WHO/FOOD ADD/71.42



    Issued jointly by FAO and WHO

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



    Rome, 1971



    Chemical name



    Mendrin (R), Compound 269 (R)

    Structural formula (see also Figure 1)


    Other relevant chemical properties

    Endrin (molecular weight 380.93) is a cream to light tan coloured
    flowable powder which melts at 200+°C with decomposition. It has a
    vapour pressure of 2 × 10-7mm Hg (Torr) at 77°F (25°C). It is stable
    in the presence of ordinary alkaline reagents but tends to rearrange
    to less insecticidally active substances in the presence of acids,
    certain metal salts and catalytically active carriers. Endrin is
    moderately soluble in benzene and acetone; sparingly soluble in
    alcohols, paraffins, and xylene; insoluble in water.


    Endrin, technical, 95 percent minimum


    The toxicology of this compound was evaluated by the WHO Expert
    Committee on Pesticide Residues at the Joint FAO/WHO Meetings in 1963
    and 1965 (FAO/WHO, 1964, 1965). Since that time considerable new
    information has become available,  and a completely revised monograph
    has been produced.


    Absorption, distribution and excretion

    From early studies it was thought that, like other chlorinated
    hydrocarbons, endrin, when fed to animals, was partly stored unchanged
    in the tissues particularly in the body fat (Kiigemagi et al., 1958;

    Street et al., 1957; Terriere et al., 1958, 1959 and Treon et al.,
    1955). When fed at high levels it had been reported to be excreted in
    milk and eggs (Ely et al., 1957; Street et al., 1957 and Terriere et
    al., 1958). The ratio of the level in fatty tissue to the dietary
    level has been estimated at 0.5-2, depending upon the dietary level
    (Kiigemagi et al., 1958; Terriere et al., 1958 and Treon et al.,

    Unlike the situation with its stereoisomer dieldrin, the extent of
    storage of endrin is relatively small and the compound is eliminated
    more quickly, due probably to its rapid biliary excretion (Cole et
    al., 1970). Levels of the 9-keto metabolite of endrin in four human
    fat samples were all less than 0.0004 ppm (Richardson, 1970).

    A male rat was fed a dietary level of 30 ppm of 14C-labelled endrin
    for eight days. About 60-70 percent excretion was noted from the first
    day, and after three days the faeces contained more than 80 percent of
    the administered radioactivity. On day 9, 84 percent had been
    excreted, and there appeared to be a level of saturation after 6-7
    days of feeding. The faeces contained about 75-80 percent
    metabolities, of which there were at least two different compounds.
    The fatty tissue stored 3-4 ppm of endrin, giving a storage ratio of
    about 10. Compared to 84 percent excretion in the faeces, only about
    0.5 percent was found in the urine (Ludwig, 1965, 1966).

    The rapid rate of metabolism and excretion of endrin compared to that
    of other chlorinated hydrocarbon insecticides has been confirmed by a
    study on rats with and without bile fistula and on the isolated
    perfused rat liver (Cole, et al., 1970; Altmeier, et al., 1969). In
    rats on daily oral administration of 32 µg/kg, the storage reached a
    state of equilibrium after 5-6 days. The half life in male rats was
    three days and in female rats four days under these conditions (Klein
    and Drefahl, 1970).


    The information available on the metabolism of endrin up to 1967 has
    been reviewed (Soto and Deichmann, 1967; Brooks, 1969). The following
    experimental data summarizes the pertinent information leading to the
    current knowledge on the metabolism of endrin (see figure 1).

    In rats, Klein et al. (1968a) and Richardson et al. (1970) found that
    endrin is rapidly metabolized and excreted, principally in the faeces.
    The faeces contain two metabolites as well as endrin itself. Baldwin
    et al. (1970) have now found that the major faecal metabolite is a
    secondary alcohol formed by substituting a hydroxyl group for one of
    the hydrogens of the methano-bridge of endrin (II). The other faecal

    FIGURE 1

    metabolite is also an alcohol. Three days after a single oral dose of
    14C-labelled endrin, approximately half of the 14C radioactivity
    remained in the bodies of the rats. This material was principally one
    metabolite which was identified as 9-keto endrin (I), an oxidation
    product of the secondary alcohol found in faeces.

    When 14C-labelled endrin was applied orally to rabbits at 0.5 mg/kg
    body-weight and at three and four day intervals, four metabolites were
    isolated from the urine which appear to have the following chemical
    natures: A (40% of excreted radioactivity) is a conjugate compound of
    a hydroxy derivative of endrin; B (12%) is a monohydroxy derivative of
    an unbridged endrin isomeric ketone; C (40%) is the 4a-hydroxyendrin;
    D (8%) has a molecular weight of 420 and the C-C double bond intact in
    the chlorinated ring. None of these compounds is the delta-keto endrin
    (Korte and Porter, 1970).

    Effects on enzymes and other biochemical parameters

    In monkeys which had received exposure to an unspecified quantity of
    endrin, there were significant changes in the enzymes serum
    glutamic-oxaloacetic transaminase and serum glutamic-pyruvic
    transaminase (Barth, 1967).

    Elevation of serum alkaline phosphatase has been observed in rats fed
    25 ppm and possibly 5 or 1 ppm of endrin for 16 weeks (Nelson et al.,
    1956) but not in dogs fed 4 ppm of endrin for two years (Jolley et
    al., 1969) nor in human subjects occupationally exposed to unspecified
    levels of endrin (Shell, 1965).


    Special studies on carcinogenicity


    See under "Long-term studies" (Witherup et al., 1970).


    Commencing at weaning, varying numbers of rats of mixed sex were fed
    dietary levels of 0, 2, 6 or 12 ppm of endrin throughout their
    lifetime. No primary malignant hepatic tumours were found in any
    animals upon histological examination. Two benign hepatic tumours
    (haemangiomas) were found in one male control rat and the other in a
    female fed 6 ppm of endrin. Tumour incidence in other tissues was also
    not significantly different between the control and experimental
    animals (Diechmann et al., 1970).

