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    PESTICIDE RESIDUES IN FOOD - 1981


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1981







    Food and Agriculture Organization of the United Nations
    Rome

    FAO PLANT PRODUCTION AND PROTECTION PAPER 42

    pesticide residues in food:
    1981 evaluations

     the monographs

    data and recommendations
    of the joint meeting
    of the
    FAO panel of experts on pesticide residues
    in food and the environment
    and the
    WHO expert group on pesticide residues

    Geneva, 23 November-2 December 1981

    FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
    Rome 1982

    AZOCYCLOTIN

    Explanation

         Although this compound was reviewed by the 1979 JMPR*, the
    toxicological evaluation was not undertaken at that time.

    DATA FOR THE ESTIMATION OF ACCEPTABLE DAILY INTAKE

    BIOCHEMICAL ASPECTS

    Uptake, distribution and excretion

         Studies on rats to investigate uptake, distribution and excretion
    of azocyclotin were conducted with both the [113Sn]-labelled and
    [1-14C]-labelled compound (Bayer AG 1981; Grubenbecher and Figge
    1979a, b). [113Sn] Azocyclotin was administered orally to rats in a
    single dose of approximately 8 mg/kg body weight. In the studies with
    [1-14C] azocyclotin, possible dependence of elimination kinetics
    on dose level was also investigated by comparing a single dose of
    10 mg/kg body weight with a single dose of 1 mg/kg body weight.

         Labelled azocyclotin was absorbed at a relatively slow rate and
    in a small amount. Excretion in urine was slight (1.1% of the
    administered radioactivity for the [113Sn]label; 12.6% for the
    [1-14C]label.

         The amount of radioactivity present in the gastrointestinal
    tract after the first 24h was approximately 60% of the administered
    radioactivity. Between 24 and 48h, the level of radioactivity
    decreased quickly owing to excretion in faeces, with the result that
    after 3 days all radioactivity had been virtually completely
    eliminated from the animal body.

         The radioactivity present in the body less gastrointestinal tract
    (3% of administered radioactivity after 3 days, approximately 1% of
    administered radioactivity after 10 days) was distributed uniformly
    among the organs and tissues.

         No radioactivity levels exceeding approximately 1% of the initial
    dose were measured in any organ. Somewhat elevated values were
    measured at 4h after administration in liver and kidney. Thereafter,
    the values decreased continuously in all organs and tissues (Bayer AG
    1981).

              

    *    See Annex II for FAO and WHO documentation.

    TOXICOLOGICAL STUDIES

         The acute toxicity of azocyclotin, which was studied in seven
    animal species, is reported in Table 1.

        TABLE 1.  Acute toxicity of azocyclotin
                                                                                               

    Species        Sex       Route of            LD50           Reference
                             application         (mg/kg)
                                                                                               

    Rat            M         oral                      99       Thyssen and Kimmerle 1974a,b
    Rat            F         oral                      76       ibid.
    Rat            M         oral                     180       Iyatomi 1980
    Rat            F         oral                     150       ibid.
    Rat            M         oral                     102       Flucke 1980
    Rat*           M         oral                      93       ibid.
    Rat            F         oral                     118       ibid.
    Rat*           F         oral                     128       ibid.

    Mouse          M         oral                     453       Thyssen and Kimmerle 1974a,b
    Mouse          F         oral                     417       ibid.
    Mouse          M         oral                     980       Iyatomi 1980
    Mouse          F         oral                     870       ibid.

    Cat            F         oral                    > 25       Thyssen and Kimmerle 1974a,b

    Dog            F         oral                    < 50       ibid.

    Guinea pig     M         oral                     261       Thyssen 1974
    Guinea pig     F         oral                     261       ibid.

    Quail          M         oral                     144       Thyssen 1979
    Quail          F         oral                     195       ibid.
    Quail          F         oral              >175 < 250       Kimmerle 1973

    Hen                      oral               250 - 375       ibid.

    Rat            M         intraperitoneal         3.65       Thyssen and Kimmerle 1974a,b
    Rat            F         "                       3.54       ibid.
    Rat            M         "                        4.6       Iyatomi 1980
    Rat            F         "                        5.9       ibid.

