats
    (one with chlorothalonil and the other with the monoglutathione
    conjugate of chlorothalonil), several mutagenicity studies and three
    histopathological re-evaluations have been made available to the 1987
    JMPR and have been summarized in this monograph addendum.

    EVALUATION FOR ACCEPTABLE INTAKE

    BIOLOGICAL DATA

    Biochemical aspects

    Metabolism

    Rats

         The absorption, tissue accumulation and excretion of radiolabel
    were studied in male Sprague-Dawley rats given a single oral dose of
    either 0, 5, 50 and 200 mg/kg bw 14C-chlorothalonil (96-98% pure) in
    water, uniformly labelled in the benzene ring. Rats were fasted from
    12 hours before dosing to termination and were probably without water
    supply between dosing and termination. In 3 separate experiments, 5
    animals/sex/group were sacrificed 2, 9 and 24 hours after dosing, in 8
    different tissues, in carcasses, in blood, in contents of stomach,
    small and large intestine and in cage washings at termination.

         The total recovery of radioactivity was 86-104% of the
    administered dose at all sampling times for all dose levels. In rats
    of all three dose groups sacrificed 2 hours after dosing, 76 to 80% of
    the administered radioactivity was found in the small intestinal
    content. Less than 1% of the administered dose was found in blood,
    liver, kidney, lung, heart, fat and muscle. Nine hours after dosing
    87-90% of the administered dose was found in the large intestinal
    content. After 24 hours from dosing 88-95% of the administered dose
    was still in the large intestinal content. Faecal excretion, however,
    was very minor in this study, possibly due to the animal fasting.
    Recovery of radioactivity in the urine of rats killed 24 hours after
    dosing was also minor (0.4 to 0.6%). Urine output was minimal during
    this period due to the fact that the animals were probably without
    water supply during the time between dosing and termination.

         Concentration of chlorothalonil g equivalents in blood and
    tissues of rodents dosed with 50 and 200 mg/kg bw and killed at 24
    hours was proportionately higher than expected when compared with rats
    of the low dose group. The authors of the study interpreted these
    results as the "saturation of an absorption and/or elimination
    mechanism in male rats between doses of 50 and 200 mg/kg".

         The HPLC analysis of methanol extracts of faeces showed at least
    7 radioactive peaks. Two of these peaks had identical retention times
    as chlorothalonil and 4-hydroxy-2,3,5-trichloroisophthalonitrole. A
    higher proportion of chlorothalonil was apparently metabolized by the
    5 mg/kg bw dose rats than by the animals of the two higher dose groups
    (Lee et al., 1982).

         In another study excrete (urine and faeces) and tissues from male
    Sprague-Dawley rats administered single oral doses of 5 or
    200 mg/kg bw 14C-chlorothalonil (96-98% pure, labelled in the
    benzene ring) in water were analysed by HPLC to determine the extent
    of metabolism and the identity of the compounds to which
    chlorothalonil was metabolized. Rats were starved for 12 hours before
    and 24 hours after dosing and were given drinking water  ad libitum.
    Urine samples and faeces were collected at 2, 9, 24, 36, 48, 60, 72,
    84 and 96 hours after dosing. The total mean recovery of the
    administered radioactivity in faeces and urine 96 hours after dosing
    was 77% and 8.6% for the low dose animals, and 62% and 4.7% for the
    high dose rats, respectively. Maximum elevation was between 24 and 36
    hours for faeces in all groups, between 2 and 9 hours for urine of the
    low dose group and between 9 and 24 hours for urine of the high dose
    group. At 200 mg/kg bw, the urine radioactivity increased and then
    decreased slower than at 5 mg/kg bw. Extraction of radioactivity with
    methanol from faeces was dose- and time-dependent. It was higher at
    the 200 mg/kg bw dose and at early times. HPLC analysis of faeces
    extracts indicated that chlorothalonil more extensively metabolized
    after the low level than after the high dose level. With the low dose
    level, several peaks were present in the HPLC profile, 3 of which
    corresponded to those seen in the HPLC profile obtained from faeces of
    high dose animals. The majority of radioactivity at both dose levels
    was unextracted and apparently bound to faecal components. In urine
    only about 15% of the radioactivity was lost during purification. HPLC
    analysis of purified urine showed at least 3 peaks at both dose
    levels, 64% of the radioactivity being in the form of highly polar
    metabolite(s). These three metabolites recovered in urine were 0.05,
    0.3 and 3.5% (high dose urine) and 0.08, 0.6 and 4.5% (low dose urine)
    of the administered dose, respectively (Marciniszyn et al., 1983).

         The biliary excretion of radioactivity after a single oral dose
    of 5 mg/kg bw 14C-chlorothalonil (95.5% radiochemically pure) was
    studied in 8 male and 4 female Sprague-Dawley rats. Chlorothalonil
    uniformly labelled in the benzene ring was administered as a
    suspension in 0.75% methylcellulose with a mean particle size of 3.8
    microns. Bile was collected by cannulation in 60 min fractions for 48
    hours; blood and urine samples were collected at 6, 24 and 48 hours
    and faeces at 24 and 48 hours after dosing. Total mean recovery of
    radioactivity in this study was 83 to 97%. In 48 hours, male and
    female rats excreted 21.1% and 16.7% of the administered dose in bile
    and 7.6% and 11.7% in urine, respectively. Peak concentrations of
    radioactivity in bile were reached within 2 hours after dosing for
    both sexes. Levels of radioactivity in blood were higher at 6 than 24
    or 48 hours after dosing for both sexes. Faeces contained 50 and 61%
    of the administered radioactivity in male and female rats,
    respectively.

         It was concluded by the authors of the study that absorption of
    chlorothalonil is particle size-dependant and that approximately 34%
    of the administered dose was absorbed by both male and female animals
    (Marciniszyn et al., 1985a).

         The enzymatic and non-enzymatic conjugation of gluthathione with
    14C-chlorothalonil (99% radiochemically pure) labelled in the
    benzene ring was investigated  in vitro. The isolation and
    identification of the gluthathione conjugates as metabolites of
    chlorothalonil in the bile of rats administered 14C-chlorothalonil
    was also investigated. HPLC analysis showed that on incubation of
    14C-chlorothalonil with reduced gluthathione (GSH) under aqueous
    conditions both in the presence and absence of GSH S-transferase, 3 or
    4 polar products were formed. These products were tentatively
    identified as gluthathione conjugates of chlorothalonil, formed
    apparently in the following stepwise manner, chlorothalonil ->
    monoconjugate -> diconjugate -> triconjupte. Mono- and diconjugates
    of chlorothalonil were also synthesized under organic conditions.
    These were apparently identical, by TLC and HPLC analysis, to those
    formed under aqueous conditions, both before and after peptide bond
    cleavage.

