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    CAMPHECHLOR     JMPR 1973

    Explanation

         This insecticide was previously evaluated (as Toxaphene) in 1968
    (FAO/WHO, 1969b) at which time no recommendations were made because of
    the many unresolved questions related to this compound.

         New toxicological data relating to reproduction have become
    available. These data and all the previous data were considered by the
    meeting although only new data summarized in the following monograph
    addendum.

    IDENTITY

         Camphechlor is a complex mixture of chloro bicyclic terpenes
    resulting from the chlorination of camphene.

         Absorption and gas-liquid chromatography separate camphechlor
    into at least 175 C10-polychloro compounds including C16, C17, C18,
    C19 and C110 derivatives (Casida, 1973). One toxic component has been
    isolated and its structure determined to be 2,5-endo, 2,6-exo,
    8,9,10-heptachlorobornane. More than 100 octochloro structures are
    possible, hence, control of camphene feedstock quality, chlorine
    content and process variables is important in achieving a material of
    uniform composition. Examination of infrared spectra, electron capture
    gas chromatograms and bioassays shows that camphechlor produced by
    Hercules Incorporated over a 25-year period has been a reproducible
    product with uniform biological, chemical, and physical properties.
    For example, bioassay of 10 samples of camphechlor produced during the
    period 1949-1970 had an average LD50 to female houseflies of
    19.34 mg/g with a range of 18.9-19.9 mg/g (Buntin, 1970).

         Infrared spectra and electron capture gas chromatograms obtained
    from these samples also demonstrate the uniformity of camphechlor. The
    information which follows has been obtained from investigations
    conducted on commercial camphechlor of uniform composition meeting
    official FAO specifications 23/1/S/5.

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    Biochemical aspects

         Following a single oral dose of camphechlor to rats (20 mg/kg)
    recovery of 36Cl was found to be predominantly in the faeces (70%)
    with the urine having 29.1%. Total recovery following single dose was
    in the range of 40-50% in urine and faeces. The major quantity was
    eliminated within 24-48 hours after dosing (Crowder, 1973). At the end
    of nine days following single dose, 3.65% of 36Cl was observed in the
    fatty tissue (Crowder, 1973).

    TOXICOLOGICAL STUDIES

    Special studies on reproduction

    Mouse.  Groups of mice (four males and 14 females per group) were
    fed camphechlor in the diet at levels of 0 and 25 ppm in a
    five-generation, two litters per generation, reproduction study. There
    were no effects noted with camphechlor on any of the reproduction
    parameters measured (Keplinger et al., 1970).

    Rat.  A three-generation, six-litter reproduction study was
    conducted with toxaphene. Groups of weanling rats were fed 25 ppm  and
    100 ppm for 79 days before mating. All animals were continued on their
    respective dietary concentration of toxaphene during the mating,
    gestation, weaning of two generations, or for a period of 36 to 39
    weeks. Weanlings from the second litter were selected as parents lot
    the second generation and continued on their respective diets until
    after weaning of a second litter. A third generation was selected in
    the same manner. Complete gross and histological examination was
    performed on all three parental generations after 36 weeks of
    toxaphene administration. The only pathologic changes found were
    slight alterations in the livers of the 100 ppm group similar to those
    changes seen in long-term studies. Reproductive performance, fertility
    and lactation were normal. The progeny were viable, normal in size and
    anatomical structure. Findings among all test animals, three parental
    generations and six litters of progeny were comparable to control
    animals for all parameters (Kennedy et al., 1973).

    Special studies on teratogenicity

         Camphechlor was injected into the yolk of fertile eggs after
    seven days incubation at doses ranging from 0 to 1.5 mg/egg. No
    effects on hatchability or teratogenic potential were observed (Smith
    et al., 1970).

    Short-term studies

    Rat. Toxaphene did not significantly affect the physical appearance,
    gross pathology, weight gain or liver cell histology of albino rats
    given levels from 2.33 to 189 ppm in their diets for up to 12 weeks.
    There were male-female differences in liver cell diameters, as well as
    in weight gain and residue patterns. Dunnett's comparison test
    indicated that significant levels of toxaphene were present in liver,
    omental fat and whole body samples (minus liver and omental fat) with
    each dose at four, eight and 12 weeks (Clapp et al., 1971).

         Administration to rats of 1.2 mg/kg technical polychlorcampher
    for 12 months resulted in changes in the liver function evidenced by
    increased sleeping time and hippuric acid synthesis (Spinu et al.,
    1970). At higher doses (4.8 mg/kg) hypoglycaemia resulted while at 2.4
    mg/kg the increase in sleeping time was noted after two months and on
    cessation of treatment returned to normal on the fourth month
    (Grebenjuk, 1970).

    Observations in man

         No porphyrin was found in the urine of 45 workers daily exposed
    to a variety of pesticides, predominantly parathion, toxaphene, DDT,
    and dieldrin. The qualitative method used was capable of detecting 0.4
    g/ml. No correlations were found between serum pesticide levels and
    urinary excretion of ALA, PBG, and CCA. Parathion depressed plasma
    and/or red cell ChE in five workers. The negative findings suggest
    that ordinary occupational exposure to the pesticides noted above has
    no strong porphyrinogenic or sympathotonic effects (Embry et al.,
    1972).

    Comments

         The Joint Meeting considered new data on distribution and
    excretion and on the lack of reproductive hazard associated with
    camphechlor. The Meeting reaffirmed the principles set forth by the
    1968 Joint Meeting that an ADI could not be established for material
    whose composition may vary with the method of manufacture.