    Special studies on reproduction

    Chicken egg

    Hen eggs were injected with 0.5 or 5 mg per egg. The hatching rate was
    40 or 20 percent, respectively (Dunachie and Fletcher, 1966).

    When endrin was injected into the yolk of fertile eggs incubated for
    seven days in amounts of 0.2 and 2.0 mg/egg, the hatchability was 40
    and 6.9 percent, respectively (Smith et al., 1970).


    No eggs were produced from quail which received 1 ppm of endrin in
    their diet either as winter maintenance or during the reproductive
    period (DeWitt, 1965).


    In pheasants there was reduced egg production when fed 10 ppm of
    endrin but not at 2 ppm or less. Survival of the chicks to two or six
    weeks was also markedly reduced at 10 ppm, but not at lower doses
    (DeWitt, 1965).


    Groups of male and female mice were fed endrin at dietary levels of 0
    or 5 ppm for 30 days. Test and control mice were then randomly paired
    and continued on the test diet for a further 90 days, there being a
    total of 101 pairs in the group fed endrin. The first litters were
    significantly smaller than the control group. The time taken to
    produce the first litter was not significantly different between the
    two groups (Good and Ware, 1969).

    Deer mouse

    Five groups each of 13-14 pairs of Saskatchewan deer mice
    (Peromyscus manicalatus) of varying ages were fed dietary levels of
    0, 1, 2, 4 or 7 ppm of endrin over intermittent periods between which
    times the animals were either fed a normal diet or were subjected to
    48 hours starvation. The animals were sacrificed by exposing them to
    cold stress at -16°C and the time of death recorded. During feeding,
    parental mortality increased in proportion to the level of endrin.
    Young animals were more susceptible than old. Starvation increased
    mortality in all test groups but not in the controls; this effect was
    more evident with increasing dose levels. Litter production frequency
    and mean litter size before and during experimental feeding were
    similar. However, post-natal mortality prior to weaning increased in
    the young from parents fed 4 or 7 ppm. Endrin adversely affected the
    survival time during cold stress in the females but not in the males
    (Morris, 1968).


    In a later study from the same laboratory, groups of ten male and 20
    female rats were fed dietary levels of 0, 0.1, 1.0 and 2.0 ppm of
    endrin over a period of three generations. The F0 generation was
    mated after 79 days on the test diets, and the males were rotated as
    in the previous experiment.

    The young from the first litter were discarded at weaning and the
    parents mated again after ten days to form the F1b generation. Young
    from this generation were mated when 100 days old, and this protocol
    was followed for three generations, using the second litter in all
    cases. The size of the litter in the F3 generation from the 2.0 ppm
    group was significantly larger than that from the controls. Mortality
    was high in the controls, which resulted in a greater percentage
    survival in the F3a litters in the 0.1 ppm group and in all F3b
    litters in the test groups. The weights of weanlings were comparable
    to the controls except in the F3a litters from the 0.1 ppm, which
    were significantly less due probably to the large litter sizes in that
    group. Examination of the F3b weanlings revealed no differences in
    organ to body-weight ratios. It was stated that there were no
    histological abnormalities, but details of the pathology were not
    available. Fertility, gestation, viability and lactation indices did
    not indicate that endrin affected any of these parameters (Hine et
    al., 1968).

    Special studies on the photoisomerization product of endrin

    When endrin is irradiated with short wavelength ultraviolet light, the
    delta-keto compound is formed in 37 percent yield as well as an
    aldehyde in 9 percent yield. Under the influence of sunlight, only the
    ketone is formed. The ketone is about a quarter as toxic to rate as
    endrin and like endrin is more toxic to the male than to the female
    (Soto and Diechmann, 1970) (see also "Fate of residues").

    Acute toxicity

    The major clinical manifestation of endrin intoxication in man
    involves convulsions of several minutes duration which may be isolated
    and followed by semiconciousness for 15-30 minutes, with complete
    recovery after 2-4 weeks. More serious symptoms are continuous
    convulsions, high fever and decerebrate rigidity prior to death. Mild
    symptoms of poisoning include dizziness, weakness of the legs,
    abdominal discomfort and nausea. Temporary deafness and insomnia may
    also occur. It has been estimated, based upon reports of outbreaks of
    poisoning, that 0.2-0.25 mg/kg body-weight will produce a single
    convulsion in man, and that repeated fits will result from 1 mg/kg
    (Hayes, 1963).


    Animal               mg/kg body-weight       References

    Rat, adult (F)       7                       Treon et al., 1955

    Rat, young (F)       17                      Treon at al., 1955

    Rat, adult (F)       40-43                   Speck and Maaske, 1958

    Rat, young (M)       29                      Treon at al., 1955

    Rabbit (F)           7-10                    Treon at al., 1955

    Guinea-pig           16-36                   Treon at al., 1955

    Monkey               3                       Treon at al., 1955

    Monkey               12                      Barth, 1967

    The acute toxicity of endrin appears to be influenced by the diet.
    Three groups each comprising about 100 male rats were fed for 28 days
    either a normal diet, a normal protein diet containing protein only as
    casein or a low protein diet. The acute toxicity to endrin was then
    determined by a single oral administration of the pesticide. The LD50
    values were 27, 17 and 7 for the animals fed the respective diets,
    indicating an approximately four-fold increase in toxicity between the
    normal and low-protein diet as well as an effect due to the type of
    protein fed (Boyd and Stefec, 1969).

    Short-term studies


    Groups each of 40 quail, starting when one day old, were fed dietary
    levels of 0, 0.5, 1, 5, 10, 20 or 50 ppm in their diet. Survival was
    adversely affected in all the test groups, and there were no survivors
    beyond two weeks in the birds fed 10 ppm or more. Food consumption was
    abnormally low. Symptoms involved lack of muscular coordination,
    tremors, bedraggled appearance and rigidity with occasional convulsive
    movements (De Witt, 1956).