         Based on the limited preliminary data presented (polarity,
    molecular weight and chromatography), the authors of the study
    suggested that the major metabolite in the bile of rats dosed orally
    with 5 mg/kg bw 14C-chlorothalonil was the di-gluthathione conjugate
    of chlorothalonil (Savides et al., 1985a).

         The urinary metabolites of chlorothalonil were studied in 4 male
    Sprague-Dawely rats given a single oral dose of 200 mg/kg bw
    14C-chlorothalonil (98.6% radiochemically pure) uniformly labelled
    in the benzene ring. Chlorothalonil was given as a homogeneous
    suspension in 0.75% methylcellulose in water, with a particle size of
    3.2 microns. The pooled urine samples collected from 0 to 24 hours
    after dosing contained 2.3% of the administered dose. Two metabolites
    were identified by gas chromatography/mass spectrometry (GC/MS)
    analysis: dithiodichloroisophthalonitrile and
    trithiochioroisophthalonitrile, in both the free sulfhydryl and the
    methylated form.

          Extraction of urine with ethylacetate removed 15.4% of the
    radioactivity present in urine. GC/MS analysis of these ethyl acetate
    extracts identified trimethylthiomonochloroisophthalonitrile and
    dimethylthiodichloroisophthalonitrile in a 1:1 ratio. Acidification of
    urine and further extraction with ethylacetate removed an additional
    54.4% of the urine radioactivity. When this acid extract was applied
    onto a C18 Sep-Pak cartridge, 30% of the radiolabel was eluted with
    methylene chloride and 70% with methanol. GC/MS analysis of the
    methylene chloride eluate resulted in identification of the trimethyl

    and dimethyl thiols. GC/MS analysis of the fraction eluted with
    methanol before and after methylation with diazomethane indicated that
    both methylated and non-methylated thiols were present in the urine.
    It was concluded by the authors of the study that thiol metabolites of
    chlorothalonil were formed from its conjugation with gluthathione
    (Marciniszyn et al., 1985b).

         The biliary excretion of radioactivity was studied in groups of 6
    male Sprague-Dawley rats administered a single dose of 1.5, 5, 50 or
    200 mg/kg bw 14C-chlorothalonil (98% radiochemically pure) uniformly
    labelled in the aromatic ring as a suspension with a mean particle
    size of 3.6 to 5.0 microns in 0.75% methylcellulose in water. Rat bile
    duct was cannulated and bile was collected in 1 hour fractions for 48
    hours after dosing. Blood, urine and faeces were also collected at
    various times after dosing and at termination. During the 48 hours
    after a single dose of 1.5, 5, 50 and 200 mg/kg bw, biliary excretion
    was 22.5, 16.4, 16.3 and 7.7% of the administered dose, respectively.
    Profiles of radioactivity excretion after the two low doses were
    quantitatively different from those obtained after the two high doses.
    The authors of the study interpreted these results as indicative of a
    change in metabolism occurring between 5 and 50 mg/kg bw, possibly due
    to saturation of biliary excretion.

         Mean urinary excretion in the 48 hours after dosing was 8.0, 8.2
    and 7.6% of the administered dose at 1.5, 5 and 50 mg/kg bw,
    respectively, and only 4.7% at the high dose level of 200 mg/kg bw.
    Excretion of radioactivity in urine within 6 hours after dosing was
    inversely related to the dose administered. Total recovery of
    radioactivity in this study was 89-99% in the 3 low dose groups and
    74% after the 200 mg/kg bw dose. After doses of 1.5, 5, 50 and
    200 mg/kg bw, rats absorbed 32, 25.7, 25.9 and 15.5% of the
    administered dose, respectively. It was concluded by the authors of
    the sponsor report that enterohepatic circulation or reabsorption of
    biliary metabolites from the gastrointestinal tract did not contribute
    significantly to the amount of radiolabel in the kidney. Based on a
    one-compartment model for chlorothalonil absorption and excretion and
    using several assumptions, it was calculated that the rate of
    absorption of the 200 mg/kg bw dose was only twice as fast as that of
    the 50 mg/kg bw dose (Marciniszyn et al., 1986a).

         The absorption, tissue distribution and excretion of
    radioactivity was investigated in male Sprague-Dawley rats
    administered orally 5 successive daily doses of 14C-chlorothalonil
    (98.4% radiochemically pure) labelled in the benzene ring and
    suspended in 0.75% methylcellulose. Groups of 20 animals each received
    1.5, 5, 50 or 160 mg/kg bw and were killed 2, 9, 24, 96, and 168 hours

    after the 5th dose and at termination. Four additional groups of 2
    rats each were treated similarly and used for blood radioactivity
    determination at 2 and 24 hours after the 1st, 3rd and 5th dose
    administration. Some contamination of urine samples by loose faeces
    may have occurred during the first 24 hours after the first dose in
    this study.

         The major excretion of radiolabel was through the faeces in all
    groups. During the 5-day dosing period and the 168 hours after the 5th
    dose administration rats excreted 82-85% of the administered dose in
    faeces and 5 to 6.7% in urine. At the 50 and 160 mg/kg bw dose levels
    the percent of administered dose excreted in urine was at least 25%
    less than that excreted at 1.5 or 5 mg/kg bw. Radioactivity in blood
    was consistently higher at 6 than at 24 hours after each
    administration. The blood concentrations 6 hours after the first dose
    and 6 hours after the 5th dose were similar (71 and 90 ng/ml,
    respectively). A plateau in blood radioactivity was reached apparently
    after one dose administration and maintained through 5
    administrations. The maximum concentration of radiolabel in kidneys
    (< 0.2%) after the 5th dose administration was reached at 2 hours for
    all dose levels. Seven days after the 5th dose administration kidneys
    contained 14, 16, 23 and 25% of these maximum concentrations,
    respectively. Maximum concentrations of radioactivity in kidneys after
    50 and 160 mg/kg bw/day were not proportional to that found after the
    2 lower dose levels. Liver contained 6 to 7 fold less radioactivity
    than kidneys.

         It was concluded by the authors of the sponsor report that rats
    responded to high doses (50 and 160 mg/kg bw/day) of chlorothalonil in
    a different manner than to low doses (< 5 mg/kg bw/day) (Marciniszyn
    et al., 1986b).

         The effects of the renal secretion inhibitor probenecid on
    plasma, urine and kidney levels of chlorothalonil was studied in 3
    groups of male Sprague-Dawely rats given a single oral dose of 4.7 or
    52 mg/kg bw 14C-chlorothalonil (99% radiochemically pure) labelled
    in the benzene ring and present as a suspension of 3.7 microns
    particle size in 0.75% methylcellulose. In 3 different experiments
    rats were injected i.p. with 139 (Expt. 1 and 2) or 244 (Expt. 3)
    mg/kg bw probenecid in corn oil 1 hour before chlorothalonii
    administration (52 mg/kg bw in Expt. 1 and 2, and 4.7 mg/kg bw in 
    Expt. 3 control rats were given 14C-chloronthalonil and corn oil but 
    no probenecid. Rats of Expt. 1 and 3 were terminated six hours and rats 
    of Expt. 2 two hours after chlorothalonil administration.

