WHO/FOOD ADD/71.42



    Issued jointly by FAO and WHO

    The content of this document is the result of the deliberations of the
    Joint Meeting of the FAO Working Party of Experts and the WHO Expert
    Group on Pesticide Residues, which met in Rome, 9-16 November, 1970.



    Rome, 1971



    Chemical name

    Tricyclohexyltin hydroxide


    DOWCO (R) 213, PLICTRAN (R)

    Structural formula


    Other relevant chemical properties

    The compound in a white, crystalline powder with an apparent melting
    point of 245°C. The compound undergoes loss of water at 120-130°C and
    In converted to the bis (tricyclohexyltin) oxide. The technical
    product has the following solubilities at 25°C: acetone 0.13 g/100 ml,
    benzene 1.6 g/100 ml, carbon tetrachloride 2.8 g/100 ml, chloroform
    21.6 g/ml, methanol 3.7 g/100 ml and water < 0.0001 g/100 ml.


    The technical product contains 95-96% tricyclohexyltin hydroxide. It
    is formulated as a wettable powder.




    In the studies with rats and dogs, in addition to the parent compound,
    dicyclohexyltin oxide and trace amounts of cyclohexylstannoic acid in
    organic tin were identified (Smith and Fischer, 1970; Anon, 1970a).

    The metabolic fate of the limited amounts of compound absorbed from
    the gastrointestinal tract in animals appears to occur by the

    (C6H11)3 SnOH---> (C6H11)2 SnO---> C6H11SnO2H---> Sn+4

    Absorption, distribution and excretion

    Two rats received, each in a gelatine capsule, a single oral dose of 5
    mg of 119Sn-labelled tricyclohexyltin hydroxide, corresponding to 25
    mg/kg body-weight. Essentially quantitative recovery (99.9 and 100
    percent) of the total radioactivity was obtained in the excreta
    collected for ten days after dosing. Most (75-80 percent) was excreted
    in the first four days after administration. Almost all of the
    radioactivity occurred in the faeces (97.5 and 98.9 percent versus 1.8
    to 2.5 percent in the urine). The practical lack of gastrointestinal
    absorption was also confirmed by the absence of radioactivity in the
    bile of two guinea pigs, which were administered the labelled compound
    and sacrificed, respectively, 24 and 48 hours after dosing (Smith and
    Fischer, 1970).

    Groups of rats and dogs of both sexes were fed tricyclohexyltin
    hydroxide in their diet at rates of 0.75, 3, 6 and 12 mg/kg
    body-weight per day, for periods ranging from 45 days to two years.
    Tin compounds, primarily the parent compound, were distributed through
    the tissues only in trace amounts. As an example: in rats which were
    fed 3 mg compound/kg/day, the levels were: fat (0.1 ppm tin) < muscle
    < adrenals < heart < brain <liver kidney (0.8 ppm). The biological
    half-life of the tin compounds was approximately 5 to 40 days after
    compound withdrawal from the diet (Anon, 1970a). Dicyclohexyltin
    oxide, trace amounts of cyclohexylstannoic acid, and inorganic tin
    were identified as metabolites in rats and dogs. Generally, from 60 to
    95 percent of the tin was present as organotin (Smith and Fischer,
    1970; Anon, 1970a).

    Rats were fed 100 ppm of 119Sn-labelled tricyclohexyltin hydroxide for
    90 days, and several tissues were analysed for uptake of 119Sn.
    Continuous uptake resulted in an equilibrium being reached between
    40-60 days with the females accumulating slightly more than the males.
    Tin was eliminated slowly from the tissues upon cessation of feeding,
    with the brain being one of the slowest tissues. Traces of tin were
    noted after 115 days, although the major quantity was removed in 20
    days (Smith and Fischer, 1970).

    Effect on enzymes and other biochemical parameters

    In a series of pharmacological and biochemical studies, intravenous
    injection to dogs and cats resulted in no effect on blood pressure,
    pulse rate or cholinesterase levels, and in no potentiation of drugs
    (epinphrine chloride, norepinephrine bitartrate, tyramine
    monohydrochloride or nicotine sulfate). The primary effect noted on
    intravenous injection was stimulation of respiration accompanied by an

    increase in blood lactate and a decrease in blood pCO2, without
    changes in either pH or pO2 in the blood (Hine at al., 1969).