    Groups each of 20 seven-day old chicks were unaffected by a diet
    containing 0, 1.5 or 3 ppm of endrin. When the concentration was
    increased to 6 or 12 ppm, the birds became highly excitable, failed to

    gain as much weight as the controls and the survival rates over a 12
    week period were 85 and 5 percent, respectively, compared to 100 per
    cent in the controls (Sherman and Rosenberg, 1954).


    Day-old pheasants, in groups of 40, did not survive beyond eight days
    when fed dietary levels of 5 or 20 ppm. Reduced food consumption
    occurred, and the symptoms were the same as those seen in quail (De
    Witt, 1956).


    Groups comprising five male and five female rats were fed dietary
    levels of 0, 1, 5, 25, 50 or 100 ppm of endrin for up to 16 weeks. All
    of the group fed 100 ppm died within the first two weeks, and only two
    rats fed 50 ppm and three fed 25 ppm survived. Three males fed 5 ppm
    also died; the other animals were continued on the test diet for the
    full 16 weeks. Weight loss was roughly dose related but was evident in
    all test groups, as was hypersensitivity to tactile stimuli. There was
    an initial drop in serum alkaline phosphatase during the first three
    to eight weeks' feeding, which was then followed by an increase at all
    dose levels. At the end of the 16 weeks, the phosphatase level was
    elevated above the controls in all the test groups, the levels being
    highest in the groups fed 25 and 50 ppm (Nelson et al., 1956).
    However, other statisticians have considered that the elevation of
    serum alkaline phosphatase was not significant in the groups fed 1 and
    5 ppm of endrin (Williams, 1966).


    In a series of experiments, dogs were fed diets containing from 1 to
    50 ppm endrin along with control groups. Two of four animals fed a
    diet containing 8 ppm and the one fed 5 ppm died. The two surviving
    dogs on 8 ppm were kept on the diet for about six months and then
    sacrificed; increased organ to body-weight ratios for the liver,
    kidney and brain were found, and histopathological examination showed
    degeneration of kidney tissue. Three of four dogs on 4 ppm of endrin
    survived, and there were no symptoms in dogs fed 1 or 3 ppm (Treon et
    al., 1955).

    In an experiment of about 19 months' duration, groups comprising two
    male and two female dogs were placed on diets containing 0, 1 or 3 ppm
    of endrin. All dogs on 3 ppm had increased organ to body-weight ratios
    for the kidney and heart. Some female dogs fed 1 or 3 ppm of endrin
    had a renal abnormality characterized by a slight tubular vacuolation;
    this change was also observed in the female control dog. Male dogs in
    both control and test groups had normal viscera (Treon et al., 1955).

    Groups comprising seven male and seven female dogs were fed dietary
    levels of 0, 0.1, 0.5, 1.0, 2.0 or 4.0 ppm of dieldrin for two years.
    Scheduled autopsies were performed on two dogs of each sex from the 0,
    1.0 and 4.0 ppm groups at six and 12 months. There were no deaths due

    to the treatment nor were there any changes in body-weight increase or
    food consumption in any group. The only clinical abnormalities were in
    one female and two male dogs fed 4.0 ppm and one female fed 2.0 ppm
    that showed evidence of, or were observed having, convulsions; the
    earliest incidence in a male dog after five months on 4.0 ppm. The
    only changes in organ weights were occasional slight increases in
    liver or liver to body-weight ratios in the dogs fed 2.0 and 4.0 ppm.
    After two years, pathological examination showed slight vacuolation of
    hepatic cells in the females and diffuse pigmentation in one male and
    all females. At 4.0 ppm, vacuolar degeneration and diffuse brown
    pigment in the hepatic cells was evident in all dogs, without any sex
    differentiation. In two only of the dogs, which had convulsions,
    autopsies revealed some pathological changes in the brain. All other
    organs in the dogs fed 2.0 or 4.0 ppm and all organs in the dogs fed
    1.0 ppm or less showed no morphological changes which were considered
    to be attributable to feeding endrin. There were no significant
    changes in the blood picture or in the chemical or physical
    characteristics of the urine attributable to endrin. After two years,
    levels of liver enzymes, prothrombin time bromsulphthalein clearance,
    serum protein electrophoresis, glucose, urea nitrogen, cholesterol,
    calcium, inorganic phosphorus, total bilirubin or uric acid showed no
    changes attributable to endrin feeding (Jolley et al., 1969).

    Cattle and sheep

    Cattle and sheep were not affected by 5 ppm of endrin in their diet
    for 112 days (Radeleff, 1956).

    Long-term studies


    A total of 1600 mice in equal numbers of each sex, consisting of one
    inbred and one hybrid strain, were divided into four groups, two of
    which were fed a control diet and the other two fed 0.3 or 3.0 ppm of
    endrin. Feeding the test diet was started at five weeks of age and
    continued through out their normal lifespan, or until sacrifice.
    Because of an early high incidence of fibroadenomas occurring in both
    control and test groups in the hybrid strain, all the females of that
    strain were sacrificed after 72 weeks for pathological examination. A
    few of the mice, fed 3.0 ppm only, displayed convulsions in the early
    stages of feeding but recovered and survived. Mortality was not
    adversely affected by endrin, nor was body-weight or food intake. No
    haematological abnormalities were evident except in two males in the
    hybrid group fed 0.3 ppm, which had severe leukaemia. In either sex,
    the total number of neoplasms was not influenced by the endrin content
    of the diet, except in the case of hepatomas in the females of the
    hybrid strain, which were significantly higher than the controls in
    the mice of the group fed 3.0 ppm, and sacrificed between weeks 53 and
    60 of the feeding period. Because of a relatively high incidence of

    hepatomas in one group of controls of this strain, the increase at the
    3.0 ppm level was considered not due to endrin. It was noted that in
    no animals of either sex were there any metastases of the hepatomas
    into the lungs (Witherup et al., 1970).