         In probenecid-treated rats of Expt. 1 and 2, the mean plasma
    level of radioactivity was 146 and 156% of that of controls, the mean
    urinary excretion of radioactivity as a percent of the administered
    dose was 50 and 40% of that of controls and radiolabel content in
    kidneys (as g equiv./g of kidney) was 70 and 58% of that of controls,
    respectively. In Expt. 3, where a lower chlorothalonil/higher
    probenecid dosage was used, the% of the administered dose of
    chlorothalonil present in the kidneys 6 hours from termination was
    even lower than was found in Expt. 1 and 2 (48% of that of controls
    compared with 73 and 69% of that of controls in Experiment 1 and 2,
    respectively). The authors of the study reported that GC/MS analysis
    of these extracts after methylation revealed the presence of the
    trimethylthiol derivative of chlorothalonil in urine of treated and
    control animals (6.2 and 8.3% of the urinary radioactivity,
    respectively). A small amount of the dimethylthiol derivative was also
    present in control urine. It was concluded by the authors of the study
    that probenecid pretreatment decreased the active secretion by the
    kidney of the majority of the urinary metabolites of chlorothalonil
    (Savides et al., 1985b).

         The effect of multiple dosing with chlorothalonil on the
    excretion of thiol metabolites in urine was studied in 4 groups of 20
    Sprague-Dawely rats orally administered 1.5, 5, 50 or 60 mg/kg bw/day
    14C-chlorothalonil for 5 consecutive days. Four rats from each dose
    level were sacrificed at 2, 9, 24, 96 and 168 hours after the final
    (5th) dose administration. Urine samples were collected at 24 hour
    intervals after each dose administration, acidified and extracted with
    ethylacetate. The extractability of radiolabel from acidified urine
    decreased both with increasing dose level and with repetitive dosing,
    ranging from 84% (on day 1 at the 1.5 mg/kg bw/day dose level) to 49%
    (on day 5 at 160 mg/kg bw/day). GC/MS analysis of urine samples
    identified dithiol (dithiodichloroisophthalonitrile) and trithiol
    (trithiochloroisophthalonitrile) metabolites of chlorothalonil in all
    samples analyzed. The amount of the dithiol excreted in the urine on
    day 1 as a percent of the total urine radioactivity was 5.2, 9 and
    15.4% at 5, 50 and 160 mg/kg bw/day. In contrast, the amount of the
    trithiol excreted in the same urine was approximately the same at all
    3 dose levels (15.7, 16 and 16.8% of total urine radioactivity,
    respectively). The absolute amounts of both thiols excreted in 4
    subsequent days of treatment at 50 and 160 mg/kg bw/day decreased
    dramatically. The ratio between the absolute amounts of trithiol and
    dithiol in urine at 50 and 160 mg/kg bw/day also increased with
    multiple dosing. This ratio was also inversely related to the dose in
    day 1 urine (3, 1.8 and 1.1 at 5, 50 and 160 mg/kg bw/day,
    respectively). GC/MS analysis of the non-extractable phase of urine
    from rats of the 160 mg/kg bw/day group gave spectra which were
    tentatively identified as those of cysteinyltrichloroisophthalonitrile
    and cysteinyltrichlorocyanobenzoic acid. The 4-and 5-hydroxy and the
    4- and 5-dechlorinated analog of chlorothalonil were not found to be
    present in any of the urine samples that were analyzed.

         It was concluded by the authors of the study that the glutathione
    pathway is specifically involved in chlorothalonil metabolism and that
    a second pathway becomes increasingly involved in chlorothalonil
    metabolism with successive dose administrations (Savides et al.,
    1986a).

         The  in vitro metabolism of 14C-chlorothalonil by mucosal
    cells from the stomach and/or small intestine of Sprague-Dawely rats
    was investigated quantitatively using an HPLC/LSC technique. During
    the incubation of chlorothalonil with stomach squamous or stomach
    glandular cells and with intestinal cells, several products were
    formed (2 in stomach incubations and 5 in intestinal incubations)
    which were more polar than chlorothalonil. In all incubations two
    compounds were found with elution times corresponding to those of the
    di- and monogluthathione conjugates of chlorothalonil. It was
    speculated that bacteria, which were probably present in the
    incubations, may have contributed to chlorothalonil metabolism
    (Savides et al., 1986c).

         The distribution of radioactivity was investigated in kidney
    organelles of CD Sprague-Dawely rats administered a single oral dose
    of 50 mg/kg bw 14C-chlorothalonil (97% radiochemically pure)
    labelled in the benzene ring. Chlorothalonil was given as a suspension
    of 5 microns particle size in 0.75% methylcellulose in water. Six
    hours after dosing rats were terminated and kidneys were removed,
    homogenized and fractionated by ultracentrifugation for radiolabel
    assay. The radiolabel was distributed in all fractions of kidney
    homosenate: 0.2% in the nuclear fraction, 6.3% in cellular debris, 7%
    in heavy mitochondrial fraction, 3.2% in light mitochondrial-lysosomal
    fraction, 2% in microspinal fraction and 81.2% in soluble fraction.
    The total organelle fraction contained 18.7% of the radioactivity
    present in the homosenate (Savides et al., 1987).

         An  in vitro gut sac apparatus was used to study the absorption
    of chlorothalonil through the intestinal wall of Sprague-Dawely rats.
    Five hundred microliters of a 3.4 microns particle size suspension of
    14C-chlorothalonil (97.1% radiochemically pure) in 0.75%
    methylcellulose, corresponding to approximately 2.5 mg test material,
    were instilled into each of 3 rat intestinal segments sealed at both
    ends (gut sac) and incubated at 37C for 6 hours in Krebbs Henseleit
    buffer gassed with 95% O2/5% CO2.

         At the end of the incubation the mean recovery of radioactivity
    in mucosal compartment, serosal compartment and intestinal segment was
    71, 5.8 and 1.3%, respectively. HPLC analysis of the buffer of the
    serosal side of the gut sac showed that none of the transferred
    material was chlorothalonil. It was suggested by the authors of the
    study that following an oral dose of chlorothalonil to rats,
    chlorothalonil is converted to polar metabolites in the
    gastrointestinal tract and that these metabolites, not chlorothalonil,
    are absorbed (Savides et al., 1986d).