    Mouse          M         "                        3.6       ibid.
    Mouse          F         "                        4.0       ibid.
                                                                                               

    TABLE 1.  (con't)
                                                                                               

    Species        Sex       Route of            LD50           Reference
                             application         (mg/kg)
                                                                                               

    Rat            M         subcutaneous           >1000       Iyatomi 1980
    Rat            F         "                      >1000       ibid.

    Mouse          M         "                        250       ibid.
    Mouse          F         "                        300       ibid.

    Rat            M         dermal              ca. 1000       Thyssen and Kimmerle 1974a,b
    Rat            F         dermal                > 1000       ibid.
    Rat            M         "                     > 5000       Iyatomi 1980
    Rat            F         "                     > 5000       ibid.

    Mouse          M         "                     > 5000       ibid.
    Mouse          F         "                     > 5000       ibid.
                                                                                               

    *  = fasted
    
         Symptoms seen in rats after both oral and intraperitoneal
    administration were characterized by impairment of general health,
    drowsiness and at elevated dose levels, breathing disorders and
    diarrhoea. Onset of these symptoms at the high dose levels were within
    one hour of application, and they persisted for up to 14 days.
    Following dermal application, the effects seen were local irritation,
    increased blood flow and formation of edoema on the ears resulting in
    necroses from pressure on the margins of the ears. Subcutaneous
    application induced ulcers. Symptoms seen in mice and guinea pigs were
    characterized by depression of the general health, drowsiness and
    breathing disorders, which persisted for up to 14 and 15 days,
    respectively after application. Cats and dogs vomited within one hour
    of oral application (Bayer AG 1981).

         Single doses of the 25% WP formulation of azocyclotin were also
    tested for acute toxicity to rats and mice. The results obtained are
    summarized in Table 2.

    TABLE 2.  Acute toxicity of azocyclotin 25% WP
                                                                        

    Species  Sex    Route of      LD50
                    application   (mg/kg)   Reference
                                                                        

    Rat      M         oral        631

    Rat      F         oral        611

    Mouse    M         oral       2451      Thyssen and Kimmerle 1974a,b

    Mouse    F         oral       1936

    Rat      M         i.p.         16.7

    Rat      F         i.p.         22.6
                                                                        

         The poisoning symptoms seen in the rats following oral and
    intraperitoneal administrations were characterized by impairment of
    the general health, breathing disorders and body weight depression.
    Additional effects observed at the elevated dose levels were diarrhoea
    and cyanosis. Symptoms seen in the mice were characterized by
    impairment of the general health and breathing disorders.

    Short-term studies

    Rat

         Groups of 15 male and 15 female Wistar rats were orally dosed
    with azocyclotin at levels of 0.2, 2 and 20 mg/kg bw, emulsified in
    distilled water and Cremophor EL, administered by gavage on 30
    consecutive days. A similar control group received the vehicle only.
    Male rats tolerated doses of 0.2 and 2 mg/kg bw without any adverse
    effects. The female rats tolerated only the lowest dose of 0.2 mg/kg
    bw without showing any signs of treatment-related effects. Although
    they also tolerated 2 mg/kg bw without showing any noteworthy clinical
    symptoms, this dose level caused a slight reduction in their relative
    thymus and brain weights. At the 20 mg/kg dose level, some male and
    female mortalities occurred. This dose caused an impairment of the
    general health and affected the growth rate. Additionally, the
    haematological tests showed a tendency towards leucopenia.
    Interference with liver function was indicated by increased alkaline
    phosphatase activity. Some organ weight alterations were noted at
    20 mg/kg, viz. reduction of thymus, heart, lung and kidney weights and
    an increase in liver, adrenal and brain weights in males; reduction of
    thymus and brain weights and an increase in liver weight in females.

    Neither gross pathology or histopathology revealed any variations or
    alterations from the physiological norm in the tissues of either sex.
    The wet weight of the brains and the weight of freeze-dried brains
    provided no indication of the brain having an increased water content
    (Thyssen and Luckhaus 1974).

         In another study on Wistar rats, groups of 15 males and 15
    females were maintained for 3 months on a diet containing azocyclotin
    at concentrations of 0, 5, 15, 50 and 150 ppm. Dietary concentrations
    of 5 and 15 ppm did not affect physical appearance, behavioural
    patterns, growth rate or survival rate of the males and females.
    At dietary levels of 50 and 150 ppm, food consumption was less and
    body weights were lower than in the control group. The dietary level
    of 150 ppm caused mild drowsiness. Clinical chemical tests,
    haematological tests and urinalyses performed during and at the end of
    the study yielded no indication of any damage to body functions at
    dietary levels of up to and including 150 ppm. Gross pathology and
    histopathology revealed no indication of any damaging effects from
    administration of azocyclotin at dietary levels of up to and including
    150 ppm. The dietary level of 15 ppm was tolerated by the rats for 3
    months without having any damaging effects whatsoever (Löser and
    Luckhaus 1975).