    In a two year experiment, groups each of 20 male and 20 female rats
    were given diets containing 0, 1, 5, 25, 50 and 100 ppm of endrin.
    Concentrations of 50 and 100 ppm were lethal within a few weeks. The
    concentration of 25 ppm increased the mortality rate of the females.
    Non-survivors at the three higher levels exhibited diffuse
    degeneration of the brain, liver, kidneys and adrenal glands. The
    survivors in the two higher levels showed degenerative changes in the
    liver only, while those fed at the lower levels had normal viscera.
    The level of 5 ppm caused an increase in liver to body-weight ratio in
    males and an increase in kidney to body-weight ratio in females. There
    was no effect at the 1 ppm level (Treon et al., 1955).


    A total of 874 persons were hospitalized, and there were 26 deaths in
    several outbreaks of poisoning in Saudi Arabia in 1967 due to
    consumption of bread containing endrin. Approximate average levels in
    the bread in various outbreaks were 48, 1500 or 400 ppm, corresponding
    to a percentage of fatalities of 1.4, 9.5 and 0.4, respectively, among
    those poisoned. Signs and symptoms were typical of central nervous
    system stimulation and all survivors rapidly returned to normal
    (Weeks, 1967).

    Three persons in Egypt experienced convulsions after eating bread
    containing 126 to 176 ppm of diedrin. There were no deaths (Coble et
    al., 1967).

    In an incident in the UK, 59 people became ill from ingesting bread
    which contained about 150 ppm of endrin, but there were no deaths
    (Davies and Lewis, 1956). The maximum amount of endrin consumed has
    been estimated to have been 1 mg/kg body-weight (Zavon, 1961).

    Studies in human subjects experiencing intoxication from endrin (Coble
    et al., 1967, Weeks, 1967) and from occupational workers (Hayes and
    Curley, 1968, Jager, 1970) have demonstrated that endrin rapidly
    disappears from the blood in cases of acute intoxication and cannot be
    detected in the fat or blood of people exposed to endrin unless
    symptoms of intoxication are evident.

    Endrin has not been reported to be found from studies involving levels
    of organochlorine pesticides in human body fat in India, UK or USA
    using analytical methods sensitive to <0.03 ppm (Dale et al., 1965;
    Hayes et al., 1965, Robinson et al., 1965 and Zavon et al., 1965).
    Levels of the 9-keto metabolite of endrin in four human fat samples
    were all less than 0.0004 ppm (Richardson, 1970).

    Among workers in a plant manufacturing endrin and a number of other
    pesticides, no detectable amounts of endrin were found in samples of
    plasma, fat or urine. Exposure was for an average time of 2,106 hours.
    Based upon the limit of detection, the levels of endrin, were <0.0030
    ppm in plasma, <0.03 ppm in fat and <0.0016 ppm in urine. Endrin
    has, however, been detected in the serum and urine of people who
    received amounts sufficient to produce intoxication (Hayes and Curley,

    Serum alkaline phosphatase was determined in 30 workers who had been
    exposed to endrin for periods from six weeks to eight years. There was
    no difference in the levels found in the exposed group and those found
    in a group comprising nine unexposed individuals, nor was there any
    relationship detected between the phosphatase levels and the duration
    of exposure of the workers (Shell, 1965).

    In workers exposed to endrin during periods up to eight years, no
    significant changes in the level of serum alkaline phosphatase were
    observed during a 13-month observation period (Van Dijk, 1968).

    It is estimated that the blood level of endrin below which no signs or
    symptoms of intoxication occurs is in the range of 0.05 - 0.100 µg/ml.
    Measurable blood levels (detection level 0.005 µg/ml) occur only after
    gross over-exposure. The half-life of endrin appears to be
    approximately 24 hours. Medical control of a group of workers exposed
    over periods up to 13 years has failed to show any effects of
    long-term exposure. The blood picture, results of urinalysis,
    activities of serum glutamic-oxaloacetic and glutamic-pyruvic
    transaminases, alkaline phosphatase and lactic dehydrogenase remained
    all within normal limits. Occasional electroencephalographic changes
    returned to normal. Absenteeism due to disease or accidents was
    comparable to that of a control group. Because of the short half-life
    of endrin, it is (unlike dieldrin) impossible to calculate the average
    level of exposure of the workers to endrin (Jager, 1970).

    A decrease in the blood levels of pp'-DDE and an increased excretion
    of 6-ß-hydrocortisol in relation to 17-hydroxy-corticosteroids was
    present in the workers employed in manufacturing and who were exposed
    to endrin and its intermediates. The compound responsible is not known
    and further studies are in progress (Jager, 1970).


    The primary site of action of endrin is the central nervous system.
    This fact is evidenced by convulsions which result from acute
    poisoning and from administration of repeated relatively high doses.

    Unlike dieldrin, endrin is rapidly metabolized by animals; the storage
    in the fat of animals is very low compared with other compounds of
    similar chemical structure. In rats, it is excreted mainly in the
    faeces as endrin, 4a-hydroxyendrin, and an unidentified endrin

    alcohol; a third metabolite, 9-keto-endrin, is stored in the tissues.
    In rabbit, the main route of excretion is the urine, in which four
    metabolites were demonstrated, one of which is the 4a-hydroxyendrin.

    The plant metabolite of endrin, delta-keto endrin, is rapidly
    metabolized by animals. Three metabolites were found in rabbit urine
    after oral administration of delta-keto endrin. It is understood that
    delta-keto endrin is unlikely to be formed under conditions of good
    agricultural practice, and that the compound is less toxic to mammals
    than endrin.

    A long-term study in mice failed to produce conclusive results
    relative to the carcinogenic potential of endrin. Endrin is more
    acutely toxic to animals fed a low protein diet. Reproduction studies
    with endrin in several species revealed no influence of endrin on
    maturation, but foetal and postnatal mortality were increased. There
    is no evidence of teratogenic activity. The two-year studies in the
    dog and rat are used as a basis for determining a no-effect level.