    Special studies on reproduction

    Japanese Quail

    Investigations were started on four groups of birds, each containing
    eight to ten females plus an equal number of males. Dietary levels of
    0, 1, 10 or 100 ppm of tricyclohexyltin hydroxide were given to the
    adults (ten weeks of age) of the first generation, and, afterwards,
    through the entire life cycle of the second and the third generation.
    Body and egg weights, food-consumption, survival of live chicks from
    eggs, adult mortality, general physical condition and appearance and
    gross observation of the ovaries and gonads were comparable to the
    controls for all dietary levels. Similarly, no gross teratogenic or
    lenticular effects were observed in any of the treated groups.
    Definite effects on embryonic mortality, egg production, fertility and
    hatchability were observed at the 100 ppm dietary levels. At 10 ppm,
    there were effects of questionable significance on egg fertility and
    hatchability. None of those criteria was affected at the level of 1
    ppm (Stevenson and Kenaga, 1969).


    Groups of pregnant New Zealand white rabbits, 28 in all, received oral
    doses of respectively 0, 0.75 or 3 mg tricyclohexyltin hydroxide/kg
    body-weight/day on the eighth to the 16th day inclusive of gestation.
    There was no evidence of significant adverse effects due to the
    compound as judged by indices of fertility, gestation, viability and
    lactation or by examination of the foetuses for teratogenic effects
    (Hine at al., 1969b).


    A three generation (two litters per generation) reproduction,
    fertility and teratology study was conducted in groups of 10 male and
    20 female rats maintained continuously on diets containing 0, 12.5, 50
    or 100 ppm of tricyclohexyltin hydroxide (the uppermost dietary level
    corresponds to approximately 4 to 6 mg test compound/kg
    body-weight/day on the basis of adult and female rats). There was no
    evidence of significant adverse effects due to the compound under test
    when judged by indices of fertility, gestation, viability and
    lactation, or by examination of the foetuses for teratogenic effects
    (Hine et al., 1969a).

    Special studies on metabolites and photodecomposition products

    In addition to having been identified as metabolites in animals (Smith
    and Fischer, 1970), dicyclohexyltin oxide and cyclohexylstannoic acid
    occur as a relatively minor proportion of the residues on fruit,

    having been formed by sunlight degradation (Getzendaner, 1968) (see
    'Fate of Residues, in plants').

    LD50 values for dicyclohexyltin oxide, as determined in five studies
    involving varying strains of rats, averaged 355 mg/kg body-weight
    (Anon, 1970c). Cyclohexylstannoic acid exhibits low toxicity to rats
    with an LD50 value of < 3 600 mg/kg body-weight (Hine, 1967).

    Male and female rats were fed dicyclohexyltin oxide in their diet for
    90 days at dose levels of 0, 1, 3 and 6 mg/kg body-weight/day. No
    unusual alterations in behaviour and appearance occured during this
    study nor were any pharmacodynamic or toxic signs exhibited which
    could be related to the feeding of the test compound in the diet. No
    compound related variations were found in haematological and
    biochemical values, in gross and microscopic examination of tissues
    and in organ-weights and ratios (Wazeter et al., 1968).

    Acute toxicity


    Summary of acute toxicities by various workers

    Animal             Route      body-weight     Reference

    Chick (M)          Oral            650        Olson, 1964
      Peromyscus       Oral            7101/      Kenaga, 1968
      Swiss White      Oral           10701/      Kenaga, 1968
    Rat                Oral            5402/      Anon, 1970b
    Rat                ip               13        Hine et al., 1969a
    Guinea pig (M)     Oral            780        Olson, 1964
    Guinea pig (M)     ip                9        Norris, 1968
    Rabbit             Oral     >500,<1000        Olson, 1964
    Rabbit             ip             >126        Norris, 1968
    Dog                iv               14        Hine et al., 1969a
    Cat                iv                6        Hine et al., 1969a

    1/ Approximate lethal dosage (100 percent deaths)
    2/ Average LD50 value from 10 studies in both sexes of three strains

    These data reveal that acute toxicity by the oral route is, because of
    very poor gastrointestinal absorption, considerably lower than by the
    parenteral route.

    The compound appears to be principally a depressant of the central
    nervous system, but not nearly to the same extent as the triethyltin
    acetate in comparable doses. Neither interperitoneal, intravenous nor

    oral administration resulted in cerebral oedema or significant
    pathologic lesions (Hine at al., 1969).