         In a subacute inhalational toxicity study, male and female Wistar
    rats (10 per sex per group) were exposed for 6h daily over a 3-week
    period (total of fifteen 6h-exposures) to azocyclotin aerosols
    (ethanol + polyethylene glycol 400; 20 ml/m3) at concentrations
    averaging 0.0901, 0.275 and 0.961 mg/m3 air. A control group of
    identical composition was exposed to the solvent mixture only. During
    the exposure period, the rats were inspected for their behavioural
    reactions, and their body weights were measured. At the end of the
    study, haematological tests, clinical chemical tests, urinalyses,
    macroscopic tissue examinations, organ weight measurements and
    histopathological examinations of the major tissues were performed.
    The concentration levels of 0.0901 and 0.275 mg/m3 air had no adverse
    effects on behavioural patterns, physical appearance and growth rate.
    Haematology, clinical chemistry and urinalyses did not reveal any
    signs of damage at these concentration levels. Exposure of the rats to
    0.961 mg azocyclotin/m3 air caused poisoning symptoms, reduced weight
    gain and organ weight alterations. The symptoms were characterized by
    impairment of the general health and breathing disorders. One male rat
    died after the seventh exposure. Measurement of the organ weights
    revealed a reduction of the liver and thymus weights and an increase
    in the lung weight at the highest concentration level. The
    histological examinations did not reveal any morphological equivalent
    of the observed clinical symptoms and organ weight alterations
    (Kimmerle 1974).

    Dog

         In a 13-week feeding experiment, groups of 4 male and 4 female
    beagle dogs were maintained on a diet containing azocyclotin at
    concentrations of 0, 5, 50 and 500 ppm. In this study, the no-toxic
    effect dietary level of azocyclotin was 5 ppm. Higher dietary
    concentrations caused slow and reduced food intake, slow weight gain,
    diarrhoea and vomiting, in a dose-related manner. The dogs fed dietary
    levels of 50 and 500 ppm also had an ungroomed appearance. The dogs of
    the 500 ppm group had a slightly drowsy appearance, particularly
    during the first phase of the treatment. This was associated with the
    depression of their general health. However, all the dogs survived the
    treatment. Special haematological tests did not provide any indication
    of treatment-related damage at dietary levels of 5 and 50 ppm. At the
    dietary concentration of 500 ppm, some male dogs showed signs of
    anaemia, manifested by a reduction of the erythrocyte count and
    concomitantly by a reduction of the haemoglobin content and the
    haematocrit level. Clinical chemistry revealed a slight, treatment-
    related increase in serum cholesterol in some female dogs of the 50
    and 500 ppm groups at the end of the treatment period. The serum
    calcium values showed a slight reduction in comparison with the
    initial values in the 50 and 500 ppm groups. One male dog in the
    500 ppm group exhibited marked signs of liver damage. The urinalyses
    and macroscopic examinations performed at the end of the study
    provided no indication of any damage from azocyclotin administration.
    Organ weight measurements showed a slight increase in adrenal weights
    only in females of the 50 and 500 ppm groups. Histopathology did not
    reveal any treatment-related alterations in any tissue in any treated
    group (Hoffman and Schilde 1975).

    Rabbit

         Groups of 3 male and 3 female White New Zealand rabbits were
    treated dermally on 5 days per week over a 3-week period (total of
    15 applications) with azocyclotin at doses of 0 (vehicle), 5 and
    25 mg/kg bw, respectively, applied to either intact or abraded skin
    areas. Evaluation of the treated skin areas for reaction to
    azocyclotin revealed severe skin reactions (irritations and
    corrosions) at both dose levels and on both intact and abraded skin
    areas, as compared with the controls. Neither male nor female rabbits
    exposed to azocyclotin applied to intact and abraded skin showed any
    systematic damage attributable to absorption of azocyclotin. Some of
    the rabbits in the highest dose group did not exhibit the same weight
    gains as the controls. Since there were no signs whatsoever of
    systemic damage, this effect on body weight development was evidently
    associated with the severe skin injury and the associated pain.
    Therefore, 25 mg/kg body weight applied dermally to rabbits was a no-
    effect dose from the systemic toxicity aspect. However, azocyclotin
    that was applied emulsified in distilled water and Cremophor EL caused
    local intolerance and had strong skin-irritating and skin-corrosive
    effects (Thyssen and Kaliner 1978).

