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



    This pesticide was first evaluated by the WHO Expert Committee on
    Pesticide Residues at the 1963 and 1965 Joint FAO/WHO Meetings on
    Pesticide Residues (FAO/WHO, 1964, 1965). A completely revised
    monograph on chlordane was produced after the 1967 Joint Meeting
    (FAO/WHO, 1968). Since that time additional data, particularly on the
    metabolism of chlordane, have become available and these and pertinent
    older data are summarized in this monograph addendum.


    The chemical name and structure of chlordane is given in the previous
    monograph (FAO/WHO, 1968). The configuration of the two isomers is
    shown in Fig. 1.

    Nomenclature of chlordane isomers

    Three systems are now used in the literature to name the principal
    isomers of chlordane. The oldest has been used since about 1947 by
    Velsicol Chemical Corporation, in whose laboratories chlordane was
    discovered. This nomenclature (hereinafter called System 1) was
    employed in technical literature in documents considered by regulatory
    agencies and in the identification of Reference Analytical Standards
    which were freely distributed to researchers, regulatory laboratories
    and quality control analysts. System 2 appeared in the technical
    literature in the early 1950's: System 3 was first used in 1969.

    The three systems are correlated in Table I, to which is appended some
    references employing each. Unequivocal bases for experimental
    distinction of the two isomers are chromatographic relative retention
    times and accompanying infra-red spectra and NMR spectra (Velsicol,


    Chlordane isomers

    Correlation of nomenclature systems

    System 1            System 2            System 3

    Alpha-chlordane     Beta-chlordane      cis-chlordane

    Gamma-chlordane     Alpha-chlordane     trans-chlordane

    Examples of use of nomenclatures:


    1.   Velsicol Chemical Corp., technical documents for regulatory
         agencies, publications and correspondence, Reference Analytical
         Standards, since 1947; FAO/WHO, 1968; IUPAC, 1968, 1969.

    2.   March, 1952; Büchel et al., 1966; IUPAC 1967; Riemschneider,

    3.   Chau and Cochrane, 1969.

    Designation of salient chromatographic peaks

    In the analytical reports on constituents of residue, certain minor
    components of chlordane are named by letters. The designations usually
    correspond to those marked on a chromatogram presented to IUPAC
    Commission on Terminal Pesticide Residues (Polen, 1966) or another set
    used in the USFDA "Pesticide Analytical Manual, Vol. I" (1968). The
    letter designations are compared in Table II, and the relevant
    chromatograms of technical chlordane are given in Figure 2.



    The current knowledge concerning the metabolism of chlordane in
    mammals is shown in Figure 1. Work in rats and rabbits leading to the
    identification of the hydrophilic metabolites has already been
    reviewed in the previous monograph (Poonawalla and Korte, 1964;
    Ludwig, 1966; Korte, 1967a, 1967b). The metabolism of chlordane has
    also been the subject of a general review of the metabolism of the
    cyclodiene insecticides (Brooks, 1969).

    Recently, another metabolite termed "oxychlordane" has been isolated
    from the fat and milk of several animal species which had been fed
    chlordane. Details of the levels found in the tissues are given in the
    section entitled, "Fate of residues in animals". The structure (see
    Figure 1) has been determined spectrographically and by chemical
    synthesis by workers in two independent laboratories (Schwemmer et
    al., 1970; Lawrence et al., 1970). "Oxychlordane" has not been
    detected as a plant metabolite. Heptachlor and its metabolites may
    occur as residues from the use of chlordane; although it is uncertain
    if they are derived from the metabolism of chlordane or from the
    presence of impurities of heptachlor in the chlordane used (Calo,
    1970). (See also the monograph on heptachlor)

    FIGURE 1

    FIGURE 2

    Chromatograms of technical chlordane using, above, the letter
    designation of Velsicol (Polen, 1966) and below, that of USFDA (US
    Dept. of Health, Education and Welfare, Food and Drug Administration,


    Chlordane chromatographic peaks:
    correlation of letter designations
    Velsicol 1/  USFDA 2/

    C              A

    D              B

    E              C

    F              D

    H 3/           E 3/

    I 4/           F 4/

    K              G

    1/ Polen, 1966

    2/ US Dept. of Health, Education and Welfare, Food and Drug
       Administration, 1968

    3/ Peak for trans-chlordane

    4/ Peak for cis-chlordane

    No further experimental information is available to enable complete
    elucidation of the significance of liver hypertrophy or the
    stimulation of liver microsomal activity following administration of
    chlordane. The significance of these changes was discussed in the
    previous monograph on chlordane (FAO/WHO, 1968).


    Special studies on carcinogenicity


    In the 78-weeks feeding study in rats reviewed under "Long-term
    studies", no tumours were evident when dietary levels up to 35 ppm of
    the cis- or 75 ppm of the trans-isomer were fed (Ingle 1969).

    There is no report that tumours have been looked for in any other
    species fed chlordane.