    Death usually occurred within two to seven days after administration.
    Acute signs of poisoning in rats include anal wetting, piloerection,
    wet nares and mouth, lethargy, hyporeflexia, arching, depressed
    respiration, emaciation, diarrhoea and flexure of all four limbs when
    picked up by the scruff of the neck. Gross examination of the dead
    animals showed that the adrenal gland of rats was 2-3 times heavier
    than the controls and the spleen was 0.3-0.4 time heavier than the
    controls (Hine, 1966).

    Short-term studies


    A total of 96 beagle dogs, half male and half female, averaging eight
    months of age, were fed tricyclohexyltin hydroxide in the diet, at
    levels adjusted to give ingestion rates of 0, 0.75, 3 or 6 mg/kg
    body-weight/day, for two years, or of 12 mg/kg/day for six months.
    Animals were sacrificed in each group after 3, 6, 12 or 24 months. All
    diets containing the compound under test were rejected by the animals
    to some extent during the first stages of the treatment, particularly
    at the highest levels. Diets designed to administer 12 mg/kg/day were
    very unpalatable; many dogs completely refused diets at this level,
    most progressively lost weight and some died of starvation. Ingestion
    of 6 mg/kg/day for two years caused no direct toxic effect on tissues,
    but did cause an apparent reduction in final body weight, which in
    turn affected organs to body-weight ratios, but no pathological
    changes were found. At the 3 mg/kg/day dietary level, mortality,
    behaviour, food intake, growth rate, gross and microscopic pathology,
    haematology and biochemical values were comparable to the controls.
    The same conclusion applies to organ-weights and ratios, except for
    statistically significant increased heart to body-weight ratio
    averages, but not actual heart weights, in both sexes, and average
    liver weight and ratio in the males only. These observations were not
    associated with significant alterations in these two organs at either
    the interim or final necropsy periods or upon microscopic examination.
    Copper content in the urine was decreased at all dose levels examined.
    A notable undefined effect in dogs was a tanning or brown
    discoloration of the serosal surface of the small intestine in dogs
    fed 3 and 6 mg/kg levels. This effect was not noted at 0.75 mg/kg.
    Measurement of tin content indicated higher levels of tin in all
    tissues examined. Levels in the males were lower than in the females
    and were proportional in both sexes to the dietary intake. An
    equilibrium level was apparently reached between six and 12 weeks of
    feeding and remained constant for the remainder of the testing.
    Tissues of rats and dogs contained similar concentrations of tin,
    except for the liver of dogs, which contained five to 14 times the tin
    content of rats and a higher proportion of inorganic tin. No signs of
    toxic injury were observed at the level of 0.75 mg/kg (Hine, 1970).


    Tricyclohexyltin hydroxide administered to the conjunctival sac
    resulted in irritational corneal injury which subsided in one week
    (Olson, 1964).

    Groups of rabbits (ten male and ton female) were treated dermally at
    doses of 0, 1.2, 6, 12 or 60 mg/kg/body-weight/day, five days per week
    for three weeks. All animals developed erythema, oedema, atonia,
    desquamation and fissuring of the skin. The signs of toxicity were
    severe at all done levels examined. Other than dermal problems, no
    other effects were noted (Wazeter, 1969).


    Exploratory experiments in rats showed that an oral dose of 12.5 mg/kg
    body-weight/day did not produce tissue damage when given daily by
    gavage for 19 days. A dose of 25 mg/kg/day was toxic within two weeks,
    and doses of 50 and 100 mg/kg/day were toxic within one week. Rats
    that received 12 mg/kg body-weight/day for ten or 16 weeks showed no
    direct toxic effects. Poor weight gain observed at this dietary level
    was judged to be caused by unpalatability of diets containing
    tricyclohexyltin hydroxide. Due to diet unpalatability, higher doses
    had to be administered by gavage. Direct toxic effects were not
    achieved until doses of 25 mg/kg bodyweight/day were administered.
    This level resulted in clinical symptoms, such as severe diarrhoea and
    weight loss, as well as morphological effects, such as
    gastroenteritis, intrahepatic and extrahepatic cholangitis,
    degenerative changes in adrenal glands and toxic nephrosis (Tucker,

