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    DICLORAN             JMPR 1998

    First draft prepared by
    C.E. Moase
    Health Evaluation Division, Pest Management Regulatory Agency, Ottawa,
    Ontario, Canada

         Explanation
         Evaluation for acceptable daily intake
              Biochemical aspects
                   Absorption, distribution, and excretion
                   Biotransformation
                   Effects on enzymes and other biochemical parameters
              Toxicological studies
                   Acute toxicity
                   Short-term studies of toxicity 
                   Long-term studies of toxicity and carcinogenicity
                   Genotoxicity
                   Reproductive toxicity
                        Single-generation reproductive toxicity
                        Multigeneration reproductive toxicity
                        Developmental toxicity 
                   Special studies
                        Cataractogenicity
                        Haematological effects
              Observations in humans
         Comments
         Toxicological evaluation
         References


    Explanation

         Dicloran was evaluated for toxicological effects by the Joint
    Meetings in 1974 and 1977 (Annex 1, references 22 and 28). A temporary
    ADI of 0-0.03 mg/kg bw was established in 1974 on the basis of the
    results of a two-year study in dogs and short- and long-term studies
    in rats. The 1977 Meeting established an ADI of 0-0.03 mg/kg bw on the
    basis of these studies, after examination of further data on
    oculotoxicity in dogs, metabolism and pharmacokinetics in pigs, and
    the effects of dicloran on liver microsomal enzymes, in compliance
    with the request of the 1974 Joint Meeting.

         Dicloran was reviewed by the present Meeting within the CCPR
    periodic review programme. In addition to studies previously reviewed,
    newly available studies, including those on metabolism, short-term
    toxicity in mice and rats, carcinogenicity in mice, genotoxicity,
    reproductive toxicity in rats, and developmental toxicity in rabbits,
    were reviewed. This monograph summarizes the new data and includes
    relevant data from the previous monograph and monograph addendum
    (Annex 1, references 23 and 29).


    Evaluation for acceptable daily intake

    1.  Biochemical aspects

     (a)  Absorption, distribution, and excretion

         The 1974 Joint Meeting concluded that dicloran is rapidly
    absorbed, metabolized, and excreted by mammals, including humans, with
    the formation of chlorinated phenylenediamine and aminophenol, which
    are conjugated and excreted. 

         When dicloran was administered orally or intraperitoneally at
    single doses of 10-40 mg/kg bw to rats, 91% of the oral dose was
    excreted in the urine within three days (77% in 24 h) and 1% in the
    faeces, and 83% of the intraperitoneal dose was excreted in the urine
    within three days (70% in 24 h) and 1.5% in the faeces. A small amount
    appeared to be excreted in the bile, amounting to 2% of the dose 6 h
    after intraperitoneal injection and 5% within 12 h after oral delivery
    (Mat et al., 1967). 

         14C-Dicloran administered orally to groups of three male
    Sprague-Dawley rats at a dose of 1.7 or 8 mg/kg bw was rapidly
    excreted. Urinary excretion accounted for approximately 90% of the
    administered dose, which was recovered within 48 h; up to 85% was
    recovered within 8 h of treatment. The remainder was present in the
    faeces. Small quantities of radiolabel were detected in the
    gastrointestinal tract, urinary tract, and liver. 14C-Dicloran
    administered to three male volunteers at a dose of 50 mg was also
    rapidly absorbed and excreted, with 72-79% of the administered dose in
    urine and 24-36% in faeces. Although recovery was considered to be
    complete, excretion was somewhat slower in humans than in rats, with
    49% of the administered dose recovered in urine and faeces within 24 h
    and 76% within 48 h; most of the material was excreted within 1.5 days
    (Eberts, 1965). 

         [U-14C]-Dicloran (purity, > 99%) was administered by gavage to
    groups of five male and five female Sprague-Dawley rats as a single
    dose of 5 or 500 mg/kg bw. Dicloran appeared to be well absorbed from
    the intestinal tract and was rapidly excreted in the urine, most of
    the radiolabel (90-96%) being excreted within 24 h of administration
    of the low dose and 91% within 48 h of the high dose; 93-98% had been
    eliminated by day 4 after treatment with both the low and the high
    dose. The urine was the principle route of elimination (> 77% at the
    low dose, > 70% at the high dose), with an additional 13% eliminated
    in the faeces of animals at the low dose and 22% in faeces of those at
    the high dose. Radiolabelled residues in the tissues and carcass
    accounted for < 1% of the administered dose, the liver and carcass
    containing the highest concentrations (O'Boyle & Challis, 1991a,b). 

         In groups of five hens dosed with 14C-dicloran in capsules (0.37
    or 6 mg/hen per day) for five days, dicloran was rapidly absorbed,
    metabolized, and eliminated. More than 80% was excreted, and 50-57% of

    the administered dose was recovered within 24 h of dosing (Dawson,
    1988).

         In goats intubated with 14C-dicloran, the administered
    radiolabel was completely recovered from urine and faeces by 72 h; 38%
    was recovered within the first 24 h from goats treated with 1.5 mg/kg
    bw and 96% from those given 8 mg/kg bw. More than 10 times more
    residues were found in goats than in Sprague-Dawley rats 72 h after
    treatment, with only trace amounts of residues in other tissues. The
    liver residues in goats could not be extracted with organic solvents,
    whereas most of the radiolabelled residues were extractable from rat
    liver. In contrast, muscle residues from goats treated with a single
    dose of 8 mg/kg bw were not covalently bound to macromolecules (Jaglan
    & Arnold, 1985a,b; Jaglan et al., 1985a). In a lactating goat given
    613 mg 14C-dicloran in a capsule daily for five days, 0.5% of the
    administered radiolabel was detected in milk. The parent compound and
    4-amino-2,6-dichlorophenol were the major residues (Cheng, 1996a).

     (b)  Biotransformation

         Preliminary studies suggested that dicloran metabolites in humans
    are similar to those in rats. 2,6-Dichloro-4-hydroxyaniline sulfate
    represented about 85% of the total radiolabel excreted in rat urine
    (Eberts, 1965).

         14C-Dicloran administered to rats intraperitoneally or orally at
    a dose of 20 mg/kg bw was metabolized to dichloroamino-phenol and
    dichlorophenylenediamine derivatives. The major metabolite in urine
    was 2,6-dichloro-4-hydroxyaniline (4-amino-3,5-dichlorophenol), which
    represented 50% of the dose and 70% of the urinary activity. This was
    excreted as a conjugate, therefore undergoing rapid deactivation
     in vivo. The only other metabolite detected in the urine was
    2,6-dichlorophenylenediamine (4-amino-2,6-dichloroaniline),
    representing 2.4% of urinary activity, although Cheng (1996b; see
    below) reported concentrations of < 0.1% of the administered dose.
    Studies with mouse liver microsomes  in vitro showed limited
    conversion of dicloran to the same two metabolites (~20 % each; Mat
    et al., 1967). These were also reported to be the principal
    metabolites in dogs and monkeys (Bachmann et al., 1971).

          Groups of five Sprague-Dawley rats of each sex received repeated
    doses of 5 mg/kg bw unlabelled dicloran (purity, > 97%) by gavage for
    two weeks or a single oral dose of 500 mg/kg bw before treatment with
    [U-14C]-dicloran (purity, > 99%). The compound appeared to be well
    absorbed from the intestinal tract and was rapidly excreted in the
    urine, most of radiolabel being excreted within 24 h of dosing. There
    were no apparent sex-related differences in absorption or elimination,
    and urine was the principal route of excretion (~85% of the low dose,
    66% of the high dose) in males and females. Within 48 h, 92-93% of the
    administered dose had been metabolized and excreted by animals at the
    low dose and 82-86% by those at the high dose. The concentrations of
    residues in tissues were low, the highest concentrations being found
    in liver (0.05-0.06 ppm) and kidney (0.02 ppm) seven days after dosing

    with 5 mg/kg bw; the concentrations in other tissues were < 0.01
    ppm. The concentrations of radiolabelled residues were comparable in
    males and females, and the total residues accounted for 0.2-0.3% of
    the administered dose. The major urine metabolites were
    2,6-dichloro-4-hydroxyaniline sulfate (22-63% of administered dose)
    and 2,6-dichloro-4-hydroxyaniline glucuronide (16-29%). Unchanged
    parent compound was detected in faeces of animals at the high dose
    only. The major faecal metabolites were derivatives of glutathione
    conjugates. The excretion and metabolite profiles were essentially
    independent of dose and pretreatment, although there were some
    quantitative, sex-dependent differences in the distribution of major
    urinary metabolite fractions (Cheng, 1996b). 

         An integrated pathway for the metabolism of dicloran in rats,
    goats, hens, plants, and soil is indicated in Figure 1. The parent
    compound and its glutathione conjugates were the major metabolites of
    plants, comprising 32-51% of residues in peaches, potatoes, and
    lettuces (Hawkins et al., 1988; Smith, 1989; O'Neal, 1997a,b). None of
    the metabolites was of toxicological concern.

         The highest residues in tissues of hens dosed with capsules
    containing 14C-dicloran at 150 g/bird per day for three days were
    found in egg yolk, fat, and liver (0.74, 0.21, and 0.10 g/g,
    respectively). Only the parent compound was detected in egg yolk and
    fat. The residues in liver consisted of 4-amino-3,5-dichloroacetilide
    (24%), 2,6-dichloro-4-nitrophenol (21%), and parent (54.8%; Dawson,
    1988). 

         Groups of five hens treated with dicloran at a dose of 0.37 or 6
    mg/day for five days excreted more than 80%, 3-11% of which was parent
    compound. The percentage of the residues that were extractable (i.e.
    unbound) was 87% (in liver) to 100%, with the highest residue
    concentrations in liver and egg yolk of hens given either dose and in
    abdominal fat of those given the high dose. Parent compound was the
    major component of fat (94%) and egg yolk (> 80%), and
    2,6-dichloro-4-nitrophenol was the major metabolite in liver (45-58%
    of residue). 4-Amino-3,5-dichloroacetilide and
    3,5-dichloro-4-hydroxyacetanilide were found at concentrations of
    1-12% and 12-33%, respectively, in liver and muscle. The
    concentrations of other metabolites represented < 10% of radiolabel
    in tissue. The metabolites underwent subsequent sulfate or glutathione
    conjugation and excretion (Cheng, 1996c).

         The major metabolite in rat urine (2,6-dichloro-4-hydroxyaniline)
    was not present in goat urine, and rat urine contained more polar
    metabolites than goat urine, whereas goat urine had more polar
    conjugates that could not be hydrolysed by glucuronidase or sulfatase.
    In goats, dicloran is reduced to 2,6-dichlorophenylenediamine and
    acetylated to 3,5-dichloro-4-aminoacetanilide (4-6% in urine), which
    is rapidly metabolized and excreted in the urine and faeces. Although
    the reactive intermediate is formed in goat liver and is bound
    covalently to macromolecules, goat liver-bound residues had little

    FIGURE 1


    DCNA, 2.6-dichloro-4-nitroaniline; HCNA,
    2-hydroxy-4-nitro-6-chloroaniline; DCHA,
    2,6-dichloro-4-hydroxyaniline; DCAP, 4-amino-2,6-dichlorophenol;
    DCNAP; 3,5-dichloro-4-hydroxyacetanilide; DCDP,
    2,6-diclorophenylenediamine; DCAA, 4-amino-3,5-dichloroacetanilide;
    DCNP, 2,6-dicholoro-4-nitrophenol; DCP, 2,6-dichlorophenol; DCA, 
    2,6 dichloroaniline; A1, A2, A3, glutathione conjugate deriviatives.
    R, G, H, P, S correspond to metabolites in rats, goats, hens, plants, 
    and soil or sediment, respectively. Major metabolites are represented
    by letters in upper-case, minor metabolites are represented by
    lower-case letters.
    
    potential to form reactive intermediates after ingestion by rats
    (Jaglan & Arnold, 1985a; Jaglan et al., 1985a,b).

     (c)  Effects on enzymes and other biochemical parameters

         Oral administration of dicloran at a dose of 400 or 1000 mg/kg bw
    per day to rats for three months resulted in increased hepatic
    demethylase and desulfurase activity, and liver mitochondrial oxygen
    consumption was increased (Serrone et al., 1967). Dicloran at oral
    doses of > 10 mg/kg bw stimulated rat liver mixed-function
    oxidases, and a dose of 500 mg/kg bw decreased mitochondrial oxidation
    of succinate without concomitant uncoupling of oxidative
    phosphorylation. Oxidative phosphorylation was not affected by single
    doses at any concentration. Daily administration of 1000 mg/kg bw to
    rats induced uncoupling of oxidative phosphorylation after four days
    (Bachmann et al., 1971). These liver enzymes were not stimulated in
    rhesus monkeys treated with 160 mg/kg bw per day dicloran for three
    months (Serrone et al., 1967), and no effect was seen on brain or
    liver mitochondrial function in mice (Bachmann et al., 1971). 