         The 1968 Joint Meeting evaluated the available data indicating
    that although adequate work has been done on a product of defined
    specifications the materials in worldwide agricultural use may not
    conform to the specifications of the original product tested nor to
    those specifications set by the FAO. Although the specifications of
    FAO have been met by one manufacturer, the product from other sources
    cannot be considered in the light of the known data. It was suggested
    that the toxicological studies reported over the past 20 years were
    performed with a product of uniform reproducible composition. However,
    a question was raised concerning certain studies performed 20 years
    ago, particularly on the question of carcinogenesis, in light of
    current thinking concerning the effects of chlorinated pesticides.

         The Meeting was informed of current research with camphechlor
    which may resolve some of the problems facing the Meeting in its
    evaluation of camphechlor. The Meeting re-affirmed the principles set
    forth by the 1968 Joint Meeting and considered that it could not
    establish an ADI on the product available on a worldwide basis.
    Although available data might be adequate to establish an ADI such
    action could not be accomplished where material used in world trade
    may not be uniform. The Meeting further hoped that the questions
    raised concerning uniformity of the product over the years be more
    completely resolved. The Meeting expressed the hope that further
    research in progress will aid in resolving the questions on the
    uniformity of the product conforming to FAO specifications and those
    products used in worldwide agriculture.

    RESIDUES IN FOOD AND THEIR EVALUATION

    Use pattern

    Pre-harvest treatments

         Camphechlor is used to control a variety of arthropod pests which
    attack agronomic and horticultural crops and livestock.  The major
    areas of use include cotton, livestock, oil seeds, cereal grains,
    vegetables, fruits and nuts. Camphechlor has a particular advantage in
    that it can be used on crops such as seed alfalfa and vegetables
    without causing great damage to bee pollinators. Crop pest control is
    by foliar application of sprays, dust and granules except for the use
    of baits against cutworms. Emulsion sprays and dips and oil solutions,
    self-applied by backrubbers, are the usual means of treating livestock
    with camphechlor for the control of external pest.

         Camphechlor is usually applied to crops at rates of 1-3 kg per
    hectare and to livestock at concentrations of 0.25-0.5% by dips and
    sprays and 2.5-5% by backrubbers. Camphechlor has been especially
    valuable in the control of ticks and of mites.

         On crops, camphechlor is frequently applied with other pesticides
    such as DDT, methyl or ethyl parathion, maneb and others. Camphechlor
    is also registered for use in 70 countries. The principal crop and
    livestock uses and the geographic areas of use are tabulated below:

    Crop use outside United States of America

         Geographic area        Principal crop use

         Central America          cotton
         South America            cotton, small grains, soybean, bananas
         Africa                   cotton, vegetables
         Europe                   cotton, rapeseed, vegetables
         Asia                     cotton, peanuts, vegetables, rice
         Oceania                  cotton

    Livestock use outside United States of America

         Africa

         East, Central and South Africa, including Uganda, Kenya,
         Tanzania, Rhodesia, Angola, Nigeria, and South Africa.

         South America

         Brazil, Columbia, Peru, Venezuela and Ecuador.

         Central America

         Mexico, Costa Rica, El Salvador and Panama.

         North America

         Canada

    Post-harvest treatment

         Camphechlor is not used for post-harvest treatments.

    Residues resulting from supervised trials

         The available data were summarized as Table 1 in the first
    evaluation of camphechlor (FAO/WHO, 1969), which is repeated here for
    clarity and continuity. It selectively summarizes camphechlor residue
    data on representative crops and livestock when approved agricultural
    practices are followed.

    Residues in crops

         The half-life of camphechlor residues on growing leafy crops is
    in the range of 5-10 days; residues from emulsifiable formulations are
    typically higher than those from wettable powders or dusts.

         Studies of camphechlor residues on alfalfa and clover show that
    the half-life (corrected for crop growth dilution) is consistently in
    the range of 9-13 days under widely varying climatic conditions.
    Studies were conducted in Arizona, California and Delaware (United
    States of America).

         Residues on crops are kept within established levels by  suitable
    restrictions such as dosage rate, application before the formation of
    edible parts or by appropriate pre-harvest or pre-slaughter intervals.

    Residues in livestock

         Camphechlor residues can be accumulated in fat of animals from
    ingestion and by dermal absorption. The storage level is much less
    than that of most other chlorinated hydrocarbon pesticides, and an
    equilibrium with the exposure level is rather quickly achieved.
    Elimination of camphechlor from the fat is quite rapid when the input
    is reduced. This is true at both high and low levels of ingestion.
    Storage/feed ratios for various animal species are summarized as
    follows:

                        Storage/feeda     Observation
                        ratio               period
                                                         
         Rat            0.4                 2 years
         Dog            0.3                 2 years
         Sheep          0.3                 16 weeks
         Cattle         0.5                 16 weeks
                                                         
         a Storage/feed ration = ppm in fat
                                 ppm in feed



    
    TABLE 1. CAMPHECHLOR RESIDUES RESULTING FROM SUPERVISED TRIALS
                                                                                                            

                        Rate of       No. of       Pre-harvesta    Residue
                        application   treatments   interval        at harvest     Comments
                        (kg/ha)                    (days)          (ppm)
                                                                                                            