    Long-term studies


    A total of 720 rats, half males and half females, aged four weeks,
    were fed 0, 0.75, 3, 6 or 12 mg tricyclohexyltin hydroxide/kg
    body-weight/day for up to two years. None of the dietary levels of
    treatment caused any change in behaviour, mortality records,
    haematologic and biochemical values, gross appearances and
    histological characteristics of organs and tissues. Effects observed
    at the 12 mg/kg level wore decreased weight gains in both sexes and
    increased organ to body-weight ratios for spleen and liver in the
    females. The pattern of tumour incidence appeared to be random and not
    suggestive of a dose relationship. The occurrence of many cysts seen
    throughout this study at all levels may be related to the particular
    strain of animals, although in the females at 12 mg/kg, 17 liver cysts
    and five pituitary cysts were noted as compared to one liver cyst and
    five pituitary cysts in the controls. At six mg/kg, only a slight
    decrease of food intake and a related mild depression of growth rate
    were observed during the first three months on treatment. These
    effects were absent at the level of 3 mg/kg (Hine, 1970a).


    A wettable powder formulation (50 percent tricyclohexyltin hydroxide)
    was examined for its irritation and sensitization potential to human
    subjects. No adverse reactions were observed in 53 females following
    sensitization applications and a challenge application 20 days later
    of 0.5 ml of a 0.1 percent emulsion. Tricyclohexyltin hydroxide was
    not dermally irritating at a concentration of about 0.01 mg/kg
    body-weight (Laker et al., 1966).


    The Meeting expressed concern that the only toxicological data that
    had been presented for consideration were unpublished, and had
    therefore not already been subject to critical scrutiny by the general
    scientific community.

    A difficulty with the toxicological evaluation of this compound is
    that its presence made laboratory diets unpalatable. A need for
    carefully controlled paired-feeding experiments was therefore evident.
    Concern was expressed that residual tin remained in the tissues of
    exposed animals for prolonged periods and that brown discoloration of
    the serosal surface of the small intestine occurred in dogs fed 3
    mg/kg body-weight/day or higher dose levels of the compound. It was
    noted that, in dogs fed 0.75 mg/kg body-weight/day or more, there was
    a reduction in urinary copper output. In view of this observation, the
    need for information on the copper content of the liver of exposed
    animals was stressed. The observation of an increased incidence of
    cysts of the liver and pituitary gland of female rats fed 12 mg/kg
    body-weight/day was regarded with some concern. For these reasons the
    Committee considered that only a temporary acceptable daily intake
    could be established.


    Level causing no toxicological effects

    Dog: level in the diet adjusted to give 0.75 mg/kg body-weight/day
    Rat: level in the diet adjusted to give 3 mg/kg body-weight/day


    0-0.0075 mg/kg body-weight



    Pre-harvest treatments

    Tricyclohexyltin hydroxide is a non-systemic acaricide used or under
    development for use in several countries to control phytophagous mites
    on apple and pear trees. The compound exhibits little or no activity

    against insects,including pollinating bees,and it is relatively
    harmless to predatory mites. Thus it may be advantageously applied in
    integrated control schemes (Gray, 1968; Zambelli et al., 1968; Jeppson
    et al., 1968). Typically, tricyclohexyltin hydroxide is recommended
    for use in dilute sprays at concentrations of 15 to 30 g/100 litres,
    the total amount applied per unit area ranging from 0.42 to 1.68

    In addition to use on apples and pears, tricyclohexyltin hydroxide is
    expected to prove useful for control of mites on stone fruits, citrus,
    grapes and certain other crops.

    Post-harvest treatments

    Post-harvest use on apples is under investigation.


    The following typical data (Table II) are extracted from unpublished
    reports supplied to FAO/WHO by Dow Chemical Company (Getzendaner,
    1968; Komblas, 1969; Getzendaner and Corbin, 1969; Anon, 1970b).