    Level causing no toxicological effects

    Rat: 1 ppm in the diet, equivalent to 0.05 mg/kg body-weight/day

    Dog: 1 ppm in the diet, equivalent to 0.025 mg/kg body-weight/day


    0 - 0.0002 mg/kg body-weight



    Pre-harvest treatments

    The most important of all endrin uses, worldwide, and accounting for
    some 80% of all endrin applied is as a spray for the control of
    insects of cotton. It is also used extensively for the control of
    insect pests in rice, to some extent in sugar cane and to a limited
    extent in grain crops and sugar beets. In Australia, endrin is used
    for insect control on tobacco and crucifers.

    Post-harvest treatments

    Endrin is accepted and occasionally used in some countries for rodent
    control in orchards, where it is sprayed onto the ground under the
    trees either in autumn or springtime. Rates vary from 2.4 kg/ha for
    deciduous fruits in the United States to 0.02 or 0.03% solutions,
    often in combination with mineral oil, in Australia.

    Seed treatments

    Endrin is used as a seed treatment on cotton at 2 oz /100 lb seed in
    the United States and on beans at 1 oz /30 lb seed in Australia.


    Summary of Registered Uses

                        Rate of
    Crop                application       No. of           Pre-harvest
                        (kg/ha)           applications     interval (days)

    Cotton              0.25-0.50         1-12             none

    Rice                0.2-0.50          1-4              30

    Sugar cane          0.25 (only        1-8              45

    Wheat               0.25-0.50         1                45

    Barley              "                 "                "

    Oats                "                 "                "

    Sorghum             "                 "                "

    Tobacco             0.25-0.5          -                -

    Crucifers           0.04% soln.       -                -

    Potatoes            0.8 (USA)         -                -
                        0.03% soln.

    Sugar beets         0.4               1-2              60

    Other uses

    Endrin has a minor use in the United States as a bait formulation for
    control of cutworms in corn and potatoes. It is applied to the soil
    surface at 0.8 kg/ha, and preharvest intervals are observed.


    In cotton seed and its products

    From the view point of residues of endrin arising in food products,
    cotton seed and its products are of primary interest; the refined
    cottonseed oil is used for cooking or margarine manufacture, while the
    extracted cake is used as cattle feed. Therefore residue levels in
    cottonseed oil products which may reach the food consumer are
    determined not so much by levels in products harvested in the field,
    but to an appreciable extent by mill processes.

    The effect of extraction processes on endrin residues was studied by
    Smith et al. (1968) using crude cottonseed oil and soy bean oil
    fortified with 1 ppm (mg/g) endrin. They found that alkali washing and
    bleaching did not have a marked effect but that deodorization by
    vacuum steam stripping effectively reduced endrin levels to below the
    limits of detection (0.03 ppm). These authors also quote unpublished
    work by Evans of the USDA using radio-labelled endrin. At initial
    levels of up to 3.5 ppm in the crude oil, 96 percent of the added
    radioactivity was lost during the process of steam stripping. The
    effectiveness of the deodorization step in removing endrin residues
    from vegetable oils was further demonstrated by Barrantine and Cain
    (1970) in studies of commercial scale operations. Endrin residues are
    summarized in Tables II and III. (Shell Development Co. Reports,
    RES-64-3. RES-64-9; Shell Chemical Co., New York PRL-67-24; Velsicol
    Corp., unpublished data).

    The cottonseed cake left after the extraction of oil commonly contains
    1%-5% oil. These cottonseed cakes are widely used as an important
    ingredient of cattle feed concentrates and could contribute up to 20%
    of the daily diet of a dairy cow. The relationship between cattle feed
    and milk residues was studied by Williams and Mills (1964), Kiigemagi
    et al., (1958), and Ely et al., (1957). Consideration of their
    combined results indicates that at feed levels in the region of
    0.25-2.0 ppm endrin in total feed, milk residues will eventually reach
    0.04 times the concentration in the total feed, if feeding is
    continued until a plateau is reached. Both Williams and Kiigemagi
    found that when endrin was withdrawn from the feed, levels in the milk
    fell fairly quickly. At 0.25 and 0.75 ppm in feed, levels fell to
    0.002 ppm in six weeks after endrin was withdrawn (Kiigemagi, 1958).
    At the 2 ppm feed level, residues fell from 0.06 to 0.02 ppm in the
    same period. In Williams' experiments residue from the highest feed
    level (0.50 ppm in whole dry feed) fell to 0.002 ppm in about 15 days.

    In rice, rice bran and rice straw

    The results of experiments in a number of rice growing regions are
    summarized in Table IV.

        TABLE II

    Residues of endrin in whole cotton seed, U.S.A.

                              Dosage/       Harvest        Residue ppm
                 No.of        applic.       interval                 delta-
    Location     applics.     (lb/acre)     (days)     endrin        keto

    Oklahoma     control      -             -          <0.004        N.D.

                 2            0.5           58         <0.004 to
                                                       0.013         N.D.

                 2            1.0           58         <0.004        N.D.

    Louisiana    4-5          2.67(total)   -          0.02 to       <0.02

    Texas        not stated   0.5 (total)   -          <0.04         <0.04

                              1.0 (total)   -          0.06 to       <0.04

                              2.0 (total)   -          <0.04         <0.04

    Endrin residues in crude and alkali-extract

    Cottonseed oil obtained from endrin treated cotton in Texas, U.S.A.
                                                            Residues in oil - ppm
    Dosage rate           Post harvest                Crude                   Alkali extracted
    lb/acre total         interval-days      Endrin          delta-Keto    Endrin      delta-Keto

    Control               -                  <0.01           <0.03         <0.01       <0.03
    0.5                   not stated         0.05            <0.03         0.05        <0.03
    1.0                   not stated         0.43*           <0.03         0.39*       <0.03
    1.0                   not stated         0.05            <0.03         0.05        <0.03
    2.0                   not stated         0.04            <0.03         0.01        <0.03

    Control               -                  <0.01           -             <0.01       -
    0.4, ten times        5                  0.05            -             <0.01       -
                          10                 <0.01           -             <0.01       -
                          20                 <0.01           -             <0.01       -
                          30                 <0.01           -             <0.01       -

    0.8, ten times        5                  0.02            -             <0.01       -
                          10                 0.03            -             <0.01       -
                          20                 0.08            -             <0.01       -
                          30                 0.01            -             <0.01       -

    Control               -                  <0.02-<0.03     -             -           -
     0.4                  8                  0.02            -             -           -
                          13                 <0.02           -             -           -
                          28                 <0.02-<0.07     -             -           -
                          52                 0.04            -             -           -

     0.8                  8                  0.07            -             -           -
                          13                 "neg"           -             -           -
                          28                 <0.02           -             -           -
                          42                 <0.02-0.02      -             -           -

    *  These figures are regarded as exceptional in light of all other available data.