    Vegetables

    Lettuce             5.5           1-1          10              5.8-7.9        whole head
    Kale                5.0           4            36              3.3-7.2
    Cabbage             1.9-1.2       2-6          9-38            0.8-6.6        on outer leaves
    Spinach             5.0           4            30              16.7-18.8
    Celery              1.1-1.6       9            13              1.8 stalks     washed
                                                                   6.5 leaves

    Cauliflower         3.8           1            8               1.1            (processed commercially
    Broccoli            10            1            8               3.4            and frozen before analysis)

    Tomatoes            1.3-2.5       8-9          5-7             2.0-4.3
    Green beans         7.5           1            7               1.3            unwashed
    Lima Beans          3.9           1            14              0.3            shelled beans
    Carrots             25            2-4                          0.9-3.3        soil application 1 year
    Potatoes            0.95-2.5      6            21              0 detected
    Field peas          2.5           3            4               1.8

    Oil seeds

    Cotton (seed)       3.9-5.0       15           6               3.6-5.2        lint bearing seed
    Soybeans            3.8           3            60              0.5
    Peanuts
    (shelled)           25-50         1                            0 detected     soil treatment

    Fruit

    Oranges             5.7           2            7-70            0-10.9 skins
                                                                   0-0.3 pulp

    TABLE 1. (Cont'd.)

                                                                                                            

                        Rate of       No. of       Pre-harvesta    Residue
                        application   treatments   interval        at harvest     Comments
                        (kg/ha)                    (days)          (ppm)
                                                                                                            

    Bananas             3.8           1            1               0.3-1.3        whole fruit
    Pineapple           2.8           2            81-96           1.3-2.7        whole fruit

    Cereal grains

    Wheat               1.9-3.8       1            14-21           0.5-1.8
    Barley              1.9-3.8       1            7-28            0.7-14.2
    Oats                1.9-3.8       1            7               1.0-2.6
    Rice                1.9-3.8       1            7-28            1.5-5.6        unfinished grain
    Sorghum             2.5           1            28              2.5-3.1
    Corn (maize)        2.5           1            12              0.08 kernels

    Fat of meat

    Animals

    Beef                0.5%          12           28              5.0            12 weekly sprays
    Swine               0.5%          2            28              0-0.6          2 sprays

    Shelled nuts

    Almonds             4.0           3            136             1.5
                                                                                                            

    a Interval from last application if multiple applications were made.

    



         The rapid elimination of camphechlor residues from the fat of
    animals allows it to be used for ectoparasite control on livestock
    within 28 days of slaughter. Where shorter preslaughter intervals are
    required, other pesticides must be used.

    Residues in milk

         Consistent with the fat-storage properties of camphechlor in
    livestock, transmission of camphechlor residues to milk follows the
    same pattern (Claborn et al., 1960; Zweig et al., 1963). Equilibrium
    with input is reached within about one week, and the ratio of
    camphechlor concentration in the feed to that in the milk is about
    100:1. Excretion of camphechlor in milk declines quickly when exposure
    ceases.

         In feeding trials, milk free of camphechlor residues was produced
    within two weeks after cessation of feeding 10 ppm in the ration. At a
    feeding level of 20 ppm in the daily diet for 11 weeks,
    camphechlor-free milk was produced four weeks after
    camphechlor-containing feed was discontinued.

         Restrictions against the application of camphechlor to dairy
    animals and against feeding dairy animals certain forages and crop
    refuse treated with camphechlor have been successful in preventing
    unwanted camphechlor residue in fluid milk and other dairy products as
    indicated by the results of the United States Food and Drug
    Administration market basket surveys and other surveillance
    programmes.

    Fate of residues

    On plants

    Evaporation

         Camphechlor is not systemic. Residues on crops are therefore
    essentially confined to the surface of leaves and other plant parts.
    The observed half-life of camphechlor residues on plants ranges from
    5-13 days. Recent studies have established that volatility is a major
    factor in the loss of thin films of camphechlor from glass plates and
    from the surface of leaves. Sunlight has little effect on the rate of
    loss of camphechlor from thin films on glass plates. Camphechlor is
    easily washed from smooth glass surfaces by heavy rains in contrast to
    deposits on crops, which are much more resistant to wash-off by rain
    (Carlin, 1970b, Hercules Inc., unpublished report, 1970a).

    Chemical nature of the residue

         There is no evidence of the existence of camphechlor conversion
    products in weathered crop residues. Such residues are composed of
    unaltered camphechlor.

         Klein and Link (1967) examined residues on camphechlor-sprayed
    kale and found that over 99% of the original residue was lost during
    the first two weeks. Gas chromatographic analysis of the residues
    indicated a modest loss of early-eluting GLC components. However, the
    composition of the residue even after four weeks was readily
    recognizable as camphechlor from the GLC elution pattern. Carter et
    al. (1950) examined weathered camphechlor residues on alfalfa and
    found insecticidal activity was the same as that of camphechlor.

         Carlin (1970a) concluded that no camphechlor conversion products
    were formed in alfalfa allowed to weather after being treated with
    camphechlor. These conclusions were based on measurements by "total
    chloride" methods, electron capture GLC, and bioassays, the last
    showing no greater toxicity than authentic camphechlor. A study of
    residues on cotton plants led to the same conclusion.

    Possible metabolites of camphechlor

         Attempts to introduce functional groups into camphechlor by in
    vitro chemical reaction have been unsuccessful, and the availability
    of model compounds as authentic reference standards for various
    separation and detection systems has been limited.