    Long-term studies

    Rat

         Azocyclotin was evaluated for potential chronic toxicity and
    carcinogenicity in a 24-month study on groups of 50 male and 50 female
    Wistar-TNO W74 rats fed dietary levels of 5, 15 and 50 ppm,
    respectively. The control group fed a diet without azocyclotin
    consisted of 100 male and 100 female rats. For clinical laboratory
    tests (haematology, clinical chemistry, urinalyses, enzyme induction
    assays) and intermediate necropsies, 10 rats per group and per sex
    were used additionally. At the end of the 24-month feeding experiment,
    all survivors were sacrificed and necropsied. All major organs were
    weighed and histopathologically examined. The tests provided no
    indication of azocyclotin causing carcinogenic effects in rats. With
    respect to chronic toxicity, the no-effect dose was 5 ppm for both
    males and females. Although the two higher dietary levels tested, viz.
    15 and 50 ppm, caused retarded growth in both sexes, they did not have
    any specific effects on organs and organ functions (Bomhard, Löser and
    Vogel 1979).

    Mouse

         Azocyclotin was evaluated for potential chronic toxicity and
    carcinogenicity on groups of 50 male and 50 female CF 1 mice fed the
    compound for 24 months at dietary concentrations of 0 (control), 5,
    15 and 50 ppm, respectively. For intermediate tests and intermediate
    necropsies at 6 and 12 months, 10 male and 10 female mice per group
    were used additionally. Clinical inspections, body weight
    measurements, food intake measurements, macroscopic examinations and
    comprehensive histological examinations were performed.

         The study revealed no indication of carcinogenic effects, as the
    nature, localization and incidence of tumours, as well as the time of
    their occurrence, were comparable in all groups. No chronic toxic
    effects were seen at the two lower dietary levels of 5 and 15 ppm. At
    the dietary level of 50 ppm, male mice showed less weight gain,
    particularly in the first half of the feeding experiment, whereas the
    females showed weight gain similar to that of the controls. However,
    specific effects on organs or on organ functions were not seen either
    in female mice or in males at any of the dietary levels up to and
    including 50 ppm (Krötlinger and Löser 1981).

    Dog

         In a chronic toxicity study, azocyclotin was fed to groups of
    4 male and 4 female beagle dogs for 104 weeks at dietary levels of
    0, 10, 30, 100 (up to week 53), 200 (week 54 to 82) and 400 ppm (week
    83 to 104) respectively. Clinical inspections, haematological tests,

    clinical chemical tests and urinalyses were performed. At the end of
    the feeding experiment, the dogs were sacrificed and necropsied, organ
    weights were measured and tissues were histopathologically examined.

         Azocyclotin at a dietary level of 10 ppm was tolerated by both
    males and females throughout the two-year period without causing any
    untoward effects. Dietary levels of 30 ppm, 100 ppm and above caused
    increased diarrhoea. At the highest concentration, which was raised
    from 100 ppm through 200 ppm to 400 ppm in order to obtain an effect,
    body weight gain was also seen to have been affected, especially in
    the second half of the study. However, clinical laboratory tests,
    gross pathology and histopathology did not provide any indication of
    specific damage to tissues (Hoffman and Schilde 1979).