         The 2,6-dichloro-4-hydroxyaniline metabolite was as active as
    2,4-dinitrophenol  in vitro in uncoupling oxidative phosphorylation,
    whereas dicloran was only one-tenth as effective.
    2,6-Dichlorophenylenediamine had no effect on mitochondrial
    respiration or oxidative phosphorylation  in vitro (Bachmann et al.,
    1971).

         Dicloran and 2,6-dichloro-4-hydroxyaniline at 10-5 mol/L
    inhibited electron transport and uncoupled oxidative phosphorylation
     in vitro, whereas 2,6-dichlorophenylenediamine at 10-4 mol/L
    induced only slight uncoupling. These inhibitory effects  in vitro 
    cannot be considered serious adverse effects since they were not
    confirmed by similar observations  in vivo. Mitochondria isolated
    from rats treated with dicloran or its metabolites were functionally
    normal (Gallo et al., 1976).

         In a preliminary study, oral doses of 1000 mg/kg bw dicloran per
    day for four days to female Sprague-Dawley rats did not significantly
    induce cytochrome P450 activity (Basting et al., 1984). After oral
    administration of 100 mg/kg bw twice a day for four days to male
    Sprague-Dawley rats, however, significant increases were found in the
    activities of cytochrome P450 (55% increase), cytochromeb5 (24%
    increase), benzphetamine demethylase, and ethoxycoumarin deethylase 
    (51-68% increases) in comparison with controls. The pattern of enzyme
    induction was reported to indicate that dicloran significantly induces
    phenobarbital-type enzymes in rat microsomes (Creedy et al., 1985).

    2.  Toxicological studies

     (a)  Acute toxicity

         The results of studies on the acute toxicity of dicloran are
    presented in Table 1. Technical-grade dicloran was of low or slight
    acute toxicity by all routes of administration in all species
    examined. Oral administration resulted in nasal haemorrhage,
    paralysis, depression, and excessive yellow urine and faeces.
    Intraperitoneal administration resulted in sleep, depression, and
    excessive yellow urine and faeces. The effects of subcutaneous
    injection were confined to local damage in which the test substance
    became enclosed in a fibrous sac, sometimes followed by abscess
    formation and eventual ulceration. Dermal administration resulted in
    no systemic clinical effects.

         Technical-grade dicloran (purity, 96%) was not irritating to the
    intact or abraded skin of male or female New Zealand white rabbits at
    a concentration of 500 mg per site (Raczniak & Wood, 1980b) or after
    repeated daily applications of 10 mg dry material or 0.1 ml of 10%
    aqueous suspension to the abraded or unabraded skin of albino rabbits
    over five days (Boots Pure Drug Co., 1962).

         Technical-grade dicloran (purity, 96%) caused a minimal
    conjunctival response in the eys of New Zealand white rabbits,
    consisting of redness and chemosis 24 and 48 h after treatment.
    Corneal opacity or injury to superficial layers of the corneal or
    conjunctival epithelium was not observed (Raczniak & Wood, 1980c).

         Four successive daily applications of 2-3 mg dicloran to the
    conjunctival sac of four rabbits resulted in a slight inflammatory
    reaction of the cornea, which was of short duration (Boots Pure Drug
    Co., 1962).

         Dicloran was inactive in two tests for skin sensitization in
    guinea-pigs (Boots Pure Drug Co., 1962; Johnston & Schwikert, 1963).

     (b)  Short-term studies of toxicity

     Mice

         Groups of Charles River COBS mice were fed diets containing 0,
    1250, 2500, 5000, or 10 000 ppm technical-grade dicloran for two
    weeks, equivalent to 0, 190, 380, 750, and 1500 mg/kg bw per day. At
    10 000 ppm, 20% of animals of each sex died; the only clinical sign
    observed was hunched posture. Food consumption and body weight were
    significantly reduced. Female mice fed 5000 or 10 000 ppm had
    significantly increased absolute liver weights, and animals of each
    sex fed doses of 2500 ppm or more had an increased liver:body-weight
    ratio. Food consumption was slightly reduced in animals of each sex at
    2500 and 5000 ppm, and a slight reduc-tion in food consumption was
    noted at 1250 ppm only in females (Mallyon & Rawcliffe, 1985).


        Table 1. Acute toxicity of dicloran

                                                                                                                  

    Species        Strain               Sex      Route              LD50             Reference
                                                                    (mg/kg bw)
                                                                                                                  

    Rat            Sherman SPF          M/F      Oral                  > 4000        Gaines & Linder (1986)
    Rat            NR                   NR       Oral                    4040        Boots Pure Drug Co. (1962)
    Rat            NR                   NR       Oral                  ~ 8000        Serrone et al. (1967)
    Rat            NR                   NR       Oral                > 10 000        Johnston & Ceru (1961)
    Mouse          NR                   NR       Oral               1500-2500        Boots Pure Drug Co. (1962)
    Guinea-pig     NR                   NR       Oral                    1400        Boots Pure Drug Co. (1962)
    Rabbit         New Zealand white    M/F      Dermal (abraded)      > 2000        Raczniak & Wood (1980a)
    Mouse          NR                   NR       Intraperitoneal         5500        Johnston & Ceru (1961)
    Mouse          NR                   NR       Intraperitoneal         2500        Boots Pure Drug Co. (1962)
    Rat            NR                   NR       Intraperitoneal         1500        Boots Pure Drug Co. (1962)
    Rat            NR                   NR       Subcutaneous          > 5000        Boots Pure Drug Co. (1962)
    Mouse          NR                   NR       Subcutaneous          > 6000        Boots Pure Drug Co. (1962)
                                                                                                                  

    SPF, specific pathogen-free; M/F, male and female; NR, not reported
    

         Groups of 10 male and 10 female CD-1 (ICR) mice received dicloran
    (purity, 95.8%) in the diet at 0, 300, 600, or 1200 ppm, equal to 0,
    49, 100, and 200 mg/kg bw per day in males and 0, 53, 100, and 220
    mg/kg bw per day in females, for 60 days. There were no
    treatment-related effects on survival, clinical signs, body weight,
    food or water consumption, or food conversion. A significant increase
    in methaemoglobin concentrations in the blood of both males and
    females was noted at 600 and 1200 ppm (males: 1, 1.3, 1.4, and 1.6%;
    females: 0.6, 0.7, 0.9, and 1.2%, control to high dose, respectively).
    Cholesterol and bilirubin concentrations were significantly increased
    in high-dose females (cholesterol: 2.4  0.58, 2.2  0.50, 2.5  0.2,
    3.0  0.65 mmol/L; bilirubin: 4.3  0.6, 5.4  1.4, 5.5  2.4, 5.8 
    1.7 mol/L, control to high dose, respectively). These changes were
    dose-related but were not observed in males, which, unlike females,
    had specific liver lesions. Minimal to slight centrilobular
    hepatocytic enlargement (2-5/10 versus 0/10 controls) and fatty liver
    degeneration (2-4/10 versus 0/10 controls) with an increased severity
    of haemosiderosis in the spleen was noted in males at 600 and 1200
    ppm, and a slight increase in the degree of haematopoietic activity
    was noted in the spleen of males and females combined at the
    intermediate and high doses. The NOAEL was 300 ppm, equal to 49 mg/kg
    bw per day in males (Mallyon et al., 1986).

         Dicloran (purity, 97%) was administered to groups of 15 B6C3HF1
    mice of each sex (five of each sex per dose for interim sacrifice) by
    gavage at doses of 0, 15, 45, 135, 400, or 600 mg/kg bw per day for 90
    days, with an interim sacrifice at 49 days. There were no
    treatment-related effects on survival or body weight; data on food
    consumption were not provided. Significant polycythaemia was seen in
    males, and hypercholesterolaemia at 1.2-2.1 times the control level
    and a significant increase in the incidence of splenic extramedullary
    haematopoiesis were seen in females at > 45 mg/kg bw per day.
    Dose-related increases in cholesterol concentrations (1.3-2.3 times
    the control concentration) were also noted in males, which were
    statistically significant at > 135 mg/kg bw per day. A deep-yellow
    colouration of the urine was noted in all treated groups and was
    attributed to the yellow colour of the test material. In the absence
    of any associated lesion in the group at the lowest dose, this effect
    was considered not to be adverse. Other effects at higher doses
    included kidney nephrosis in males at 400 and 600 mg/kg bw per day (5,
    4, 6, 5, 15, 14/15, control to high dose, respectively) and females
    (3, 5, 2, 4, 8, 12/15), with kidney tubular regeneration in males (0,
    0, 3, 1, 8, 11/15), increased liver weights in animals of each sex at
    > 135 mg/kg bw per day (7-64% increase), hepatocyte hypertrophy in
    males (0, 0, 0, 4, 15, 15/15) and females (0, 0, 0, 0, 5, 12/15) at 
    > 400 mg/kg bw per day, liver necrosis in males (0, 0, 0, 0, 3,
    3/15) and females (0, 0, 0, 0, 1, 1/15) at 400 and 600 mg/kg bw per
    day, a significantly higher incidence of splenic extramedullary
    haematopoiesis in males at > 135 mg/kg bw per day (0, 1, 2, 13, 15,
    15/15) and in females at > 45 mg/kg bw per day (2, 5, 9, 10, 14,
    15/15), increased spleen weight at the two higher doses (11-29%
    increase), and epithelial hyperplasia of the urinary bladder in males

    (0, 1, 2, 10, 12, 15/15) and females (0, 0, 0, 1, 7, 13/15) at doses
    > 135 mg/kg bw per day. The NOAEL was 15 mg/kg bw per day (Kakuk,
    1986).

     Rats

         Dicloran (unspecified purity) was administered by gavage to rats
    (strain unspecified) at 400 or 1000 mg/kg bw per day for three months.
    Deaths occurred among rats at the high dose. Significantly enlarged
    livers and unspecified renal changes were observed by light and
    electron microscopy, with increases in liver mitochondrial enzyme
    activity and mitochondrial oxygen use (Serrone et al., 1967).

         Groups of five newly weaned rats (strain unspecified) of each sex
    were given dicloran (purity unspecified) by gavage at doses of 0, 140,
    or 350 mg/kg bw per day, six days/week for four weeks. The growth of
    males at 350 mg/kg bw per day was reduced to 60% of the control value.
    At both doses, increased liver weight (120-155% of control) with
    hepatic vacuolation were noted. There was no apparent effect on blood
    parameters or on the kidneys at the end of the study (Boots Pure Drug
    Co., 1962).

         Groups of 10 rats (strain unspecified) were given dicloran
    (purity unspecified) by gavage at doses of 35, 140, or 350 mg/kg bw
    per day, six days/week, for four weeks. Groups of 20 controls of each
    sex were available. Growth depression was observed in animals of each
    sex at 350 mg/kg bw per day and in males at 140 mg/kg bw per day.
    Increased liver weights and microscopic findings were also seen at
    these doses. The liver lesions included a dose-related increase in
    hepatocytic hypertrophy with increased vacuolization, especially in
    the outer lobes. The liver had returned to normal size in half of the
    animals which were maintained for two weeks after the end of the
    treatment, except for males at the highest dose. The histopathological
    changes in the liver caused by repeated short-term dosing was
    apparently reversible within two weeks of the end of treatment. The
    NOAEL was 35 mg/kg bw per day on the basis of effects on body weight
    and liver at 140 mg/kg bw per day (Boots Pure Drug Co., 1962).

         Technical-grade dicloran was fed to rats (strain unspecified) for
    six months at doses of 0 (25 rats), 30 (15 rats), 300 (15 rats), or
    3000 (10 rats) ppm, equal to 0, 2.2, 22, and 230 mg/kg bw per day in
    males and 0, 2.5, 25, and 270 mg/kg bw per day in females. Another
    10 animals of each sex per group received recrystallized dicloran at
    3000 ppm, equivalent to 230 mg/kg bw per day for males and 260 mg/kg
    bw per day for females. At 3000 ppm, growth of both males and females
    was impaired (70-83% of control), whereas males fed purified material
    had only a slight reduction in growth (89% of control). Significantly
    increased liver weights (120-144% of control) were noted in both
    groups at the high dose, with a significant increase in spleen weight
    (129% of control) in females. Haematological parameters were not
    affected at 12 weeks or at termination, and no microscopic lesions
    were noted. The NOAEL was 300 ppm, equal to 22 mg/kg bw per day, on

    the basis of changes in body weight and increased liver and spleen
    weights at 3000 ppm (Boots Pure Drug Co., 1962).