         Recently, samples of "keto-camphechlor" and "hydroxy-camphechlor"
    were prepared by Buntin. Camphor was chlorinated to a value
    corresponding to the addition of seven atoms of chlorine. The
    resulting "keto-camphechlor", a viscous pale yellow liquid, was
    reduced with lithium aluminum hydride to form "hydroxy-camphechlor".
    These compounds are less toxic to flies and rats than camphechlor; gas
    chromatography shows they elute with the early peaks of camphechlor.

         Clean-up techniques applied to keto-camphechlor and
    hydroxy-camphechlor show that the former survives fuming sulfuric
    acid, but that hydroxy-camphechlor does not. Dehydrohalogenation (as
    applied to camphechlor prior to gas chromatography) showed that these
    compounds are retained in the alkaline aqueous phase when it is
    extracted with hexane. Both compounds are extracted by hexane from
    distilled water.

         Weathered camphechlor residues from alfalfa were examined for the
    possible presence of keto-camphechlor or hydroxycamphechlor. No
    evidence for their presence was found.

    In animals

         As discussed above, the accumulation of residues in animal fat as
    the result of typical application or ingestion of camphechlor is
    characterized as follows:

    (1)  At any given subacute level of intake, a certain storage level is
         attained and additional intake does not result in further
         increase.

    (2)  When the source of camphechlor is removed, the residue is rapidly
         eliminated.

    (3)  The level of storage is lower and elimination more rapid than
         with most other chlorinated hydrocarbons.

         As with weathered residues on crops, stored residues in animal
    fat consist of unmodified camphechlor. Carter et al. (1950) reported
    that residues in the fat of steers wintered on camphechlor-treated
    alfalfa hay were similar in infrared absorption and insecticidal
    activity to authentic camphechlor.

         Recently 36Cl-labelled camphechlor was orally administered to
    rats in a preliminary study of the metabolic fate of camphechlor in a
    mammal. Each rat was given a single oral dose of 25 mg/kg bw. The rats
    were sacrificed 72 h after dosing. Faeces, urine (up to 72 hours),
    kidneys, liver, and fat were analysed as were the remainder of each
    carcass. The bulk of the activity found was found in the urine,
    faeces, and carcass with only small amounts present in the fat, liver,
    and kidney. Of the total activity detected in the rats (including
    urine and faeces), one-half was ionic 36Cl, one-quarter was
    water-soluble but not ionic 36Cl and one-quarter was hexane soluble
    (Hercules Inc.).

         Very similar results were obtained by Casida et al. (1973) who
    administered 36Cl-camphechlor orally to rats at about 14 mg/kg to
    determine the extent of dechlorination and rate of elimination over a
    14-day period. Less than 0.7% of the 36Cl appeared in urine and less
    than 3% in faeces as unmetabolized camphechlor. Approximately 25% of
    the 36Cl appeared in urine and faeces (mostly) as partially
    dechlorinated metabolites of camphechlor. The remainder, 44-57% of
    dose, appeared as chloride ion (36Cl-) in the urine.

         These studies are being continued to define more completely the
    composition of technical camphechlor and the structure, metabolic fate
    and environmental persistence of the various components.

    In the honey bee

         A study of camphechlor residues in rape-seed oil, honey, and bees
    was conducted by Jumar and Sieber (1967). They prepared a 36Cl-tagged
    camphechlor and determined that residues were transmitted to rape-seed
    oil in the range of 0.3-1.5 ppm, depending on the method of
    application to the rape-seed plant. Honey made by bees exposed to the
    camphechlor-treated plants contained less than 0.01 ppm camphechlor.
    The study on camphechlor in bees employed 82Br-camphechlor (one Cl
    atom replaced by 82Br). More than 95% of camphechlor absorbed by bees
    from feeding was stored briefly in the body before release as a
    chlorine-containing water-soluble compound which was not identified.

    In animal feeds and forage

         Residues of camphechlor in forages such as alfalfa and clover
    typically have a half-life of 9-13 days (corrected for dilution by
    crop growth). As previously discussed, the major mechanism of loss is
    by evaporation.

    In water

         The solubility of camphechlor in water is 0.4 mg/1. Camphechlor
    is stable in distilled water and in dilute emulsions but recent
    evidence demonstrates that changes may occur in natural waters and in
    sediments, probably as a consequence of microbial activity. The lower
    limit of detection by taste is about 5 ppb camphechlor. Treatment of
    water with activated carbon is an effective means of removal to
    produce potable water (Cohen et al., 19-60; ibid., 1961).

    In soils

         Camphechlor is not normally used to control soil insects with the
    exception of surface sprays and baits for cutworm control. Most
    camphechlor residues in soil therefore result from foliar sprays which
    missed the target and to a lesser extent to residues from
    non-harvested portions of treated crops.

         Camphechlor residues in and on soil may be detected for varying
    periods of time after application depending on soil type, climate, and
    rate of application. In recent work with 36Cl-labelled camphechlor
    the half-life varied from 70 days for moist sandy soil to 179 days in
    a moist clay soil. The half-life in these same soils kept dry was 136
    and 705 days respectively (Hercules Inc.).

         The application of camphechlor at the rates used for insect
    control has not resulted in the build-up of residues in the soil in
    areas of regular usage. Bradley et al. (1972) working on small plots
    of loamy sand and sandy loam soils in North Carolina applied
    camphechlor foliar sprays at approximately weekly intervals from early
    June until September 1969. The total amount applied was 23.9 lb per
    acre. Only 5-10% remained in the soils in September 1969; 4% was found
    the following March. Less than 1% was accounted for in water and
    sediment run-off.