    Special studies on reproduction

    Rat

         Azocyclotin was evaluated for its potential effect on
    reproduction in a three-generation study on Wistar rats. There were
    two matings per generation and azocyclotin was fed to groups of 10
    male and 20 female rats throughout the study at dietary concentrations
    of 0 (control), 5, 15 and 50 ppm, respectively. The treated rats were
    studied for the effects of oral azocyclotin on behavioural pattern,
    growth rate, mortality, fertility, lactation performance (ability to
    successfully nourish the resulting offspring) and development of
    offspring. The F0 generation was about 30 to 35 days old at the start
    of the study and was treated for 70 days before the first mating. The
    pups of the F3b generation were sacrificed at an age of 4 weeks,
    dissected, and 17 major tissues were examined histopathologically.
    Dietary concentrations of 5 and 15 ppm had no adverse effect on the
    reproductive performance of the rats, and 50 ppm in the diet resulted
    in lower fertility rates after only one of six matings and usually
    caused body weight depressions in the pups during the lactation
    period and also in the parent rats. Azocyclotin did not cause any
    malformations in the young at any of the tested dietary levels.
    Histopathological examination of the major tissues from the 4-week old
    pups of the F3b generation did not reveal any alterations. Therefore,
    15 ppm was tolerated in the three-generation study without having any
    untoward effects (Löser 1980).

    Special studies on mutagenicity

    Microorganisms

         Azocyclotin was tested for mutagenicity by the
    Salmonella/microsome test (Ames test) using strains TA 1535, 1537, 100
    and 98 and metabolic activation with S-9 microsomal fraction of adult
    male rat livers. Azocyclotin was tested at doses of 4, 20, 100, 500
    and 2 500 µg per plate; four agar plates were used per dose. Doses of

    up to and including 100 µg per plate did not cause any bacteriotoxic
    effects, while higher dose levels caused inhibition of bacterial
    growth. There were no mutagenic effects found in any of the test
    strains used (Herbold 1979b).

         In a rec-assay (repair test), azocyclotin was tested for
    potential DNA-damaging effects on two  Bacillus subtilis strains at
    concentrations ranging up to and including, 5 000 µg per plate.
    Reversion assays were conducted by the Ames test on the  Salmonella 
     typhimurium strains TA 1535, 1537, 1538, 98 and 100 and on
     Escherichia coli WP 2. In these assays, azocyclotin was tested
    at concentrations ranging up to and including a maximum of
    5 000 µg/plate, with and without metabolic activation. Azocyclotin
    induced neither DNA-damage nor any point mutations.

         Azocyclotin was evaluated for potential genetic activity
    (recombinogenic activity) on two  B; subtilis strains and for
    potential point mutation activity in a reverse mutation induction
    assay (eukaryotic test) employing two  S. cerevisiae strains (S 138
    and S 211) in comparison with negative (solvent) and positive
    controls, with and without metabolic activation. Azocyclotin had
    no mutagenic activity at concentrations of up to toxic levels
    (100 µg/plate) (Jagannath and Hoorn 1980).

    Mouse - micronucleus test

         Azocyclotin was evaluated for mutagenicity in a micronucleus test
    using the procedure of Schmid (1973) on groups of 10 NMRI mice dosed
    orally with the test compound at levels of 2 × 50 mg/kg bw. The study
    included a negative control group and a positive control group dosed
    with cyclophosphamide. The two applications of azocyclotin were made
    at an interval of 24h, and the femoral marrow was prepared 6h after
    the second application. Polychromatic erythrocytes, 1000 per mouse,
    were analysed; the number of normochromatic erythrocytes per 1 000
    polychromatic erythrocytes was counted. No indication of mutagenicity
    was found in the mouse at oral doses of up to and including
    2 × 100 mg/kg. Erythropoiesis, as measured by the ratio of
    polychromatic to normochromatic erythrocytes, was not adversely
    affected (Herbold 1979a).

         Azocyclotin was tested by the same procedure in male Swiss mice
    at oral dose levels of 2 × 50 mg/kg, 2 × 100 mg/kg and 2 × 150 mg/kg
    bw. The control group and the lowest dose group each consisted of 10
    mice; the middle dose group comprised 15 mice; the highest dose group
    consisted of 5 mice. No indication of mutagenicity of azocyclotin was
    found. However, some of the doses were toxic; 4 of the 15 mice died at
    an oral dose of 2 × 100 mg/kg bw, and 1 of the 5 mice died in the
    group dosed orally with 2 × 150 mg/kg bw (Siou 1979).

    Mouse (male) - Dominant lethal test

         A group of 50 male NMRI mice each received a single oral dose of
    2.5 mg/kg bw; a control group of 50 male mice received the vehicle
    only. The 2.5 mg/kg dose is within the toxic range (Thyssen and
    Kimmerle 1974a). The treated mice exhibited transient drowsiness on
    the day of administration, but they all survived. After administration
    of the test compound, each male was mated with a fresh untreated
    virgin female every 4 days, this procedure being repeated for a total
    of 12 matings. The pre-implantation and post-implantation losses and
    the fertility data were tested for statistically significant
    differences between the treated groups and the controls. Azocyclotin
    was not mutagenic in this test system (Machemer 1977a).