         The effect of the Gamma-Glutamyl Transpeptidase inhibitor AT-125
    on the metabolism of 14C-chlorothalonil (97.1% radiochemically pure)
    in male Sprague-Dawley rats is being invest in a pilot study still in
    progress. A group of 3 rats were administered intraperitoneally
    10 mg/kg bw AT-125 in saline, 1 hour before a single oral dose of
    560 mg/&kg bw 14C-chlorothanil in 0.75% methylcellulose suspension.
    Three control rats received saline and chlorothalonil. Data available
    from an interim report indicated that AT-125 inhibited the  in vivo
    activity of Gamma-Glutamyl Transpeptidase for at least 12 hours, since
    during this period percent extractability of radiolabel from urine of
    rats pretreated with AT-125 was significantly (20%) lower than that
    from urine of controls (> 70%). The major (42% of the total
    radiolabel in urine) non-extractible metabolite excreted in urine of
    AT-125-pretreated animals was tentatively identified by HPLC analysis
    as the diglutathione conjugate of chlorothalonil. It was suggested by
    the authors of the study that almost 60% of the radiolabel excreted in
    the urine samples analysed were multiple glutathione conjugates of
    chlorothalonil (Marciniszyn and Killeen, 1987a).

         The covalent binding of radiolabel to kidney DNA was studied in 4
    male Sprague-Dawley rats administered by gavage a single dose of
    49 mg/kg bw 14C-chlorothalonil (99% radiochemically pure) as a
    3.8 micron particle size suspension in 0.75% methylcellulose. Three
    control groups of 4 rats each were given either a single oral dose of
    methylcellulose solution or a single i.p. injection of 27 mg/kg bw
    14C-dimethylnitrosamine (14C-DMNA) in saline (positive control) or
    saline alone. Rats were terminated 6 hours after treatment and kidneys
    were removed, homogenized and assayed for protein and DNA binding
    after purification by chromatography or hydroxylapatite/ethanol
    precipitation. Both compounds were found to bind covalently to
    proteins (2259  627 and 2112  293 dpm/mg, of protein for
    14C-chlorothalonil and 14C-DMNA, respectively). DNA fractions from
    14C-DMNA-treated rats contained 2.9-15.5% of the radioactivity
    recovered from chromatography (recovery was 78-93%). DNA from
    14C-chlorothalonil-dosed rats contained 0.02 to 1.4% of the
    recovered radioactivity. A mean covalent binding index of 245  91 was
    calculated for 14C-DMNA-administered animals. No radioactivity was
    found bound to purified DNA of 14C-chlorothalonil treated rats
    (Marciniszyn et al., 1987).

    Special studies on metabolites

         The concentration of radioacitivity in blood and kidneys was
    studied in male Sprague-Dawley rats administered a single oral or
    intraperitoneal dose of the mono-glutathione conjugate of
    14C-chlorothalonil (91.3% radiochemically pure) uniformly labelled
    in the benzene ring. The conjugate was administered as a 0.75%
    methylcellulose suspension at a dosage of 115 mg/kg bw (equivalent to
    57 mg/kg bw chlorothalonil).

         Six hours after dosing the mean blood concentrations of
    radiolabel were 10 times higher in i.p. dosed rats than in orally
    administered animals. The mean percent of the administered dose found
    in kidneys at this time was 0.02 and 3.2% in orally and i.p.
    administered rats, respectively. Extractability of radioactivity in
    urine with acidified ethylacetate was 55 and 86% in orally and i.p.
    dosed rats, respectively. The urine of orally dosed rats were shown by
    GC/MS analysis of the methylated extracts to contain 9% of the
    radioactivity as the trithiol derivative of chlorothalonil and 5.1% as
    the dithiol derivative. In contrast, the urine of i.p. dosed rats
    contained less than 1% of the radiolabel as the dimethylthiol but not
    trimethylthiol derivative. When the results were compared with those
    of a previous study where 54 mg/kg bw chlorothalonil was administered
    orally to rats, the percentages of the administered dose found in
    kidney, blood and urine were similar in the two studies.

         It was concluded by the authors of the study that the addition of
    a glutathione molecule to the chlorothalonil ring reduced the acute
    toxicity of chlorothalonil when administered intraperitoneally. It was
    also suggested that orally administered mono-glutathione conjugate of
    chlorothalonil is further conjugated with glutathione in the
    gastrointestinal tract prior to absorption (Savides et al., 1986b).

    Toxicological studies

    Special studies on carcinogenicity

    Mice

         Groups of 60 male Charles River CD-1 mice were administered diets
    containing 0, 10, 40, 175, and 750 ppm technical chlorothalonil (98.0%
    pure) for up to two years. At week 16 the 10 ppm dosage was changed to
    15 ppm to assure a minimum dose of 1.5 mg/kg bw/day throughout the
    study. Ten mice/group underwent haematological examination at 12, 18
    and 24 months. All mice terminated on schedule,  in extremis or found
    dead were necropsied. The absolute and relative weights of brain and
    kidney of the animals terminated at interim and terminal sacrifices
    were measured. The kidneys, stomach and related lymph nodes from all
    animals were examined microscopically.

         No compound-related effects were noted on the distribution of
    overt signs of toxicity, mortality, body weight of food consumption
    throughout the study. At 12 months, but not at 18 and 24 months,
    animals at 750 ppm had a statistically significant decrease in
    haemoglobin and hematocrit values, which were not considered to be
    treatment-related. No treatment-related changes or masses were found
    by macroscopic examination of mice sacrificed or dying during the

    study. At interim sacrifice a statistically significant increase of
    relative kidney to body weight was noted in mice at 750 ppm when
    compared to controls. At terminal sacrifice absolute kidney weight and
    relative kidney to body or kidney to brain weights of mice at 750 ppm
    were significantly higher than in controls.

         Histopathological examination of the kidneys, stomach, renal and
    gastric lymph nodes performed by a different laboratory on all the
    animals used in those study showed treatment-related non-neoplastic
    changes in both organs. The reported renal changes included an
    increase in the incidence and severity of epithelial hyperplasia in
    the proximal convoluted tubules and in the incidence of karyomegaly
    (increased nuclear size) at 175 and 750 ppm and, possibly, an increase
    in the incidence of tubular hypertrophy at 750 ppm. The treatment
    related changes seen in the stomach included an increased incidence of
    hyperkeratosis and squamous epithelial hyperplasia of the forestomach
    at 40, 175 and 750 ppm chlorothalonil. Treatment-related neoplasms
    were not seen in the kidneys at any dose level tested. Only two mice,
    one at 40 ppm and the other at 175 ppm dietary level, had tubular
    adenoma. The incidence of all tumors (papilloma and squamous cell
    carcinoma) in the forestomach was 2/60, 0/60, 0/60, 1/60 and 4/60 at
    0, 15, 40, 175 and 750 ppm, respectively. No treatment-related
    microscopic alterations were seen in either renal or gastric lymph
    nodes.

         Based on the non-neoplastic gastric lesions, the NOEL of
    chlorothalonil for Charles River CD-1 mice in this study was 15 ppm,
    equal to 1.57 mg/kg bw/day. Based on the neoplastic changes, the NOEL
    in this study was considered by the authors of the study to be at
    least 175 ppm, equal to 21.3 mg/kg bw/day (Wilson and Killeen, 1987a).

