IPCS INCHEM Home



    PESTICIDE RESIDUES IN FOOD - 1997


    Sponsored jointly by FAO and WHO
    with the support of the International Programme
    on Chemical Safety (IPCS)




    TOXICOLOGICAL AND ENVIRONMENTAL
    EVALUATIONS 1994




    Joint meeting of the
    FAO Panel of Experts on Pesticide Residues
    in Food and the Environment
    and the
    WHO Core Assessment Group 

    Lyon 22 September - 1 October 1997



    The summaries and evaluations contained in this book are, in most
    cases, based on unpublished proprietary data submitted for the purpose
    of the JMPR assessment. A registration authority should not grant a
    registration on the basis of an evaluation unless it has first
    received authorization for such use from the owner who submitted the
    data for JMPR review or has received the data on which the summaries
    are based, either from the owner of the data or from a second party
    that has obtained permission from the owner of the data for this
    purpose.



    CHLORMEQUAT (addendum)

    First draft prepared by
    J.-J. Larsen
    Institute of Toxicology, Danish Veterinary and Food Administration,
    Ministry of Food, Agriculture and Fisheries, Soborg, Denmark

         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 toxicity
                   Long-term toxicity and carcinogenicity
                   Genotoxicity
                   Reproductive toxicity
                   Special studies: Dermal and ocular irritation and
                   dermal sensitization 
         Comments
         Toxicological evaluation
         References

    Explanation

         Chlormequat (2-chloroethyltrimethylammonium chloride) was
    evaluated by the Joint Meeting in 1970, 1972, and 1994 (Annex 1,
    references 14, 18, and 71). In 1972, an ADI of 0-0.05 mg/kg bw was
    established on the basis of the NOAEL in a study of reproductive
    toxicity in rats. In 1994, this ADI was withdrawn owing to the
    inadequacy of the database in comparison with acceptable contemporary
    standards. The compound was reviewed at the present Meeting in
    response to a request from the manufacturer. New data on the
    absorption, distribution, excretion, and biotransformation of
    chlormequat and on its long-term toxicity in rats and dogs,
    carcinogenicity in mice and rats, reproductive toxicity in rats, and
    skin sensitization potential in guinea-pigs were reviewed.

    Evaluation for acceptable daily intake

    1.  Biochemical aspects

    (a)  Absorption, distribution, and excretion

         Experiments are described in articles published in the open
    literature in which the absorption, distribution, and excretion of
    chlormequat were investigated. The level of detail in these papers did
    not permit a complete evaluation by the present Meeting. In the first
    study, the bulk (61%) of an oral dose of 14C-chlormequat administered

    to male rats was excreted in the urine within 4 h, and 96% was
    eliminated within 47 h; faecal excretion accounted for 2.3%, and less
    than 1% was expired as 14C-carbon dioxide. The remainder was found in
    the tissues, with the largest amounts in the carcass (0.25%),
    intestines (0.11%), and liver (0.08%). Analysis of urine samples by
    four different thin-layer and paper chromatographic systems showed
    that all of the radiolabel was on chlormequat (Blinn, 1967).

         In a second study, rats were given a single oral dose of 60 mg
    15N-chlormequat or received 2 mg of the labelled compound daily for
    100 days. After the single dose, the amount of compound in the brain
    decreased quickly, but there was considerable accumulation in the
    kidneys over the 20 days of the investigation. After continuous
    administration, chlormequat was found particularly in active muscles
    such as those of the heart and diaphragm (Bier & Ackermann, 1970).

         In a third study, a lactating cow received a single oral dose of
    1000 mg 15N-chlormequat. The compound was found in the milk and urine
    3 h after administration; most (490 mg) was found 15-39 h after
    administration. Only 22 mg were excreted in the milk, and the
    concentration never exceeded 1 ppm; the peak concentration was found
    12-60 h after administration (Lampeter & Bier, 1970).

         In a more recent study, 136 male and female rats were treated
    intravenously with a single dose of 0.1 mg/kg bw or orally with a
    single dose of 0.5 or 30 mg/kg bw 14C-chlormequat (radiochemical
    purity, 96.8%). Urine, faeces, organs, bile, and expired air were
    collected from all animals at various intervals up to 168 h after
    treatment; 82-103% of the radiolabel was recovered. Most was excreted
    during the first 24 h. More than 85% of the radiolabel was excreted
    with urine and < 6% with faeces; < 1% was eliminated as volatile
    compounds. The maximum blood level was reached about 2 h after oral
    administration of either the low or the high dose. Less than 1% of the
    radiolabel was eliminated in bile during the first 24 h. The maximum
    radiolabel appeared 2-5 h after oral administration. Little radiolabel
    was found in organs or tissues after 168 h, the highest concentrations
    being found in liver and kidney (Giese & Hoffmann, 1989).

    (b)  Biotransformation

         Only chlormequat and two other compounds, which may have been
    other salts of chlorcholine, were reported in the urine of rats that
    had received 200 mg/kg bw of chlormequat orally. Choline itself was
    not identified (Bronisz & Romanowski, 1968).

         A group of 74 male and females rats were given a single
    intravenous dose of 0.1 mg/kg bw or a single oral dose of 0.5 mg/kg bw
    (with or without preteatment with unlabelled chlormequat for 14 days)
    or 30 mg/kg bw 14C-chlormequat (radiochemical purity, 96.8%). Urine,
    faeces, bile, liver, kidney, gastrointestinal tract, brain, muscle,
    spleen, bone, lung, heart, fat, testes, and uterus were examined for
    radiolabel for up to 168 h after treatment. Expired air from two males
    was examined within 0-24 h. A total of 81% of the dose of radiolabel

    was excreted during the test period. In all cases, > 85% of the
    radiolabel was found in urine and < 5% in faeces. Chlormequat was
    excreted mainly unmetabolized. A very polar but unidentified
    metabolite was found in faeces (Giese & Kohl, 1989). 

    (c)  Effects on enzymes and other biochemical parameters

         General pharmacological tests were carried out to determine the
    physiological effects of chlormequat injected intravenously.
    Oligopnoea, salivation, and a tendency to inhibition of intestinal
    propulsion were observed in mice immediately after they were given 7.4
    mg/kg bw. In cats, there was mild inhibition of the vasopressor effect
    of noradrenaline 30 min after administration of 1 mg/kg bw
    chlormequat. In rabbits, neuromuscular junctions were blocked by doses
    of > 1 mg/kg bw; this effect was counteracted by administration of
    10 mg/kg bw D-tubocurarine and potentiated by administration of 1
    mg/kg bw neostigmine. Coagulation of rat blood was unaffected by
    concentrations up to 3 mg/ml. In dogs, doses of > 3 mg/kg bw caused
    a drop in blood pressure; at higher doses, increased respiratory and
    heart rates were observed. These effects were mitigated by prior
    intravenous administration of 1 mg/kg bw atropine (Mutoh et al.,
    1987).

         The action of chlormequat was tested  in vitro with the patch
    clamp technique for electrophysiological measurements described by
    Hamill  et al. (1981). Muscles were excised from the feet of adult
    NMRI mice and dissociated enzymatically to obtain individual muscle
    cells. Chlormequat (purity, 95.6%) activated the nicotinic
    acetylcholine receptor channel at all concentrations between 10 and
    100 mmol/L (Franke & Mellert, 1991).

         The affinity of chlormequat for subtypes of muscarinic
    acetylcholine receptors was investigated  in vitro on membranes from
    bovine cerebral cortex, rat heart, and rat submaxillary gland. The
    results were compared with those obtained for subtype-specific
    reference substances, and atropine was included as a high-affinity
    reference compound with no subtype selectivity. Chlormequat had low
    affinity for the muscarinic receptors in comparison with the reference
    substances (Weifenbach, 1991).