    General comments

    Tricyclohexyltin hydroxide is decomposed by sunlight as evidenced by
    (1) a half-life of 8 "sunny days" for disappearance from glass slides
    (Smith et al., 1970c) and (2) detection of inorganic tin as
    approximately 15 to 30 or more percent of the total tin residues on
    fruit exposed to 3 or 4 applications of the miticide (Getzendaner and
    Corbin, 1969).
        TABLE II

    Residues found in apples and pears in various countries

                    Rate of        Number     Post-treatment     Residue, total tin,
    Location      application        of          interval          as Cy3SnOH, ppm
                    g/100 l      Treatments        days

                                                                average       maximum


    U.S.A.            15              1              0            0.8            -
                                                     8            1.0            -
                                                    16            0.6            -
                                                    32            0.5            -

    TABLE II (cont'd)

    Residues found in apples and pears in various countries

                    Rate of        Number     Post-treatment     Residue, total tin,
    Location      application        of          interval          as Cy3SnOH, ppm
                    g/100 l      Treatments        days

                                                                average       maximum

    U.S.A.            23              4              0            1.7           2.5
                                                    14            1.6           2.2
                                                    28            1.1           1.5
                                                    35            0.9           1.0

    Netherlands       25              4              0            1.2           1.9
                                                    14            1.2           1.6
                                                    28            0.5           0.7
                                                    42            0.5           0.7

    Italy             30              2              7            1.1           1.3
                                                    16            1.2           1.3
                                                    28            0.8           1.0

    U.S.A.            30              3             17            1.9            -

    Australia         30              3              0             -            1.94

    France            30              1              0            0.7           1.8
                                                    15            0.5           0.5
                                                    42            0.4           0.4

    Japan             33              3              0            2.0            -
                                                    14            1.5            -
                                                    30            1.1            -


    U.S.A.            23              3              0            1.4           2.1
                                                    15            1.1           1.4
                                                    29            0.7           1.0
                                                    42            0.6           0.6
                                                    61            0.4           0.6

    Australia         23              1             31             -            1.0

    Italy             30              2              7            1.0           1.5
                                                    16            0.8           1.0
                                                    28            0.4           0.6
    Photodegradation occurs by the sequence, which is identical with that
    owing in the animal body:


    Tricyclohexyltin hydroxide is not volatile from dry surfaces, but
    'co-distils', with water from moist surfaces at a slow but finite rate
    (Smith et al., 1970). Field experiments show that the half-life of the
    compound is about four days on grass and about three weeks on apples
    and pears; the disappearance results from photodegradation,
    'co-distillation' with water from moist surfaces and weathering
    factors (Getzendaner and Gentry, 1970a; Getzendaner and Corbin, 1969).

    In animals

    As indicated under "BIOCHEMICAL ASPECTS", tricyclohexyltin hydroxide
    is not readily absorbed from the gastrointestinal tract.

    When the miticide is fed daily to rats, dogs or cattle, tin compounds,
    primarily unchanged tricyclohexyltin hydroxide, accumulate in the
    tissues to a limited extent, reach equilibrium values in a few months
    to a year, and are slowly eliminated from the tissues after the
    compound is withdrawn from the diet. It does not selectively partition
    into fat, and the distribution pattern in tissues is similar for rats,
    dogs and cattle (Smith and Fischer, 1970; Anon, 1970a; Getzendaner and
    Gentry, 1970b). For example, tissues from calves fed 30 ppm of the
    compound in the diet for 90 days showed 0.07 ppm total tin in fat,
    0.09 ppm in muscle, 0.37 ppm in liver and 0.20 ppm in kidney
    (Getzendaner and Gentry, 1970b).

    Levels of tricyclohexyltin hydroxide equivalent were 0.05 ppm in milk
    and 0.4 ppm in cream obtained from cows fed 100 ppm of the compound in
    the diet for 53 days (Getzendaner and Gentry, 1970c).

    In plants

    Residues occurring on apples were identified by a series of extraction
    techniques followed by analysis. Tricyclohexyltin hydroxide was the
    main component of the tin residues, comprising 67% (0.66 ppm) of the
    residue (eight days post-treatment). Small amounts of dicyclohexyltin
    oxide and cyclohexylstannoic acid were present (5% of each), as well
    as 23% inorganic tin (Getzendaner, 1968).

    Tricyclohexyltin hydroxide and its sunlight decomposition products are
    not translocated in plants to a significant extent. This has been
    demonstrated by (1) the absence of significant residues of tin
    compounds in the interior portions of fruit, even after periods of
    several months between application of the first of up to 5 spray
    applications and harvest (Getzendaner and Corbin, 1969), (2) the

    absence of radioactive residues in bean and maize plants grown in soil
    treated with exaggerated amounts (3 lb/acre) of 119Sn-labelled
    miticide or its degradation (Smith at al. 1970), and (3) the essential
    absence of translocation across the narrow thickness of the leaf of
    cotton plants as determined by bioassay experiments (Allison, 1969).