         Dicloran (purity, 97.4%) was administered to groups of 10 male
    and 10 female Sprague-Dawley rats in the diet at doses of 0, 1000,
    3000, or 5000 ppm, equal to 0, 75, 230, and 370 mg/kg bw per day in
    males and 0, 80, 230, and 420 mg/kg bw per day in females, for 90
    days. There were no treatment-related effects on survival or
    ophthalmological parameters. Significantly lower body-weight gain was
    seen in all treated groups (17-32% less than controls for males and
    18-22% less for females). Although palatability may have accounted for
    the lower body-weight gains during the first week of the study, food
    consumption was comparable in all groups at week 2; however, it was
    consistently lower than control values throughout the remainder of the
    study (males, 10-14% less than controls; females, 12-21%; weeks 2-13).
    Many of the haematological and clinical chemical findings were
    considered to be associated with reductions in food consumption. The
    treatment-related hepatic effects included increased cholesterol
    concentrations, which were dose-related and statistically significant
    in males at all doses (1.3-1.5 times the control concentration) and in
    females at the intermediate and high doses (1.4-2.0 times control),
    minimal to moderate centrilobular hypertrophy in males in all treated
    groups (0, 3, 9, 9/10) and in females at the two higher doses (0, 0,
    9, 9/10), and significant increases in liver weight in males and
    females at the two higher doses (29-66%). Minimal thyroid
    follicular-cell hypertrophy was noted in males in all treated groups
    (0, 5, 6, 6/10) and in females at the intermediate and high doses (0,
    0, 4, 7/10). The dose of 1000 ppm, equal to a daily intake of 75 and
    80 mg/kg bw per day for males and females, respectively, was
    considered to be at the upper limit of a suitable high-level dose for
    a long-term study of toxicity and carcinogenicity in rats. An NOAEL
    was not identified because significantly lower body-weight gains were
    seen at all doses (Peters et al., 1990). 

         A second short-term study was conducted to investigate the
    effects of dicloran at doses lower than those administered in the
    90-day study. Dicloran (purity, 96.4%) was given in the diet to groups
    of 10 Sprague-Dawley rats of each sex at doses of 0, 500, or 750 ppm,
    equal to 0, 44, and 71 mg/kg bw per day for males, and 0, 48, and 71
    mg/kg bw per day for females, for eight weeks. There were no
    treatment-related effects on survival. The overall body-weight gain of
    females at 750 ppm was significantly less than that of controls (12%
    less overall), the greatest difference occurring during the final two
    weeks of treatment (41-58% less than control). This decrease
    correlated with a slight decrease in food consumption in this group
    during treatment, which was 10-11% less than that of controls during
    the last two weeks of treatment. Increased liver weight relative to
    body weight (13-21%) in animals of each sex at 750 ppm was associated
    in 10/10 males with minimal centrilobular hepatocyte enlargement. The
    NOAEL was 500 ppm, equal to 44 mg/kg bw per day, on the basis of lower
    body-weight gain and decreased food consumption in females at 750 ppm
    and increased liver weights in males and females, with associated
    centrilobular hepatocyte enlargement in males at 750 ppm; however, a

    full histological examination was not carried out (only of the liver
    and thyroid), and although alterations were found in the livers of
    males at the high dose, the livers of males at the low dose were not
    examined histologically (Waterson et al., 1992). 

     Rabbits

         Technical-grade dicloran (purity, 96.2%) was moistened with
    distilled water and applied to the intact skin of groups of five male
    and female New Zealand white rabbits under an occluded patch for 6 h
    per day for 21 consecutive days at doses of 12, 120, or 1200 mg/kg bw
    per day. Animals at the two higher doses showed yellow staining of
    untreated fur and extremities from day 4 onwards, but there were no
    adverse clinical findings. One male and one female rabbit at 12 mg/kg
    bw per day had slight, transient erythema lasting for two to four
    days, and most rabbits at 120 and 1200 mg/kg bw per day had slight
    erythema beginning in the second week of the study, which tended to
    persist until study termination. The reaction did not progress beyond
    slight erythema, and there did not appear to be a dose-related
    difference above 120 mg/kg bw per day. At termination, male rabbits at
    1200 mg/kg bw per day had significantly greater (36%) adrenal weights
    than controls, but the adrenals were not examined histologically. The
    liver weights were 18% greater in females at 1200 mg/kg bw per day
    than in controls. No other effects were seen on body weight, food
    consumption, or haematological, biochemical, or histological
    parameters. The NOAEL was 120 mg/kg bw per day (Elliot et al., 1988).

     Rats, rabbits, and dogs

         Groups of 10 male and 10 female TUC/SPD rats, one male and one
    female New Zealand white rabbit, and two male beagle dogs were exposed
    to a dust aerosol of technical-grade dicloran by whole-body exposure
    for 6 h per day, five days per week for three weeks. The nominal
    concentration of the aerosol was 2 mg/L; the actual concentration and
    particle size were not provided. Two rats died on the third day of
    exposure, and one rabbit died on day 13. The food consumption and
    body-weight gains of the treated animals were depressed. There were no
    consistent haematological changes attributable to treatment. The blood
    cholesterol concentration was significantly elevated in exposed dogs
    and rabbits. The liver weights of exposed animals were increased,
    although the histological appearance was unremarkable, with no
    evidence of hepatocellular effects in any species (Seaman et al.,
    1980).

     Monkeys

         Oral doses of 160 mg/kg bw per day were lethal to rhesus monkeys
    within three months, with a greater effect on females than males. The
    colouration of the urine differed from that of rat urine, suggesting a
    difference in metabolism in the two species. Centrilobular fatty
    infiltration was observed in the liver, and liver and kidney changes
    were observed on electron microscopic examination, which included

    swelling of mitochondria with distortion of the cristae. Hepatic
    microsomal enzyme activity was not enhanced (Serrone et al., 1967).

     (c)  Long-term studies of toxicity and carcinogenicity

     Mice

         In a screening study, groups of 18 mice of each sex of each of
    two susceptible hybrid strains (unspecified) were given dicloran at
    215 mg/kg bw per day for three weeks from day 7 after birth.
    Thereafter, for 18 months, the mice were fed 600 ppm (equivalent to
    100 mg/kg bw per day) in the diet, sacrificed, and examined for
    tumours. Dicloran did not cause a significant increase in the
    incidence of tumours (Innes et al., 1969).

         Dicloran (purity, 96.2-97.2%) was administered to groups of 50
    CD-1 mice of each sex at dietary concentrations of 0, 50, 175, or 600
    ppm, equal to 0, 7.4, 24, and 86 mg/kg bw per day in males and 0, 10,
    36, and 120 mg/kg bw per day in females, for 80 weeks. The doses were
    based on a the results of a 60-day dietary study in mice in which a
    concentration of 600 ppm was associated with increased methaemoglobin
    concentration, splenic pigment change, increased haematopoiesis,
    centrilobular hepatocyte enlargement, and fatty degeneration of
    hepatocytes. There was no adverse effect on mortality (percent
    survival at termination: males, 50, 50, 64, and 56%; females, 84, 76,
    76, and 78%, control to high dose, respectively). There were no
    treatment-related effects on clinical signs, body weight, palpable
    masses, food consumption, food conversion, or differential leukocyte
    counts. Clinical chemistry and urinalysis were not performed. There
    was no increase in tumour incidence. The liver was the principal
    target organ, with increased absolute and relative weights (10-12%) in
    males and females at the high dose, which were statistically
    significant in females, and histopathological changes. These included
    centrilobular hepatocyte enlargement (males: 8, 8, 7, and 26/50;
    females: 1, 0, 2, and 5/50), centrilobular haemosiderosis (males: 1,
    2, 4, and 12/50; females: 7, 5, 3, and 13/50), focal (4, 2, 5, and
    10/50) and single-cell (1, 1, 0, and 6/50) liver necrosis in males,
    and vacuolation of centrilobular hepatocytes (4, 3, 3, and 12/50) in
    females. Acute inflammatory cell infiltration was seen in males at the
    intermediate and high doses (2, 4, 9, and 9/50), but no other hepatic
    changes were seen in males at this dose. Other changes at 600 ppm
    included a higher incidence of erythropoiesis in the spleens of males
    (7, 7, 8, and 15/50), an increased number of females with an
    enlarged/distended uterus (5, 9, 9, and 15/50), associated with a
    significant increase in the incidence and severity of cystic uterine
    endometrial hyperplasia (17, 21, 24, and 31/50), and an increased
    number of females at the high dose with distended mammary gland ducts
    (9/50 versus 3/50 in control; animals at the low and intermediate
    doses were not assessed). An 11% increase in kidney weight in males
    was not associated with histopathological lesions. On the basis of the
    above findings, the NOAEL was 175 ppm, equal to 24 mg/kg bw per day
    (Mallyon & Markham, 1989). 

     Rats

         Groups of 35 rats (strain unspecified) of each sex were fed
    dicloran (purity unspecified) in the diet at concentrations of 0, 20,
    100, or 3000 ppm for two years, equal to 0, 1.6, 8, and 240 mg/kg bw
    per day, with an interim sacrifice of five animals of each sex per
    dose at 13 weeks. The dose of 100 ppm had no effect on behaviour,
    mortality, or growth, and all values were comparable to those of
    controls. At 3000 ppm, growth and food consumption of males and
    females were depressed, and haematological parameters (haemoglobin and
    packed cell volume) were reduced but only after the first year of
    treatment. Gross and microscopic examination at 13 weeks and at the
    conclusion of the study showed slightly heavier livers, kidneys, and
    testes in males at 3000 ppm. The incidence and location of neoplasms
    were similar in treated and control rats. Histological examination
    revealed changes in the liver at 3000 ppm, characterized by
    hepatic-cell enlargement, increased severity of glycogen depletion,
    increased basophilia of the cytoplasm, and the presence of dead cells.
    Other observations were increased thyroid hypertrophy and increased
    pigmentation of the spleen in males and females at 3000 ppm.
    Hepatic-cell changes and slight adrenal cortical atrophy were seen in
    several animals at this dose at 13 weeks, but the adrenal changes were
    not seen at 104 weeks. The NOAEL was 100 ppm, equal to 8 mg/kg bw per
    day (Woodard et al., 1964). 

         Groups of 25 Boots-Wistar strain rats of each sex were fed
    dicloran (purity unspecified) in the diet at a concentration of 0 or
    1000 ppm for two years, equal to 59 mg/kg bw per day in males and 71
    mg/kg bw per day in females. There was no effect on survival, food
    consumption, growth, haematological parameters, or gross or
    histological appearance of tissues and organs at the conclusion of the
    study. There were no differences in the size or cellular constitution
    of the liver, kidney, or spleen. The incidence of tumours in control
    and treated groups was similar. The NOAEL was 1000 ppm, equal to 59
    mg/kg bw per day, the highest dose tested (Lessel, 1974).

     Dogs 

         Groups of four male and four female beagle dogs were fed dry
    diets containing dicloran (purity unspecified) at concentrations of 0,
    20, 100, or 3000 ppm for two years, equal to 0, 0.33, 1.7, and 44
    mg/kg bw per day for males and 0, 0.36, 1.8, and 62 mg/kg bw per day
    for females, with an interim sacrifice of one animal of each sex per
    dose at 14 weeks. No compound-related changes in behaviour, food
    consumption, or growth were observed. One female at 3000 ppm died at
    74 weeks, with treatment-related signs of haemolytic anaemia (reduced
    haemoglobin, immature erythrocytes, polychromophilic macrocytes,
    increased leukocyte count, and increased myeloid: erythroid ratio in
    the bone marrow) before death. One control male lost considerable
    weight but survived to the end of the study. All dogs at 3000 ppm had
    watery lachrymation, which persisted throughout treatment; the
    examination of the eyes was not adequate to determine any ocular
    toxicity of dicloran. Yellowing of the sclera, mucous membranes, and

    abdominal skin were noted at the high dose. Changes in haematological
    and clinical chemical parameters in males and females at the high dose
    included significant reductions in haemoglobin from week 26 to
    termination and reduced serum protein at termination; increased
    activity of alanine and aspartate aminotransferases and increased
    prothrombin time, blood urea nitrogen, and bromosulphthalein retention
    were observed in one male and the one female that died at the high
    dose, both of which had received 20-94% more test material than the
    other dogs in this group owing to gradual body-weight loss relative to
    the constant concentration in the diet. Gross and microscopic
    examination revealed significantly increased liver, spleen, and kidney
    weights accompanied by histological changes at 3000 ppm, which
    included irregular hepatic-cell size (3/5 versus 0/6 in other groups),
    moderate hepatic-cell hypertrophy (3/5 versus 0/6 in controls) and
    increased pigmentation of the liver (4/5 versus 0/6 in control), and
    spleen (5/5 versus 0/6 in controls). One male and two females at 3000
    ppm (including the female that died) and one male at 20 ppm also had
    enlarged gall-bladders containing tar-like, viscous bile, although
    this was stated to be a spontaneous lesion in dogs (cystic mucinous
    hypertrophy). Changes at 100 ppm which included irregular hepatic
    cells, slight focal hepatocytic hypertrophy, slight vacuolation,
    moderate liver pigmentation, and/or marked spleen pigmentation were
    noted in two female dogs. A company re-evaluation attributed the
    findings at 100 ppm to enzyme induction, although the
    histopathological findings in this group were complicated by the
    presence of parasitic hepatitis. No degenerative lesions were noted at
    study termination, and there was no progression in the severity of
    hepatocellular effects between interim and terminal sacrifice. The
    NOAEL was 100 ppm, equal to 1.7 mg/kg bw per day, on the basis of
    significant reductions in haemoglobin, reduced serum protein, and
    histopathological changes in the liver and spleen at 3000 ppm (Woodard
    et al., 1964; Kakuk et al., 1979).