    2.  Toxicological studies

    (a)  Acute toxicity

         Clinical signs of toxicity seen after treatment with chlormequat
    (Table 1) generally consisted of salivation, writhing,
    chromodacryorrhoea, decreased activity, tremors, diuresis, and
    piloerection. Death generally occurred within 24 h of treatment;
    animals that survived recovered within 48 h. The findings at autopsy
    were not consistent or related to treatment.

        Table 1. Acute toxicity of chlormequat

                                                                                         

    Species      Route             LD50 or LC50     Purity    Reference
                                   (mg/kg bw or    (%)
                                   mg/L air)
                                                                                         

    Mouse        Oral              215-1020        NR        Oettel ( 1965 )
                                                   NR        Levinskas & Shaffer (1966)
                                                   NR        Ignatiev (1967)
                                                   98.0      Hattori (1981)
    Mouse        Intraperitoneal   60-68           NR        Shaffer (1970)
                                                   98.0      Hattori (1981)
    Mouse        Subcutaneous      88-92           98.0      Hattori (1981)
    Rat          Oral              330-750         NR        Oettel (1965)
                                                   NR        Levinskas & Shaffer (1966)
                                                   NR        Ignatiev (1967)
                                                   NR        Stefaniek (1969)
                                                   98.1      Hattori (1981)
    Rat          Oral              522             66.1a     Fischer & Lowe (1990)
    Rat          Intraperitoneal   53-75           98.1      Hattori (1981)
    Rat          Subcutaneous      113-118         98.1      Hattori (1981)
    Rat          Dermal            > 4000          NR        Gelbke & Freisberg (1978)
    Rat          Dermal            > 5000          98.1      Hattori (1981)
    Rat          Inhalation        > 5.2           99        Zeller & Klimisch (1979)
    Rat          Inhalation        > 4.6           66.1      Hershman (1990)
    Hamster      Oral              1070            NR        Levinskas & Shaffer (1966)
    Guinea-pig   Oral              215-620         NR        Oettel (1965)
                                                   NR        Levinskas & Shaffer (1966)
    Rabbit       Oral              60-81           NR        Oettel (1965)
                                                   NR        Levinskas & Shaffer (1966)
    Rabbit       Dermal            1250            66.1a     Fischer et al. (1990a)
    Cat          Oral              7-50            NR        Oettel (1965)
                                                   NR        Levinskas & Shaffer (1966)
    Dog          Oral              < 50            NR        Levinskas & Shaffer (1966)
    Sheep        Oral              150-200         NR        Schulz et al. (1970)
    Monkey       Oral              > 800           NR        Costa et al. (1967)
                                                                                         

    NR, not reported
    a Technical material consisting of 66.1% aqueous solution
    
         Rabbits, cats and dogs may be more sensitive to the toxic effects
    of chlormequat than rats and mice. The acute toxicity in monkeys was
    similar to that seen in rats and mice.

    (b)  Short-term toxicity

     Rats

         Two short-term studies of toxicity are described in the 1972 JMPR
    monograph addendum (Annex 1, reference 19), but detailed reports were
    not available for evaluation at the present Meeting. The summary of
    the first study states that groups of 10 male rats were fed
    chlormequat at dietary levels of 0, 500, 1000, or 2000 ppm (equivalent
    to 0, 25, 50, or 100 mg/kg bw per day) for 29 days. There were no
    deaths and no clinical signs of reaction to treatment; body-weight
    gain and food intake remained undisturbed by treatment, and no gross
    pathological changes were observed at termination of the study
    (Levinskas & Shaffer, 1962).

         In the second study, groups of 20 male and 20 female rats were
    fed chlormequat at dietary levels of 0, 200, 600, or 1800 ppm
    (equivalent to 0, 10, 30, or 90 mg/kg bw per day) for 90 days. There
    were no deaths, no clinical signs of reaction to treatment, and no
    treatment-related changes in blood chemistry. The body-weight gain of
    males fed 1800 ppm was slightly depressed in comparison with that of
    controls. Slightly increased kidney weights were recorded in treated
    female rats and slightly increased liver weights in treated males,
    particularly at 1800 ppm; however, histopathological examination of
    major organs revealed no treatment-related changes (Levinskas, 1965).

         In a more recent experiment of acceptable scientific quality,
    groups of five male and five female Wistar rats were fed chlormequat
    at dietary levels of 0, 500, 1500, 3000, or 4500 ppm (equal to 0, 46,
    140, 270, or 410 mg/kg bw per day) for four weeks. The test material
    was a technical-grade formulation of 66.7% purity, but the dietary
    levels were expressed as pure chlormequat. Clinical signs of general
    deterioration in health were seen in males and females receiving 4500
    ppm and, temporarily, in one male and one female receiving 3000 ppm.
    Reduced body-weight gain and food intake were seen in animals fed 4500
    ppm, and slightly reduced weight gain was seen among those fed 3000
    ppm. Serum creatinine levels in males and females receiving 4500 ppm
    and in females receiving 3000 ppm were lower than those of controls.
    Decreased serum concentrations of total protein (in males) and of urea
    (in females) were also seen at the high dietary level. Tests of
    locomotor activity and swimming, gross pathological examinations,
    organ weighing, and histopathological examination revealed no reaction
    to treatment. The NOAEL was 1500 ppm, equal to 140 mg/kg bw per day
    (Schilling et al., 1990).

     Rabbits

         In a recent experiment of acceptable scientific quality, groups
    of 10 male and 10 female New Zealand white rabbits received
    chlormequat (purity, 99%) by repeated occluded dermal applications on
    shaven skin, five days per week for three weeks at doses of 0, 20, 50,
    or 150 mg/kg bw per day. Possible reactions to treatment at the
    application site were limited to erythema during the first two weeks
    of the study; however, these reactions were no more severe than
    reactions frequently seen after repeated occluded dermal applications
    of control compounds. There were no other clinical signs of reaction
    to treatment, and body-weight gain and food intake remained
    undisturbed by treatment. Investigations of haematological parameters
    and blood chemistry, gross pathology, organ weights, and
    histopathology revealed no reaction to treatment (Buch & Finn, 1981).

     Dogs

         In an experiment for which no detailed report was available to
    the Meeting (Annex 1, reference 19), groups of two male and two female
    dogs were fed chlormequat at dietary levels of 0, 20, 60, or 180 ppm
    (equivalent to 0, 0.5, 1.5, or 4.5 mg/kg bw per day) for 106-108 days.
    There were no deaths and no clinical signs of reaction to treatment,
    and body-weight gain and food intake were unaffected. Organ weight
    analysis and histopathological examination at termination of the
    experiment revealed no treatment-related changes (Levinskas, 1965).

         In a study reported in 1967, which was not conducted to currently
    acceptable scientific standards, groups of three male and three female
    beagle dogs were fed chlormequat (technical-grade purified twice by
    recrystallization) at dietary levels of 100, 300, or 1000 ppm
    (equivalent to 0, 2.5, 7.5, or 25 mg/kg bw per day) for two years;
    groups of 10 males and 10 females served as controls. Excessive
    salivation and hindlimb weakness were seen in some animals receiving
    1000 ppm, and one male died after 22 days and one female after 38
    days. The deaths were considered by the authors to be secondary to the
    clinical signs of hindlimb weakness. Analysis of blood chemistry and
    urinalysis revealed no treatment-related changes other than the
    presence of chlormequat in the urine of treated animals. At
    termination, gross pathology, organ weight analysis, and
    histopathology revealed no changes attributable to treatment. The
    NOAEL was probably 300 ppm (equivalent to 7.5 mg/kg bw per day), but
    the absence of further investigation into the signs of hindlimb
    weakness precluded establishment of a definitive NOAEL (Oettel &
    Sachsse, 1967).