         Stevens et al. (1970) made a nationwide survey of pesticide
    levels in soils. Samples were taken from 51 locations about equally
    divided between areas where pesticides were used regularly, areas with
    no history of pesticide use and areas which had received at least one
    pesticide application. No evidence of camphechlor build-up was found.
    In areas of regular pesticide use, 60% of the vegetable and/or cotton
    field samples and 12% of small grain and root crop field samples
    contained camphechlor residue. The data show that the residues of
    camphechlor from crop applications made over periods of 1-14 years

    were present at only small fractions of the amount applied. No
    camphechlor was found in soils from areas where pesticides had been
    used infrequently or areas where no pesticides were used.

         More recently Wiersma et al. (1972) have reported the 1969
    results of the National Soils Monitoring Study. Pesticide residues
    found in cropland soil for 43 states and for non-cropland soils for 11
    states are summarized. Dieldrin was found to be the most widely
    distributed organochlorine pesticide. Detectable residues of dieldrin
    were found at 27.8% of the sites sampled. Toxaphene (camphechlor)
    residues occurred at only 4.2% of the sites in spite of the fact that
    the 43 states from which cropland soil was sampled include the areas
    of major camphechlor use with the exception of Texas. Camphechlor
    occurred in a single sample of 199 non-cropland soil samples.

         Camphechlor residues in soil do not leach appreciably and
    downward migration through the soil does not occur to a significant
    degree. Nash and Woolson (1968) determined the vertical distribution
    of camphechlor over a three-year period. Between 85% and 90% of the
    camphechlor remaining, three years after the last application was
    found in the upper 23 cm, corresponding to the cultivated zone. Thomas
    (1970) studied the distribution of camphechlor in Texas soils to a
    depth of 5 ft. He found that very little camphechlor occurred below a
    depth of 1 ft. Only about 20% of the camphechlor applied in the
    preceding 10 years could be accounted for in the soil profile.

         The longer period of biological activity of camphechlor
    mechanically mixed with soil (Mulla, 1961) in contrast to camphechlor
    applied to the soil surface (Shaw and Riviello, 1961) suggests that
    persistence on the soil surface is less than when incorporated into
    the soil. Recent work on the mechanism of the decline of camphechlor
    residues indicates that a major mechanism is evaporation. Studies with
    36Cl-labelled camphechlor (Hercules Inc.) confirm that camphochlor
    disappears from the surface of soil by evaporation as well as by
    chemical reaction involving the formation of chloride.

         Camphechlor residues in soil are subject to degradation by soil
    microorganisms. Both soil bacteria and fungi degrade camphechlor, the
    bacteria using it as a source of carbon (Smith and Wengel, 1947). This
    work and other evidence of microbial degradation has been summarized
    by Paris and Lewis (1973).

    During storage, processing, cooking

         Farrow et al. (1968) have demonstrated that in commercial
    canning, surface residues are reduced by washing, peeling, and
    abrasive peeling. Since camphechlor is non-systemic, surface residues
    of camphechlor will be removed by these operations both in commercial
    canning and in the preparation of fruits and vegetables for culinary
    purposes in the home.

         Washing alone will remove significant amounts of camphechlor
    residues. Thompson and Van Middelem (1955) found that washing with
    water removed significant amounts of the residues on certain
    vegetables. The addition of 0.1% synthetic detergent or 1.0% neutral
    soap to the wash water increased the percentage removed.

                                                                            

                            Percentage of initial camphechlor residues removed
    Washing treatment                                                       

                                          Green                       Mustard
                            Tomatoes      Beans         Celery        greens
                                                                            

    Water                   N.S.a         20            57            57

    1% neutral soap         N.S.a         67            73            91

    0.1% alkyl-aryl         N.S.a         58            72            90
    polyether alcohol
                                                                            

    a Not significant.


         Since camphechlor residues are located in the fat of meat,
    trimming to remove excess fat will reduce the residue. Cooking at
    temperatures sufficiently high to render out fat will also physically
    remove some of the residue (Liska and Stadelman, 1968).

         Heat processing used in producing canned foods will also
    significantly reduce camphochlor residues initially present on the raw
    product. Elkins et al (1972) fortified apricots and spinach at 7 ppm
    (the United States tolerance level for these products). Samples were
    analysed immediately after processing and after storage for one year
    at ambient temperature. Processing of spinach resulted in a 27%
    reduction in residue level and a 60% loss after processing followed by
    storage for one year. Losses in apricots were somewhat less, 7% due to
    processing and 35% after processing and storage.

    Evidence of residues in food moving in commerce or at consumption

         Camphechlor is registered for a variety of uses on food crops and
    livestock. During 1965-1968, United States Food and Drug
    Administration market-basket surveys showed camphechlor to be
    virtually absent from these samples. The frequency of occurrence of
    camphechlor residues in these studies was less than that of the first
    15 most commonly found pesticides. The market-basket samples represent
    the total diet of a 16-19-year-old male, and are obtained from retail
    stores in five regions at bi-monthly intervals. Food is prepared for

    consumption and analysed for pesticide residues using gas-liquid
    chromatography methods.

         In the later period, June 1968 April 1969, camphechlor was
    detected in 13 of the 360 composite samples analysed. Range of
    residues was 0.02-0.33 ppm in food categories, garden fruit,
    vegetables, and meat fat.