    Special studies on the metabolite "oxychlordane"


    A group comprising two male and two female rats was fed a level of the
    chlordane metabolite "oxychlordane" in their diet, sufficient to
    maintain a daily intake of 2.0 mg/kg body-weight. The compound was fed
    for 90 days, after which time the surviving animals were sacrificed
    for autopsy. Body-weight increase, food consumption, mortality,
    organ-weights and organ to body-weight ratios, behaviour, haematology
    and blood chemistry and urologic studies were all considered to be
    within the normal range for the strain of rat used. No gross
    pathological abnormalities were evident, and no histopathological
    lesions could be attributed to "oxychlordane". A parallel control
    Group of rats fed a normal diet does not appear to have been examined
    in this experiment (Plant et al., 1970). Feeding studies with
    "oxychlordane" utilizing a larger number of animals are reported to be
    in progress (Calo, 1970).

    Special studies on the possible metabolite 1-hydroxychlordene


    Groups of 25 males and 25 females were fed dietary levels of 0, 100,
    250, 500, 1000, and 2000 ppm of 1-hydroxychlordene for up to 224 days.
    After 110 days, three females from each feeding level were mated with
    males at all levels. Mortality in all groups was low, and no real
    differences existed. At 224 days, autopsy revealed no gross
    abnormality. Histopathology of all visceral organs was negative,
    except for the slight to moderate cytoplasmic margination of a few
    liver cells at 1000 and 2000 ppm (Ingle, 1965).

    Special studies on photodecomposition


    No information is available on the mammalian toxicity of the
    photoisomer of chlordane.

    Acute toxicity

    The acute toxicity of the two isomers of chlordane and some
    metabolites is summarized in Table III.

    Rats were fed for 28 days from weaning on either (a) a diet containing
    3.5 percent protein as casein; (b) a diet containing a normal amount
    of protein as casein or (c) a standard laboratory diet. A single oral

        TABLE III

    Acute toxicity of chlordane isomers and metabolites
                                         LD50 mg/kg
    Compound               Animal        body weight     Reference

    cis-chlordane          Rat (M)       392             Wazeter et al., 1968

    trans-chlordane        Rat (M)       327             Wazeter et al,, 1963

    cis-trans-chlordane    Rat (M)       371             Wazeter et al., 1968
      (1:1 by weight)

    oxychlordane           Rat (M,F)     19.1            Kastri et al., 1969 a

    chlordane              Rat (M,F)     >4600           Nastri et al., 1969 b

    3-chlorochlordene      Rat (M,F)     >4600           Mastri et al., 1969 b

    1-hydroxychlordene     Rat (M,F)     >4600           Mastri et al., 1969 b

    chlordene epoxide      Rat (M,F)     >4600           Mastri et al., 1969 b

    1-hydroxy 2,3-epoxy    Rat (F)       >4600 and       Mastri et al., 1969 c
      chlordene                          <10200

    2 chlorochlordene      Rat (F)       >10200          Mastri et al., 1969 c
    dose of chlordane was administered after the feeding period. The LD50
    values for the three groups were 137, 267, or 311 mg/kg body-weight,
    respectively. Clinical symptoms and pathology were the same in all
    groups (Boyd and Taylor, 1969).

    Long-term studies


    Groups, each of 20 male and 20 female rats were fed dietary levels of
    0, 5, 15, 25 or 35 ppm of cis-chlordane or 15, 25, 35 or 75 ppm of
    trans-chlordane or 5, 15, 25, 35 or 50 ppm of a 1 : 1 mixture of
    cis and trans-chlordane. In the group fed cis-chlordane, growth
    retardation became apparent in the group fed 35 ppm after four months
    in the males and after five months in the females; with
    trans-chlordane, the 75 ppm group of males only displayed growth
    retardation after eight months. With the mixture, growth retardation
    was evident in both sexes fed 50 ppm, beginning early in the males and
    later in the females. Growth retardation was not evident in any groups
    fed lower doses of either isomer. Food consumption bore a relationship
    to growth. Increased mortality for both sexes became significant in
    the groups fed 35 ppm of cis-chlordane, 75 ppm of trans-chlordane
    or 50 ppm of the cis-trans mixture.

    Haematocrit was normal for all test groups. Autopsy revealed no gross
    pathological lesion, in particular there was no evidence of tumours.
    Histological examination of all organs showed no changes from feeding
    chlordane at any level, except in the case of the liver. Compression
    of sinusoids due to slight hepatic cell hypertrophy in the
    centrolobular region and minimal bile duct proliferation were evident
    at 35 ppm of cis-chlordane. The above were noted, but were minimal,
    at 25 ppm of the same isomer. Slight to moderate cytoplasmic
    homogeneity of the hepatic cells in the centrolobular region, minimal
    perinuclear vacuolation and minimal cell hypertrophy with constriction
    of sinusoids were noted at 75 ppm of the trans-chlordane. Slight
    cytoplasmic homogeneity of hepatic cells in the centrolobular region
    and occasional cytoplasmic margination were observed at 50 ppm of the
    cis-trans mixture. The above alterations were minimal at 35 ppm of
    the same mixture. No liver abnormalities were evident after feeding
    lower levels of the chlordane isomers (Ingle, 1969)


    The study on cis and trans-isomers of chlordane, which was
    considered desirable at the 1967 Joint Meeting, has now been completed
    and indicates that the no-effect levels of the two isomers and of the
    technical product are all within the same range, The toxic metabolite,
    oxychlordane, which becomes stored in the fat or excreted in the milk
    of lactating animals fed high doses of chlordane, does not appear to
    be a residue in plants. For this reason, the toxicity of oxychlordane
    was not considered to be a matter of concern. No information is
    available on the mammalian toxicity of the photoisomer of chlordane. A
    satisfactory reproduction study in one species has been previously

    reported and is considered adequate. However, in view of the
    observations from other organochlorine compounds, an adequate
    carcinogenicity study in another species is needed.