    Special studies on teratogenicity

    Rat

         Azocyclotin was tested on Long Evans rats at oral doses of 3, 10
    and 30 mg/kg bw/day and, in another experiment, at oral doses of 0.3,
    1.0 and 3.0 mg/kg bw/day. Each experiment included a control group.
    Twenty fertilized females, which were used per group, were tested
    daily from day 6 to 15 post coitum. On gestation day 20, the foetuses
    were removed by caesarean section. Doses of up to and including
    3 mg/kg had no damaging effects on the dams. Doses of 10 mg/kg and
    above depressed dam weight gain. The 30 mg/kg dose level also caused
    toxic symptoms and the death of 2 dams. Embryonic and foetal
    development were not affected by doses of up to and including
    10 mg/kg. Although the dose level of 30 mg/kg had a marked embryo-
    lethal effect and caused an increase in the frequency of stunted
    foetuses, there were no indications of azocyclotin having any
    teratogenic or primary embryotoxic effects at any of the tested dose
    levels of up to and including 30 mg/kg; even the maternal toxic dose
    of 10 mg/kg did not have any damaging effects on embryonic and foetal
    development. Only the dose level of 30 mg/kg, that was markedly toxic
    and lethal to dams, increased lethality in embryos (Machemer 1977b).

    Special studies on liver and kidney function

    Rats

         Ten male Wistar rats each received 50 mg azocyclotin/kg bw
    administered orally in an aqueous formulation. Ten control males
    were dosed with the formulating aids only. The rats were sacrificed
    24h after administration, and blood for tests was obtained by
    cardiopuncturc. Liver function was assessed by measuring the following
    parameters: GOT, GPT, alkaline phosphatase, GLDH, SDH and bilirubin.
    Kidney function was assessed by measuring the urea and creatinine
    levels in plasma. No evidence was found of liver and kidney function
    having been adversely affected by administration of azocyclotin
    (Thyssen 1974).

    Special studies on haematology

    Guinea pig

         Ten male and ten female Pirbright guinea pigs received a single
    dose of 100 mg azocyclotin/kg bw administered orally in an aqueous
    formulation. A control group of the same animal composition received
    the formulating aids only. The guinea pigs were sacrificed 4 days
    after applications and the blood for the haematological tests was
    obtained by cardiopuncture. There was no indication of the treatment
    having had any adverse effects on the red blood cells or the while
    blood cell differential count (Thyssen 1974).

    Special studies on effect on liver enzymes

    Rat

         Groups of 5 male Wistar rats were treated with a single dose of
    25 mg azocyclotin/kg bw administered orally in an aqueous formulation.
    The groups were then sacrificed at different intervals, viz. at 24h,
    48h, 3 days, 5 days and 7 days, respectively, and the activities
    of the EPN-oxidase (enzyme system which oxidises O-ethyl-O-
    (4-nitrophenyl)-phenylphonothioate), the O-demethylase and the
    N-demethylase in the liver tissue of the rats were then measured. The
    results showed that azocyclotin had an inhibitory effect on the
    activities of the EPN-oxidase and the N-demethylase in liver tissue.
    The activity of O-demethylase was only minimally depressed. While the
    activity of the EPN-oxidase was still inhibited 7 days after
    administration of azocyclotin, the activity of the O-demethylase was
    again within the physiological range only 5 days after administration.
    The activity of the N-demethylase corresponded to the physiological
    norm at 7 days post-administration (Thyssen 1974).

    Special studies on blood clotting

    Rats

         Azocyclotin applied in an aqueous formulation at a dose of
    250 mg/kg bw to the clipped dorsal skin of each of 5 male Wistar rats
    for a contact time of 7 days had no effect on the thromboplastin time,
    as compared with the results obtained for a control group of similar
    composition (Thyssen 1974).

    EVALUATION

    COMMENTS

         Azocyclotin is poorly absorbed from the rat gastro-intestinal
    tract. The small amount of absorbed material is evenly distributed
    throughout the body tissues and is excreted relatively slowly.

         There were no indications of azocyclotin having mutagenic
    effects, primary embryo-toxic effects, teratogenic effects or adverse
    effects on reproductive performance.