         A summary of the United States Food and Drug Administration
    surveillance programme and market-basket results for camphechlor in
    the period 1964-1969 (Duggan et al., 1971) using the food categories
    established by the United States Food and Drug Administration is given
    in Table 2. These data reflect the widespread usage of camphechlor on
    vegetables and the retention of some of the residue in the processed
    (canned, dried, or frozen) food. Camphechlor residues were sixth most
    frequent in occurrence of all pesticides in processed foods, but few,
    if any, were in excess of the 7 ppm tolerance.

         Camphechlor finds its most intensive agricultural use on cotton.
    It is also used to a lesser extent on other oil seed crops such as
    soybeans, peanuts, and corn. Analysis of oil and other products
    derived from these crops show camphechlor is found in about 30% of the
    cotton-seed samples, 8% of the soybean samples, and 2% of the peanut
    samples. Above-tolerance residues have not been a problem either in
    the raw agricultural commodities or in the processed oils and meals.

         Duggan and Corneliussen (1972) calculated the daily intake of
    pesticide residues in the United States from market-basket sample
    data. The period covered was June 1968 to April 1970.

         For the period June 1968 to April 1969, the calculated daily
    intake of camphechlor (in milligrams per day) was 0.001 in leafy
    vegetables; 0.002 in garden fruits; and less than 0.001 each in meat,
    fish, and poultry, in legume vegetables, and in root vegetables. For
    the period June 1969 to April 1970, the calculated daily intake of
    camphechlor (in milligrams per day) was 0.001 in garden fruits and
    less than 0.001 in leafy vegetables. In the six-year period 1965-1970,
    the average daily intake of camphechlor as measured in this series of
    studies was only 0.0015 mg per day.

         In addition to the FDA surveillance and market-basket programme,
    the United States Department of Agriculture regularly examine tissues
    from meat animals and poultry slaughtered in federally inspected
    plants. A tabulation of their findings for the year 1969 and the first
    six months of 1970 is given in Table 3. It is notable that, in spite
    of the widespread use of camphechlor on grains and other ingredients
    of animal feeds and its application to animals for ectoparasite
    control, camphechlor was found in only two of the 3169 meat samples in
    1969 and in but two of the 2199 poultry samples in the same year. In
    the first half of 1970, three of 1871 meat samples and none of 1486
    poultry samples contained camphechlor. In comparison, DDT was found in
    2671 meat samples in 1969 and in 1432 samples in the first half of

    1970. Because of the low levels of camphechlor in the environment and
    the ability of the animals to quickly excrete camphechlor, residues of
    camphechlor in meat and poultry are virtually non-existent.

    
    TABLE 2. CAMPHECHLOR RESIDUES IN FOOD BOTH DOMESTIC PRODUCTION AND
             IMPORTED - UNITED STATES, 1964-1969 (DUGGAN ET AL., 1971)

                                                                                        

                                         No. samples       Incidence %       Average ppm
    Food group                                                                          
                                       Dom.      Imp.      Dom.   Imp.       Dom.    Imp.
                                                                                        

    Fluid milk (fat basis)             12 989    -         -      -          -       -
    Dairy products (fat basis)         6 231     1 981     -      -          -       -
    Large fruits                       6 763     2 495     0.2    0.4        T       0.02
    Small fruits                       2 695     496       0.9    0.2        0.01    T
    Grain and cereals (human use)      8 005     104       0.4    -          T
    Leaf and stem vegetables           13 864    153       7.9    2.7        0.20    1.24
    Vine and ear vegetables            8 072     1 791     1.3    5.0        0.01    0.02
    Root vegetables                    13 561    533       1.4    -          0.01    -
    Beans                              1 492     144       1.1    1.4        0.01    T
    Meat (fat basis)                   12 146    3 674     1.4    0.1        0.01    T
    Poultry (1968-1969)                3 414               -                 -
    Eggs                               4 046     121       0.1    -          T       -
    Fish                               2 150     378       1.9    0.8        0.04    T
    Shellfish                          830       167       -      -          -       -
    Grain (animal) (1966-1969)         1 168     60        -      -          -       -
    Infant and junior foods            2 078               -                 -
    Tree nuts                          418       128       T      T          0.2     1.6
    Peanut products
      Nuts                             229                 1.3               0.005
      Crude oil                        41                  2.4               0.008
      Meal (cake)                      36                  -                 -
      Refined oil                      11                  -                 -
    Cotton-seed products
      Seed                             31                  29                0.017
      Crude oil                        282                 1.1               0.008
      Meal (cake)                      287                 3.5               0.002
      Refined oil                      48                  10.4              0.12
    Soybean products
      Soybeans                         690                 7.1               0.006
      Crude oil                        118                 8.5               0.114
      Meal (cake)                      248                 -                 -
      Refined oil                      34                  2.9               T

    TABLE 2. (cont'd)

                                                                                        

                                         No. samples       Incidence %       Average ppm
    Food group                                                                          
                                       Dom.      Imp.      Dom.   Imp.       Dom.    Imp.
                                                                                        

    Corn products
      Grain                            1 314               -                 -
      Crude oil                        28                  -                 -
      Refined oil                      10                  -                 -
    Oleomargarine                      85                  -                 -
                                                                                        

    T = Less than 0.005 ppm.
    - = Not detected.