     (d)  Genotoxicity 

         The results of studies on the mutagenicity and genotoxicity of
    dicloran are presented in Table 2. Dicloran gave occasional positive
    responses in the most recent tests for reverse mutation and in a test
    for mitotic recombination, with a 2-2.5-fold increase in mitotic
    recombination. The results of the test for sex-linked recessive lethal
    mutation in  Drosophila were equivocal, even after re-analysis in
    conjunction with historical control data.

     (e)  Reproductive toxicity

    (i)   Single-generation reproductive toxicity

         Male rats (strain unspecified) were treated with dicloran (purity
    unspecified) in the diet at concentrations of 0, 1000, or 2000 ppm,
    equivalent to 0, 50, and 100 mg/kg bw per day, for 90 days. The dose
    of 1000 ppm increased liver and kidney weights. When the males were
    mated with untreated females, no difference was observed in the number


        Table 2. Results of assays for the genotoxicity of dicloran

                                                                                                                                  

    End-point                 Test object               Concentration             Purity    Result       Reference
                                                                                  (%)
                                                                                                                                  

    In vitro
    Reverse mutationa         S. typhimurium TA98,      16, 31, 62, 125,          99.9      Negativeb    Everest & Tuplin (1977)
                              TA100, TA1535,            250, 500, 1000 
                              TA1537, TA1538            g/plate in DMSO

    Reverse mutationa         S. typhimurium            100 g/plate in           NR        Negative     Shirasu et al. (1976)
                              TA1535, TA1536,           DMSO
                              TA1537, TA1538

    Reverse mutationc         S. typhimurium TA98,      20-200 g/plate           99.5      Negatived    Jeang & Li (1978)
                              TA100                     in DMSO

    Reverse mutatione         S. typhimurium TA98,      2, 20, 200 g/plate       99.5      Negativef    Jeang & Li (1980)
                              TA100                     in DMSO

    Reverse mutationa         S. typhimurium TA98,      6 concentrations          NR        Negative     Waters et al. (1982);  
                              TA100, TA1535,            up to 10 000 g/plate                            Garrett et al. (1986)
                              TA1537, TA1538

    Reverse mutationa         S. typhimurium TA98,      62, 100, 155, 200,        NR        Positiveg    Basting et al. (1983); 
                              TA98 NRF, TA100,          310, 415 g/plate in                             Myers-Basting (1986)
                              TA100 NRF                 ethyl cellosolve/ethanol 
                                                        or DMSO

    Reverse mutationa         S. typhimurium TA98,      50, 150, 500, 1500,       97.5      Positiveh    Jones & Fenner (1987)
                              TA100, TA1535,            5000 g/plate in 
                              TA1537, TA1538            DMSO

    Reverse mutationa         S. typhimurium TA98,      10, 33, 100, 333,         98        Positivei    Zeiger et al. (1992)
                              TA100                     1000, 2000 g/plate 
                                                        in DMSO

    Table 2. (continued)

                                                                                                                                  

    End-point                 Test object               Concentration             Purity    Result       Reference
                                                                                  (%)
                                                                                                                                  

    Reverse mutationc         E. coli WP2, WP2uvrA-     62, 125, 250, 500,        99.9      Negativej    Everest & Tuplin (1977)
                                                        1000 g/plate in 
                                                        DMSO

    Reverse mutationc         E. coli B/r try WP2,      20 g/plate in DMSO       NR        Negative     Shirasu et al. (1976)
                              WP2 try hcr

    Reverse mutationa         E. coli WP2uvrA-          6 concentrations          NR        Negativek    Waters et al. (1982);  
                                                        up to 10 000 g/plate                            Garrett et al. (1986)

    Mitotic recombationa      S. cerevisiae D3          5 concentrations          NR        Negative     Waters et al. (1982)
                                                        (unspecified)

    Mitotic aneuploidy        Neurospora crassa         5 or 10 g/ml             NR        Negativel    Griffiths et al. (1986;  
                              I-41-5, I-34-8            in DMSO                                          Moustacchi (1986)

    DNA repairc               B. subtilis H17 rec+,     20 g/disc in DMSO         NR        Negative     Shirasu et al. (1976)
                              M45 rec-

    DNA repaira               B. subtilis H17 rec+,     20 g/disc in DMSO         99.5      Negativem    Jeang & Li (1978)
                              M45 rec-

    DNA repairc               B. subtilis H17 rec+,     2 concentrations          NR        Negativem    Waters et al. (1982);  
                              M45 rec-                  (not specified)                                  Garrett et al. (1986)

    DNA repairc               E. coli P3478 (polA-),    2 concentrations          NR        Negativem    Waters et al. (1982);  
                              W3110 (polA+)             (not specified)                                  Garrett et al. (1986)

    Unscheduled DNA           Rat hepatocytes           3, 4, 5, 6, 7, 8, 9,      97.5      Negativen    McBride & McGregor 
    synthesis                                           10 g/ml in DMSO                                 (1987)

    Table 2. (continued)

                                                                                                                                  

    End-point                 Test object               Concentration             Purity    Result       Reference
                                                                                  (%)
                                                                                                                                  

    Mitotic recombination     Aspergillus nidulans      2070, 4140, 6210          NR        Positiveo    Kappas (1978);
    and aneuploidy            (heterozygous diploid     g/plate in ethanol                              Moustacchi (1986)
                              strain)

    Cytogenetic               Human lymphocytes         2, 10, 20 g/ml in        97.5      Negativep    Allen et al. (1988)
    alterationsa                                        DMSO

    In vivo
    Recessive lethal          Drosophila melanogaster   Feeding at 1250 and       98        Equivocal    Woodruff et al. (1985)
    mutation                  Canton-S                  1389 ppm in 5% 
                                                        ethanol:5% Tween 80

    Recessive lethal          Drosophila melanogaster   Re-analysis of data       NR        Equivocal    Mason et al. (1992)
    mutation                  Canton-S                  of Woodruff et al. 
                                                        (1985)
                                                                                                                                  

    NR, not reported; DMSO, dimethyl sulfoxide; NRF, nitroreductase-free
    a  With and without metabolic activation
    b  The positive controls, cyclophosphamide, 6-aminochrysene, and 2-aminofluorene, gave the expected results.
    c  Without metabolic activation
    d  The positive control nitroquinoline N-oxide gave the expected result.
    e  With metabolic activation
    f  The positive control sterigmatocystin gave the expected result.
    g  Positive in TA98 (> 100 g/plate) only without metabolic activation
    h  Positive in TA98 and TA1538 (> 500 g/plate) with and without metabolic activation and in TA100 without metabolic 
       activation. The positive controls, N-ethyl-N'-nitro-N-nitrosoguanidine, 9-aminoacridine, 2-aminoanthracene, and 
       2-nitrofluorene, gave the expected results.
    i  Positive in TA98 (> 100 g/plate) with and without metabolic activation; positive control unknown
    j  The positive control ethyl methanesulfonate gave the expected result.

    Table 2. (continued)

    k  The positive controls, 2-aminoanthracene and 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide, gave the expected results.
    l  This test system has not been fully validated. The positive control para-fluorophenylaniline gave the expected result.
    m  The positive control methyl methanesulfoxide gave the expected result.
    n  The positive control, Mischler's ketone [4,4'-bis(dimethylaminobenzophenone) in ethanol], gave the expected result. 
    o  A 2-2.5-fold increase in mitotic recombination. This test system has not been fully validated.
    p  The positive controls, ethyl methanesulfonate and cyclophosphamide, gave the expected results.
    

    of litters or in the number of animals born or weaned (US
    Environmental Protection Agency, 1974). 

         Dicloran (purity unspecified) was fed to groups of 10 female rats
    at concentrations of 0, 500, or 1000 ppm, equivalent to 0, 25, and 50
    mg/kg bw per day, for 188 days before mating and then through
    gestation and lactation. A reduced number of pups was reported when
    females were treated with 1000 ppm. There was no apparent effect on
    the survival of pups, although the mean body weight of those at 1000
    ppm was slightly reduced (US Environmental Protection Agency, 1974). 

    (ii)   Multigeneration reproductive toxicity

         In a two-generation study of reproductive toxicity, with one
    litter per generation, dicloran (purity, 99.2%) was administered to
    groups of 28 male and 28 (F0) and 24 male and 24 female (F1) female
    Sprague-Dawley rats in the diet at doses of 0, 50, 250, or 1250 ppm,
    equal to 0, 4, 21, and 110 mg/kg bw per day. The doses were based on
    the results of a range-finding study (Wilcox & Barton, 1996) in which
    concentrations up to 1000 ppm did not produce any obvious alterations
    in body weight, food consumption, duration of gestation, or litter
    parameters. The animals were fed the test diet during the 10- (F0) or
    11-week (F1) pre-mating period and then randomly allocated to mating
    pairs (l:1) for a maximum of seven nights. Treatment was continued for
    animals of each sex throughout the mating, gestation, and lactation
    periods until termination of the F2 litters. 

         The treatment-related clinical signs included yellow staining of
    the tray paper and, in some cases, yellow staining of the fur of all
    animals at the high dose in both generations, due to the yellow colour
    of the test material. There were no significant differences in mean
    body weights or body-weight gain between control and treated males.
    The mean body weights of F0 females at the high dose throughout the
    pre-mating period was 2-5% lower than that of controls, resulting in a
    12% lower mean overall gain at the end of the pre-mating period. This
    was considered to be treatment-related. The mean body weights of F1
    females at the high dose were, on average, 6% lower than those of
    controls during pre-mating, but the overall mean body-weight gain was
    only 5% lower. F0 and F1 females at the high dose had slightly lower
    overall body-weight gain during gestation, the greatest difference
    occurring during the first week of gestation (64% of control values in
    F0 females and 86% in F1). There were no apparent effects on the
    food consumption of F0 or F1 males or females during pre-mating and
    gestation; however, the food consumption of females of both
    generations at the high dose was 11% lower during the first week of
    lactation, and these animals weighed more than controls and those
    given lower doses at the end of lactation, indicating that pups in the
    high-dose group were less demanding with respect to suckling than pups
    in the other groups. 

         At the end of the study, a greater proportion of F0 and F1
    females at the high dose were in pro-estrus (4/28 F0 controls versus
    19/28 at the high dose; 4/24 F1 controls versus 11/24 at the high
    dose). Since there was no indication of altered cycling, this result
    was considered to be of no toxicological concern. Sperm-stage analysis
    indicated no difference between control F0 and F1 males and those at
    the high dose with respect to the number of testicular tubules at
    various spermatogenic stages or in tubule diameter. There was a
    dose-related increase in the incidence of abnormal sperm, particularly
    with respect to tail defects, in F0 males (0.25  0.26 and 0.29 
    0.31% in the two control groups, 0.59  0.96% at the low dose, 0.6 
    0.65% at the intermediate dose, and 0.67  0.58% at the high dose);
    however, no such increase was observed in F1 males at the high dose
    (0.21% versus 0.23% in controls). Furthermore, the mean values for F0
    animals were within the historical control range, 0.0-0.8%. Thus,
    these findings were considered incidental. The fertility and
    gestational indices of control and treated F0 and F1 females were
    similar. The male fertility indices of F0 males at the intermediate
    and high doses were lower than that of controls (82 and 86%,
    respectively), as was that of F1 males at the low dose (75%). Since
    the fertility index of F1 males at the intermediate and high doses
    approached 100%, the lower fertility indices were considered
    incidental. 