    Level causing no toxicological effect

    Rat: 20 ppm of technical chlordane in the diet, equivalent to 1 mg/kg

    Dog: 3 ppm of technical chlordane in the diet, equivalent to 0.075
         mg/kg body-weight/day


    0-0.001 mg/kg body-weight



    Several million pounds of chlordane have been used annually in a broad
    spectrum of applications in the U.S.A. for nearly 25 years. Outside
    the U.S.A. its use is somewhat less, but comparable.

    Velsicol (1970) has presented the approximate distribution of use of
    chlordane outside of the continental United States of America as

    Area                               Percentage

    Europe                             55

    North America (excludes U.S.A.)    15

    South America                      15

    Asia                               10

    Africa                              5

    Total                              100

    In the U.S.A. about half and outside the U.S.A. about 10 percent of
    chlordane usage is estimated to be non-agricultural (household pest
    control, lawn protection, etc.)

    Chlordane is used in protection of the following crops:

    Europe:              Potatoes, vegetables, small grains, sugar beets 
                         and sugar cane.

    Western hemisphere:  Sugar cane, maize, small grains, potatoes and

    Asia:                Rice, cotton and jute.

    Other uses of chlordane are in the protection of fruits, nuts and oil
    seed crops.


    A substantial amount of new information on the residues resulting from
    supervised trials is made available to the Working Party. Present
    application of electron capture gas chromatography on chlordane
    residues has allowed fairly detailed evaluation of several
    constituents of the residues. The available new information is
    summarized in Table IV. The data are based on the records of Velsicol
    Chemical Corporation (1970).

    Evidence of residues in food in commerce or at consumption

    In a series of papers (Duggan et al., 1966, 1967; Duggan and
    Weatherwax, 1967; Duggan and Lipscomb, 1969) the pesticide residue
    levels have been reported in 11 food and feed categories, as raw
    agricultural products or ready-to-eat foods, domestic and imported,
    and they have assessed the dietary intake during 1964 to 1968 in the
    United States. The observations on chlordane levels are summarized in
    Table V.

    Chlordane was undetected in all but three categories of raw
    agricultural products where levels were <0.005 ppm and at maximum
    incidence of 3.3 percent in imported grain. Ready-to-eat foods in
    these three categories contained less (in one category) or undetected

    Chlordane residues found in vegetable oil seeds, oils and byproducts
    are summarized in Table VI. The traces of chlordane were reported in
    less than 1 percent of the sample of soybeans, but none appeared in
    the finished oil. Chlordane residues were reported in 3.7 per cent of
    the crude maize oil samples, but were not found in the finished oil. A
    small number of samples of crude cottonseed oil showed occasional
    residues of chlordane, but the concentration in finished oil was lower
    by about 59 percent. No chlordane residues were observed in
    oleomargarine or in the total diet composites consisting of salad
    dressings, salad oils, mayonnaise, shortenings and peanut butter
    (Duggan, 1968 a, 1968 b). These empirical observations corroborate the
    evidence that commercial processing removes chlordane residues, if
    present, from edible vegetable oils and oil products.

    From 750 meal cake samples (Table VI), chlordane was detected in 0.7
    percent of the soybean cakes and in 6.5 percent of the cottonseed

        TABLE IV

    Summary of maximum observed chlordane residues1,2


                                      maximum rate
    Root vegetables                   lb/acre                      ppm

    Parsnip                           10                           0.07
    Potato                            10                           0.23
    Rutabaga                          10                           0.5
    Sugar beets (root)                10                           0.11
                (wet pulp)            10                           0.15
                (dried pulp)          10                           0.3
                (juice)               10                           0.063
    Sweet potato                      10                           0.04

    Leafy and stalk vegetables

    Asparagus                         44                           0.07
    Broccoli                          44                           0.063
    Brussel sprouts                   44                           o.36
    Cabbage                           44                           0.09
    Celery                            124                          0.063
    Cauliflower                       44 (foliar)                  0.06
    Mustard greens                    10                           0.07
    Spinach                           10                           0.10
    Swiss chard                       10                           0.07

    Other vegetables

    Snap beans                        10                           0.01


    Barley (Grain)                    104 (foliar and soil)        0.063
      "    (straw)                    104                          0.42
    Oats  (grain)                     10                           0.063
      "   (straw)                     10                           0.10
    Rye (grain)                       10                           0:063
     "  (straw)                       10                           0 07
    Wheat (grain)                     4 (foliar)                   0:063
      "   (straw)                     4 (  "   )                   0.38
      "   (grain)                     10                           0:063
      "   (straw)                     10                           0.10
    Rice  (grain)                     10 (soil or seed dressing)   0.033
      "   (straw)                     10                           0.033