         Groups of five male and five female beagle dogs were given
    technical-grade chlormequat (purity, 67.4%) mixed in the diet at doses
    of 0, 150, 300, or 1000 ppm, equal to 0, 4.7, 9.2, or 31 mg/kg bw per
    day in males and 0, 5.2, 10, or 32 mg/kg bw per day in females, for 12
    months. Food consumption was determined daily and body weight once a
    week. In addition to clinical, hematological, and ophthalmological
    examinations, urinalysis and neurofunctional examinations were carried

    out. At the end of study, all animals were subjected to gross
    pathological and histopathological examination. Animals at 1000 ppm
    had diarrhoea, vomiting, salivation, apathy, and other severe clinical
    symptoms as well as many changes in clinicochemical and haematological
    parameters. Two dogs at this dose died. Diarrhoea, vomiting, and
    salivation were also seen at 300 ppm. The NOAEL was 150 ppm, equal to
    4.7 mg/kg bw per day, on the basis of diarrhoea, vomiting, and
    salivation (Mellert et al., 1993).

    (c)  Long-term toxicity and carcinogenicity

     Mice

         In a study reported in 1971, the design of which was clearly not
    in accordance with currently acceptable scientific standards, groups
    of 52 male and 52 female CFLP mice were fed chlormequat (purity, about
    98.5%) at dietary levels of 0 or 1000 ppm (equivalent to 0 or 150
    mg/kg bw per day) for 78 weeks. Survival was unaffected, and there
    were no clinical signs of reaction to treatment, except that treated
    animals gained less weight than controls. Histopathological
    examination was initially restricted to 10 males and 10 females from
    each group but was extended to all tissues from animals in which a
    treatment-related effect was seen. The incidence of benign lung
    tumours was higher (20/52) in treated males than in controls (10/51)
    but was considered to be within the normal range in untreated mice.
    The incidences of lung tumours in females and of tumours in all other
    organs examined in animals of each sex were not significantly higher
    in the treated group than in controls (Weldon et al., 1971).

         Groups of 50 male and 50 female B6C3F1 mice were fed diets
    containing chlormequat (purity, 97-98%) at 0, 500, or 2000 ppm (equal
    to 0, 70, or 290 mg/kg bw per day) for 102 weeks. The dietary levels
    were set on the basis of the results of an eight-week study with doses
    of 1200-20 000 ppm designed to provide a statistical estimate of the
    dose that would depress body-weight gain by 10%. The control group
    consisted of 20 males and 20 females. Body-weight gain remained
    largely unaffected by treatment, and there were no treatment-related
    clinical signs. Survival was unaffected by treatment and was adequate
    for assessment of carcinogenicity, as at least 80% of animals in each
    group survived until termination of the experiment. The incidence of
    haemangiomas and haemangiosarcomas was slightly increased in treated
    females (1/20 in controls, 4/50 at 500 ppm, and 5/50 at 2000 ppm), but
    the authors concluded that there was no clear evidence for the
    carcinogenicity of chlormequat in these mice (National Cancer
    Institute, 1979).

         Groups of 50 male and 50 female B6C3F1 mice were fed diets
    containing technical-grade chlormequat (purity, 67.4%) at 0, 150, 600,
    or 2400 ppm, equal to 0, 21, 84, or 340 mg/kg bw per day in males and
    0, 23, 91, or 390 mg/kg bw per day in females, for 110 weeks.
    Satellite groups of 10 male and 10 female mice at each dose were
    killed after 52 weeks. Food consumption and body weight were
    determined weekly during the first 14 weeks and every four weeks

    thereafter. The health of the animals was checked daily, and clinical
    signs were followed up thoroughly once a week. All animals that died
    or were killed in a moribund condition during the study or were killed
    terminally were subjected to gross pathological and histopathological
    examinations. The body weight of animals in the satellite goup at 2400
    ppm was reduced. The incidence and severity of tubular down-growth in
    the ovaries and the incidence of endometrial hyperplasia were
    increased in mice at 600 and 2400 ppm. There was no significant
    increase in the incidence of benign or malignant tumours. The NOAEL
    was 150 ppm, equal to 21 mg/kg bw per day, on the basis of tubular
    down-growth in the ovaries and endometrial hyperplasia (Mellert et
    al., 1994).

     Rats

         In 1994, the Meeting reviewed a short summary of a two-year study
    reported in 1967, the design of which was not in accordance with
    contemporary scientific standards. Groups of 50 male and 50 female
    Sprague-Dawley rats were fed chlormequat (technical grade, purified
    twice by recrystallization) at dietary levels of 0, 500, or 1000 ppm
    (equivalant to 0, 25, or 50 mg/kg bw per day) for two years. The
    authors reported that survival was unaffected, there were no clinical
    signs of reaction to treatment, and food intake and body-weight gain
    were unchanged. Haematological examinations, analysis of blood
    chemistry, and urinalysis carried out after three and 12 months and
    before termination revealed no reaction to treatment. Gross
    pathological examination, analyses of liver and kidney weights, and
    histopathological examination revealed no abnormalities attributable
    to treatment. Normal, age-related pathological changes were seen; in
    particular, the tumour profiles in treated and control animals were
    indistinguishable. Detailed evaluation of this report was not possible
    (Oettel & Froberg, 1967).

         A summary of another long-term study was available in which
    groups of 50 male and 50 female Sprague-Dawley rats were fed diets
    containing chlormequat (technical grade purified twice by
    recrystallization) and choline chloride in a ratio of 10:7 for two
    years. The dietary levels of chlormequat were 0, 500, 1000, or 5000
    ppm (equivalent to 0, 25, 50, and 250 mg/kg bw per day). The control
    group consisted of 100 male and 100 female rats. Survival was
    unaffected by treatment; the survival rates after two years were
    72-82% in male rats and 48-64% in females. There were no clinical
    signs of reaction to treatment, and body-weight gain and food intake
    remained unaffected. Haematological examination, limited analyses of
    blood chemistry, and urinalysis carried out after three and 12 months
    and before termination revealed no indication of reaction to
    treatment. Gross pathological examination, analysis of liver and
    kidney weights, and histopathological examination of a range of organs
    and tissues revealed no abnormalities attributable to treatment.
    Normal, age-related pathological changes were seen; in particular, the
    tumour profiles in treated and control animals were indistinguishable
    (Oettel & Sachsse, 1974).

         In a study designed to assess the tumorigenicity of chlormequat
    in rats, groups of 50 male and 50 female Fischer 344 rats were fed
    diets containing chlormequat (purity, 97-98%) at 0, 1500, or 3000 ppm
    (equivalent to 0, 75, or 150 mg/kg bw per day) for 108 weeks. The
    dietary levels were set on the basis of the results of an eight-week
    study with doses of 3150-14 700 ppm designed to provide a statistical
    estimate of the dose that would depress body-weight gain by 10%. The
    control group consisted of 20 males and 20 females. The body-weight
    gain of treated rats was slightly lower than that of controls, but
    there were no treatment-related clinical signs. Survival was
    unaffected by treatment and was adequate for assessment of
    carcinogenicity, as at least 64% of animals in each group survived
    until termination of the experiment. The incidence of leukaemia or
    malignant lymphoma was slightly increased in treated females (3/20 in
    controls, 11/50 at 1500 ppm, and 14/50 at 3000 ppm), and there was an
    apparently dose-related increase in the incidence of islet-cell
    adenomas of the pancreas in treated males (0/18 in controls, 1/47 at
    1500 ppm, and 7/45 at 3000 ppm); however, the authors concluded that
    there was no clear evidence for the carcinogenicity of chlormequat in
    these rats (National Cancer Institute, 1979). 