    In soil

    Tricyclohexyltin hydroxide is markedly absorbed by soil and it is not
    leached from soil, as demonstrated by soil-column leaching studies and
    by study of the transfer from water to soil (Smith et al., 1970a,
    Smith and Taylor, 1970; Whitney, 1966). No significant amounts of the
    miticide will remain in or on the soil from one growing season to the

    In storage and processing

    Results of several residue trials, involving separate analysis of peel
    and pulp or surface extraction, indicate that at least 90% of the
    residue in or on apples and pears is on the surface of the fruit
    (Getzendaner, 1968; Komblas, 1969; Getzendaner and Corbin, 1969).
    Typically, about 0.1 ppm tricyclohexyltin hydroxide equivalent may be
    expected in fruit when the peeling is removed. Mild water washing
    removed up to 50% of the residue from apples and pears with an average
    of >20% removed (Getzendaner and Corbin, 1969).

    Evidence of residues in food in commerce or at consumption

    No information is available.


    Corbin (1970) recently published a method suitable for determination
    of the total organotin and inorganic tin present in fruit The sample
    is subjected to a wet oxidation treatment with sulfuric and nitric
    acids to destroy organic matter, remove volatile acids and halogens
    and convert the tin to a soluble inorganic form. The tin is then
    separated from elements which would interfere in the colorimetric
    method (heavy metals) and from non-interfering salts. This separation
    involves extracting tin as SnI4, with n-hexane from a strong sulfuric
    solution of KI. Evaporation of hexane and conversion to sulfate leaves
    the tin in a form measurable by a dithiol colorimetric method.
    Sensitivity of the method is 0.01 ppm. Optional steps are included in
    the method for removal of arsenic and antimony, if these elements are
    suspected of being present in amounts which might cause interference
    (> 0.15 mg and > 2 mg, respectively).

    A complementary method has been developed for determining residues of
    organotin in fruit by M & T Chemicals (Anon, 1969). Tri-, di-, and
    monocyclohexyltin are solubilized by treatment of the fruit sample

    with hydrochloric acid (9 molar) and then extracted with chloroform
    from inorganic tin and heavy metals, which remain in the acidic
    aqueous phase. The organotin compounds are then oxidized and
    determined colorimetrically.


    Tolerances have been established (provisional) or are proposed for
    residues of tricyclohexyltin hydroxide in or on apples and pears in
    various countries including the following:

    Country             Tolerance      Withdrawal between
                        ppm            treatment and harvest, days

    Australia1          3              2

    Belgium             12           28

    Italy               1              20

    Israel              1              30

    Netherlands         1              28

    U.S.A.              23           14

    1 Stone fruits
    2 Proposed
    3 Tolerance proposed on 23 June 1970

    Use of the miticide is registered for apples and pears in Chile,
    France and Korea, but without provision for tolerance.


    Tricyclohexyltin hydroxide is a non-systematic acaricide now used in
    many countries and likely to be used worldwide on apples and pears,
    with indications of future use on citrus, stone fruits and other
    crops. Post-harvest use on apples is under investigation. The compound
    is relatively harmless to beneficial insects and mites, and it is
    usefully applied to integrated control schemes. Tricyclohexyltin
    hydroxide is used as wettable powder at a rate of about 0.5 to 1.5 kg
    per hectare.

    Comprehensive residue data on tricyclohexyltin hydroxide on apples and
    pears are available from the United States and from five other
    countries, which are consistent with those from the U.S.A. Residue
    data on other crops were not available to the Meeting. When apples and

    pears are peeled, most of the tricyclohexyltin hydroxide residue is
    removed; only 0.1 ppm may be expected in the fruit flesh. Washing is
    found to remove 20-50% of the residues, more from apples than from

    Field experiments show that the residues of tricyclohexyltin hydroxide
    declined to half in about three weeks on apples and pears. The
    disappearance is due to photodegradation, codistillation with water
    and weathering factors. The residues are found to occur on the surface
    of the treated plants. The degradation of tricyclohexyltin hydroxide
    is found to produce dicyclohexyltin oxide and monocyclohexylstannoic
    acid and finally inorganic tin salts.