    TABLE 3. CHLORINATED PESTICIDE RESIDUES IN MEAT AND POULTRY -1969 AND 1970

                                                                                 
                        No. of tissues                                 No. with
    Species             analysed               No. with a residue      toxaphene
                                                                                 
                        1969     1970          1969     1970           1969   1970
                                 (6 months)             (6 months)
                                                                                 

    Meat

    Cattle              739      583           712      a              2      0

    Calves              142      67            141      a              0      0

    Swine               1 964    1 076         1 741    a              0      2

    Sheep               312      137           303      a              0      1

    Goats               12       8             10       a              0      0
                                                                                 

      Total             3 169    1 871         2 907    1 721          2      3
                                                                                 


    Table 3. (cont'd)

                                                                                 
                        No. of tissues                                 No. with
    Species             analysed               No. with a residue      toxaphene
                                                                                 
                        1969     1970          1969     1970           1969   1970
                                 (6 months)             (6 months)
                                                                                 

    Poultry

    Young chickens      1 909    1 405         1 898    a              2      0

    Mature chickens     78       -             77       a              0      0

    Turkeys             169      67            164      a              0      0

    Ducks               42       8             41       a              0      0

    Geese               1        2             1        a              0      0

    Other               -        4             -        a              0      0
                                                                                 

      Total             2 199    1 486         2 181    1 472         2      0
                                                                                 

    a Breakdown by species not available from 1970 interim report.
    
    The level of camphechlor in the four positive samples was in the range
    of 0.11-0.50 ppm as shown in Table 4.

        TABLE 4. NUMBER OF ANIMAL AND POULTRY SAMPLES SHOWING A SPECIFIC AMOUNT
             OF CHLORINATED HYDROCARBON INSECTICIDE RESIDUES
                                                                                                 
                                            (Parts per million - fat basis)
                                                                                                 
    Insecticide             0.01     0.11    0.51    11.01    2.01    4.01   6.01    7.01    15.01
                            to       to      to      to       to      to     to      to      to
                            0.10     0.50    1.00    2.00     4.00    6.00   7.00    15.00   above
                                                                                                 

    Animal

    Aldrin                  13       1
    Benzene hexachloride    479      37      2       1        3                      1
    Chlordane               1        1
    Dieldrin                1 156    169     8       1        1       1
    DDT and metabolites     924      1 341   229     113      39      12     5       7       1
    Endrin                  23       4


    TABLE 4. (cont'd)
             
                                                                                                 
                                            (Parts per million - fat basis)
                                                                                                 
    Insecticide             0.01     0.11    0.51    11.01    2.01    4.01   6.01    7.01    15.01
                            to       to      to      to       to      to     to      to      to
                            0.10     0.50    1.00    2.00     4.00    6.00   7.00    15.00   above
                                                                                                 

    Heptachlor              637      114                      1
    Lindane                 456      48                       1
    Methoxychlor            20       40      10      2        2
    Toxaphene                        2
                                                                                                 

    Poultry

    Aldrin                  3        3
    Benzene hexachloride    275      19
    Chlordane
    Dieldrin                1 363    274     2
    DDT and metabolites     312      1 512   284     63       11      6              1
    Endrin                  75       10      2
    Heptachlor              276      36      1
    Lindane                 192      5
    Methoxychlor            6        19      2       1
    Toxaphene                        2
                                                                                                 
    
    Methods of residue analysis

         The recommended method for the residue analysis of camphechlor
    involves a sulfuric acid-Celite 545 column cleanup followed by
    dehydrochlorination and gas chromatography with electron capture
    detection. The sulfuric acid column removes fat and oils, and the
    dehydrochlorination gives a characteristic, reproducible pattern for
    dehydrochlorinated camphechlor. If additional clean-up is required,
    this can be accomplished by Florisil column chromatography. Details of
    this and other methods are given by Hercules and by Zweig (1972). It
    should be noted that unequivocal identification of camphechlor in
    samples of unknown history cannot be achieved by these or any known
    chromatographic methods other than combined gas chromatography-mass
    spectrometry.


    National tolerances

         The following tolerances for camphechlor residues in raw
    agricultural crops have been established and were in effect as of May
    1973 in the United States of America, Canada, Germany, and the
    Netherlands:

    United States of America:

    Soybeans                                               2 ppm

    Pineapples
    Bananas (0.3 ppm in edible pulp)                       3 ppm

    Grain barley oats, rice, rye, sorghum grain,
    wheat, cotton-seed)                                    5 ppm

    Crude soybean oil                                      6 ppm

    Fruits (stone, pome, citrus, cane, and
    strawberries)
    Nuts (hazel, hickory, pecan, walnut)
    Meat fat (beef, sheep, goat, swine, horse)
    Vegetables (beans, black-eyed peas, broccoli,
    brussels sprouts, cabbage, cauliflower,
    carrots, celery, collards, corn, cowpeas,
    eggplant, green beans, horseradish, kale,
    kohlrabi, lettuce, lima beans, okra, onions,
    parsnips, peanuts, peas, peppers, radishes,
    rutabagas, snap beans, spinach, tomatoes)              7 ppm

    Canada:

    Oats, rye, wheat, pineapples                           3 ppm

    Barley, grain sorghum, rice                            5 ppm

    Fruits (citrus, pears, strawberries)
    Meat fat (cattle, goats, sheep, swine)
    Vegetables (beans, black-eyed peas, broccoli,
    brussels sprouts, cabbage, cauliflower,
    celery, eggplant, kohlrabi, lettuce, okra,
    onions, peas, tomatoes)                                7 ppm

    Germany:

    Pears, strawberries, raspberries, cherries,
    plums                                                  0.4 ppm

    The Netherlands:

    Fruit, vegetables (except potatoes)                    0.4 ppm

    Australia:

    Fruit                                                  3 ppm

    Appraisal

         The data evaluated and recommendations made in this monograph
    addendum refer only to camphechlor meeting FAO specifications
    AGP:CP/43-

         Camphechlor is widely used as a pre-harvest foliar treatment for
    the control of a variety of insect pests on cotton, oil seed crops,
    cereal grains, vegetables, fruits, and nuts. Control of external
    livestock pests is also a major area of use in many countries.