         Groups of 20 male and 20 female Wistar rats were fed diets
    containing technical-grade chlormequat (purity, 67.4%) at 0, 280, 940,
    or 2800 ppm, equal to 0, 13, 43, or 140 mg/kg bw per day in males and
    0, 17, 56, or 170 mg/kg bw per day in females, for 78 weeks. Food
    consumption and body weight were determined once a week during the
    first 14 weeks and then at four-week intervals. The animals were
    observed daily and inspected thoroughly once a week for clinical
    signs. At the start and end of the study, controls and those at the
    highest dose were examined for ophthalmological signs. All animals
    were subjected to haematological examination, blood chemical analyses,
    and urinalysis at 3, 6, 12, and 18 months. All rats still alive at the
    end of study and rats that died intercurrently were subjected to gross
    pathological and histopathological examination. Statistically
    significant reductions in body weight (18% in males and 10% in
    females) and a minor reduction in food intake were observed in animals
    at 2800 ppm. Pathological examination revealed no substance-induced
    changes in any organ. Higher incidences of tubular mineralization and
    tubular atrophy in the kidneys of treated males were considered to be
    toxicologically insignificant. Tumour incidences were not enhanced.
    The NOAEL was 940 ppm, equal to 43 mg/kg bw per day, on the basis of
    reduced body weight in males (Schilling et al., 1992). 

         Groups of 50 male and 50 female Wistar rats were fed diets
    containing technical-grade chlormequat (purity, 67.4%) at 0, 280, 940,
    or 2800 ppm (equal to 0, 13, 42, or130 mg/kg bw per day in males and
    0, 16, 55, and 170 mg/kg bw per day in females) for two years. Food
    consumption and body weight were determined once a week during the
    first 14 weeks and then at four-week intervals. The animals were
    observed daily and inspected thoroughly once a week for clinical
    signs. At the end of the study, all surviving rats (40 controls, 34 at
    280 ppm, 36 at 940 ppm, and 32 at 2800 ppm) were subjected to
    haematological examination, blood chemical analysis, and urinalysis

    and then to gross pathological and histopathological examination.
    Reduced body weights (14% in males and 22% in females) and food
    consumption (10% in males and 6% in females) were observed in animals
    at 2800 ppm at the end of the study. No signs of carcinogenicity were
    observed. The NOAEL was 940 ppm, equal to 42 mg/kg bw per day, on the
    basis of reduced body weight (Mellert et al., 1992).

    (d)  Genotoxicity

         The results of tests for the genotoxicity of chlormequat are
    summarized in Table 2. All of the assays for gene mutation carried out
    in bacteria and mammalian cells gave negative results. No cytogenetic
    anomalies were found in human lymphocytes  in vitro, and unscheduled
    DNA synthesis was not seen in rat hepatocytes. Neither dominant lethal
    mutation nor micronuclei were seen in mice  in vivo, and no
    chromosomal aberrations occurred in rats.

    (e)  Reproductive toxicity

     Mice

         The results of three experiments in mice were summarized in the
    1972 monograph addendum (Annex 1, reference 19), but detailed reports
    were not available for evaluation by the present Meeting. In the first
    experiment, groups of pregnant mice received intraperitoneal
    injections of chlormequat at 30 mg/kg bw on days 14 and 15 or days
    11-15 of gestation. Another group of mice received 200 mg/kg bw per
    day by gavage on days 11-15 of gestation. All mice were killed on day
    19. The number of fetuses per dam, fetal size, frequency of
    resorptions, and incidence of malformations were similar in the test
    and control groups. In the second experiment, pregnant mice were fed
    chlormequat at dietary levels of 0, 1000, or 10 000 ppm (equivalent to
    0, 150, or 1500 mg/kg bw per day) on days 1-15 of gestation or 25 000
    ppm (equivalant to 3750 mg/kg bw per day) on days 11-15. All animals
    were killed on day 19. The number of fetuses per dam, fetal size, and
    frequency of resorptions were similar in the test and control groups.
    Dams fed 10 000 or 25 000 ppm had slightly more malformed fetuses than
    controls. In the third experiment, groups of mature male and female
    mice were fed chlormequat at dietary levels of 0, 1000, or 5000 ppm
    (equivalent to 0, 150, or 750 mg/kg bw per day) and mated after 1, 3,
    4, and 10 weeks. All mice were killed on day 19 of gestation. Feeding
    of chlormequat was found to have no effect on fertility, and no
    evidence of teratogenicity was seen in the offspring (Shaffer, 1970).

     Rats

         In a study conducted between 1965 and 1967 which was not in
    accordance with currently acceptable scientific standards, groups of
    20 male and 20 female rats received diets containing chlormequat at 0,
    100, 300, or 900 ppm (equivalent to 0, 5, 15, or 45 mg/kg bw per day)
    throughout three generations. No abnormalities were seen in the
    appearance, behaviour, food intake, body-weight gain, fertility,
    gestation, lactation, or viability of the offspring, and no fetal



        Table 2. Results of tests for the genotoxicity of chlormequat
                                                                                                                            
    End-point          Test system                 Concentration        Purity         Result        Reference
                                                   of chlormequat       (%)
                                                                                                                            
    In vitro
    Reverse            S. typhimurium TA98,        < 5000 g/plate      66.1a          Negativeb     Traul & Mulligan
    mutation           100, 1535, 1537, 1538                                                         (1990)
                       E. coli WP2uvrA

    Reverse            S. typhimurium TA98,        < 2500 g/plate      92.4           Negativeb     Zeller & Engelhardt
    mutation           100, 1535, 1537, 1538                                                         (1979)

    Reverse            Chinese hamster             < 5000 g/ml         66.1a          Negativeb     Traul & Johnson
    mutation           ovary cells, hprt locus                                                       (1990)

    Reverse            Chinese hamster V79         < 5000 g/ml         94.5-98.9      Negativeb     Debets et al. (1986)
    mutation           cells, hprt locus

    Chromosomal        Human lymphocytes           < 5000 g/ml         94.5-98.9      Negativeb     Enninga et al. (1987)
    aberration

    Unscheduled        Rat hepatocytes             < 7.5 g/ml          66.1a          Negative      Pant & Law (1990)
    DNA synthesis

    Unscheduled        Rat hepatocytes             < 10 000 nl/ml       72c            Negative      Cifone & Myhr (1987)
    DNA synthesis

    In vivo
    Dominant           Male NMRI mice              1  261 mg/kg bw     99.6           Negative      Gelbke & Engelhardt
    lethal mutation                                                                                  (1979)

    Micronucleus       Male and female             < 2  202.5          94.5-98.9      Negative      Geunard et al. (1983)
    formation          NMRI mice                   mg/kg bw

    Chromosomal        Male and female             < 1  500            66.1           Negative      Sharma & Caterson
    aberration         Sprague-Dawley rats         mg/kg bw                                          (1991)
                                                                                                                            

    a Technical material consisting of 66.1% aqueous solution
    b With and without metabolic activation
    c Technical material consisting of 72% aqueous solution
    


    malformations occurred that could be attributed to treatment.
    Histopathological examination of 10 rats of each sex of the F3
    generation at each dose after nine weeks of treatment revealed the
    presence of giant cells in the testicular tubules of four rats treated
    with 900 ppm and two treated with 300 ppm. The authors suggested that
    the cells were an expression of delayed maturation during
    spermatogenesis; however, the Meeting found it difficult to assess the
    significance of the finding and concluded that the NOAEL was 100 ppm,
    equivalent to 5 mg/kg bw per day (Leuschner et al., 1967).

         In a study described in the 1972 monograph addendum (Annex 1,
    reference 19), groups of pregnant rats were fed chlormequat at dietary
    levels of 0, 1000, or 5000 ppm (equivalent to 0, 50, or 250 mg/kg bw
    per day) on days 1-21 of gestation. When the animals were killed the
    day before parturition, no teratogenic effects were observed (Shaffer,
    1970).