    The absorption of tricyclohexyltin hydroxide from the gastrointestinal
    tract of animals is small. The distribution patterns of the compound
    are determined in rats, dogs and cattle. When cows were fed residues
    of 30 and 100 ppm, the residues found in milk were less than 0.1 ppm
    and in various tissues less than 0.5 ppm. Limited feeding of apple and
    pear pulp to cows is not expected to produce detectable residues in
    meat or milk.

    A colorimetric method with a detectability of 0.01 ppm tin is
    available to determine tricyclohexyltin hydroxide and its organic
    degradation products. The method is not able to distinguish between
    the various compounds,but reflects the total amount of the compounds
    in the sample analyzed.


    The tolerance is expressed in terms of tricyclohexyltin hydroxide. The
    organic degradation products and the inorganic tin salts derived from
    tricyclohexyltin hydroxide are not included in the tolerance. A
    temporary tolerance of 2 ppm, based on an interval of two weeks from
    the last treatment to the harvest, is recommended for apples and


    REQUIRED (by June 1973)

    1. Further studies on the effects of exposure to tricyclohexyltin
       hydroxide on copper balance and, in particular, on the copper 
       content of the liver.

    2. Further information on the occurrence of liver and pituitary gland
       cysts in female rate fed the compound.

    3. Further information on the effect of the compound on the rate of
       body-weight gain after allowing for the unpalatability of test

    4. Further information on the significance of the brown discoloration
       of the serosal surface of the intestine of treated animals.

    5. Establishment of analytical procedures capable of distinguishing
       qualitatively between tricyclohexyltin compounds and other 
       organotin compounds, particularly the fentin compounds, and, where 
       possible, of quantitative measurement of the separate compounds.


    Data on residues of tricyclohexyltin hydroxide on apples and pears
    moving in international commerce.


    Allison, W.E. (1969) An evaluation of the systemic (soil and foliar)
    acaricidal activity of tricyclohexyltin hydroxide. Unpublished report
    from the Dow Chemical Co.

    Anon. (1969) Determination of small amounts of organotin in macerated
    fruit. Method No. TA-2-2. Unpublished report from M & T Chemicals,

    Anon. (1970a) Tin content of tissues of rats and dogs fed varying
    amounts of tricyclohexyltin hydroxide in the daily diet for two years.
    Unpublished report from the Dow Chemical Co.

    Anon. (1970b) Compilation of studies on residues of tricyclohexyltin
    hydroxide in or on apples and pears: Australia, France, Netherlands,
    and Japan. Unpublished report

    Anon. (1970c) Dicyclohexyltin oxide: summary of acute oral toxicity
    tests. Unpublished report from the Dow Chemical Company

    Corbin, H.B. (1970) Separation and determination of trace amounts of
    tin present as organotin residues on fruits. J. Assoc. Offic. Anal.
    Chemists, 53: 140-146

    Getzendaner, M.E. (1968) A review of residue information on 
    tricyclohexyltin hydroxide. Unpublished report from the Dow Chemical

    Getzendaner, M.E. and Corbin, H.A. (1969) Residue study: inorganic 
    and organic tin compounds in or on apples and pears from field
    applications of PLICTRAN(R) miticide. Unpublished report from the Dow
    Chemical Co.

    Getzendaner, M.E. and Gentry, W.M. (1970a) Determination of tin
    residues in orchard grass exposed to tricyclohexyltin hydroxide
    miticide. Unpublished report from the Dow Chemical Co.

    Getzendaner, M.E. and Gentry, W.M. (1970b) Determination of tin
    residues in beef calves fed tricyclohexyltin hydroxide for ninety
    days. Unpublished report from the Dow Chemical Co.

    Getzendaner, M.E. and Gentry, W.M. (1970c) Determination of tin
    residues in milk, cream, and body tissue of dairy cows fed
    tricyclohexyltin hydroxide. Unpublished report from the Dow Chemical

    Gray, H.E. (1968) PLICTRAN miticide - new approach to mite control.
    Down to Earth, 23 (4): 3-5

    Hine, C.H. (1966) Acute oral toxicity of tricyclohexyltin hydroxide in
    Long Evans strain rats (17 March 1966). Unpublished report from the
    Hine Laboratories, Inc. to Dow Chemical Co.

    Hine, C.H. (1967) Acute oral toxicity: Cyclohexylstannoic-acid,
    dicyclohexyltin oxide, tetracyclohexyltin, hexacyclohexylditin.
    Unpublished report from the Hine Laboratories, Inc.