         There were significant increases in absolute and body
    weight-adjusted mean liver weights in F1 males and females at the
    high dose; no data were collected for F0 animals. The weights of the
    kidneys of F1 animals at the high dose were increased, and the
    increase was significant in males. Brain weights were significantly
    lower in F1 females at the high dose, and thymus weights were
    significantly lower in F1 males and females at the high dose relative
    to controls. No microscopic examinations were conducted on these
    tissues. The mean absolute epididymal weights of F0 males at the high
    dose and the absolute and body weight-adjusted epididymal weights of
    F1 males at the intermediate and high doses were significantly lower
    than those of controls. The authors indicated that the values for the
    F1 males were similar to 'recent control values for animals of
    similar age'; however, data on these controls were not provided. The
    mean absolute and body weight-adjusted testicular weights were
    statistically significantly increased in F1 males at the high dose
    and non-significantly increased in F0 males at this dose. There was a
    dose-related decrease in mean ovarian weights in F1 females, which
    was statistically significant in the high-dose group. No
    treatment-associated histopathological lesions were seen in the
    reproductive tissues that were examined. In the absence of
    histological data on non-reproductive tissues, the toxicological
    significance of the observed changes in organ weights in these tissues
    is equivocal.

         No difference was observed in the mean number of implantation
    sites per litter, litter size, sex ratio, or litter indices in control
    and treated groups. A slight increase in the number of F1 pups that

    died during days 4-21 of lactation was not observed in the F2
    generation and was considered to be incidental. The group mean weights
    of F1 and F2 litters were decreased throughout the lactation period,
    as reflected in the lower mean pup body weights at this dose. Although
    the magnitude of the difference was not as great in F2 pups as in F1
    pups, these observations were consistent and considered to be related
    to treatment. The mean litter weights of dams at the low and
    intermediate doses were lower than those of controls on day 1 of
    gestation, but the mean pup weights were comparable to those of
    controls on days 1-21 of lactation, in contrast to the high-dose
    group, and were therefore considered not to be related to treatment.
    There were no treatment-related clinical observations or
    malformations.

         The NOAEL for systemic toxicity was 250 ppm, equal to 21 mg/kg bw
    per day, on the basis of reduced body-weight gain at 1250 ppm in
    females during pre-mating and gestation and increased liver and kidney
    weights in males and females at this dose. The NOAEL for reproductive
    and developmental toxicity was also 250 ppm, equal to 21 mg/kg bw per
    day, on the basis of lower F1 and F2 pup weights at the next highest
    dose. There were no histopathological lesions in the reproductive
    tissues that would indicate that the changes in organ weights should
    be considered adverse (Barton & Wilcox, 1997).

         In a three-generation study, with two litters per generation,
    dicloran (purity unspecified) was administered to groups of 20 rats
    (strain unspecified) of each sex at 0 or 100 ppm, equivalent to 5
    mg/kg bw per day, in the diet. On the basis of the reproduction
    parameters examined, including the numbers of litters, stillbirths,
    live births, birth weight, and lactation indices, dicloran had no
    effect on reproduction (Lobdell & Johnston, 1965).

    (iii)   Developmental toxicity 

     Rats

         Groups of 24 pregnant Sprague-Dawley rats (Upj:TUC (SD) SPF) were
    dosed by gavage with dicloran (purity, 93.7%) in 0.25% carboxymethyl
    cellulose and 0.5% Tween 20 at doses of 0, 100, 200, or 400 mg/kg bw
    per day on days 6-15 of gestation, the day of mating being considered
    gestation day 0. These doses were derived from the results of a
    range-finding study in which 5/5 rats died at doses of 2000 and 4000
    mg/kg bw per day, and 3/5 at 1000 mg/kg bw per day. Neither of the two
    survivors treated with 1000 mg/kg bw per day had pups, and one had 15
    early resorptions. The mean body-weight gain of females treated with
    500 mg/kg bw per day was 25% less than that of controls. 

         The dams were sacrificed on day 20 of gestation, and the uterine
    contents were examined; the uteri of non-pregnant dams were stained
    with ammonium sulfide, and all fetuses were assessed for viability,
    sex, weight, and external malformations and variations. Equal numbers
    of fetuses from each group were assigned to either visceral or
    skeletal examination. There were no deaths. The treatment-related

    clinical signs included yellow staining of the urogenital region in
    some animals at each dose due to the colour of the test material, and
    slight central nervous system depression throughout the treatment
    period in animals at 200 and 400 mg/kg bw per day. The mean
    body-weight gain (corrected for gravid uterine weights) of treated
    animals was significantly lower (16-33% less) than that of the the
    controls. The incidence of dams with totally resorbed litters (early
    implants only) was increased in all treated groups (1, 5, 9, 10;
    control to high dose, respectively); however, there were no
    differences in the mean numbers of implants or resorptions or in the
    mean litter sizes of dams with live litters. The fetal weights were
    significantly lower at 200 and 400 mg/kg bw per day (7 and 20% less
    than control, respectively), and a significant trend for an increased
    incidence of delayed or reduced ossification was noted in these two
    groups. Increased incidences of other skeletal variations (bipartite
    sternebrae) were also seen at the high dose, but there were no
    teratogenic effects. (The authors maintained that the low dose was not
    maternally or embryotoxic. The conclusion concerning embryotoxicity
    was based on statistical significance rather than biological
    significance, and an erroneously large control value appears to have
    been used for statistical comparison.) On the basis of the
    significantly lower mean body-weight gains and the higher incidences
    of dams with totally resorbed litters (i.e. early implants only) in
    all treated groups, an NOAEL was not identified for maternal or
    developmental toxicity. (The authors indicated that
    sialodacryoadenitis viral infection was present during much of the
    dosing period and indicated that this may have had some effect on
    weight gain; however, in previous studies this virus had no
    teratogenic effects. If this is a valid conclusion, the increased
    incidence of total resorption of litters at all doses should be
    considered treatment-related.) (Marks et al., 1982).

     Rabbits

         Groups of 10, 12, and 14 pregnant New Zealand white rabbits were
    fed dicloran (purity unspecified) in the diet at 0, 100, or 1000 ppm,
    equivalent to 0, 3, and 30 mg/kg bw per day, on days 8-16 of
    gestation, the day of mating being considered gestation day 1.
    Pregnant females were allowed to deliver naturally, and the pups and
    parental females were sacrificed on post-natal day 21. There were no
    effects on maternal body weight during treatment. The mean litter size
    was slightly lower in the group at the high dose than in controls,
    with values of 7.1, 6.6, and 6.1 for the control, low, and high dose,
    respectively. In the absence of data on resorption, however, it could
    not be determined whether this effect was treatment-related. The pup
    weights at birth were not provided, but the mean pup weights at
    weaning (day 21) were comparable in all groups. There were no
    malformations and no increase in the incidence of skeletal
    malformations in treated pups (Wazeter, 1966).

         Groups of 15-16 naturally mated New Zealand white rabbits were
    dosed by gavage with dicloran (purity, 98.3%) in 1% carboxymethyl
    cellulose at 0, 8, 20, or 50 mg/kg bw per day on days 6-18 of
    gestation, the day of mating being considered gestation day 0. These
    doses were based on the results of a range-finding study in which a
    dose of 100 mg/kg bw per day caused two deaths, marked reduction in
    food intake, reduced body-weight gain during treatment, slightly
    increased post-implantation loss, and reduced litter and mean fetal
    weights, with gross malformations in 4/11 fetuses from one litter. The
    dose of 50 mg/kg bw per day resulted in reduced food intake and lower
    body-weight gains throughout treatment, and at 20 mg/kg bw per day
    there was a slight, transient reduction in food intake, with reduced
    body-weight gain and slight body-weight loss on days 9-11 of gestation
    (James & Brennan, 1991). 

         The dams were sacrificed on day 29 of gestation, the uterine
    contents were examined, and all fetuses were assessed for viability,
    sex, and external, visceral, and skeletal malformations and
    variations. There were no treatment-related effects on mortality,
    clinical signs, or food consumption. The mean body weights and body-
    weight gain were slightly but consistently lower than those of
    controls in females at the intermediate and high doses throughout both
    the treatment and post-treatment periods. This resulted in an overall
    mean body-weight gain in these animals that was 17-32% less than that
    of controls during treatment and at termination. The mean gravid
    uterine weights were also lower in these animals than in controls,
    whereas the carcass weights were similar in all groups, indicating
    that the weight changes were attributable primarily to effects on the
    litters rather than the dams. The lower body-weight gain of dams at
    the intermediate dose in the latter stages of gestation may be due
    partially to the smaller litter sizes of this group, which were not
    treatment-related; however, the effects seen in females at the
    intermediate dose early during treatment (days 6-9) may indicate
    maternal toxicity. The differences in body-weight gain in animals at
    the high dose were also considered to be toxicologically significant.
    Dams at the two higher doses had a slight increase in the frequency of
    post-implantation loss (7.4, 9, 4.8, and 10% for control to high dose,
    respectively). There were slight increases in the incidence of minor
    anomalies of the gall-bladder in three fetuses in three litters and
    delays in ossification of all limb epiphyseal sites in four fetuses in
    three litters (with none in controls) at 50 mg/kg bw per day. The
    NOAEL for maternal toxicity was 8 mg/kg bw per day on the basis of
    lower body-weight gain early in the treatment period at 20 and 50
    mg/kg bw per day. The NOAEL for developmental toxicity was 20 mg/kg bw
    per day (Barton & Wilcox, 1996).

     (f)  Special studies

    (i)   Cataractogenicity

         Dogs have been shown to develop lesions of the cornea and lens
    after prolonged oral administration of dicloran. It has been suggested
    that a photochemical product reaction is responsible for the lesion as

    it occurs only when dogs are exposed to sunlight. Groups of four to
    eight beagle dogs and six Hormel-Hanford miniature swine were fed
    dicloran (purity, 95.8%) at concentrations of 0, 0.75, 6, 24, 48, or
    192 mg/kg bw per day for periods varying from 50 to 306 days. Corneal
    opacity appeared in dogs within 53-104 days after administration of 24
    or 48 mg/kg bw per day, when they were exposed to sunlight. Dogs that
    were not exposed to sunlight and eyes that had been sutured closed did
    not develop lesions. Dogs given 192 mg/kg bw per day refused to eat
    after 38 days and were given dicloran by capsule. All of these animals
    died 49-53 days after the study began; no eye lesions were detected.
    In several dogs with eye damage that were maintained for four months
    to one year after dicloran administration had ceased, the pathological
    changes seen in the cornea and lens were not reversed. Dicloran did
    not appear to affect miniature swine at any concentration, and no
    histopathological changes were seen in the eyes. A dose-related
    increase in the presence of Heinz bodies was seen in the blood of both
    dogs and swine, with at least one dog affected per dose and pigs
    affected at doses of 48 mg/kg bw per day or more. No methaemoglobin
    formation was found in dogs or pigs. Administration of dicloran as a
    dust (0.1 mg) or a 5% solution directly into the eyes of dogs for
    three months had no effect on corneal opacity or irritation of the
    conjunctivae (Curtis et al., 1968; Bernstein et al, 1970; Earl et al.,
    1971).

         Ocular toxicity was not observed in rats or rhesus monkeys
    (Serrone et al., 1967), and administration of 0.143 mg/kg bw per day
    for three months to 20 human volunteers produced no ocular symptoms
    (Strough, 1962). 

         The 1977 Joint Meeting (Annex 1, reference 28) reviewed
    additional data requested by the 1974 JMPR and concluded that a
    species difference in the kinetics of dicloran may partly explain the
    photosensitive ocular toxicity observed in dogs,but not in other
    mammals. 14C-Dicloran was administered orally at 100 mg/kg bw per day
    for five days to four beagle dogs, four pigs (breed unspecified), and
    eight Wistar rats. The concentration of radiolabelled residues was
    highest in the dogs and slightly lower in pig tissues, but the tissue
    residues in both species were 2.4-11-fold higher than those in liver
    or plasma residues of rats. All three species had a high concentration
    of residue in the liver, but in dogs and pigs the highest
    concentrations were found in the pigmented tissues of the eye, the dog
    having two to three times more residue in the iris and pigmented
    retina than the pig. Nonpigmented eye tissues (cornea and lens) had
    low concentrations. There was no correlation between ocular toxicity
    and tissue residues of dicloran and its metabolites. The plasma
    concentrations of radiolabel increased more rapidly in the dogs, but
    24 h after three days of dosing the plateau plasma concentrations in
    the pigs and dogs were similar (10-15 mg/kg bw). High concentrations
    of radiolabel were excreted in the bile of dogs and pigs (Hamilton,
    1977). 