         There was no indication that azocyclotin has a cumulative toxic
    effect of any significance. No histological changes were observed in
    short-term or long-term studies. The highest no-effect dose in a
    30-day oral experiment on rats was 0.2 mg/kg bw/day. In a 2-year
    feeding experiment on rats, the no-effect dietary level was 5 ppm. The
    no-effect dietary level in a 2-year feeding experiment on dogs was
    10 ppm (0.25 mg/kg bw/day), and the no-effect dietary level in a
    2-year feeding study on mice was 15 ppm (2.0 mg/kg bw/day). Two-year
    feeding studies in rats and mice did not indicate any carcinogenic
    potential.

         As it is known that some organic tin compounds affect the immune
    system, and as thymus weight was decreased in some studies, further
    investigation of possible immune effects was felt to be desirable.

    Level causing no toxicological effect

         Rat   :  5 ppm, in the diet equivalent to 0.25 mg/kg bw/day

         Mouse : 15 ppm, in the diet equivalent to 2.0 mg/kg bw/day

         Dog   : 10 ppm, in the diet equivalent to 0.25 mg/kg bw/day

    Estimate of acceptable daily intake for man

         0 - 0.003 mg/kg bw

    FURTHER WORK OR INFORMATION

    Desirable

    1.   Studies to determine the potential for central nervous system
         toxicity.

    2.   Studies to examine the possibility of effects on the immunal
         system.

    REFERENCES

    Ames, B.N.  et al. Am improved bacterial test system for the detection
    1973      and classification of mutagens and carcinogens. Proceedings
              of the National Academy of Sciences, 70: 782-786.

    Bayer AG. Azocyclotin: Monograph. Prepared for FAO/WHO 1981 JMPR.
    1981      Report submitted by Bayer AG, September, 1981 (Unpublished).

    Bomhard, E., Löser, E. and Vogel, O. BUE 1452/chronic toxicity study
    1979      on rats (two-year feeding experiment), December 14, Report
              No 8780, Bayer AG, Institut für Toxikologie. Report
              submitted by Bayer, AG. (Unpublished)

    Grubenbecher, F. and Figge, K. BUE 1452 ([1-14C]-Cyclohexyl markiert):
    1979a     Ausscheidung und Organverteilung an Ratten. September,
              Report No. Na 760043. Natec, Institut für
              naturwissenschaftlichtechnische Dienste GmbH. Report
              submitted by Bayer AG. (Unpublished)

    1979b     BUE 1452-113Sn: Ausscheidung und Organverteilung an Ratten.
              September 1979, Report No. Na 760043. Natec, Institut für
              naturwissenschaftlichtechnische Dienste GmbH. Report
              submitted by Bayer AG. (Unpublished)

    Herbold, B. BUE 1452/micronucleus test on mouse to evaluate BUE 1452
    1979a     for potential mutagenic effects. 26 January 1979, Report No.
              8129, Bayer AG, Institut für Toxikologie. Report submitted
              by Bayer, AG. (Unpublished)

    1979b     BUE 1452/Salmonella/Microsome test for detection of point-
              mutagenic effects. 23 February 1979, Report No. 8205, Bayer
              AG, Institut für Toxikologie. Report submitted by Bayer, AG.
              (Unpublished)

    Hoffman, K. and Schilde, B. BUE 1452/subchronic toxicity study on dogs
    1975      (Thirteen-week feeding experiment). 2 July 1975, Report No.
              5506, Bayer AG, Institut für Toxikologie. Report submitted
              by Bayer, AG. (Unpublished)

    1979      BUE 1452/chronic toxicity study on dogs (two-year feeding
              experiment). 12 October 1979, Report No. 8680, Bayer AG,
              Institut für Toxikologie. Report submitted by Bayer, AG,
              (Unpublished)

    Iyatomi, A. Report of acute toxicity - A. 19 September 1980. Report
    1980      sheet No. A-32, Nitokuno, Agricultural Chemicals Institute,
              Japan. Report submitted by Bayer AG. (Unpublished)

    Jagannath, D.R. and Hoorn, A.J.W. Mutagenicity evaluation of BUE 1452
    1980      in the rec-assay and the reverse mutation induction assay.
              January, 1980. KR-Bericht Nr. 1674, Litton Bionetics, Inc.,
              USA. Report submitted by Bayer AG. (Unpublished)