         A histopathological re-evaluation of the kidneys was conducted by
    Dr. Busey (Wilson et al., 1986) for the mouse oncogenicity study by
    Wilson et. al. (1983). The re-evaluation confirmed the treatment-
    related higher incidence of tubular adenomas and carcinomas observed
    in males, but not in female CD-1 mice, during the original evaluation.
    The incidences of these tumors found in male mice by the two authors are
    compared in Table 1.

         This re-evaluation showed also compound-related, not clearly
    dose-related non neoplastic lesions of the kidney in both male and
    female mice at all three dose levels tested. These changes were not
    found during the original evaluation and included epithelial
    hyperplasia and tubular hypertrophy. The incidence of epithelial
    hyperplasia was 0/60, 31/60, 36/60 and 30/60 in males and 0/60, 8/60,
    4/60 and 17/60 in females at 0, 750, 1500 and 3000 ppm, respectively.
    This change was present in 13/15 mice with tubular tumor. In the
    remaining two animals with tumor, autolysis of the renal tissue
    prevented the comparison. It was stated by the pathologist (personal
    communication from Dr. W.M. Busey, Experimental Pathology

    Laboratories, Inc., Herndon, VA, USA, 1986, submitted to WHO by
    Fermenta Plant Protection Co., Painesville, OH, USA) that this
    epithelial hyperplasia was qualitatively similar to the hyperplasia
    seen in kidneys of a previous subchronic mouse study. The authors of
    the Sponsor report considered this change preneoplastic in nature.
    Detection of this change by the pathologist, however, was reported to
    be highly dependent upon the prior knowledge of its potential presence
    (Wilson et al., 1986).

    Table 1.  Comparison of the incidences of renal tubular adenomas and
              carcinomas found in male mice by Brown (Wilson et al., 1983)
              and Busey (Wilson et al., 1986)
                                                                        

    Diagnosis                                    Dose level (ppm)

                                        0*      750*      1500*     3000*
                                                                        

    Brown:

    Tubular adenoma                     0       4         4         2
    Tubular carcinoma                   0       2         0         2
    Total animals with these tumors:    0       6+        4         4
                                                                        

    Busey:

    Tubular adenoma                     0       3         3         4
    Tubular carcinoma                   0       3         1         1
    Total animals with these tumors:    0       6+        4         5
                                                                        

    *    The kidneys from 60 animals/group/sex were examined.
    +    p < 0.05, when compared to controls.

    Rats

    (ongoing study)

         Groups of 65 male and female Fischer 344 rats are being given
    diets containing 0, 2, 4, 15 and 175 mg/kg bw/day chlorothalonil.
    Potential effects of chlorothalonil administration on body weight and
    histopathology of selected tissues from all animals (kidneys, stomach,
    renal and gastric lymph nodes) are being or will be evaluated.
    Histopathological evaluation of rats which died or were killed
     in extremis during the first year of the study or underwent the
    one-year interim sacrifice on December 11 and 12, 1986, is ongoing.
    All surviving animals will be terminated after 30 months of
    chlorothalonil administration.

         By week 56 of this study the mean body weights of the high dose
    (175 mg/kg bw/ day) male and female rats were lower than those of the
    animals of the relative control groups. In addition, during this
    period dark yellow urine was noted in 50 male and 38 female rats of
    the high dose group, but not in controls or in low/intermediate dose
    animals.

         A final report of this study is scheduled to be completed in
    December 1988 (Wilson & Killeen, 1987b).

         A histopathological re-evaluation by Busey (Wilson et al.,
    1986b) of the kidneys of the oncogenicity study in Fischer 344 rats by
    McGee & Brown (1985) confirmed the original finding of treatment
    related tubular adenomas and carcinomas in both male and female rats.
    When the single diagnosis of tubular adenomas and carcinomas made in
    the two evaluations are compared, an overall 65% (45/69) agreement was
    observed. A comparison of the incidences of renal tumors found in male
    and female rats by the two pathologists is reported in Table 2.

         Treatment-related, non-neoplastic lesions of the renal tubules
    which were not observed in the original evaluation were found during
    this re-evaluation in both male and female rats. These changes were
    epithelial hyperplasia and tubular hypertrophy in both sexes and
    cortical cyst(s) in males. The incidence of epithelial hyperplasia was
    0/60, 32/60, 30/60 and 36/60 in males and 5/60, 35/60, 39/60 and 48/60
    in females at 0, 40, 80 and 175 mg/kg bw/day, respectively. The
    occurrence of tubular hyperplasia and that of tubular tumors appeared
    to be highly correlated. In only one animal of the high dose group,
    out of 69 rats with tubular adenoma or carcinoma, no tubular
    hyperplasia was found. In three other cases autolysis of the renal
    tissue prevented the comparison. It was concluded by the pathologist
    (personal communication from Dr. W.M. Busey, Experimental Pathology
    Laboratories, Inc., Herndon, VA, USA, 1986, submitted to WHO by
    Fermenta Plant Protection Co., Painesville, OH, USA) that the
    epithelial hyperplasia observed in this study was qualitatively
    similar to that seen in recent subchronic and old chronic studies with
    chlorothalonil in rats. This tubular hyperplasia was considered by the
    authors of the Sponsor report to be preneoplastic in nature. They
    reported, however, that detection of this change by the pathologist
    was highly dependent upon prior knowledge of its potential presence
    (Wilson et al., 1986).


        Table 2.  Comparison of the incidences of renal tubular adenomas and carcinomas found
              in male and female rats by Brown (Mcgee & Brown, 1985) & Busey (Wilson et al.
              1986b).
                                                                                                       

                                                       Dose level (mg/kg bw/day)

                                            0            40            80            175
    Diagnosis                           M*     F*     M      F      M      F      M      F
                                                                                                       

    Brown:

    Tubular adenoma                     0      0      2      2      4      4      11     9
    Tubular carcinoma                   0      0      5      1      2      2      7      11
    Anaplastic renal carcinoma          0      0      0      0      1      0      0      3

    Total animals with these tumors:    0      0      7+     3      7+     6+     18++   23++
                                                                                                       

    Busey:

    Tubular adenoma                     0      0      3      3      5      10     7      15
    Tubular carcinoma                   0      0      4      1      2      0      13     11

    Total animals with these tumors:    0      0      7+     4      7+     10+    18++   23++
                                                                                                       

    *    60 animals/group/sex were examined.
    +    p < 0.05, when compared to controls.
    ++   p < 0.01, when compared to controls.
    