     (ii)  Haematological effects

         Groups of 10 or 15 rats (strain unspecified) of each sex were
    treated with dicloran at concentrations of 0, 5, 20, or 100 mg/kg bw
    per day by gavage for four months or in the diet at a concentration of
    0 or 20 ppm, equivalent to 1 mg/kg bw per day for four months.
    Measurements of red blood cells, total and differential leukocyte
    counts, platelet count, haematocrit, haemoglobin concentration,
    glucose, growth, and food consumption indicated no significant effect
    attributable to dicloran at any dose by either route (Evans et al.,
    1963). 

         Because of the known ability of 4-nitroaniline to induce specific
    blood dyscrasias, short-term studies were performed to compare
    dicloran and 4-nitroaniline. Groups of five weanling rats (strain
    unspecified) of each sex were given dicloran by gavage at 0 or 400
    mg/kg bw per day, five days/week, for four weeks, and 4-nitroaniline
    was administered at 200 or 400 mg/kg bw per day to two comparable
    groups over the same interval. In a second experiment, groups of six
    male weanling rats were given dicloran by gavage at 0 or 800 mg/kg bw
    per day or 4-nitroaniline at 400 or 800 mg/kg bw per day, five days
    per week, for two weeks. Haematological parameters were normal in rats
    treated at 400 mg/kg bw per day -- no Heinz bodies were detected and
    the reticulocyte counts were normal -- although their body-weight gain
    was 50-60% of that of controls. At 800 mg/kg bw per day, there was
    slight weight loss. Red blood cell count, packed cell volume, and
    haemoglobin measurements were normal, while the lymphocyte counts were
    reduced to 65% of that of controls. At the end of the study, no
    effects were seen on the spleen. In contrast, 4-nitroaniline had
    definitive effects on growth at 200 mg/kg bw per day (70% of control),
    Heinz bodies were identified in the blood, and the reticulocyte count
    was markedly elevated to two to four times the control value. The bone
    marrow was not affected. At 400 mg/kg bw per day, growth was reduced
    to 60% of the control value, and a reduced red blood cell count (65%
    of control with polychromasia and nucleation) was seen, accompanied by
    increased spleen weight (200% of control). These effects were more
    pronounced at 800 mg/kg bw per day where, in addition, the haemoglobin
    concentration was reduced and the lymphocyte count greatly increased.
    Although the high doses of dicloran caused lymphopenia, the other
    haemotoxic effects seen with 4-nitro-aniline were not observed with
    dicloran (Boots Pure Drug Co., 1962). 

         In studies to substantiate the difference between the effects of
    4-nitroaniline and dicloran, a single oral dose of 500 mg/kg bw
    dicloran was given to cats. No methaemoglobin was noted at any time
    between 1 and 48 h after dosing; however, administration of
    4-nitroaniline as a single dose of 100 mg/kg bw resulted in
    methaemoglobin over the same time. In addition, the cats given
    4-nitroaniline were cyanotic and showed extensive muscle weakness
    (Gurd, 1974). Although methaemoglobin was not assessed in all studies,
    it is noteworthy that the 60-day study in mice was the only one that
    showed an association between dicloran and significantly elevated
    methaemoglobin concentrations in the blood at doses of 100 and

    200 mg/kg bw per day (Mallyon et al., 1986). No effect on
    methaemoglobin was seen in the two-year study in dogs (Woodard et al.,
    1964).

    3.  Observations in humans

         In a double-blind clinical study, 20 male volunteers were given
    10 mg of dicloran (purity unspecified), equivalent to 0.14 mg/kg bw
    per day, and 10 received a placebo, once daily, for 90 days. The dose
    and duration were based on the estimated maximum residues obtained
    from consumption of fruits and vegetables over one year.
    Haematological examinations and tests for liver and kidney function
    were performed at various intervals over the course of the study; the
    results were found to be normal (Strough, 1962).

         Extensive examinations were made on an industrial worker who had
    been occupationally exposed to dicloran for three years, with
    considerable exposure by inhalation and dermal contact for about 60
    days per year. No adverse effects were observed (Brooks & Boyack,
    1963).

    Comments

         Dicloran is rapidly absorbed, metabolized, and eliminated, mainly
    in the urine, after oral administration to rats, goats, and humans; it
    is also rapidly excreted by hens. Rats excreted most of the radiolabel
    (90-96%) within 24 h, with > 70% in the urine and an additional
    13-22% in the faeces, depending on the dose. Elimination was
    essentially complete (91-97% of the administered dose) by 48 h, with
    total tissue residues accounting for 0.2-0.3%. The highest tissue
    concentrations were found in the liver (0.05-0.06 mg/kg) and kidneys
    (0.02 mg/kg). Unchanged parent compound was detected in the faeces of
    animals at the high dose only. The major urinary metabolites were the
    sulfate and glucuronide conjugates of 2,6-dichloro-4-hydroxyaniline,
    which accounted for 55-79% of the total administered radiolabel, and
    the major faecal metabolites were derivatives of glutathione
    conjugates. The parent compound and its glutathione conjugates were
    the major residues in plants. None of the metabolites was of
    toxicological concern. The rapid excretion of dicloran as a conjugate
    indicates that it is readily metabolized  in vivo.

         The major metabolite in rat urine (2,6-dichloro-4-hydroxyaniline)
    was not present in goat urine, which contained more polar conjugates
    that could not be hydrolysed by glucuronidase or sulfatase. In goats,
    dicloran is reduced to 4-amino-2,6-dichloro-aniline and acetylated to
    4-amino-3,5-dichloroacetanilide (4-6% in urine), which is rapidly
    metabolized and excreted in the urine and faeces, although a reactive
    intermediate is formed in goat liver and bound covalently to
    macromolecules. Species differences in dicloran metabolism were also
    apparent in dogs and mice, which partly explain the photosensitive
    oculotoxic effects observed in dogs and the methaemo-globinaemia noted
    in mice, which are not seen in other mammals. Preliminary studies
    suggested that the metabolites of dicloran in humans are similar to

    those in rats. Although recovery was considered complete, excretion
    was somewhat slower in humans than in rats, most of the material being
    excreted within 1.5 days.

         Dicloran has low or slight toxicity when administered by the oral
    route, depending on species. It has low dermal toxicity, is not
    irritating to the skin, is a mild eye irritant, and is not a skin
    sensitizer.

         WHO has classified dicloran as unlikely to present an acute
    hazard in normal use (WHO, 1996).

         The results of short-term studies of toxicity in rabbits treated
    dermally and in mice and rats treated in the diet or by gavage and of
    long-term studies of toxicity in mice, rats, and dogs treated in the
    diet indicate that the liver is the primary target organ. Increased
    liver weights and centrilobular hepatic hypertrophy were observed
    consistently in all species treated orally, and increased splenic
    activity and splenic extramedullary haematopoiesis were noted in
    short- and long-term studies in mice.

         When dicloran was fed to mice at 0, 300, 600, or 1200 ppm for 60
    days, the NOAEL was 300 ppm (equal to 49 mg/kg per day), on the basis
    of hepatic lesions, splenic extramedullary haematopoiesis, and
    increased methaemoglobin at doses of 600 ppm and above.

         In a 90-day study in mice treated by gavage with 0, 15, 45, 135,
    400, or 600 mg/kg bw per day, the NOAEL was 15 mg/kg bw per day on the
    basis of significant polycythaemia in males and hypercholesterolaemia
    and a significant increase in the incidence of splenic extramedullary
    haematopoiesis in females at 45 mg/kg bw per day and above.

         A NOAEL was not identified in a 90-day study in rats fed diets
    containing 0, 1000, 3000, or 5000 ppm dicloran because of
    significantly reduced body-weight gain in conjunction with effects on
    the liver and thyroid in all treated groups. In an eight-week study in
    which rats were given diets containing dicloran at doses of 0, 500, or
    750 ppm, the NOAEL was 500 ppm (equal to 44 mg/kg bw per day) on the
    basis of reduced body-weight gain, decreased food consumption, and
    increased liver weights with associated hepatic histopathological
    manifestations at 750 ppm.

         In a study in which dicloran was fed to rats for six months at 0,
    30, 300, or 3000 ppm, the NOAEL was 300 ppm (equal to 22 mg/kg bw per
    day) on the basis of reduced body weights and increased liver and
    spleen weights at 3000 ppm.

         In a four-week study in rats given a dose of 0, 35, 140, or 350
    mg/kg bw per day by gavage, the NOAEL was 35 mg/kg bw per day on the
    basis of growth depression and hepatic hypertrophy and vacuolation at
    140 mg/kg bw per day.

         In an 18-month study of carcinogenicity in mice at dietary
    concentrations of 0, 50, 175, or 600 ppm, the NOAEL was 175 ppm (equal
    to 25 mg/kg bw per day) on the basis of increased liver weights,
    centrilobular hepatocyte enlargement, centrilobular haemosiderosis,
    focal and single-cell liver necrosis, and vacuolation of centrilobular
    hepatocytes.There was no evidence of carcinogenicity in mice.

         Two studies were conducted in rats to assess toxicity over a
    two-year period of exposure. Rats were fed diets containing dicloran
    at concentrations of 0, 20, 100, or 3000 ppm or 0 or 1000 ppm. The
    overall NOAEL was 1000 ppm (equal to 59 mg/kg bw per day), on the
    basis of changes in body-weight, food consumption, and haematological
    parameters, spleen pigmentation, increased liver weights,
    centrilobular hepatocyte enlargement, and thyroid hypertrophy at 3000
    ppm. There was no evidence of carcinogenicity in these studies, but
    they were considered inadequate for complete evaluation of the
    carcinogenetic potential of dicloran.

         Dogs fed dicloran at dietary concentrations of 0, 20, 100, or
    3000 ppm for two years had treatment-related changes in haematological
    and clinical chemical parameters and significant increases in liver,
    spleen, and kidney weights, accompanied by histological changes at
    3000 ppm that included irregular hepatic-cell size, moderate
    hepatic-cell hypertrophy, and increased pigmentation of the liver and
    spleen. The NOAEL was 100 ppm, equal to 1.7 mg/kg bw per day.

         Dicloran was not mutagenic in most assays, although occasional
    positive responses were seen in more recent tests for reverse mutation
    and in a test for mitotic recombination. The results of an assay for
    sex-linked recessive mutation in  Drosophila were equivocal. The
    Meeting concluded that dicloran is unlikely to be genotoxic.

         Studies of reproductive and developmental toxicity indicated that
    dicloran is not a reproductive toxicant and is not teratogenic in rats
    or rabbits. Dicloran was embryotoxic at maternally toxic doses in
    rabbits, but an NOAEL for maternal or developmental toxicity was not
    identified in rats.

         In a two-generation study of reproductive toxicity in rats (one
    litter per generation) at dietary concentrations of 0, 50, 250, or
    1250 ppm, the NOAEL for systemic toxicity was 250 ppm (equal to 21
    mg/kg bw per day) on the basis of reduced body-weight gains and
    increased liver weights at 1250 ppm. The NOAEL for reproductive and
    developmental toxicity was 250 ppm (equal to 21 mg/kg bw per day) on
    the basis of reduced weights of F1 and F2 pups at 1250 ppm.

         In a study of developmental toxicity, dicloran was administered
    by gavage to rats on days 6-15 of gestation at doses of 0, 100, 200,
    or 400 mg/kg bw per day. Because of significantly reduced mean
    maternal body-weight gains and higher incidences of totally resorbed
    litters in all treated groups, NOAEL values for maternal or
    developmental toxicity were not identified. Dicloran was not
    teratogenic in this study.

         In a study of developmental toxicity in rabbits, dicloran was
    administered by gavage at doses of 0, 8, 20, or 50 mg/kg bw per day on
    days 6-18 of gestation. The NOAEL for maternal toxicity was 8 mg/kg bw
    per day, on the basis of reduced maternal body-weight gains early
    during treatment with 20 or 50 mg/kg bw per day. The NOAEL for
    developmental toxicity was 20 mg/kg bw per day on the basis of a
    slight increase in post-implantation losses, a slight increase in the
    incidence of minor anomalies of the gall-bladder, and delays in
    ossification of all limb epiphyseal sites in fetuses at 50 mg/kg bw
    per day.

         Dogs have been shown to develop lesions in the cornea and lens
    after prolonged oral administration of dicloran. The 1977 Joint
    Meeting reviewed additional data requested by the 1974 Meeting and
    concluded that the photosensitive oculotoxic effects observed in dogs
    but not in other mammals were due partly to a species difference in
    the kinetics of dicloran. No oculotoxic effects were seen in any of
    the more recent studies, although no further studies have been
    conducted in dogs.

         In a double-blind clinical study, 20 men were given 10 mg
    dicloran (equivalent to 0.14 mg/kg bw per day) and 10 received a
    placebo once daily for 90 days. The dose and duration were chosen on
    the basis of the maximum residues estimated to be derived from
    consumption of fruits and vegetables over one year. There was no
    indication that administration of dicloran at this dosage had any
    adverse effect.