    Kimmerle, G. BUE 1452/acute oral toxicity study on hens, 22 May 1973.
    1973      Bayer AG, Institut für Toxikologie. Report submitted by
              Bayer, AG. (Unpublished)

    1974      BUE 1452/subacute inhalation toxicity study on rats. 12
              August, 1974. Report No. 4842, Bayer AG, Institut für
              Toxikologie. Report submitted by Bayer AG. (Unpublished)

    Krötlinger, F. and Löser, E. BUE 1452 (Peropal active ingredient,
    1981      azocyclotin) chronic toxicity studies on mice (two-year
              feeding experiment), 7 January 1981, Report No. 9680, Bayer
              AG, Institut für Toxikologie. Report submitted by Bayer AG.
              Addendum: Glaister, J.R., Histopathology Hazleton
              Laboratories Europe Ltd., Harrogate. (Unpublished)

    Löser, E. BUE 1452/multigeneration reproduction study on rats, 8
    1980      April, 1980. Report No. 9387, Bayer AG, Institut für
              Toxikologie. Report submitted by Bayer AG. (Unpublished)

    Löser, E. and Luckhaus, G. BUE 1452/subchronic toxicity study on rats
    1975      (three-month feeding experiment), 30 June 1975, Report No.
              5499, Bayer AG, Institut für Toxikologie. Report submitted
              by Bayer, AG. (Unpublished).

    Machemer, L. BUE 1452/dominant lethal study on male mice to test for
    1977a     mutagenic effects, 25 March 1977. Report No. 6682, Bayer AG,
              Institut für Toxikologie. Report submitted by Bayer, AG.
              (Unpublished)

    1977b     BUE 1452 (azocyclotin) evaluation for embryotoxic and
              teratogenic effects on rats following oral administration,
              26 May 1977. Report No. 6805, Bayer AG, Institut für
              Toxikologie. Report submitted by Bayer, AG. (Unpublished)

    1979      BUE 1452 (Peropal) - Guide for Physicians, 20 April 1979.
              Bayer AG, Institut für Toxikologie. Report submitted by
              Bayer, AG. (Unpublished)

    Schmid, W. Chemical mutagen testing on in vivo somatic mammalian
    1973      cells. Agents Actions, 3: 77-85.

    Siou, G. Recherche de l'action mutagene du Peropal par la technique
    1979      des crops de Howell-Jolly (micronucleus test) 6 Fevrier,
              1979. C.E.R.T.I., Versailles. Report submitted by Bayer AG.
              (Unpublished)

    Thyssen, J. BUE 1452/special toxicity studies, 30 September 1974.
    1974      Report No. 4949, Bayer AG, Institut für Toxikologie. Report
              submitted by Bayer AG. (Unpublished)

    1979      BUE 1452/Akute toxikologische Untersuchungen an Wachtteln,
              August 22, Bayer AG, Institut für Toxikologie. Report
              submitted by Bayer, AG. (Unpublished)

    Thyssen, J. and Kaliner, G. BUE 1452/subacute dermal cumulative
    1978      toxicity study on rabbits, 11 May 1978. Report No. 7513,
              Bayer AG, Institut für Toxikologie. Report submitted by
              Bayer, AG. (Unpublished)

    Thyssen, J. and Kimmerle, G. BUE 1452/acute toxicity studies, 1 April
    1974a     1974, Report No. 4617, Bayer AG, Institut für Toxikologie.
              Report submitted by Bayer, AG. (Unpublished)

    1974b     Formulation 6734/Toxicity Studies, 27 November 1974. Report
              No. 5027, Bayer AG, Institut für Toxikologie. Report
              submitted by Bayer, AG: (Unpublished)

    Thyssen, J. and Luckhaus, G. BUE 1452/subacute toxicity studies, 18
    1974      July 1974. Report No. 4827, Bayer AG, Institut für
              Toxikologie. Report submitted by Bayer, AG. (Unpublished)


    See Also:
       Toxicological Abbreviations
       Azocyclotin (Pesticide residues in food: 1979 evaluations)
       Azocyclotin (Pesticide residues in food: 1983 evaluations)
       Azocyclotin (Pesticide residues in food: 1989 evaluations Part II Toxicology)
       Azocyclotin (JMPR Evaluations 2005 Part II Toxicological)