    Special studies in mutagenicity

         The ability of chlorothalonil (98.8% pure) to induce chromosomal
    aberrations in Chinese hamster ovary cells was tested in the presence
    and absence of metabolic activation by liver S9 mix from
    Aroclor-pretreated rats. A longer incubation time was used in the
    assay without metabolic activation due to cell cycle delay.
    Triethylenemelanine and cyclophosphamide were used as the positive
    control in the assay without and with activation, respectively. A
    statistically significant treatment-related, apparently dose-dependant
    increase in the number of cells with structural aberrations was found
    in the absence but not in the presence of metabolic activation when
    compared with the solvent control. The authors of the Sponsor report
    suggested that the positive result without metabolic activation may be
    of no biological significance to the intact mammalian organism since
    chlorothalonil was negative in  in vivo chromosomal aberration assays
    and metabolism studies in rats suggest that only metabolites are
    absorbed through the gastrointestinal tract (Mizens et al., 1986c).

         The mutagenic potential of a number of compounds related to
    chlorothalonil has been evaluated in the Ames test with and without
    metabolic activation with S9 from kidney of male Fischer rats. These
    compounds were 2,5-dichloro-4,6-bismercaptoisophtaonitrile,
    S-(2,4-dicyano-3,5,6-trichlorophenyl) glutathione, 5-chloro-2,4,6-
    trimercap- toisophtalonitrile, S,S'-(2,4-dicyano-3.6-dichlorophenyl)
    dicysteine and S,S',S"-(2,4-dicyano-6-chlorophenyl)-tricysteine (purity
    ranging 90.5-97.5%). Four other compounds were used as positive controls.
    The  Salmonella typhimurium tester strains TA98, TA100, TA1535, TA1537
    and TA1538 were used. In all these studies, there was no significant
    increase (doubling) over solvent control values in the number of
    revertants for any of the five tester strains used either with or
    without metabolic activation (Mizens et al., 1985a, 1985b, 1986a,
    1986b and 1987).

    Short-term studies

    Rats

         Two groups of 15 male Fischer 344 rats were administered either
    single daily doses of 75 mg/kg bw chlorothalonil technical (97.9%
    pure) or equimolar doses (150 mg/kg bw) of its monoglutathione
    conjugate (92.5% pure) in aqueous 0.5% methylcellulose suspensions by
    gavage for 93 days. A control group of 15 animals was administered the
    vehicle by gavage for 93 days. The homogeneity and stability of the
    two test compounds in the vehicle were controlled throughout the
    study.

         One rat dosed with chlorothalonil was considered moribund and was
    sacrificed on the 73rd day of the study. Dark yellow urine was
    reported irregularly in all but one animal administered
    chlorothalonil. Statistically significant lower (5 to 9%) mean body
    weights were noted from week 4 for rats treated with chlorothalonil
    when compared to controls. Absolute food consumption was lower for
    chlorothalonil-treated animals during the first week of the study due
    to gastric irritation. Significantly lower mean SGPT values were
    observed in both treatment groups when compared to controls after 7 or
    13 weeks of treatment. A statistically significant increase in kidney
    weight was noted in both treated groups when compared to the control
    group at termination.

         The histopathological examination of the kidneys showed
    treatment-related changes in rats of both treated groups. These
    changes included vacuolar degeneration (which was absent in control
    animals), proliferative interstitial fibrosis, tubular ectasis and
    tubular casts. Important foci of tubular necrosis have been found in
    all treated and non-treated animals. The origin of this change was
    unknown. Both macroscopic and microscopic alterations were observed in
    the forestomach of rats treated with chlorothalonil but not in those
    administered the monoglutathione conjugate or in control animals.
    These changes were hyperplasia of the squamous epithelium,
    hyperkeratosis and gastritis, often associated with ulcerations and
    erosions.

         In this study the urine of 10 rats/treated group were analysed on
    days 1 and 4 at the end of weeks 2, 4, 8 and 12 for the presence of
    the dithiol and trithiol metabolites of chlorothalonil. GC/MS analysis
    of the urine extracts provided unequivocal identification of these
    products. The chlorothalonil-treated rats excreted the trithiol
    metabolite on days 1 and 4 and at weeks 2 and 4, and the
    monoglutathione conjugate-treated animals excreted the trithiol on
    days 1 and 4 and at week 4. The dithiol metabolite was only detected
    in chlorothalonil-treated animals on day 1. The total amount of
    trithiol metabolite excreted by chlorothalonil-treated animals was
    approximately five times greater than the total amount of trithiol
    found in the urine of monoglutathione conjugate-treated rats.

         It was concluded by the authors of the study that the presence of
    the trithiol metabolite in urine of animals of both groups was
    consistent with the involvement of glutathione conjugation in the
    metabolism of both chlorothalonil and the monoglutathione conjugate of
    chlorothalonil (Ford & Killeen, 1987a).

         Groups of 90 male Fischer 344 rats were administered a diet
    containing 0 or 175 mg/kg bw/day chlorothalonil (97.9% pure) for up to
    91 days. Body weight, food and compound consumption were measured, and
    clinical observations were made weekly throughout the study. Ten

    animals/group were sacrificed at day 4 and 7 and at the end of week 2,
    4, 6, 8, 10, 12 and after 91 days of treatment and brain and kidney
    weights were recorded. Urine samples were collected prior to sacrifice
    for determination of thiol metabolites of chlorothalonil. For each
    animal the right and the left kidney were evaluated microscopically by
    two independent laboratories using two different fixation and staining
    procedures.

         All animals were sacrificed on schedule and no treatment-related
    clinical changes were observed throughout the study. A
    treatment-related statistically significant decrease (3-9%) in mean
    body weight values was observed throughout the study in treated
    animals when compared to controls. Mean food consumption, both
    absolute (g/animal/day) and relative (g/kg/day) to body weight, was
    significantly lower in chlorothalonil-treated rats than in controls on
    days 4 and 7. A statistically significant treatment-related increase
    in kidney weight, both absolute (5 to 24%) and relative to body (9 to
    33%) or brain (6 to 28%) weight, was observed in chlorothalonil-
    treated rats when compared to controls. Macroscopic examination of the
    stomach showed treatment-related changes of the non-glandular mucosa of
    the forestomach (multifocal erosions from day 7 to week 8 and thickening
    from week 4 to 13). No other macroscopic changes were observed which
    could be attributed to chlorothalonil administration.