         In a two-generation study of reproductive toxicity,
    technical-grade chlormequat (purity, 67.4%) was administered to groups
    of 24 male and 24 female Wistar rats at dietary levels of 0, 300, 900,
    or 2700 ppm (equal to 0, 29, 86, or 250 mg/kg bw per day in males and
    0, 23, 69, or 230 mg/kg bw per day in females). At least 70 days after
    the beginning of treatment, F0 animals were mated in order to produce
    an F1a litter and subsequently remated to produce an F1b litter.
    Groups of 24 males and 24 females from the F1 litter were selected as
    the F1 parents and kept on the diet for at least 98 days before they
    were mated to produce an F2 litter. The study was terminated after
    weaning of the F2 litter. All animals were inspected daily, and the
    food consumption of the F0 and F1 parents was determined weekly.
    Pups were observed for the usual parameters and also for physiological
    development and behavioural effects (gripping reflex, acoustic
    startle, and pupillary reflex). A statistically significant reduction
    in body weight was observed in F0 and F1 females at 2700 ppm, and
    food consumption was moderately reduced in males and females of both
    generations; transient tremor and hypersensitivity were also observed
    in F0 and F1 females at this dose, mainly during or after the
    lactation period. Also at this dose, male fertility was reduced, fewer
    pups were delivered by each dam, and the growth and development of the
    F1a, F1b, and F2 pups were retarded. The NOAEL for reproductive
    toxicity was 900 ppm, equal to 69 mg/kg bw per day, on the basis of
    reductions in male fertility and number of delivered pups (Hellwig et
    al., 1993). 

     Hamsters

         Groups of eight pregnant Syrian golden hamsters were given
    chlormequat (purity unspecified) by gavage at concentrations of 0, 25,
    50, 100, 200, 300, or 400 mg/kg bw once on day 8 of gestation or
    100 mg/kg bw daily on days 7, 8, and 9 of gestation. The control group
    consisted of 15 animals. Clinical signs of toxicity were seen in the
    groups receiving the higher doses. All animals were killed on day 14
    of gestation. Animals fed 100 mg/kg bw or more had fewer fetuses than

    controls and more fetal resorptions. In animals fed 200 mg/kg bw or
    more, fetal size and weight were reduced. No abnormalities were
    observed in animals treated with single doses of 0, 25, 50, or 100
    mg/kg bw. Malformations including anophthalmia, microphthalmia, cleft
    palate, and polydactylism and evidence of developmental retardation
    were seen in the offspring of dams treated with three doses of 100
    mg/kg bw or a single dose of 200, 300, or 400 mg/kg bw. The limited
    details presented in the publication make it difficult to assess the
    maternal toxicity; the occurrence of malformations in historical
    controls was not presented (Juszkiewicz et al., 1970).

     Rabbits

         In a study described in the 1972 monograph addendum (Annex 1,
    reference 19), groups of pregnant rabbits were fed diets containing
    chlormequat at 0 or 1000 ppm (equivalent to 0 or 30 mg/kg bw per day)
    on days 1-28 of pregnancy and were killed two days before parturition.
    No evidence of teratogenicity was seen (Shaffer, 1970).

         In a study of acceptable design, groups of 15 inseminated female
    Himalayan rabbits were given chlormequat at 0, 1.5, 3, 6, or 12 mg/kg
    bw per day by gavage on days 6-18 of gestation. Fetuses were removed
    after sacrifice of the dams on day 28 of gestation and were examined
    for abnormalities macroscopically and by X-ray; in addition, the heads
    of all fetuses were fixed in Bouin's solution, and transverse sections
    were assessed. Treatment did not affect mortality. Rapid breathing,
    salivation, and apathy were seen on single occasions in single animals
    receiving 6 or 12 mg/kg bw per day; the body-weight gain of animals
    given 12 mg/kg bw per day was reduced temporarily, and food intake was
    temporarily depressed in all treated groups. Treatment had no effect
    on the number of fetuses, conception rate, resorption rate, size or
    weight of the fetuses, or placental weights. No teratogenic effect was
    seen. Minor variations and developmental retardation were seen to the
    same extent in all groups, including controls. The NOAEL for maternal
    toxicity was 6 mg/kg bw per day, while there was no evidence of
    fetotoxicity or teratogenicity at the highest dose tested, 12 mg/kg bw
    per day (BASF, 1979).

    (f)  Special studies: Dermal and ocular irritation and dermal
    sensitization

         In two studies conducted between 1978 and 1980, which were not in
    accordance with current test guidelines, the irritancy of chlormequat
    chloride to the skin was tested in rabbits. In the first study, about
    0.5 ml of the test material (purity unspecified) was applied to intact
    and abraded sites on each of six Vienna white rabbits and left in
    place for 24 h under an occlusive dressing. At the intact sites,
    erythema and oedema were observed at the end of the application
    period, but these signs were almost fully reversed within two days.
    More severe signs were observed at the abraded sites; the signs were
    only partly reversible, and superficial necrosis was seen in three
    animals after three days (Gelbke, 1978). 

         In the second study, about 500 mg of the same material were
    tested in the same way in New Zealand white rabbits. Dermal reaction
    at the treatment sites was limited to very slight or well-defined
    erythema, which was evident only at the end of the application period.
    All reaction had resolved completely within 72 h of treatment (Buch &
    Gardner, 1980). 

         In a study based on current test guidelines, about 0.5 ml of
    chlormequat (a technical material consisting of a 66.1% aqueous
    solution) was applied to intact sites on each of six New Zealand white
    rabbits and left in place for 4 h under an occlusive dressing. Dermal
    reaction at the treatment sites was limited to barely perceptible or
    slight erythema, which was evident in three animals 1 h after
    treatment and in one animal at 24 h. All reactions had resolved
    completely within 48 h of treatment (Fischer et al., 1990b).

         The irritancy of chlormequat chloride to the eye was tested in
    Vienna white rabbits by applying about 0.1 ml of the test material
    (purity unspecified) to the conjunctival sac of the right eyelid of
    six rabbits. Conjunctival redness was seen in five rabbits 24 h after
    treatment. After 48 h, conjunctival redness was seen in two rabbits,
    one of which had a conjunctival discharge. All reactions had resolved
    by 72 h after treatment (Gelbke & Grundler, 1981). 

         The irritancy of chlormequat chloride (a technical material
    consisting of a 66.1% aqueous solution) was also tested in New Zealand
    white rabbits. About 0.1 ml was applied to the conjunctival sac of the
    left eyelid of six rabbits and left for 24 h. One hour after
    treatment, slight reactions were seen in all the rabbits. These signs
    had resolved by 48 h in two animals and by four days in all rabbits
    (Lowe & Boczon, 1990).

         The potential of chlormequat to cause delayed contact
    hypersensitivity was tested in albino guinea-pigs by the method of
    Buehler. Induction was performed by applying 0.4 ml of the test
    material to a shaven flank and leaving it for 6 h under an occlusive
    dressing. This process was repeated three times per week for a total
    of nine applications. After a two-week rest period, the animals were
    challenged by applying the test material to the opposite flank. No
    erythema or oedema was observed after the challenge, whereas a
    positive control compound (dinitrochlorobenzene) included in the study
    gave the expected results. It was concluded that chlormequat is not a
    skin sensitizer (Ventura & Moore, 1990).

         The sensitizing effect on the skin of chlormequat was tested in
    guinea-pigs in the maximization test based on the method of Magnusson
    and Kligman. After intradermal induction with a volume of 0.1 ml
    Freund's adjuvant:0.9% saline (1:1), well-defined erythema and slight
    oedema were observed at the injection sites of both control and test
    animals. Injection of the test substance in 0.9% saline caused
    well-defined erythema, and injection of the test substance in Freund's
    adjuvant:0.9% saline resulted in well-defined erythema and slight
    oedema. The control animals, treated with 0.9% saline, showed no skin

    reaction. After percutaneous induction, perfomed only in the test
    animals, partially open incrustation was observed in additon to
    erythema and slight oedema. After percutaneous challenge with 50% test
    substance, no skin reaction was observed in controls or test animals.
    The authors concluded that chlormequat has no sensitizing effect on
    the skin of the guinea-pig (Rossbacher & Kirsch, 1992).

    Comments

         In experiments with 14C-labelled chlormequat in rats, absorption
    was rapid, and elimination was essentially complete within 24 h,
    occurring almost entirely via the urine and mainly as unmetabolized
    chlormequat. Less than 1% of the administered dose remained in the
    tissues. Accumulation of 15N-labelled material in the kidneys was
    reported, but the experimental details were incomplete and detailed
    evaluation was not possible. Studies of the biotransformation of
    chlormequat suggested that the only metabolites found in rat urine may
    have been salts of chlorcholine. An unidentified polar metabolite was
    found in faeces.