    TABLE IV (cont'd)

                                      maximum rate
                                      lb/acre                      ppm


    Maize and "popcorn" (seed)        10                           0.063
      "    "      " (stalks and
                     leaves)          10                           0.033
    Sorghum (grain)                   12 (soil or seed dressing)   0.063
       "    (stalks)                  12 (         "           )   0.07


    Cantaloupe                        34 (foliar)                  0.1
    Cucumber                          34 (  "   )                  0.063
    Pumpkins (pulp)                   44 (  "   )                  0.063
       "     (rind)                   44 (  "   )                  0.10
       "     (pulp)                   10                           0.08
       "     (rind)                   10                           0.15
    Squash                            34 (foliar)                  0.09
    Watermelons                       34 (  "   )                  0.063

    Fruits and nuts

    Almonds                           10                           0.0063
    Figs                              10                           0.0033 5
    Filberts                          10                           0.0033
    Olives                            10                           0.0063
    Pecans                            10                           0.048
    Pomegranate                       10                           0.0063 5
    Walnuts                           10                           033 5
    Bananas                           10                           0.033
    Guavas                            10                           0 036
    Mangoes                           10                           0:013 5
    Passion fruit                     10                           0.035
    Papayas                           5                            0.01

    Oil seed crops

    Cotton (seed)                     1-2 (foliar, up 12           0.22
           (meal)                     1-2 (     "      )           0.07
           (crude oil)                1-2 (     "      )           0.11
           (soap stock)               1-2 (     "      )           0.063
           (stalks)                   1-2 (     "      )           0.29

    TABLE IV (cont'd)
                                      maximum rate
                                      lb/acre                      ppm

    Oil seed crops

    Linseed (seed)                    34 (foliar)                  0.22
            (meal)                    34 (  "   )                  0.09
            (crude oil)               34 (  "   )                  0.24

    Soybeans (beans)                  124                          0.38
             (crude oil)              124                          0.42; 0.72

    Rape (whole plants)               3 (foliar)                   0.35

    1  From soil treatment except where indicated; data not previously
    2  Sum of six constituents of technical chlordane.
    3  Negative reading - value shown is sum of estimated lower limits of
         sensitivity components.
    4  Exceeds maximum rate permitted in U.S.A.
    5  Shell or meat analyzed separately.
        TABLE V
    Chlordane residues in food and feed.1

                                  Raw agricultural product

    Food category          Domestic                 Import                    Ready-to-eat food

                      Incidence    Average       Incidence      Average    Incidence     Average
                      percent      ppm           percent        ppm        percent       ppm
    Large fruit       N2           -             N              -          N             -
    Small fruit       N            -             N              -          N             -

    Grain & cereals

    For human use     0.7          <0.005        3.3            <0.005     N             -

    For animal use    N            -             N              -          -             -


    Leaf and stem     N            -             N              -          N             -
    Vine and ear      2.0          <0.005        0.3            <0.005     2.7           <0.001
    Root              1.9          <0.005        0.3            <0.005     N             -
    Potatoes          -            -             -              -          N             -

    Beans             N            -             N              -          N             -

    Eggs              N            -             N              -          N             -

    Nuts              N            -             N              -          N             -

    Processed meat
    (canned frozen,

    Domestic                                                               N             -

    Imported                                                               N             -

    Chlordane residues in food and feed.1

                                  Raw agricultural product

    Food category          Domestic                 Import                    Ready-to-eat food

                      Incidence    Average       Incidence      Average    Incidence     Average
                      percent      ppm           percent        ppm        percent       ppm
    Fluid milk
    (fat basis)       N            -

    Dairy products
    (fat basis)       N            -             N              -

    1 Extracted from USA-FDA surveillances programme report (Duggan, 1968b)

    2 Not tabulated in reference, presumably because of insignificant
    frequency of incidence


    Chlordane residues in vegetable oil seeds, oils and byproducts1

                                                           Crude oil             Meal (cake)                Edible oil

    Product       Number of         Raw product
                  samples     Incidence     Average    Incident      Average    Incident    Average      Incident      Average
                  analysed    percent       ppm        percent       ppm        percent     ppm          percent       ppm

    Soybeans      550         0.9           <0.001     - 2           - 2        0.7         <0.001       - 2           - 2

    Groundnuts    177         - 2           - 2        - 2           - 2        - 2         - 2          - 2           - 2

    Cottonseed    23          8.7           0.004      2.2           0.017      6.5         0.012        2.4           0.007

    Maize         819         - 2           - 2        3.7           0.080                               - 2           - 2

    Total and
    weighted      1569        0.4           <0.001     2.0           0.042      0.9 3       <0.001 3     0.04          <0.001

    1 Extracted from USA-FDA surveillance programne reports (Duggan, 1968a)
    2 Not detected
    3 Estimates based upon 750 samples for which cake data are given

    cakes at average levels less than 0.001 and 0.012 ppm, respectively.
    Of all the samples, 0.9 percent contained a detectable level (<0.001
    ppm) of chlordane.