         Histopathological examination showed treatment-related changes in
    both the fore-stomach and kidneys. The stomach alterations observed
    remained substantially identical throughout the study and included
    slight to moderately severe squamous epithelial hyperplasia and
    hyperkeratosis in all treated animals. Ulcers were also found in all
    treated rats at day 4 and erosions of the forestomach in several
    treated animals from day 7 of study. A change in pattern of the
    chlorothalonil-dependent microscopic renal lesions with increasing
    time of chlorothalonil treatment was noted by each of the two
    different laboratories involved in the study. According to one report
    (Report 1), during the first week of treatment (days 4 and 7) all
    treated rats, but no control animal, had tubular epithelial
    degeneration and vacuolation with nuclear pyknosis, loss of brush
    border, karyomegaly. Moderate epithelial regeneration was also present
    at day 7. The second laboratory report (Report 2) reported an
    important vacuolar degeneration (but no epithelial regeneration) at
    day 4 and 7 in treated but not in untreated rats. At the end of week 2
    for both reports the kidney morphology of treated rats was not
    markedly different from that of controls. The alterations present in
    treated but not in control rats included minimal to moderate tubular
    hypertrophy in some rats (Report 1) or vacuolar degeneration, tubular
    extasis and foci of basophilic tubules in a few cases (Report 2).
    After 4 or more weeks of treatment, treated rats had epithelial
    hyperplasia and tubular hypertrophy and, after 91 days, also clear
    cell hyperplasia according to Report 1. The treatment-related changes

    after 4 weeks reported in Report 2 were-tubular ectasis, foci of
    basophilic tubules and proliferative interstitial fibrosis. Analysis
    of 24 hour urine samples from treated animals were shown to contain
    small amounts (less than 0.1% of the daily administered dose) of the
    trithiol metabolite of chlorothalonil.

         It was concluded by the authors of the study that the
    administration of 175 mg/kg bw/day chlorothalonil in the diet to
    Fischer 344 rats induced degenerative changes in the kidneys,
    ultimately resulting in epithelial hyperplasia and tubular hypertrophy
    (Ford and Killeen, 1987b).

    COMMENTS

         Several metabolism studies on the oncogenicity study in mice
    required by the 1985 JMPR and some additional data have been submitted
    and evaluated.

         14C-chlorothalonil administered orally as a suspension is
    incompletely (15-35%) and rapidly absorbed by the g.i. tract.
    Absorption probably occurs mainly through the small intestine and it
    is proportionately higher after a small dose than after a large dose.
    Chlorothalonil is rapidly distributed to the kidney, where it is
    covalently bound to proteins but not to DNA.

         Approximately 8-12% of an oral dose is excreted in the urine,
    17-21% in the bile and 50-61% remains unabsorbed in the faeces.
    Chlorothalonil metabolites are actively secreted by the kidney.
    Identification by GC-MS of the urinary metabolites indicates that
    chlorothalonil is conjugated with glutathione. The 4-hydroxy
    derivative of chlorothalonil is not a metabolite in non-ruminants. The
    data available suggest saturable absorption and excretion and a change
    in metabolism at high doses (between 5 and 50 mg/kg body weight) or
    after successive doses.

         In a 90-day study, where the toxicity of chlorothalonil and that
    of its monoglutathione conjugate were compared, both compounds induced
    microscopic changes of the renal tubules. In another short-term study
    the chlorothalonil-dependent renal lesions showed a change in pattern
    with time.

         In a recent tumorigenicity study in mice chlorothalonil,
    administered via the diet, was not oncogenic to the kidneys but
    induced a few papillomas and squamous cell carcinomas in the
    forestomach which, however, were not considered to be indicative of an
    oncogenic potential for man.

         Treatment-related non-neoplastic lesions were seen in the kidneys
    and in the forestomach. Based on these non-neoplastic gastric lesions
    the NOAEL in this study was 15 ppm, equal to 1.6 mg/kg bw/day. The
    absence in this study of treatment-related renal tumors in mice given
    750 ppm chlorothalonil in the diet is at variance with the results of
    a previous mouse oncogenicity study.

         Chlorothalonil induced chromosomal aberrations in Chinese hamster
    ovary cells  in vitro, in the absence but not in the presence of
    metabolic activation by rat kidney S9 mix. However, in a previous
    chromosomal aberration study  in vivo and in several other studies
     in vitro and  in vivo the compound was not mutagenic.

         The meeting was informed that a tumorigenicity feeding study in
    rats is being currently conducted and the final report is expected by
    December 1988. In consideration of this ongoing study, which is being
    conducted at lower doses than previous rat or mouse studies, and of
    the new metabolism data, the meeting agreed that a temporary ADI based
    on toxicity data for chlorothalonil, not the 4-hydroxy derivative,
    should be extended. Moreover, because of concern for the demonstrated
    oncogenicity in rodents, a high safety factor was used.

    TOXICOLOGICAL EVALUATION

    LEVEL CAUSING NO TOXICOLOGICAL EFFECT

          Mouse:    15 ppm in the diet, equal to 1.6 mg/kg bw/day
          Rat:      60 ppm in the diet, equivalent to 3 mg/kg bw/day
          Dog:      60 ppm in the diet, equivalent to 1.5 mg/kg bw/day

    ESTIMATE OF TEMPORARY ACCEPTABLE DAILY INTAKE FOR MAN

         0-0.003 mg/kg bw.

    STUDIES WITHOUT WHICH THE DETERMINATION OF A FULL ADI IS IMPRACTICABLE

         To be submitted to WHO by 1989

         1.   The ongoing oncogenicity study in rats.
         2.   Further studies on the mechanism of the organ-specific
              toxicity of chlorothalonil to the kidney in order to confirm
              the metabolic pathway responsible for nephrotoxicity.

    STUDIES WHICH WILL PROVIDE INFORMATION VALUABLE IN THE CONTINUED
    EVALUATION OF THE COMPOUND.

         Observations in man.

    REFERENCES

    Ford W.H. & Killeen J.C., Jr., 1987a. A 90-day study in rats with a
    monoglutathione conjugate of chlorothalonil. Unpublished report
    No. 1108-85-0078-TX-006 from Department of Toxicology and Animal
    Metabolism, Ricerca Inc., Painesville, OH, USA. Submitted to WHO by
    Fermenta Plant Protection Co., Painesville, OH, USA.