    Although neither rice bran or straw is reported to be an appreciable
    item of international trade, residues may be of importance insofar as
    they may persist in animal products. A summary of data provided by the
    references in Table IV shows bran residues for 11 sites to range from
    <0.01 to 2.30 ppm, with a mean of 0.35 ppm. The data are heavily
    weighted by one figure from India; without this figure, the range is
    <0.01 to 0.80 ppm, with a mean of 0.15 ppm. Rice straw residues from
    the same sources (25 samples) ranged from 0.04 to 2.90 ppm, with a
    mean of 1.02 ppm. Residues of delta-keto endrin were found in bran and
    straw containing high residues of endrin but seldom exceeded 10% of
    the total residue and never exceeded 20%.

    Rice bran is used mainly as a component of locally produced poultry
    feed. The significance of endrin residues in poultry feed in giving
    rise to residues in meat and eggs may be judged from data in the
    published literature.

    Cummings et al., (1967) fed diets containing between 0.05 and 0.45 ppm
    endrin to White Leghorns for 14 weeks and found residues ranging from
    <0.01 to 0.06 ppm endrin in breast meat and from 0.25 to 3.5 ppm
    endrin in depot fat. Similar diets gave endrin residues of 0.03 to
    0.32 ppm in eggs as estimated from graphs (Cummings et al., 1966).
    Terriere et al. (1959) fed diets containing 0.10 to 0.75 ppm endrin
    for 6 weeks and found <0.1 to 0.2 ppm endrin in breast meat, <0.1 to
    0.3 ppm in leg meat, 0.6 to 3.6 ppm in depot fat and <0.1 to 0.3 ppm
    in eggs. A feed level of 2.25 ppm for 6 weeks gave 17.0 ppm in depot

    In sugar cane

    In experiments extending from 1957 to 1965, Shell Development Co.
    applied endrin to sugar cane in Louisiana and Florida. When 0.3 lb
    ai/acre of 2 percent granular was applied at 3-6 applications and
    postharvest intervals ranging from 12-120 days were observed, average
    endrin residues ranging from <0.01 to 0.05 ppm were obtained.
    Keto-endrin residues were determined in four samples and did not
    exceed <0.02 on the average. Residues in control samples ranged from
    <0.01 to 0.04 ppm. No endrin was detected in molasses or refined
    sugar prepared from the treated cane. One group of samples treated
    with 0.5 lb ai/acre of E. C. had <0.1 ppm endrin (sensitivity limit
    of the method). When 2 percent granular was applied four times at 1.0
    lb ai/acre and postharvest intervals of 7-45 days were observed, the
    endrin residues ranged from 0.04 to 0.08 ppm. The same formulation
    applied four times at 0.22 lb ai/acre and eight times at 0.23 to 0.29
    lb ai/acre resulted, after postharvest intervals of 71 and 64 days,
    respectively, in endrin residues of <0.10 ppm. (Shell Development Co.
    Reports RES-61-53, RES-63-159 DLI-136 (1963), DLI-157 (1964),
    RES-64-1, DLI-160 (1965), RES-58-48A, RES-57-44.

    In grains

    Data obtained on a variety of small grains in the U.S.A. are
    summarized in Table V.

    In India, endrin (2% granular) was applied to sorghum at 0.4 kg ai/ha
    for 4 to 6 applications. Samples taken from 42 to 75 days after last
    treatment had residues in grain ranging from <0.01 to 0.02 ppm endrin
    and in straw ranging from 0.14 to 0.70 ppm endrin. Control samples had
    <0.01 to 0.02 ppm in grain and 0.03 to 0.31 ppm in straw (Shell
    Research Ltd., Report WKGR 0071/70).

    In the U.S.A., endrin E.C. was applied to sorghum once at either 0.25
    or 0.50 lb ai/acre. A pre-harvest interval of 111 days resulted in
    endrin residues of <0.02 ppm in grain, <0.02 ppm in straw, and

    <0.02 ppm in silage (73 days PHI). A pre-harvest interval of 63 days
    resulted in endrin residues of <0.02 ppm in grain, 0.03 and 0.09 ppm
    in straw, and <0.02 and 0.15 ppm in silage (39 days PHI); the latter
    value is suspect, according to the analysts (Shell Chemical Co.,
    Report PRL-66-113). A pre-harvest interval of 29 days resulted in
    residues of <0.05 and 0.05 ppm in grain (Velsicol Corp., Report

    Single applications of endrin E.C. to sweet corn (maize) in the U.S.A.
    at 0.25 or 0.50 lb ai/acre, 37 days before harvest, resulted in
    residues of <0.02 ppm of endrin in grain and husk. Some controls gave
    an apparent residue of 0.02 to 0.03 ppm (Shell Chemical Co., Report
    PRL 66-67g).

    In apples

    Experiments conducted by Shell in the U.S.A. in which endrin E.C. or
    W.P. was applied at 1.5 to 4.0 lb ai/acre to the soil of orchards gave
    no detectable residues in whole apples at harvest time; detection
    limits were 0.01-0.002 ppm for the methods employed (Shell Development
    Co., Report RES-61-60, Shell Chemical Co., Report PRL-69-119, Ibid,
    PRL-69-95). In recent studies by Horsfall et al. (1970), picked fruit
    residues ranged from <0.002-0.003 ppm. In fallen fruit, residues were
    sometimes higher, ranging up to 0.023 ppm.