         An ADI of 0-0.01 mg/kg bw per day was established on the basis of
    the NOAEL of 1.7 mg/kg bw per day for hepatic and haematological
    effects in the two-year study in dogs and a 200-fold safety factor. A
    larger than normal safety factor was used because of the inadequacy of
    the long-term studies in rats for assessing the carcinogenic potential
    of dicloran and because of the lack of a NOAEL for maternal and
    developmental toxicity in rats.

         An acute RfD was not allocated because dicloran has low or slight
    toxicity when administered orally or dermally and because acute
    effects occur only at very high doses, resulting in a 10 000-fold
    difference between the ADI and the LOAEL for maternal and
    developmental toxicity in rats. Therefore, the Meeting concluded that
    the acute intake of residues is unlikely to present a risk to
    consumers.

    Toxicological evaluation

     Levels that cause no toxic effect

         Mouse:    300 ppm, equal to 49 mg/kg bw per day (lowest dose
                   tested, eight-week study of toxicity)
                   15 mg/kg bw per day (13-week study of toxicity)
                   175 ppm, equal to 24 mg/kg bw per day (18-month study
                   of carcinogenicity)

         Rat:      35 mg/kg bw per day (lowest dose tested, four-week
                   study of toxicity)
                   500 ppm, equal to 44 mg/kg bw per day (lowest dose
                   tested, eight-week study of toxicity)
                   300 ppm, equal to 22 mg/kg bw per day (six-month study
                   of toxicity)
                   1000 ppm, equal to 59 mg/kg bw per day (two two-year
                   studies of toxicity)
                   250 ppm, equal to 21 mg/kg bw per day (two-generation
                   study of reproductive toxicity)

         Rabbit:   8 mg/kg bw per day (maternal toxicity in a study of
                   developmental toxicity)
                   20 mg/kg bw per day (developmental toxicity) 

         Dog:      100 ppm, equal to 1.7 mg/kg bw per day (two-year study
                   of toxicity)

         Human:    0.14 mg/kg bw per day (90-day study of toxicity)

     Estimate of acceptable daily intake for humans

         0-0.01 mg/kg bw

     Estimate of an acute reference dose

         Not allocated (unnecessary).

     Studies that would provide information useful for continued 
     evaluation of the compound

         1.   Combined study of toxicity and carcinogenicity in rats.

         2.   Study of developmental toxicity in rats at less than 100
              mg/kg bw per day to establish clear NOAELs for maternal and
              developmental toxicity.

         3.   Assays for genotoxicity in mammals  in vivo, such as an
              assay for micronucleus formation

         4.   Further observations in humans

        List of end-points for setting guidance values for dietary and non-dietary exposure
                                                                                                 

    Absorption, distribution, excretion and metabolism in mammals 

    Rate and extent of absorption           Rapid/complete, > 70% urinary excretion within 24 h
    Dermal absorption                       No data
    Distribution                            Liver, kidney
    Potential for accumulation              Minimal
    Rate and extent of excretion            Rapid/complete, 90-96% in urine and faeces within 24 h
    Metabolism in animals                   Metabolites differ in rats and goats
    Toxicologically significant compounds   Parent compound
    (animals, plants and environment)

    Acute toxicity

    Rat: LD50 oral                          > 4000 mg/kg bw
    Rabbit: LD50 dermal                     > 2000 mg/kg bw
    Rat: LC50 inhalation                    No data
    Skin irritation                         Not irritating
    Eye irritation                          Minimally irritating
    Skin sensitization                      Not sensitizing (Draize test)

    Short term toxicity

    Target/critical effect                  Liver/centrilobular hepatotoxicity (mice, rats, dogs)

                                            Spleen/extramedullary haematopoiesis (mice)
    Lowest relevant oral NOAEL              Rat: 44 mg/kg bw/per day (diet); 15 mg/kg bw per day 
                                            (gavage)
    Lowest relevant dermal NOAEL            Rabbit: 120 mg/kg bw per day
    Lowest relevant inhalation NOAEL        Poor study: data on actual intake, particle size not 
                                            provided

    Genotoxicity                            Unlikely to be genotoxic; no study of genotoxicity in 
                                            mammals in vivo

    Long term toxicity and carcinogenicity 

    Target/critical effect                  Liver/centrilobular hepatotoxicity (mice, rats, dogs)
                                            Spleen/extramedullary haematopoiesis (mice)
    Lowest relevant NOAEL                   Dog: 1.7 mg/kg bw per day (2-year study)
    Carcinogenicity                         No evidence of carcinogenicity in mice. The study in 
                                            rats was inadequate.

    Reproductive toxicity 

    Reproduction target/critical effect     Increased ovary/testis weights (no histological 
                                            findings)
    Lowest relevant reproductive NOAEL      Rat: 21 mg/kg bw per day (reduced body-weight gain, 
                                            increased liver weight)

    Developmental target/critical effect    Increased resorptions, delayed ossification, not 
                                            teratogenic
    Lowest relevant developmental NOAEL     20 mg/kg bw per day in rabbits; no NOAEL in rats. 
                                            A 10 000-fold difference exists between the ADI and 
                                            the LOAEL in rats.

    Neurotoxicity/Delayed neurotoxicity     No data

    Other toxicological studies 

    Cataractogenicity                       Photosensitive oculotoxic effects observed in dogs are 
                                            not seen in other mammals

    Medical data                            No indication that administration of dicloran at 
                                            10 mg/day to men for 90 days had any adverse effect. 
                                            Extensive examinations were made on one industrial 
                                            worker occupationally exposed to dicloran over three 
                                            years, with considerable inhalation and dermal 
                                            exposure for about 60 days/year. No adverse effects 
                                            were observed

    Summary                  Value                          Study                   Safety factor
    ADI                      0-0.01 mg/kg bw                2-year study, dogs      200
    Acute reference dose     Not allocated (unnecessary)
                                                                                                 
    
    References

    Allen, J.A., Brooker, P.C. & Gray, V.M. (1988) Technical dicloran:
    Metaphase chromosome analysis of human lymphocytes cultured in vitro.
    Unpublished report No. No. SMS 43/871138 from Huntingdon Research
    Centre, United Kingdom. Submitted to WHO by Gowan Company, Yuma,
    Arizona, USA. 

    Bachmann, E., Golberg, L. & Thibodeau, L. (1971) Aspects of the
    determination of biphenyl hydroxylase activity in liver homogenate.
     Exp. Mol. Pathol., 14, 303-326.

    Barton, S.J. & Wilcox, S. (1996) Dicloran: Development toxicity in
    rabbits. Unpublished report No. 11379 from Inveresk Research
    International, United Kingdom. Submitted to WHO by Gowan Company,
    Yuma, Arizona, USA. 

    Barton, S.J. & Wilcox, S. (1997) Dicloran: Two generation reproduction
    study in rats. Unpublished report No. 14271 from Inveresk Research
    International, United Kingdom. Submitted to WHO by Gowan Company,
    Yuma, Arizona, USA. 

    Basting, L.A., Cooper, C., Witmer, C.M. & Gallo, M.A. (1983) Toxicity
    and mutagenicity of 2,6-dichloro-4-nitroaniline in the Ames test.
     Fed. Proc., 42, 623.

    Basting, L.A., Witmer, C.M., Iba, M.M. & Gallo, M.A. (1984) The effect
    of 2,6-dichloro-4-nitroaniline on hepatic microsomal systems.
     Toxicologist, 4, 149. 

    Bernstein, H., Curtis, J.M., Earl, F.L. & Kuwabara, W. (1970)
    Phototoxic corneal and lens opacities.  Arch. Ophthalmol., 83,
    336-348. 

    Boots Pure Drug Co. (1962) Dicloran: Experimental data on toxicity.
    Unpublished report No. T-17 from Boots Pure Drug Co., USA. Submitted
    to WHO by Gowan Company, Yuma, Arizona, USA. 

    Boyack, G.A. & Brooks, B.W. (1963) Medical examination of a man after
    prolonged exposure to 2,6-dichloro-4-nitroaniline. Unpublished report
    No. T-21 from Upjohn Co., USA. Submitted to WHO by Gowan Company,
    Yuma, Arizona, USA. 

    Cheng, T. (1996a) Nature of the residue of 14C-dicloran in lactating
    goats. Unpublished report No. HWI6564-102 from Hazleton Wisconsin,
    Inc., USA. Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Cheng, T. (1996b) Metabolism of 14C-dicloran in rats. Unpublished
    report No. HWI6564-108 from Hazleton Wisconsin, Inc., USA. Submitted
    to WHO by Gowan Company, Yuma, Arizona, USA. 

    Cheng, T. (1996c) Nature of the residue of 14C-dicloran in laying
    hens. Unpublished report No. HWI6564-100 from Hazleton Wisconsin,
    Inc., USA. Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Creedy, C.L., Hemmings, P.A. & Needham, D. (1985) The effect of
    dicloran on the hepatic mixed-function oxidase system of the male rat
    following oral administration of 100 mg/kg body weight twice daily for
    4 days. Unpublished FBC Ltd report No. METAB/85/24, United Kingdom.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Curtis, J.M., Bernstein, H., Earl, F.L. & Smalley, H.E. (1968) Corneal
    and lens opacities in dogs treated with 2,6-dichloro-4-nitroaniline.
     Toxicol. Appl. Pharmacol., 12, 305.

    Dawson, J. R. (1988) Metabolism and residues of dicloran in the laying
    hen. Unpublished report No. ENVIR/88/26 from Schering Agrochemicals
    Ltd, United Kingdom. Submitted to WHO by Gowan Company, Yuma, Arizona,
    USA. 

    Earl, F.L., Curtis, J.M., Bernstein, H.N. & Smalley, H.E. (1971)
    Ocular effects in dogs and pigs treated with dichloran
    (2,6-dichloro-4-nitroaniline).  Food Cosmet. Toxicol., 9, 819-828. 

    Eberts, F.S. (1965) Fate of Botran (2,6,-dichloro-4-nitroaniline) in
    rat and man. Unpublished report No. M9 from Upjohn Co., USA. Submitted
    to WHO by Gowan Company, Yuma, Arizona, USA. 

    Eberts, F.S., Meeks, R.C. & Vliek, R.W. (1963) Excretion of
    Botran-14C (2,6,-dichloro-4-nitroaniline) by man. Unpublished Report
    No. M3 from Upjohn Co., USA. Submitted to WHO by Gowan Company, Yuma,
    Arizona, USA. 

    Elliot, P.H., Smith, C., Crook, D., Gibson, W.A., Singh, H. &
    Gopinath, C. (1988) Technical dicloran: Twenty-one day dermal toxicity
    study in rabbits. Unpublished report No. SMS 60/871292 from Huntingdon
    Research Centre Ltd, United Kingdom. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Evans, J., Mengel, G. & Bostwick, L. (1963) Botran (U-2069) Effect of
    oral administration. Final report four-months study. Unpublished.
    Cited from the 1974 JMPR Monograph, (Annex 1, reference 22).

    Everest, R.P. & Tuplin, J.A. (1977) Dicloran, pure reference sample:
    Mutagenicity testing in bacterial in vitro systems. Unpublished report
    No. TX 77024 from Boots Pure Drug Co., United Kingdom. Submitted to
    WHO by Gowan Company, Yuma, Arizona, USA. 

    Gaines, T.B. & Linder, R.E. (1986) Acute toxicity of pesticides in
    adult and weanling rats.  Fundam. Appl. Toxicol., 7, 299-308.

    Gallo, M.A., Bachmann, E. & Golberg, L. (1976) Mitochondrial effects
    of 2,6-dichloro-4-nitroaniline and its metabolites.  Toxicol. Appl. 
     Pharmacol., 35, 51-61.

    Garrett, N.E., Stack, H.F. & Waters, M.D. (1986) Evaluation of the
    genetic activity profiles of 65 pesticides.  Mutat. Res., 168,
    301-325.

    Griffiths, A.F.J., Brockman, H.E., DeMartini, D.M. & de Serres, F.J.
    (1986) The efficacy of  Neurospora in detecting agents that cause
    aneuploidy.  Mutat. Res., 167, 35-45.

    Gurd, P.R. (1974) Methemoglobin formation in the cat. Unpublished.
    Cited from the 1974 JMPR Monograph, (Annex 1, reference 22).

    Hamilton, D.Y. (1977) Tissue distribution of [14C]-dichloran in rats,
    dogs and pigs following repeated oral dosing at 100 mg/kg/day.
    Unpublished report from Boots Pure Drug Co., United Kingdom. Submitted
    to WHO by Gowan Company, Yuma, Arizona, USA. 