         Pharmacological tests in mice, rats, rabbits, and cats given
    chlormequat intravenously revealed a stimulatory effect on the
    parasympathetic nervous system and a myoneural blocking action.
    Further work showed that chlormequat is a partial agonist of the
    nicotinic acetylcholine receptor; the affinity for muscarinic
    receptors was low and relatively unselective.

         Chlormequat was of moderate acute oral toxicity in rats, mice,
    hamsters, guinea-pigs, and monkeys (LD50 = 200-1000 mg/kg bw), but
    rabbits and dogs appeared to be more sensitive (LD50 = 50-80 mg/kg
    bw) than the other species. The signs of toxicity may have been due to
    pharmacological activity, and there were no consistent
    treatment-related findings at autopsy. WHO has classified chlormequat
    as slightly hazardous (WHO, 1996).

         In a four-week study of toxicity in rats at dietary
    concentrations of 0, 500, 1500, 3000, or 4500 ppm, the NOAEL was 1500
    ppm, equal to 140 mg/kg bw per day, on the basis of reduced
    body-weight gain and depression of serum creatinine concentration.
    These results are largely in agreement with those of older studies in
    rats of up to 90 days' duration. In a 12-month study of toxicity in
    dogs at dietary concentrations of 0, 150, 300, or 1000 ppm, the NOAEL
    was 150 ppm, equal to 4.7 mg/kg bw per day, on the basis of diarrhoea,
    vomiting, and salivation.

         In a 110-week study of toxicity and carcinogenicity in mice at
    dietary concentrations of 0, 150, 600, or 2400 ppm, the NOAEL was 150
    ppm, equal to 21 mg/kg per day, on the basis of tubular down-growth in
    the ovaries and endometrial hyperplasia. In a 78-week study of
    toxicity and carcinogenicity in rats at dietary concentrations of 0,
    280, 940, or 2800 ppm, the NOAEL was 940 ppm, equal to 43 mg/kg bw per
    day, on the basis of reduced body weight. Tumour incidences were not

    enhanced. The potential carcinogenicity of chlormequat was
    investigated in a 104-week study in rats at dietary concentrations of
    0, 280, 940, or 2800 ppm. No carcinogenicity was observed. The NOAEL
    was 940 ppm, equal to 42 mg/kg bw per day, on the basis of reduced
    body weight. 

         In a multigeneration study of reproductive toxicity in rats at
    dietary concentrations of 0, 300, 900, or 2700 ppm, the NOAEL for
    reproductive toxicity was 900 ppm, equal to 69 mg/kg bw per day, on
    the basis of reduced numbers of pregnancies and of delivered pups and
    retarded growth and development of the pups. 

         The developmental toxicity of chlormequat has been investigated
    in mice after administration by intraperitoneal injection, gavage, or
    via the diet, in rats by dietary administration, and in hamsters and
    rabbits by gavage. Many of the study reports were available only in
    summary form. In a study in mice at dietary concentrations of 0, 1000,
    or 10 000 ppm on days 1-15 of gestation or 25 000 ppm on days 11-15 of
    gestation, the number of malformations in animals fed 10 000 ppm or 25
    000 ppm was reported to be slightly higher than that in controls;
    however, the significance of this observation was difficult to assess.
    In hamsters receiving chlormequat at levels of 0, 25, 50, 100, 200,
    300, or 400 mg/kg bw once on day 8 of gestation or 100 mg/kg bw per
    day on days 7-9 of gestation, malformations and evidence of delayed
    development were seen with doses > 200 mg/kg bw on day 8 and after
    the three doses of 100 mg/kg bw per day. Evidence of maternal and
    fetal toxicity was also seen at these doses. The study in hamsters
    could not be fully evaluated, owing to lack of detail in the
    publication. A full report of a well-conducted study in which rabbits
    were dosed orally with 0, 1.5, 3, 6 or 12 mg/kg bw per day on days 6-
    18 of gestation was available. Signs of maternal toxicity were seen at
    the highest dose, but there was no evidence of developmental toxicity.

         Chlormequat has been adequately tested for genotoxicity  in 
     vitro and  in vivo in a range of assays. The Meeting concluded that
    it was not genotoxic.

         Chlormequat was not irritating to the skin or eye in rabbits. It
    did not cause delayed contact hypersensitivity when tested in albino
    guinea-pigs by the method of Buehler or by the method of Magnusson and
    Kligman. 

         An ADI of 0-0.05 mg/kg bw was allocated on the basis of the NOAEL
    of 4.7 mg/kg bw per day for diarrhoea, vomiting, and salivation in the
    one-year study of toxicity in dogs, and using a safety factor of 100.

    Toxicological evaluation

    Levels that cause no toxicological effect

         Mouse:    150 ppm, equal to 21 mg/kg bw per day (110-week study
                   of toxicity and carcinogenicity)


        Toxicological criteria for setting guidance values for dietary and non-dietary exposure to chlormequat

                                                                                                                   

    Human exposure      Relevant route, study type, species              Results, remarks
                                                                                                                   

    Short-term          Dermal irritation, rabbit                        Not irritating
    (1-7 days)          Eye irritation, rabbit                           Not irritating
                        Skin sensitization, guinea-pig                   Non-sensitizing
                        Inhalation toxicity, rat                         LC50 > 5 mg/L air
                        Dermal toxicity, rabbit                          LD50 = 1300 mg/kg bw
                        Oral toxicity, rabbit                            LD50 = 70 mg/kg bw
                        Oral toxicity, cat                               LD50 = 7-50 mg/kg bw

    Medium-term         Repeated oral, reproductive toxicity, rabbit     NOAEL = 6 mg/kg bw per day: maternal 
    (1-26 weeks)                                                         toxicity, no reproductive toxicity

    Long-term           Repeated oral, one year, dog                     NOAEL = 4.7 mg/kg bw per day: diarrhoea,  
    (> 1 year)                                                           vomiting, and salivation
                                                                                                                   
    

         Rat:      940 ppm, equal to 42 mg/kg bw per day (104-week study
                   of toxicity and carcinogenicity)
                   900 ppm, equal to 69 mg/kg bw per day (two-generation
                   study of reproductive toxicity)

         Rabbit:   6 mg/kg bw per day (maternal toxicity in a study of
                   developmental toxicity)
                   12 mg/kg bw per day (fetotoxicity and teratogenicity in
                   a study of developmental toxicity)

         Dog:      150 ppm, equal to 4.7 mg/kg bw per day (one-year study
                   of toxicity)

    Estimate of acceptable daily intake for humans

         0-0.05 mg/kg/bw

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

         Study of developmental toxicity in rodents that meets current
         scientific standards.

    References

    BASF (1979) Study of the prenatal toxicity of
    2-chloroethyltrimethylammonium chloride (chlormequat chloride) on
    rabbits. Unpublished report from BASF AG. Submitted to WHO by BASF AG,
    Limburgerhof, Germany. 

    Bier, H. & Ackermann, H. (1970) [Localization and accumulation of
    chlorcholine chloride after oral dosing in the rat.].  Arch. Exp. 
     Vet. Med., 24, 1023-1026 (in German).

    Blinn, R.C. (1967) Plant growth regulant. Biochemical behaviour of
    2-chloroethyl trimethylammonium chloride in wheat and rats.  J. 
     Agric. Food Chem., 15, 984-988. 

    Bronisz, H. & Romanowski, H. (1968) Chromatographic study of the urine
    of rats poisoned with chlorcholine chloride.  Acta Pol. Pharmacol., 
    25, 611 (in Polish).