    Dietary intake (milligrammes/day) generally appeared to be too low to
    quantitate. Except for <0.001 mg/day (<1.7 percent of the ADI for a
    60 kg man) from legumes during June 1966 to April 1967, no other
    figures are listed for chlordane intake by Duggan and Lipscomb (1969).

    The total diet studies in England and Wales (Abbott et al., 1969)
    reveal no residues of chlordane.


    In animals

    An animal metabolite of chlordane, "oxychlordane", first reported in
    1968 to the IUPAC Commission on Terminal Residues as an analytical
    manifestation (IUPAC, 1969) has been isolated from pigs (Schwemmer et
    al., 1970) and from milk and cheese (Lawrence et al., 1970). The
    metabolite has been characterized with respect to analytical
    parameters, propensity for occurrence in milk and storage in the fat
    of dogs, cattle (beef and dairy) pigs and rats (Polen, 1970).

    "Oxychlordane" levels in milk and some tissues of cows and goats,
    following termination of ingestion of 10 ppm doses of chlordane
    isomers for ten days, has been studied (Velsicol, 1970). Maximum
    residues of "oxychlordane" found in milk were as follows:

    Isomer fed                    Cow         Goat


    cis-chlordane               0.011 ppm   0.029 ppm

    trans-chlordane             0.049 ppm   0.067 ppm

    cis-+trans-chlordane 1:1    0.048 ppm   0.040 ppm

    Highest milk level vs. feed level: goat 0.7 percent; cow 0.5 percent.

    The residue levels in milk following termination of feeding of
    chlordane declined to half in 10 to 12 days in cows and in 8 to 15
    days in goats. Fifty days after chlordane withdrawal, the fat tissue
    of cows contained up to 0.25 ppm and (2.5 percent of feeding level),
    that of goats up to 0.4 ppm (4 percent of the feeding level) of
    "oxychlordane". Some of this metabolite was occasionally found in
    liver, but none in brain. The parent chlordane isomers could sometimes
    be found in milk on the tenth day of feeding, but later none was
    detected either in milk or in tissues (Singh et al., 1970 a, 1970 b).

    At feeding levels of chlordane corresponding to proposed international
    tolerances, oxychlordane is not detected in milk (sensitivity 0.005
    ppm) but may be found in the fat of cattle at or below 0.03 ppm
    (Polen, 1970).

    When calves were fed for one month, one sixth of their ration, sugar
    beet pulp derived from chlordane treated soil (Velsicol, 1970), the
    maximum total residues found in the fat were, when fed with pulp from
    the chlordane treatment year, up to 0.62 ppm and, when fed with pulp
    from a treatment done a year prior to harvest, up to 0.06 ppm. Rates
    of chlordane applications were 6-10 lb active ingredient per acre. The
    total residue of the dry pulp varied from 0.05 to 0.30 ppm. The
    residues found in liver were much less than those in fat, and none was
    found in muscle (sensitivity 0.01 ppm).

    When cows were fed with rations containing potato and alfalfa grown in
    chlordane treated soil (Velsicol, 1970), no detectable residues were
    found. Residue of heptachlor, heptachlor epoxide, compounds C and E
    (minor components of technical chlordane), cis-chlordane and
    trans-chlordane were all less than 0.01 ppm.

    Hens fed 0.08 ppm of chlordane in their ration produced eggs with no
    detectable residues (Herrick et al., 1969).

    In plants

    Korte and Porter (1970) reported on the metabolism of
    trans-chlordane in white cabbage and carrots. Tests were under
    glasshouse conditions and are difficult to relate to practical

    White cabbage leaves, four weeks after foliar application of 14C
    labelled trans-chlordane, contained less than 1 percent of the
    radioactivity on the surface; 90 percent was in the leaves as three
    conversion products, in addition to the parent compound. At ten weeks,
    20 percent of the applied radioactivity remained, 80 percent of which
    was from metabolites. Soil treatment of carrots with 14C-labelled
    trans-chlordane resulted in 0.01 ppm in carrots (mainly metabolites)
    and 0.06 ppm in leaves (two thirds of the parent compound) 12 weeks
    after treatment.

    Polen (1970 a, 1970 b) reports that all the evidence accumulated thus
    indicates that "oxychlordane" is not normally present in the terminal
    residues of chlordane in plants.

    In soils

    Miles at al. (1969) found in their study on metabolism of heptachlor
    by soil micro-organisms that heptachlor epoxide, 1-hydroxychlordene,
    1-hydroxy- 2,3-epoxychlordane and possibly 1-keto-2,3-epoxychlordane
    are formed, but their importance under field conditions after
    chlordane treatment has not been established.

    Onsager et al. (1970) did not detect heptachlor epoxide in
    chlordane-treated soil (or in sugar beets grown therein). The
    biological half life of chlordane was estimated to be 14.3 months, in
    good agreement with other published data.