    Hawkins, D.R., Kirkpatrick, D. & Shaw, D. (1988) The metabolism of
    [14C]-dicloran in peaches: Analysis of samples. Unpublished report
    No. HRC/SMS from Huntingdon Research Centre, Ltd United Kingdom.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Innes, J.R.M., Ulland, B.M., Valerio, M.G., Petrucelli, L., Fishbein,
    I., Hart, E.R., Pallotta, A.J., Bates, R.R., Falk, H.L., Gart, J.J.,
    Klein, M., Mitchell, L. & Peters, J. (1967) Bioassay of pesticides and
    industrial chemicals for tumorigenicity in mice: A preliminary note.
     J. Natl Cancer Inst., 42, 1101-1114. 

    Jaglan, P.S. & Arnold, T.S. (1985a) Comparative metabolism of
    [14C]-dichloran in rats and goats: Nature of liver residues.
    Unpublished report No. 218-9760-85-002A from Upjohn Co., USA.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Jaglan, P.S. & Arnold, T.S. (1985b) Nature of muscle residue from the
    treatment of a goat with [14C]-dichloran
    (2,6-dichloro-4-nitroaniline). Unpublished report No. 218-9760-85-003
    from Upjohn Co., USA. Submitted to WHO by Gowan Company, Yuma,
    Arizona, USA. 

    Jaglan, P.S., Gosline, R.E. & Arnold, T.S. (1985a) Comparative
    metabolism of [14C]-dichloran in rats and goats. Unpublished report
    No. 218-9760-85-002 from Upjohn Co., USA. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Jaglan, P.S., Arnold, T.S., Gosline, R.E. & Subacz, C.J. (1985b)
    Bioavailability of [14C]-dichloran (U-2069;
    2,6-dichloro-4-nitroaniline) derived goat liver residues by the rats.
    Unpublished report No. 218-9760-85-004 from Upjohn Co. Submitted to
    WHO by Gowan Company, Yuma, Arizona, USA. 

    James, P. & Brennan, C. (1991) Technical dichloran: Rabbit oral
    developmental toxicity (teratogenicity) range finding study.
    Unpublished report No. TOX/91/199-98 (T128) from Schering AG, Germany.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Jeang, C.-L. & Li, G.-C. (1978) Screening of pesticides for
    mutagenicity in microbial systems. Taiwan Plant Protection Center
    Research Report No. 12. Submitted to WHO by Gowan Company, Yuma,
    Arizona, USA. 

    Jeang, C.-L. & Li, G.-C. (1980) Screening of pesticides for
    mutagenicity in microbial systems II: with mammalian microsomal
    activation.  Natl Sci. Council Monthly, 8, 551-559. 

    Johnston, R.L. & Ceru, J.G. (1961) Acute oral LD50 -- rat and acute
    intraperitoneal LD50 -- mouse using DCNA with 0.09% p-nitroaniline.
    Unpublished report No. T-16 from Upjohn Co., USA. Submitted to WHO by
    Gowan Company, Yuma, Arizona, USA. 

    Johnston, R.L. & Schwikert, R.S. (1963) Botran: Skin sensitization in
    guinea pigs. Unpublished report No. 5567-64-RLJ-196B from Upjohn Co.,
    USA. Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Jones, E. & Fenner, L.A. (1987) Technical dicloran: Ames bacterial
    mutagenicity test. Unpublished report No. TOX/87/199-85 from Schering
    Agrochemicals Ltd, United Kingdom. Submitted to WHO by Gowan Company,
    Yuma, Arizona, USA. 

    Kakuk, T. (1986) 90-Day oral toxicity study in B6C3F1 mice with DCNA.
    Unpublished report No. 7263/86/003 from Upjohn Co., USA. Submitted to
    WHO by Gowan Company, Yuma, Arizona, USA. 

    Kakuk, T.J., Weddon, T.W. & Thomas, R.W. (1979) Reevaluation of
    potential hepatic effects of Botran in beagle dogs: Supplemental
    report. Unpublished report No. 001-9610-79-005 from Upjohn Co., USA.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Kappas, A. (1978) On the mechanisms of induced somatic recombination
    by certain fungicides in  Aspergillus nidulans. Mutat. Res., 51,
    189-197.

    Lessel, B. (1974) Two-year feeding trial in rats on dicloran.
    Unpublished report from Boots Pure Drug Co., United Kingdom. Submitted
    to WHO by Gowan Company, Yuma, Arizona, USA. 

    Lobdell, B. & Johnson, C. (1965) U-2069: Effect on reproduction
    capacity through three generations in the rat. Unpublished report from
    Woodard Research Corporation. Cited from the 1974 JMPR Monograph
    (Annex 1, reference 22).

    Mallyon, B.A. & Markham, L.P. (1989) Technical dicloran: Oncogenicity
    study in the mouse. Unpublished report No. TOX/86006 from Schering
    Agrochemicals Ltd, United Kingdom. Submitted to WHO by Gowan Company,
    Yuma, Arizona, USA. 

    Mallyon, B.A. & Rawcliffe, L.M. (1985) Technical dicloran:
    Palatability in the diet to the mouse. Unpublished report No.
    TOX/85/199-74 from FBC Ltd, United Kingdom. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Mallyon, B.A., Rawliffe, L.M. & Major, I.R. (1986) Technical dicloran:
    60-day dietary study in the mouse. Unpublished report No.
    TOX/86/199-75 from FBC Ltd, United Kingdom. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Marks, T.A., Poppe, S.M., Moerdyk, D.L., Stuckhardt, J.L., Morris,
    D.F. & Greenberg, J.H. (1982) U-2069: A segment II teratology study in
    the rat. Unpublished report No. 9610/82/7263/005 from Upjohn Co., USA.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Mason, J.M., Valencia, R. & Zimmering, S. (1992) Chemical mutagenesis
    testing in  Drosophila: VIII: Reexamination of equivocal results.
     Environ. Mol. Mutag., 19, 227-234.

    Mat, C., Ryan, A.J. & Wright, S.E. (1967) Metabolism of some 4-
    nitroaniline derivatives in the rat.  Food Cosmet. Toxicol., 5,
    657-663. 

    McBride, D. & McGregor, D.B. (1987) Technical dicloran: Assessment of
    unscheduled DNA synthesis using rat hepatocyte cultures. Unpublished
    report No. 4414 from Inveresk Research International, Musselborgh,
    United Kingdom. Submitted to WHO by Gowan Company, Yuma, Arizona, USA.

    Moustacchi, E., Carere, A., Morpurgo, G. Ramel, C. & Wrgler, F.E.
    (1986) Assays for genetic changes in fungi. In: Montesano, R.,
    Bartsch, H., Vainio, H., Wilbourn, J. & Yamasaki, H., eds, 
     Long-term and Short-term Assays for Carcinogens: A Critical 
     Appraisal (IARC Scientific Publications No. 83), Lyon, International
    Agency for Research on Cancer, pp. 203-249. 

    Myers-Basting, L.A. (1986) Mutagenicity and characterization of the in
    vitro metabolism of 2,6-dichloro-4-nitroaniline. Unpublished report
    No. (T101) from Rutgers University, New Jersey, USA.  Submitted to WHO
    by Gowan Company, Yuma, Arizona, USA. 

    O'Boyle, F. & Challis, I.R. (1991a) The excretion and distribution of
    radiolabelled residues in the rat following oral dosing with
    [14C]-dicloran at 5 mg/kg body-weight. Unpublished report No.
    TOX/90/199-95 (M48) from Schering Agrochemicals Ltd, United Kingdom.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    O'Boyle, F. & Challis, I. R. (1991b) The excretion and distribution of
    radiolabelled residues in the rat following oral dosing with
    [14C]-dicloran at 500 mg/kg body-weight. Unpublished report No.
    TOX/90/199-96 (M49) from Schering Agrochemicals Ltd, United Kingdom.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    O'Neal, S. (1997a) Metabolic fate and distribution of 14C-dicloran in
    potatoes. Unpublished report No. 1947 from PTRL East Inc., USA.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    O'Neal, S. (1997b) Metabolic fate and distribution of 14C-dicloran in
    lettuce. Unpublished report No. 1949 from PTRL East Inc., USA.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Peters, D.H., Stuart, V., Smith, H.L., Crook, D., Gibson, W.A.,
    Majeed, S.K. & Gopinath, C. (1991) Technical dicloran: Rat 13-week
    dietary toxicity study. Unpublished report No. TOX 89324 from
    Huntingdon Research Centre, United Kingdom. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Raczniak, T.J. & Wood, D.R. (1980a) Primary eye irritation evaluation
    in New Zealand white rabbits with Botran technical. Unpublished report
    No. 218-9610-80-001 from Upjohn Co., USA. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Raczniak, T.J. & Wood, D.R. (1980b) Primary dermal irritation study in
    New Zealand white rabbits with Botran technical. Unpublished report
    No. 218-9610-80-002 from Upjohn Co., USA. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Raczniak, T. J. & Wood, D. R. (1980c) Acute dermal toxicity screen in
    New Zealand white rabbits with Botran technical. Unpublished report
    No. 218-9610-80-003 from Upjohn Co., USA. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Seaman, W.J., Weddon, T.E. & Kakuk, T.J. (1980) Three-week inhalation
    study in rats, rabbits and dogs with Botran. Unpublished report No.
    218-9610-80-004 from Upjohn Co., USA. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Serrone, D.M., Pakdaman, P., Stein, A.A. & Coulston, F. (1967)
    Comparative toxicology of 2,6-dichloro-4-nitroaniline in rats and
    rhesus monkeys.  Toxicol. Appl. Pharmacol., 10, 404.

    Shirasu, Y., Moriya, M., Kato, K. Furuhashi, A. & Kada, T. (1976)
    Mutagenicity screening of pesticides in the microbial system.
     Mutat. Res., 40, 19-30. 

    Smith, S (1989) Metabolism of [14C]-dicloran in peaches under field
    and glasshouse conditions. Unpublished report No. ENVIR/89/12 from
    Schering Agrochemicals Ltd, United Kingdom. Submitted to WHO by Gowan
    Company, Yuma, Arizona, USA. 

    Strough, A.R. (1962) Botran clinical study. Unpublished report from
    Upjohn Co., USA. Submitted to WHO by Gowan Company, Yuma, Arizona,
    USA. 

    US Environmental Protection Agency (1974) Unpublished data from EPA
    laboratories. Cited from the 1974 JMPR Monograph, (Annex 1, reference
    22).

    Waters, M.D., Sandhu, S.S., Simmon, V.F, Mortelmans, K.E., Mitchell,
    A.D., Jorgenson, T.A., Jones, D.C.L., Valencia, R. & Garrett, N. E.
    (1982) Study of pesticide genotoxicity.  Basic Life Sci., 21,
    275-326. 

    Waterson, L.A., Gibson, W.A., Morrow, J. & Gopinath, C. (1992)
    Technical dicloran rat 8-week repeat dose study. Unpublished report
    No. 91/199-97 from Huntingdon Research Centre, United Kingdom.
    Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Wazeter, F.X. (1966) Somers test in the albino rabbit. Unpublished
    report No. 100-037 from International Research and Development Corp.,
    USA. Submitted to WHO by Gowan Company, Yuma, Arizona, USA. 

    Wilcox, S., & Barton, S.J. (1996) Dicloran: Range-finding study for a
    two generation reproduction study in rats. Unpublished report No.
    14271 from Inveresk Research International, United Kingdom. Submitted
    to WHO by Gowan Company, Yuma, Arizona, USA. 

    Woodard, M. W., Cockrell, K.O. & Woodard, G. (1964) Safety evaluation
    by oral administration to rats and dogs for 104 weeks. Unpublished
    report No. U2069 from Woodard Research Corporation, USA. Submitted to
    WHO by Gowan Company, Yuma, Arizona, USA. 

    Woodruff, R.C., Mason, J.M., Valencia, R. & Zimmering, S. (1985)
    Chemical mutagenesis testing in  Drosophila: V: Results of 53 coded
    compounds tested for the National Toxicology Program.  Environ. 
     Mutag., 7, 677-702.

    WHO (1996)  The WHO Recommended Classification of Pesticides by 
     Hazard and Guidelines to Classification 1996-1997 (WHO/PCS/96.3),
    Geneva, International Programme on Chemical Safety.

    Zeiger, E., Anderson, B., Haworth, S., Lawlor, T. & Mortelmans, K.
    (1992)  Salmonella mutagenicity tests: V: results from the testing of
    311 chemicals.  Environ. Mol. Mutag., 19, 2-141.
    


    See Also:
       Toxicological Abbreviations
       Dicloran (ICSC)
       Dicloran (WHO Pesticide Residues Series 4)
       Dicloran (Pesticide residues in food: 1977 evaluations)