    General comments

    Endrin undergoes rearrangement to delta-keto endrin in sunlight, in
    the presence of strong acids, and by thermal treatment. Endrin also
    undergoes thermal and photo degradation to yield small amounts of the
    aldehyde SD 7442. Delta-keto endrin can undergo a rearrangement to the
    "bird cage alcohol" when treated with very dry Florisil adsorbent
    (Korte and Porter, 1970).

        TABLE IV

    Endrin residues in polished and unpolished rice

                                    Applic. rate        Harvest            Residues, ppm
                                    kg am/ha ×          interval,      Polished         Brown
    Country        Formulation      no. of applic.      days           rice             rice             Reference

    India          2% gran.         0.2, 0.4, 0.6,      49-79          <0.01            <0.01-0.01       Shell Res.Ltd.Report, WKTR 0023/69
                   2.0 × 4-7
                   control          -                   -              <0.01            <0.01

    Venezuela      E.C.             0.29 × 1            95              0.02             0.03            Ibid,WKGR 0046/70

    Thailand       control          -                   -              <0.01            <0.01            Ibid,WKGR 0087/70
                   2% gran.         0.2, 0.4, 0.4       56-83          <0.01            <0.01
                   20% E.C.         0.16 × 3            46-72          <0.01            <0.01-0.23*

    Philippines    control          -                   -              <0.01-0.03       <0.01-0.03       Ibid,WKGR 0078/70
                   2% gran.         0.2, 0.4, 0.4       44-60          <0.01-0.02       <0.01-0.05
                   20% E.C.         0.16 × 3            33-49          <0.01-0.03       <0.01-0.03

    Indonesia      control          -                   -              -                <0.01            Ibid,WKTR 0078/68
                   20% E.C.         0.2-0.62            21             -                 0.03-0.05
                                    × 7 or × 8

    Thailand       20% gran.        0.4 X3, X4          not            <0.02            -                Ibid,BEGR.0045/70
                                    0.8 × 3             stated         (Endrin and Keto -
                                                                       Endrin   Keto     Endrin  Keto

    India          control          -                   -              <0.02   <0.02     0.09   <0.02    Ibid
                   2% gran.         0.4                 -               0.02   <0.02     0.23    0.03
                                    0.8                 45              0.04   <0.02     0.47    0.04

    *  One exceptional result - reason not identified


    Endrin residues in small grains - U.S.A.

                 Applic. rate,        Postharvest     Endrin residues,
                 lb  ai/acre          interval,             ppm
    Crop         × no. of applic.     days            Grain        Straw        Reference

    Wheat        0.25 × 1                 26           0.03        -            Shell Dev. Co.
                 0.50 × 1                 26           0.06        -            Report RES-

    Oats         0.25 × 1                 26           0.15        -            62-124 (1963)
                 0.50 × 1                 26           0.50        -

    Wheat        0.25 × 1                 62          <0.01        0.27         Shell Chem.Co.
                 0.25 × 1                 96          <0.01        0.02         Report PRL-
                 0.25 × 2                 62          <0.01        0.37         65-41 (1966)

    Barley       0.50 × 1                 60          <0.05        0.07
                 0.50 × 1                 32          <0.05        0.09-0.38

    Wheat        0.25 × 1               >150           0.01        -            Velsicol Corp.
                 0.50 × 1               >150           0.03        -            Report TSR-

    Barley       0.25 × 1               >150          <0.01        -            2578 (1966)
                 0.50 × 1               >150          <0.01        -

    In animals

    Homogenates from cow or pig liver upon addition of NADH2 converted 38
    ug of endrin, after 72 hours incubation, to metabolites which were
    identical to those found from living organisms (Korte, 1967; Klein et
    al., 1968a). See "Biochemical aspects".

    In plants

    14C labelled endrin was applied at either 1.04 or 2.08 mg/plant to
    the leaves of tobacco under conditions of free or restricted aeration.
    Six weeks after treatment, 32-47% of the applied radioactivity was
    found on and in the tobacco plants, the lowest residues being in the
    plants grown under free aeration. (Korte and Porter, 1970).

    Shortly after the first buds emerged, the leaves of each of 11 cotton
    plants were treated with 4.2 mg 14C-labelled endrin; treatment was
    repeated after two and six weeks (total ca. 120 ppm). Twelve weeks
    after the last application, quantitative measurement of the residues
    revealed only very low concentrations in the cotton seed (0.033 ppm),
    somewhat more in the fibers (0.36 ppm), and about 80% in and on the
    leaves. Two thirds of the applied radioactivity was lost to the
    atmosphere during the test. Besides endrin, there were two groups of
    degradation products in the cotton plants, one group slightly more
    hydrophilic than endrin and one very hydrophilic. One component of the
    less hydrophilic group was isolated and gave mass and IR spectra
    identical with that of delta-keto endrin (Korte and Porter, 1970).

    When 14C-labelled endrin was applied at 50 ug/plant to young cabbage
    plants, 66 percent of the activity had evaporated after two weeks, 70
    percent after three weeks, and 75 percent after four weeks. Activity
    not evaporated was found in the plants as endrin and hydrophilic
    metabolites. After administration of 500 ug/plant, the concentration
    of activity decreased from leaves to stalks to roots to soil, while
    the ratio of metabolites to endrin increases in the same order. The
    metabolite fraction consisted of two compounds, a very hydrophilic
    main metabolite and delta-keto endrin (Weisgerber et al., 1968).
    Similar results were obtained with carrots (Klein et al., 1968b).

    Foliar application of 14C-labelled delta-keto endrin to white cabbage
    has shown that it is more persistent than endrin but metabolizes more
    rapidly (about 15 percent compared with about 10 percent for endrin).
    The converted keto-endrin consisted mainly of a very hydrophilic
    metabolite, the concentration of which is highest in leaves and stalks
    (Korte and Porter, 1970).