    Lichtenstein at al. (1970) reported that soils treated for five years
    annually with technical heptachlor (25 lb heptachlor and about 7.5 lb
    chlordane as an impurity - cumulative basis) contained 0.019 ppm of
    chlordane isomers (in addition to heptachlor derivatives) ten years
    after the first treatment.

    Polen (1970 a, 1970 b) reports that "oxychlordane" has not been found
    in the terminal residues of chlordane in soils.

    Photochemical transformations

    The possibility of conversion of constituents of residues from
    technical chlordane by ultraviolet light in vitro has been
    demonstrated by several workers (Fischler and Korte, 1969; Vollner et
    al., 1969; Benson et al., 1969; Rosen et al., 1969; McGuire et al.,
    1970). Present evidence indicates that the photochemical
    transformation compounds do not contribute significantly, if at all,
    to terminal chlordane residues under agricultural conditions.

    Observations of the IUPAC Chlordane Working Party (IUPAC 1969) on gas
    liquid chromatograms from foliar applications on beans and cabbage
    revealed no new peaks during the ageing of the residues and hence gave
    no indication of photolytic products. A more recent investigation
    directed specifically toward evaluation of the effects, if any, of
    sunlight on chlordane residues also found no significant indications
    of the production of photolytic products under typical field
    conditions (Polen, 1970).

    Pure preparations of compounds which are possible constituents of
    chlordane terminal residues (cis- and trans-chlordanes, chlordene,
    heptachlor, heptachlor epoxide and nonachlor) wore exposed to sunlight
    as films on glass, on wheat and on soil surfaces. On glass after 235
    hours of exposure, only heptachlor epoxide and cis-chlordane were
    converted, constituting respectively 54 and 1.6 percent of the
    terminal residues. After 39 days of exposure, no photoreaction
    products were detected on soil; on wheat (2 lb chlordane per acre,
    foliar application) only photo-cis-chlordane was detected as 2
    percent of the terminal residue.

    In another set of observations, 30 randomly-selected crop and soil
    samples from supervised field trials throughout the U.S.A. were
    examined for presence of photo products in chlordane residues.
    Application rates ranged from four to ten lb of technical chlordane
    per acre, soil or foliar applications; sampling intervals were from 15
    to 303 days after application. Samples were: grass; straw of rice and
    rye; seeds of rice and cotton; potato culls; soil from chlordane
    treatments on which was grown barley or rice; sugar beets; whole and
    spent cossettes; spinach; cauliflower and broccoli. Generally, no

    photo products were detected at a sensitivity level of 0.01 ppm. It
    was concluded that typically photo products are not produced in
    chlordane soil treatments and that, if present at all in terminal
    residues from foliar treatment, the contribution to the terminal
    residue is less than 2 percent.

    In storage and processing

    With a few exceptions, accumulated evidence indicates that normal food
    processing tends to reduce or eliminate chlordane residue. The lower
    incidence and levels of residues in ready-to-eat foods compared to raw
    agricultural products is evident in US Total Diet Studies, and was
    commented on above.

    In root crops, consistent evidence shows that chlordane residues from
    treatments with either technical chlordane or technical heptachlor, in
    which chlordane is a minor component, are concentrated in the peel,
    and that peeling and/or cooking reduces or eliminates the residue.

    In potatoes, peeling removes virtually the entire residue from
    chlordane treatments up to 10 lb/acre. Without peeling, baking removed
    about 80 percent of the residue and boiling up to 30 percent. (Saha et
    al., 1968).

    The residue of trans-chlordane from technical heptachlor treatments
    of rutabagas was concentrated in the peel, and about half of that
    residue was removed by boiling. The pulp was free of chlordane residue
    before and after cooking (Saha and Stewart, 1967).

    Similar patterns are observed in processing carrots, turnips and
    beets. No residues of chlordane are detected in boiled pulp of turnips
    or beets. In carrots, a 98 percent reduction resulted from peeling
    only and 63 percent from boiling alone (Saha, 1970).

    In commercial canning, washing, peeling (potatoes, tomatoes, etc.) and
    abrasive peeling (used, for example, in preparing carrots) have been
    demonstrated to reduce surface-concentrated pesticide residues (Farrow
    at al., 1969). No doubt the surface-bound residues of chlordane would
    respond in a similar way.

    Chlordane residues on cabbage or beans are not changed in level or
    composition by simple ten minute cooking (Polen, 1968). The lack of
    the loss of chlordane residues were due to the fact that chlordane is
    chemically relatively stable, co-distillation did not occur and the
    cooking water containing extractable residue was included in the
    sample extracted for residue analysis.

    Commercial processing of edible vegetable oil produces finished oil
    practically free of residues of chlordane, as well as other
    organochlorine pesticides (Gooding, 1966; IUPAC, 1970; Smith at al.,

    Samples of milk containing chlordane manufactured into condensed,
    dried whole and evaporated milk were reduced in chlordane content. The
    following figures are the percentage reduction in chlordane content
    (fat basis) of processed fractions: condensed milk 11 percent; spray
    dried milk 25 percent; evaporated milk 45 percent and drum dried milk
    55 percent (Liska and Stadelman, 1969).