    Buch, S.A. & Finn, J.P. (1981) Chlormequat chloride, subchronic dermal
    toxicity in rabbits over 21 days. Unpublished report from Life Science
    Research. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Buch, S.A. & Gardner, J.R. (1980) Chlormequat chloride, primary skin
    irritation study in rabbits. Unpublished report from Life Science
    Research. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Cifone, M.A. & Myhr, B.C. (1987) Evaluation of chlormequat chloride
    720 BASF (ZNT No. 86/246) in the rat primary hepatocyte unscheduled
    DNA synthesis assay. Unpublished report from Hazleton Laboratories
    America Inc. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Costa, D.G., Hansen, W.D. & Woodward, G. (1967) Cyclocel-toxicity in
    the monkey following single oral doses. Unpublished report from
    Woodward Research Corporation. Submitted to WHO by American Cyanamid
    Co., Princeton, NJ, USA.

    Debets, F.M.H., Enninga, I.C., Verspeek, C.M., van de Waart, E.J., van
    Oort, G., van Zandvoort, P.M. & de Man, C.A.J.J.M. (1986) Evaluation
    of the mutagenic activity of Stabilin in an in vitro mammalian cell
    gene mutation test with V79 Chinese hamster cells. Unpublished report
    from Notox Holland. Submitted to WHO by BASF AG, Limburgerhof,
    Germany. 

    Enninga, I.C., van de Waart, E.J., Verspeek, C.M. & Engelen, J.J.M.
    (1987) Evaluation of the ability of Chlorocholinchlorid techn.
    (Stabilin) to induce chromosome aberrations in cultured peripheral
    human lymphocytes. Unpublished report from Notox Holland. Submitted to
    WHO by BASF AG, Limburgerhof, Germany.

    Fischer, J.E. & Lowe, C.A. (1990) Oral LD50 study in albino rats with
    AC 38,555. Unpublished report from American Cyanamid Co., Agricultural
    Research Division. Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    Fischer, J.E., Lowe, C.A., Boczon, L. & Scubelek, S. (1990a) Dermal
    LD50 study in albino rabbits with AC 38,555 liquid technical.
    Unpublished report from American Cyanamid Co., Agricultural Research
    Division. Submitted to WHO by American Cyanamid Co., Princeton, NJ,
    USA.

    Fischer, J.E., Boczon, L. & Scubelek, S. (1990b) Skin irritation study
    in albino rabbits with AC 38,55 liquid technical. Unpublished report
    from American Cyanamid Co., Agricultural Research Division. Submitted
    to WHO by American Cyanamid Co., Princeton, NJ, USA.

    Franke, C. & Mellert, W. (1991) Report of the in vitro test of the
    action of chlormequat chloride at nicotinic acetylcholine receptors of
    adult mouse muscle. Unpublished report from the Institute of
    Physiology of the Technical University, Munich, Germany. Unpublished
    report from BASF AG. Submitted to WHO by BASF AG, Limburgerhof,
    Germany.

    Gelbke, H.P. (1978) Primary skin irritation of chlormequat chloride
    750 BASF on the intact and scarified dorsal skin of white rabbits.
    Unpublished report from BASF AG. Submitted to WHO by BASF AG,
    Limburgerhof, Germany.

    Gelbke, H.P. & Engelhardt, G. (1979) Study of
    2-chloroethyltrimethylammonium chloride (chlorcholine chloride) in the
    dominant lethal test on male mice after single oral administration.
    Unpublished report from BASF AG. Submitted to WHO by BASF AG,
    Limburgerhof, Germany.

    Gelbke, H.P. & Freisberg, G. (1978) Examination of the acute dermal
    toxicity of chlormequat chloride in the rat. Unpublished report from
    BASF AG. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Gelbke, H.P. & Grundler, O.J. (1981) Study of the primary irritation
    of chlormequat chloride (Reg. No. 24 605) to the eye of white rabbits.
    Unpublished report from BASF AG. Submitted to WHO by BASF AG,
    Limburgerhof, Germany.

    Geunard, J., Scalera, F., Fries, P. & Terrier, C. (1983) Mouse
    micronucleus assay with CCC. Unpublished report from Research &
    Consulting Co., Switzerland. Submitted to WHO by BASF AG,
    Limburgerhof, Germany.

    Giese, U. & Hoffmann, H.D. (1989) Metabolism and biokinetics of
    [14C]-chlormequatchloride ([14C]-BAS 062 W) in rats, part A,
    absorption, elimination, distribution of [14C]-BAS 062 W in rats.
    Unpublished report No. NA 879749 from Natec-institut fr
    Naturwissenschaftlich-technische Dienste Gmbh, Hamburg, Germany.
    Submitted to WHO by BASF Aktiengesellschaft, Limburgerhof, Germany. 

    Giese, U. & Kohl, W. (1989) Metabolism and biokinetics of
    [14C]-chlormequat-chloride ([14C]-BAS 062 W) in rats, part B,
    metabolic fate of [14C]-BAS 062 W in rats. Unpublished report No. NA
    879748 from Natec-institut fr Naturwissenschaftlich-technische
    Dienste GMBH, Hamburg, Germany. Submitted to WHO by BASF
    Aktiengesellschaft, Limburgerhof, Germany. 

    Hamill, O.P., Marty, A., Neher, E., Sakmann, B. & Sigworth, F.J.
    (1981) Improved patch clamp techniques for high resolution current
    recording from cells and cell-free membranes.  Pflugers Arch., 391,
    85-100.

    Hattori, K. (1981) Acute toxicity study of Cycocel on mice and rats.
    Unpublished report from Hokkaido Public Hygiene Laboratory. Submitted
    to WHO by American Cyanamid Co., Princeton, NJ, USA.

    Hellwig, J., Deckardt, K., Freisberg, K.O. & Hildebrand, B. (1993)
    Reproduction toxicity study with chlormequat-chloride in rats,
    continuous dietary administration over 2 generations (2 litters in the
    first and 1 litter in the second generation). Unpublished report No.
    71R0580/87099 from BASF Aktiengesellschaft, Department of Toxicology,
    Ludwigshafen/Rhein, Germany. Submitted to WHO by BASF
    Aktiengesellschaft, Limburgerhof, Germany. 

    Hershman, R.J. (1990) Acute inhalation toxicity study with AC 38,555.
    Unpublished report from Biosearch Inc. Submitted to WHO by American
    Cyanamid Co., Princeton, NJ, USA.

    Ignatiev, A.D. (1967) Toxicological evaluation of chlorcholine
    chloride and its agricultural use in controlling plant growth. 
     Chem. Agric. (Moscow), 5, 37-39 (cited by Lampeter & Bier, 1970) (in
    Russian).

    Juszkiewicz, T., Rakalska, Z. & Dzierzawski, A. (1970) Embryopathic
    effect of chlorocholine chloride (CCC) in the golden hamster.  Eur. 
     J. Toxicol., 3, 265-270 (in French). 

    Lampeter, W. & Bier, H. (1970) [Excretion of chlorcholine chloride via
    milk and urine after oral administration of 1 g 15N-labelled
    chlorcholine chloride to a lactating cow.]  Arch. Exp. Vet. Med., 24,
    1027-1031 (in German).

    Leuschner, F., Leuschner, A. & Schwerdtfeger, W. (1967) [On the
    chronic tolerance of CCC. Chronic 3-generation reproduction study in
    Wistar rats.] Unpublished report from Laboratory for Pharmacology and
    Toxicology (in German). Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    Levinskas, G.J. (1965) Cyclocel growth regulator, 2-chloroethyl
    trimethylammonium chloride, 90 day feeding trials on dogs and rats.
    Unpublished report prepared by Central Medical Department, American
    Cyanamid Co. Submitted to WHO by American Cyanamid Co., Princeton, NJ,
    USA.

    Levinskas, G.J. & Shaffer, C.B. (1962) 2-Chloroethyl
    trimethyl-ammonium chloride, CL 38,555, limited release toxicity
    studies. Unpublished report prepared by Central Medical Department,
    American Cyanamid Co. Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    Levinskas, G.J. & Schaffer, C.B. (1966) Cyclocel, plant growth
    regulant. Single dose oral toxicity. Unpublished report prepared by
    Central Medical Department, American Cyanamid Co. Submitted to WHO by
    American Cyanamid Co., Princeton, NJ, USA.