    Hine, C.H., Brownlow, E.K., Cummins, J.T., Eisenlord, G.H. and Wong,
    L.C.K. (1969) Studies on the mechanism of action of DOWCO 213.
    Unpublished report from the Hine Laboratories, Inc.

    Hine, C.H., Eisenlord, G.H. and Laudel, A. (1969a) DOWCO 213 
    reproduction and teratology studies in rats. Unpublished report from
    the Hine Laboratories, Inc.

    Hine, C.H., Eisenlord, G.H. and Laudel, A. (1969b) DOWCO 213 
    reproduction and teratology studies in rabbits. Unpublished report
    from the Hine Laboratories, Inc.

    Hine, C.H. (1970a) Results of two-year dietary feeding study with
    tricyclohexyltin hydroxide (DOWCO 213) in dogs. Unpublished report
    from the Hine Laboratories, Inc.

    Hine, C.H. (1970b) Results of two-year dietary feeding study with
    tricyclohexyltin hydroxide (DOWCO 213) in rats. Unpublished report
    from the Hine Laboratories, Inc.

    Jeppson, L.R., Jesser, M.J. and Complin, J.O. (1968) Responses of the
    pacific spider mite and the citrus red mite to laboratory and field
    applications of tricyclohexyltin hydroxide. J. Econ. Entomology, 61:

    Kenaga, E.E. (1968) The rodent toxicity and repellency of
    tricyclohexyltin compounds to two species of mice. Unpublished report
    from the Dow Chemical Co.

    Komblas and Kostas N. (1969) Determination of residues of PLICTRAN
    acaricide on apples and pears in Italy. (Translation of report of
    Societá Italo-Americana Prodotti Antiparassitari, Balliera/Bologna,
    Italy). Unpublished report from the Dow Chemical Co.

    Laker, T.L., Elsea, J.R. and Ede, M. (1966) Repeated insult patch test
    on M-2527 and cloth material TE98-SEU3501. Unpublished report from
    Hill Top Research, Inc.

    Norris, J.M. (1968) Toxicity of tricyclohexyltin hydroxide via i.p.
    route in laboratory animals. Unpublished report from the Dow Chemical

    Olson, K.J. (1964) Results of range finding toxicological tests on
    tricyclohexyltin hydroxide. Unpublished report from the Dow Chemical

    Smith, G.N., Axelson, R.J. and Schiesser, L.H. (1970) The loss of
    PLICTRAN(R) miticide from various soils. Unpublished report from the
    Dow Chemical Co.

    Smith, G.N. and Fischer, F.S. (1970) Metabolism of PLICTRAN(R)
    miticide. Observations on the absorption, distribution, and excretion
    of tricyclohexyltin-Sn119 hydroxide in white rats. Unpublished report
    from the Dow Chemical Co.

    Smith, G.N., Fischer, F.S. and Axelson, R.J. (1970) The volatilization
    and photodecomposition of PLICTRAN(R) miticide. Unpublished report
    from the Dow Chemical Co.

    Smith, G.N. and Taylor, Y.S. (1970) The absorption and translocation
    of PLICTRAN miticide and its decomposition products in bean and corn
    plants. Unpublished report from the Dow Chemical Co.

    Stevenson, G.T. and Kenaga, E.E. (1969) The effects of dietary feeding
    of tricyclohexyltin hydroxide on the life stages of the Japanese
    Quail. Unpublished report from the Dow Chemical Co.

    Tucker, W.E. (1966) Oral toxicity studies of tricyclohexyltin
    hydroxide in rats. Unpublished data from the Dow Chemical Co.

    Wazeter, F.X., Buller, R.H., Geil, R.G. and Long, J.E. (1968)
    Dicyclohexyltin oxide: 90-day feeding study in the Long-Evans rat.
    Unpublished report from the International Research and Development

    Wazeter, F.X. (1969) 21-day dermal study in,albino rabbits-PLICTRAN
    M-3180 miticide. Unpublished report from the International Research
    and Development Corporation

    Whitney, W.K. (1966) Leaching tests with DOWCO 213 in soil

    Zambelli, N., Komblas, W. and Kovacs, A. (1968) PLICTRAN miticide for
    the control of spider mites in Italy. Down to Earth, 24(3): 25-31

    See Also:
       Toxicological Abbreviations
       Tricyclohexyltin hydroxide (WHO Pesticide Residues Series 3)