    Ford W.H. & Killeen J.C., Jr., 1987b. A 90-day feeding study in rats
    with chlorothalonil. Unpublished report No. 1115-85-0079-TX-006 from
    Department of Toxicology and Animal Metabolism, Ricerca Inc.,
    Painesville, OH, USA. Submitted to WHO by Fermenta Plant Protection
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    Lee S.S., Marciniszyn J.P., Marks A.F. & Ignatoski J.A., 1982. Balance
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    Marciniszyn J.P., Pollock G.A., Killeen J.C., Jr. & Ignatoski J.A.,
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    Marciniszyn J.P., Killeen J.C., Jr. & Ignatoski J.A., 1985a. Pilot
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    administration of (14C-DS-2787) to Sprague-Dawley rats. Unpublished
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    Marciniszyn J.P., Killeen J.C., Jr. & Ignatoski J.A., 1985b.
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    administration of 14C-chlorothalonil (14C-DS-2787) to male rats: the
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    Marciniszyn J.P., Savides M.C., Killeen J.C., Jr. & Ignatoski J.A.,
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    Marciniszyn J.P. & Killeen J.C., Jr., 1987a. Pilot study of the effect
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    Marciniszyn J.P. & Killeen J.C., Jr., 1987b. Positive statement on
    conversion of chlorothalonil to 4-hydroxy-2,5,6-trichloro-
    isophthalonitrile (SDS-3701) in non-ruminants. Unpublished
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    kidneys of male rats administered 14C-chlorothalonil (14C-SDS-2787).
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    McGee D.H. & Brown W.R., 1985. A tumorigenicity study of T-117-11 in
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    Mizens M., Killeen J.C., Jr., & Ignatoski J.A., 1985a. Salmonella/
    mammalian-microsome plate incorporation assay (Ames Test) with and
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    Mizens M., Killeen J.C., Jr., & Baxter R.A., 1986a. Salmonella/
    mammalian-microsome plate incorporation assay (Ames Test)
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    trimercaptoisophthalonitrile (SDS-66471). Unpublished report
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    Metabolism, Ricerca Inc., Painesville, OH, USA. Study no. T50-79.1505
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    Mizens M., Killeen J.C., Jr., & Baxter R.A., 1986b. Salmonella/
    mammalian-microsome plate incorporation assay (Ames Test)
    with and without renal activation with S,S',S"-(2,4-dicyano-6-
    dichlorophenyl)tricysteine (SDS-66473). Unpublished report
    No. 1097-86-0039-TX-002 from Department of Toxicology and Animal
    Metabolism, Ricerca Inc., Painesville, OH, USA. Study no. T5081.1505
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    Submitted to WHO by Fermenta Plant Protection Co., Painesville, OH, USA.

    Mizens M., Killeen J.C., Jr., & Ignatoski J.A., 1986c.  in vitro
    chromosomal aberration assay in Chinese hamster ovary (the) cells with
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    performed by Microbiological Associates Inc., Bethesda, MD, USA.
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    Painesville, OH, USA.

    Mizens M., Killeen J.C., Jr., & Baxter R.A., 1987. Salmonella/
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    Metabolism, Ricerca Inc., Painesville, OH, USA. Study no. T5080.1505
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    Savides M.C., Marcinsizyn J.P., Killeen J.C., Jr. & Ignatoski J.A.,
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    administration of 14C-chlorothalonil (14C-SDS-2787) to male rats.
    II. Effects of multiple dose administration on the excretion of thiol
    metabolites in urine. Unpublished report No. 621-4AM-83-0061-002 SDS
    Biotech Corp., Painesville, OH, USA. Submitted to WHO by Fermenta
    Plant Protection Co., Painesville, OH, USA.

    Savides M.C., Marcinsizyn J.P., Killeen J.C., Jr. & Ignatoski J.A.,
    1986b. Pilot study to determine the concentration of radiolabel in
    kidneys following oral administration of the mono-glutathione
    conjugate of 14C-chlorothalonil to male rats. Unpublished report
    No. 631-4AM-85-0064-001 from SDS Biotech Corp., Painesville, OH, USA.
    Submitted to WHO by Fermenta Plant Protection Co., Painesville, OH, USA.

    Savides M.C., Marcinsizyn J.P., Killeen J.C., Jr. & Ignatoski J.A.,
    1986c. Animal metabolism method development studies: II.  In vitro
    incubations of 14C-chlorothalonil with stomach and intestinal cells.
    Unpublished report No. 1172-85-0081-AM-002 from SDS Biotech Corp.,
    Painesville, OH, USA. Submitted to WHO by Fermenta Plant Protection
    Co., Painesville, OH, USA.

    Savides M.C., Marcinsizyn J.P., Killeen J.C., Jr. & Ignatoski J.A.,
    1986d.  In vitro studies on the transfer of 14C-chlorothalonil
    and/or its metabolites from the mucosal to the serosal surface of the
    gastrointestinal tract. Unpublished report No. 1179-86-0020-AM-001
    from Department of Toxicology and Animal Metabolism, Ricerca Inc.,
    Painesville, OH, USA. Submitted to WHO by Fermenta Plant Protection
    Co., Painesville, OH, USA.

    Savides M.C., Kidon B.J., Marcinsizyn J.P., & Killeen J.C., Jr., 1987.
    Subcellular fractionation of kidneys from male rats administered
    14C-chlorothalonil. Unpublished report No. 1178-86-0016-AM-001 from
    Department of Toxicology and Animal Metabolism, Ricerca Inc.,
    Painesville, OH, USA. Submitted to WHO by Fermenta Plant Protection
    Co., Painesville, OH, USA.

    Wilson N.H. & Killeen J.C., Jr., 1986. Histopathologic re-evaluation
    of stomach tissue from a mouse tumorigenicity study with technical
    chlorothalonil (5TX.79-0102). Unpublished report No. 1178-86-0016-AM-001
    from Department of Toxicology and Animal Metabolism, Ricerca Inc.,
    Painesville, OH, USA. Study No. DTX-79-0102 performed by W.R. Brown,
    Research Pathology Services, Inc.. Submitted to WHO by Fermenta Plant
    Protection Co., Painesville, OH, USA.

    Wilson N.H. & Killeen J.C., Jr., 1987a. A tumorigenicity study of
    technical chlorothalonil in male mice - final report. Unpublished
    report No. 1099-84-0077-TX-006 from Department of Toxicology and
    Animal Metabolism, Ricerca Inc., Painesville, OH, USA. Submitted to
    WHO by Fermenta Plant Protection Co., Painesville, OH, USA.

    Wilson N.H. & Killeen J.C., Jr., 1987b. Report of the status of a
    tumorigenicity study of technical chlorothalonil in rats. Unpublished
    report No. 1102-84-0103-TX-001 from Department of Toxicology and
    Animal Metabolism, Ricerca Inc., Painesville, OH, USA. Submitted to
    WHO by Fermenta Plant Protection Co., Painesville, OH, USA.

    Wilson N.H., Killeen J.C., Jr. & Ignatoski J.A., 1983. A chronic
    dietary study in mice with chlorothalonil. Unpublished report
    No. 108-5TX-79-0102-004 from SDS Biotech Corp. Submitted to WHO by
    Fermenta Plant Protection Co., Painesville, OH, USA.

    Wilson N.H., Killeen J.C., Jr. & Ignatoski J.A., 1986a.
    Histopathologic re-evaluation of renal tissue from a mouse
    tumorigenicity study with chlorothalonil (5TX.79-0102). Unpublished
    report No. 764-5TX-85-0072-002 from SDS Biotech Corp., Painesville,
    OH, USA. Study performed by Busey W.M., Experimental Pathology
    Laboratories, Inc., Herndon, VA, USA. Submitted to WHO by Fermenta
    Plant Protection Co., Painesville, OH, USA.

    


    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: 1983 evaluations)
       Chlorothalonil (Pesticide residues in food: 1985 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)