    Lowe, C.A. & Boczon, L. (1990) Eye irritation study in albino rabbits
    with AC 38,555 technical. Unpublished report from American Cyanamid
    Co., Agricultural Research Division. Submitted to WHO by American
    Cyanamid Co., Princeton, NJ, USA.

    Mellert, W., Deckardt, K., Kaufmann, W., Pappritz, G. & Hildebrand, B.
    (1992) Study of the potential carcinogenic effect of
    chlormequat-chloride in Wistar rats, administration via the diet over
    24 months. Unpublished report No. 71S0580/87047 from BASF
    Aktiengesellschaft, Department of Toxicology, Ludwigshafen/Rhein,
    Germany. Submitted to WHO by BASF Aktiengesellschaft, Limburgerhof,
    Germany. 

    Mellert, W., Deckardt, K., Kaufmann, W., Pappritz, G. & Hildebrand, B.
    (1993) Study of the toxicity of chlormequat-chloride in beagle dogs,
    administration via the diet over 12 months. Unpublished report No.
    33D0580/87120 from BASF Aktiengesellschaft, Department of Toxicology,
    Ludwigshafen/Rhein, Germany. Submitted to WHO by BASF
    Aktiengesellschaft, Limburgerhof, Germany. 

    Mellert, W., Deckardt, K., Kaufmann, W., Pappritz, G. & Hildebrand, B.
    (1994) Study of the potential carcinogenic effect of
    chlormequat-chloride in B6C3F1 mice, dietary administration for 110
    weeks. Unpublished report No. 80S0580/87098 from BASF
    Aktiengesellschaft, Department of Toxicology, Ludwigshafen/Rhein,
    Germany. Submitted to WHO by BASF Aktiengesellschaft, Limburgerhof,
    Germany. 

    Mutoh, N., Kimura, M., Kurita, N., Koyama, R., Takahashi, J., Yara,
    M., Sasaki, H. & Sugiya, Y. (1987) General pharmacological study of
    cycocel. Unpublished report from Medical and Scientific Research
    Laboratory, Japan. Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    National Cancer Institute (1979) Bioassay of
    (2-Chloroethyl)-trimethylammonium Chloride for Possible
    Carcinogenicity (DHEW Publication No. (NIH) 79-1714). Carcinogenesis
    Testing Programme, Division of Cancer Cause and Prevention, National
    Institutes of Health, Bethesda, MD, USA. 

    Oettel, H. (1965) Toxicity of chlorcholine chloride (CCC). Unpublished
    report prepared by BASF AG. Submitted to WHO by BASF AG, Limburgerhof,
    Germany.

    Oettel, H. & Froberg H. (1967) Two year rat feeding experiment with
    chlorcholine chloride. Unpublished report prepared by BASF AG.
    Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Oettel, H. & Sachsse, K. (1967) Two year dog feeding experiment with
    chlorcholine chloride (CCC). Unpublished report prepared by BASF AG.
    Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Oettel, H. & Sachsse, K. (1974) Two year feeding study on rats with a
    control compound and a mixture of chlorcholine chloride and choline
    chloride in the proportion 10:7. Unpublished report prepared by BASF
    AG. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Pant, K.J. & Law L.-C. (1990) Test for chemical induction of
    unscheduled DNA synthesis in rat primary hepatocyte cultures by
    autoradiography with AC 38,555. Unpublished report from SITEK Research
    Laboratories. Submitted to WHO by American Cyanamid Co., Princeton,
    NJ, USA.

    Rossbacher, R. & Kirsch, P. (1992) On the maximization test for the
    sensitizing potential of chlormequat-chloride/Reg. No. 24605 in the
    guinea pigs. Unpublished report No. 30H0580/872388 from BASF
    Aktiengesellschaft, Department of Toxicology, Ludwigshafen/Rhein,
    Germany. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Schilling, K., Deckardt, K., Kaufmann, W. & Hildebrand, B. (1990)
    Study of the oral toxicity of chlormequat chloride in rats,
    administration in the diet over 4 weeks. Unpublished report prepared
    by BASF AG. Submitted to WHO by BASF AG, Limburgerhof, Germany.

    Schilling, K., Deckardt, K., Kaufmann, W. & Hildebrand, B. (1992)
    Study of the chronic toxicity of chlormequat-chloride in Wistar rats,
    administration via the diet over 18 months. Unpublished report No.
    60S0580/87046 from Department of Toxicology of BASF
    Aktiengesellschaft, Ludwigshafen/Rhein, Germany. Submitted to WHO by
    BASF Aktiengesellschaft, Limburgerhof, Germany.

    Schulz, J.A., Eichelberger, P., Schappel, K.F. & Johannsen, U. (1970)
    [Investigations on the tolerance of chlorcholine chloride after oral
    administration in sheep.]  Arch. Exp. Vet. Med., 24, 1033-1044 (in
    German).

    Shaffer, C.B. (1970) Unpublished report on chlormequat prepared by
    Central Medical Department, American Cyanamid Co. Submitted to WHO by
    American Cyanamid Co., Princeton, NJ, USA.

    Sharma, R.K. & Caterson, C.R. (1991) Evaluation of Cycocel (CL 38,555)
    in the in vivo chromosome aberration assay in rat bone marrow cells.
    Unpublished report prepared by American Cyanamid Co. Submitted to WHO
    by American Cyanamid Co., Princeton, NJ, USA.

    Stefaniak, B. (1969) Severe toxicity of chlorocholine chloride (CCC)
    to rats.  Med. Weter, 25, 285-286 (in Polish).

    Traul, K.A. & Johnson, E. (1990) Evaluation of CL 38,555 in the
    mammalian cell CHO/HGPRT mutagenicity test. Unpublished report
    prepared by American Cyanamid Co. Submitted to WHO by American
    Cyanamid Co., Princeton, NJ, USA.

    Traul, K.A. & Mulligan, E. (1990) Evaluation of CL 38,555 in a
    microbial/microsome mutagenicity test. Unpublished report prepared by
    American Cyanamid Co. Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    Ventura, P. & Moore, G.E. (1990) Dermal sensitization study with AC
    38,555 (Lot No. AC 6779-98A) in guinea pigs. Unpublished report from
    Biosearch Inc., USA. Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    Weifenbach, H. (1991) Study on the affinity of chlormequat chloride
    for muscarinic receptors. Unpublished report from Knoll AG, Research &
    Development, Neuropharmacology/Psychopharmacology. Submitted to WHO by
    BASF AG, Limburgerhof, Germany.

    Weldon, G.H., Hunter, B., Hague, P.H. & Spicer, E.J.F. (1971) Long
    term feeding study of Cycocel in the mouse. Unpublished report from
    Huntingdon Research Centre. Submitted to WHO by American Cyanamid Co.,
    Princeton, NJ, USA.

    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.

    Zeller, H. & Engelhardt, G. (1979) Testing of Reg. No. 24 605 in the
    Ames test. Unpublished report from BASF AG. Submitted to WHO by BASF
    AG, Limburgerhof, Germany.

    Zeller, H. & Klimisch, H.J. (1979) Investigation of the acute
    inhalation toxicity LC50 of chlormequat chloride after 4-hour exposure
    in Sprague Dawley rats. Unpublished report from BASF AG. Submitted to
    WHO by BASF AG, Limburgerhof, Germany.
    


    See Also:
       Toxicological Abbreviations
       Chlormequat (AGP:1970/M/12/1)
       Chlormequat (WHO Pesticide Residues Series 2)
       Chlormequat (Pesticide residues in food: 1976 evaluations)
       Chlormequat (Pesticide residues in food: 1994 evaluations Part II Toxicology)
       Chlormequat (JMPR Evaluations 1999 Part II Toxicological)