         Recent investigations (unpublished) using absorption and
    gas-liquid chromatography have revealed that camphechlor can be
    separated into at least 175 ClO-polychloro compounds including
    Cl6, Cl7, Cl8, Cl9 and Cl10 derivatives. One toxic component
    has been shown to be 2,5-endo 2,6-exo, 8, 9,
    10-heptachlorobornane.

         Analytical methods based on gas chromatography are available for
    the identification and quantitation of camphechlor by comparison with
    a standard sample of FAO specification camphechlor. The GLC trace
    gives multiple peaks and it is convenient to measure the total area
    under the whole trace but preferably to dehydrochlorinate the sample
    and compare the height of the major peak with the corresponding peak
    of a dehydrochlorinated standard.

         Residues on plants resulting from the application of camphechlor
    consists of unaltered camphechlor. Decline in camphechlor crop
    residues is believed to be primarily the result of evaporation. There
    is no evidence to indicate the presence of camphechlor conversion
    products in weathered crop residues.

         Camphechlor residues in animals treated with or fed camphechlor
    can accumulate in the fat, although the storage level is much less
    than that of most other chlorinated hydrocarbon pesticides.
    Equilibrium with the exposure level is quickly achieved. Rapid
    elimination of the residue from the fat occurs when input of
    camphechlor is stopped. Evidence to date indicates extensive

    degradation in mammalian systems, with excretion of water-soluble
    products, 60% of which is chloride ion.

         Camphechlor is useful for controlling a variety of arthropod
    pests of vegetables. Since camphechlor is not systemic, foliage
    applications result in camphechlor residues in the edible parts of
    root crops only indirectly through contact at harvest. Traces of
    camphechlor in the soil may also lead to incidental residues.

         Camphechlor is applied to bananas for the control of a number of
    species of leaf-eating caterpillars. Analytical data show that the
    residue is confined to the peel of the banana; none occurs in the
    edible pulp. Residues on mature banana fruit resulting from the
    application of camphechlor at the maximum rate do not exceed the
    recommended tolerance of 2 ppm.

         Use of camphechlor on pineapples is confined to Puerto Rico for
    the control of the Batrachedin moth. Two spray applications at the
    maximum rate of 2.25 lb camphechlor per acre properly timed for the
    control of this pest resulted in residues at harvest of 1.3 ppm to 2.7
    ppm. The recommended tolerance is 2 ppm.

         The refining of vegetable oils to produce products suitable for
    human consumption normally removes the entire residue present on the
    oil seed. However, United States surveys have shown that trace residue
    of camphechlor occasionally occurs in refined oils. To accommodate
    these occasional residues, a tolerance of 0.5 ppm camphechlor is
    recommended.

    RECOMMENDATIONS

         As no acceptable daily intake could be established no tolerances
    are recommended. Following officially acceptable use in various
    countries residues of camphechlor can occur in the following
    commodities up to the levels indicated.

         The figures apply to the total camphechlor residue determined by
    gas-chromatography.

    Guidelines

    Fat of meat of cattle, sheep, goats and pigs                5 ppm

    Broccoli, brussels sprouts, cabbage, celery,
      collards, eggplant, kale, kohlrabi, lettuce,
      okra, peppers, pimentos, spinach, tomatoes,
      barley, rice (rough), rye, sorghum, bananas
      (whole), pineapple, beans (snap, dry, lima),
      peas, cauliflower, oats, wheat, shelled nuts,
      carrots, onions, parsnips, radishes, rutabagas            2 ppm

    Soybeans, peanuts (ground-nut), cotton-seed oil
      (refined), rape-seed oil (refined), soybean
      oil (refined), peanut oil (refined), maize,
      rice (finished)                                           0.5 ppm

    Milk and milk products (fat basis)                          0.5 ppm

    FURTHER WORK OR INFORMATION

    Required (before an acceptable daily intake can be established)

    1.   Adequate toxicological information on camphechlor as
         currently marketed, including a carcinogenicity study.

    2.   Comparative studies evaluating the toxicological hazard
         associated with polychlorinated camphene of different manufacture
         used in worldwide agriculture.

    3.   Before recommendations can be made concerning residues
         from the use of camphechlor, other than that conforming to FAO
         specifications, information is needed on the composition, uses,
         and residues arising from such products.

    Desirable

    1.   Further results of research now in progress on the
         chemical composition and the metabolism of individual components
         of camphechlor conforming to FAO specifications.

    2.   Information from supervised trials (in progress) designed to
         determine the residues likely to be found in fat of poultry and
         in eggs from ingestion of feed containing residues.

    3.   Data on residues in fat of cattle in areas where tick
         control requires dipping shortly before slaughter.

    4.   Information on the need for use on vegetables and cereals
         at application rates and frequencies that would require a residue
         limit greater than that recommended.

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    See Also:
       Toxicological Abbreviations