    Wheat flour and rice, each contaminated by exposure to chlordane
    vapours, were processed to produce two cooked products: a baked cookie
    and boiled rice. The baked wheat flour cookie contained an average of
    50 percent less residue than the wheat and the cooked rice about 73
    percent less than the raw product (Bevenue and Yeo, 1969).


    Analytical methods 1/

    Prior to about 1961, residues from application of technical chlordane
    were determined by total organochlorine, colorimetric or bioassay
    techniques. The information derived was limited by lack of specificity
    and sensitivity. At the present time, procedures based on the use of
    electron capture gas chromatography are recommended. Four specific
    analytical methods for the multi-component residues of chlordane are
    available (Velsicol, 1970).

    The methodology is that adopted for organochlorine pesticides by the
    IUPAC Commission on Pesticide Residue Analysis and incorporates
    procedures which favour analysis of chlordane residues in several
    substrates. Detection limits are 0.002-0.02, depending on the nature
    of the sample. Analytical method AM 0506 (Velsicol, 1970) is used for
    soil in order to determine residue as chlordane, which is defined as
    the sum of residues (ppm) of unchanged compounds from technical
    chlordane plus residues of their conversion products, if present in
    minor proportions. Conversion products are estimated separately if
    they are present in significant amounts. Analytical method AM 0507
    (Velsicol, 1970) is applicable to plant tissues and crops such as,
    fruits, vegetables, grains, etc. The residue is obtained as a sum of
    residues (ppm) of unchanged compounds from technical chlordane plus
    residues of their conversion products, photolytic and metabolic, if
    present in minor proportions. Conversion products are estimated
    separately if they are present in significant amounts. Analytical
    method AM 0509 (Velsicol, 1970) is applicable to milk, milk products
    (e.g. butter and cheese), animal tissues and various animal food
    products. Residue of chlordane is the sum of residues (ppm) of
    unchanged compounds from technical chlordane plus possible residues of
    their metabolites, oxychlordane and heptachlor epoxide. Method AM 0508
    (Velsicol, 1970) is a supplementary method to describe modifications
    to existing analytical methods in order to identify and quantitate

    1/ Copies of the analytical methods and reference analytical grade
    samples of the compounds are available from Velsicol Chemical Corp.,
    341 E. Ohio Street, Chicago, Illinois 60611, U.S.A.

    minor components of technical chlordane or of possible conversion
    products (metabolic, photolytic or others). This method applies the
    procedures of the other methods referred; e.g. the following compounds
    can be determined: photo-cis-chlordane, photo-heptachlor epoxide,
    heptachlor epoxide, "oxychlordane", photo-heptachlor and

    Quantitation of residues in plant and animal products

    Several procedures have been used under various circumstances to
    quantitate the gas-chromatographic responses of chlordane residues. In
    most instances, the values calculated are good approximations of total
    residues, but fail to distinguish conversion products from unchanged
    components of technical chlordane. The methods AM 0506 to 0509
    inclusive allow for quantitation of conversion products if present.

    A method used prior to about 1968 relied upon calibration of the
    principal peak (trans-chlordane) in reference technical chlordane
    and estimation of the total residue by assuming constancy of the
    proportions of the components in the course of "weathering". This
    technique overstated the residue of chlordane by about 20-70 percent
    for foliar treatments and by roughly half that amount for residues
    from soil treatment in which conversion compounds may be in somewhat
    greater concentration (Velsicol, 1970). These factors should be given
    consideration in evaluating residue data generated before about 1968.

    The estimation of chlordane residues in plants and soils as the sum of
    cis-and trans-isomers (FAO/WHO, 1968) gives values roughly equal
    to a minimum of 70-80 percent of the total terminal residues of
    chlordane. In animal products, the sum of "oxychlordane" plus
    cis-and trans-chlordane comprises generally more than 90 percent
    of the residues in the lipoid phase.


    A comprehensive set of new data for evaluation of chlordane residues
    was provided to answer the questions raised by the 1967 Joint Meeting,
    to add new information to the Monograph, to review the temporary
    tolerances recommended in 1967 and to make new recommendations.

    Technical chlordane continues to be a standardized product produced by
    a single manufacturer. One of the characteristics of the technical
    chlordane for which the recommendations are made is its content of
    heptachlor (10 ± 2 percent).

    Chlordane is used, in addition to the U.S.A., especially in Europe and
    to a smaller extent in other American countries, Asia and Africa. Soil
    treatments represent the main usage of chlordane. Foliar applications,
    with exception of cotton, are not considered to be recommended usages
    any more. The use to forage crops has been discontinued, e.g. in the

    Thorough studies on the chlordane residues in foodstuffs and in meal
    cakes are conducted in the U.S.A. Residues were found, but in three
    categories of raw agricultural products levels were less than 0.005
    ppm. Oil seed cakes from soybeans and cotton seeds contained in 0.7
    and 6.5 percent of the samples had residues with average levels of
    less than 0.001 and 0.012 ppm, respectively.

    Dietary intakes of chlordane in the U.S.A., England and Wales have
    proved to be negligible. In most cases, the residues in the diet
    composites were less than the analytical detection limits. Due to
    this, it has not been possible to make reliable estimates of daily
    chlordane intake.

    Food processing tends to reduce or eliminate chlordane residues;
    especially those processes which include removal of the treated crop
    surface, disposal of cooking water, vacuum distillation or other type
    of dehydration processes are able to remove a substantial part of the

    Residues resulting from growing crops in land treated in previous
    years with chlordane has been studied. It was found that the residues
    in sugar beets, grown in the same land in several subsequent years,
    were proportional (about 10 percent) to the residues in the soil at
    the time of planting. Thus the chlordane level left in the soil seems
    to determine the residue level found in crops. Stability of chlordane
    in soil is well studied.

    An animal metabolite of chlordane, oxychlordane, has been found in fat
    of animals ingesting chlordane, but at significantly lower levels than
    the level of chlordane in feed. Information for recommending practical
    residue limits for meat, milk, poultry and eggs is available.

    So far there is no evidence that oxychlordane is a component of
    terminal chlordane residues in plants or in soils.

    Photochemical transformation products of chlordane, which are reported
    to be formed in vitro, are most evidently not formed in soils. In
    foliar treated plants, if at all present, they are estimated to
    contribute to the terminal residue less than 2 percent.

    Hydrophilic metabolites of chlordane are formed in plants; their
    significance is under investigation.

    Analytical methods, based on the methodology generally adopted for
    organochlorine pesticides, have been developed to determine the
    multi-component residues of chlordane as well as their metabolites
    with detection limits of 0.02-0.002 ppm. Clarification of the
    nomenclature of chlordane isomers and the letter designations of
    chlordane chromatographic peaks have been made.


    The recommendations made now are for the residues which result from
    pre-plant soil applications at a maximum level of 10 lb /acre or from

    seed dressing, except for cotton which may require multiple foliar
    applications, before the bolls open, at 1-2 lb /acre. Good
    agricultural practice for sugar beets would require that the soil
    would not contain, from the treatments of the planting and previous
    years, more than 2.5-5.0 lb /acre. In cool climates, the application
    rates should be established to lower levels to compensate the greater
    stability of the residues.

    For regulatory purposes, the chlordane residues in plant products
    should be determined as the sum of cis- and trans-chlordane and in
    animal products as the sum of cis-chlordane, trans-chlordane and

    In view of the new data for evaluating chlordane residues, the
    recommendations made by the 1967 Joint Meeting for temporary
    tolerances and practical residue limits are replaced by new
    recommendations for tolerances and practical residue limits.


    Root vegetables (practically soil-free)               0.3

    Potatoes, sweet potatoes, rutabagas, turnips,
    parsnips, sugar beets and radishes

    Leafy and stalk vegetables                            0.2

    Asparagus, broccoli, brussel sprouts, cabbage, celery,
    cauliflower, mustard greens, spinach, Swiss chard
    and lettuce

    Other vegetables                                      0.02

    Beans, peas, eggplants, tomatoes and collards
    (= cole-worts)

    Grains                                                0.05

    Wheat, rye, oats, rice (polished), maize, sorghum
    and popcorn

    Cucurbits                                             0.1

    Cantaloupes, cucumbers, pumpkins, squash and watermelons

    Fruits and nuts                                       0.1

    Almonds, bananas, figs, filberts, guavas, mangoes, 
    olives, passion fruit, papayas, pecans, pomegranates, 
    pineapple, strawberries and walnuts

    TOLERANCES (cont'd)

    Citrus, pome and stone fruits                          0.02

    Not specified above

    Vegetable oils

    Crude soybean and linseed oils                             0.5

    Crude cottonseed oil                                       0.1

    Edible cottonseed and soybean oils                         0.02


    Milk and milk products (fat basis)                         0.05

    Fat of meat                                                0.05

    Fat of poultry                                             0.05

    Eggs (shell free)                                          0.02


    REQUIRED (before June 1972)

    Further information on chlordane residues in carrots resulting from
    soil and seed treatments and from crop rotation on soils having been
    treated with chlordane in previous years.


    1. An adequate carcinogenicity study in a second species of animal.

    2. Results of the investigation of the hydrophilic plant metabolites
       of chlordane.


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    See Also:
       Toxicological Abbreviations
       Chlordane (EHC 34, 1984)
       Chlordane (HSG 13, 1988)
       Chlordane (PIM 574)
       Chlordane (FAO Meeting Report PL/1965/10/1)
       Chlordane (FAO/PL:1967/M/11/1)
       Chlordane (FAO/PL:1969/M/17/1)
       Chlordane (WHO Pesticide Residues Series 2)
       Chlordane (WHO Pesticide Residues Series 4)
       Chlordane (Pesticide residues in food: 1977 evaluations)
       Chlordane (Pesticide residues in food: 1982 evaluations)
       Chlordane (Pesticide residues in food: 1984 evaluations)
       Chlordane (Pesticide residues in food: 1986 evaluations Part II Toxicology)