    Residues in soybean plants grown in soil treated with 14C-labelled
    endrin were mainly delta-keto endrin, and endrin alcohol in addition
    to endrin aldehyde were believed present (Nash and Beall, private

    In soil

    Matsumura et al., (in press); incubated 14C-labelled endrin with 150
    cultures of microorganisms isolated from soils and found 25 active in
    degrading endrin, all of which had previously been found to degrade
    dieldrin. Seven different metabolites of endrin were found, with three
    major and four minor ones; tentative structures have been assigned
    (Korte and Porter, 1970).

    In storage and processing

    The effects of processing on the residues of endrin in dairy products
    was studied by Langlois et al., (1965). Butter, ice cream, cheese,
    condensed milk and dry whole milk were manufactured from milk
    contaminated with endrin either by direct addition or through feeding
    to cows. In general, they found that the residues concentration in the
    fat remained fairly constant during processing except for drastic heat
    treatment to produce dry whole milk which caused major reductions
    (>50 percent).

    When hens fed on a diet containing endrin were cooked in water at
    190-200°F for three hours, the residues were reduced up to 90 percent
    (Liska et al., 1967). Autoclaving the carcass at 15 psi for three
    hours removed essentially all residues. Metabolites of endrin ware not


    Residues of endrin were monitored in cottonseed oil produced by mills
    in Venezuela, Brazil, India and the United States. In Venezuela,
    weekly samples were taken for nine weeks, and endrin residues ranged
    from <0.02 to 0.05 ppm for crude oil, <0.02 to 0.02 ppm for
    decolorized oil and <0.02 ppm for deodorized oil (Shell Research
    Ltd., WKGR. 0119.70, 1970). In Brazil, seven samples were taken over
    thirteen weeks, and endrin residues ranged from <0.01 to 0.01 ppm for
    crude oil and <0.01 to <0.02 ppm for deodorized oil (Shell Research
    Ltd., WKGR.0120.70, 1970). In India, only crude oil samples were
    available, and these contained from 0.04 to 0.06 ppm endrin (Shell
    Research Ltd., Report WKGR 0091.70). In the United States, ten samples
    of refined oil from California were analyzed and found to contain
    <0.03 to 0.03 ppm endrin and <0.02 ppm delta-keto endrin (Shell
    Development Co., RES-63-155).

    In addition to oil, cottonseed cakes have also been studied for endrin
    residues, since these are used widely as an important ingredient of
    cattle feed concentrates. Figures for cattle cake samples
    corresponding to the samples of cottonseed oils given in the preceding
    paragraph are as follows: Venezuela, <0.01 to 0.02 ppm; Brazil <0.01
    to 0.08 ppm; India, <0.01 ppm. In the United States, data obtained on
    cakes and meals corresponding to the samples listed in Tables II and
    III ranged from <0.01 ppm to <0.04 ppm; most residues were below the
    detection limit of <0.01 ppm.

    Total diet studies conducted in the U.K.and the U.S.A. indicate that
    endrin residues are unlikely to arise in human diets as a result of
    the use of endrin in cotton (Abbott et al., 1969; Assoc. of Public
    Analysts, 1969; Duggan, 1968; USDA, 1968). In the U.K., no endrin
    residues were found in vegetable oils, fats, milk, milk based infant
    foods, beef, beef sausages or meats. In the U.S.A., no endrin residues
    were found in finished or crude cotton-seed oil, milk, milk products
    or manufactured milk products.


    The remarks on methods for residues of organochlorine pesticides and
    multidetection systems of analysis (FAO/WHO, 1967) apply to the
    determination of endrin. The compound can be determined in fatty and
    nonfatty foods by the multiresidue method and gas chromatography
    (Pesticide Analytical Manual., Vol. I and II, U.S. FDA). Endrin in
    eluted from the Florisil column in the 15% ethyl ether/petroleum ether
    fraction. Additional cleanup by MgO-Celite column and alkaline
    hydrolysis in required, and recovery is usually in the range of 
    80-100%. When a gas chromatograph containing 10% DC 200 on Gas-Chrom Q
    column at 200°C with 120 ml/min N2flow and an electron capture
    detector is used, the following retention times relative to aldrin are
    obtained: endrin - 2.05, endrin aldehyde - 2.30, endrin alcohol 
    - 2.50, delta-keto endrin -3.50. The sensitivity of the method is 
    good; 2 ng of endrin gives a “ full scale response on a 10-9amp full 
    scale recorder. A procedure for the determination of delta-keto endrin 
    in mammalian samples has been developed (Zavon et al., 1965), and a
    general method is available (Shell Development Co., Anal. Method MMS
    53/64). Residue methods have not yet been developed for monohydroxy
    endrin, 9-keto endrin, endrin, endrin aldehyde or the "bird cage
    alcohol" isomer of endrin.

    An infrared method for endrin has been described (Gershman, 1961). An
    absorbance peak at 10.2 microns is used for calculations. The method
    requires a 1 kg ample for 0.25 ppm.


    Country                  Commodity             Tolerance ppm
    Australia           vegetables including       0.1
                        beans, crucifers,
                        potatoes, tomatoes

    United States       broccoli, brussels         0
                        sprouts, cabbage,
                        cauliflower, cucumbers,    extended1
                        cottonseed, eggplant,
                        peppers, potatoes,

    United States
    (cont'd)            sugar beets and sugar      extended1
                        beet tops, summer squash,

    1 The word "extended" appears where action is being taken to acquire
      data to petition for a tolerance.

    Australia has not set a tolerance for endrin in cottonseed, however,
    an action level has been set for endrin residues in animal feeds at
    0.03 ppm.


    Endrin is widely used to control insect pests on cotton and to lesser
    extent on rice. It is used to a limited extent as an insecticide on
    small grains, vegetables and sugar cane and is occasionally used for
    mouse control in orchards. The ways in which endrin is applied vary
    widely, as do the numbers of applications.

    The most important consideration regarding endrin residues in food
    arise from its use on cotton; cottonseed oil is used for cooking or
    margarine manufacture, and the extracted cottonseed cake is used as
    cattle feed. Controlled feeding experiments with cattle indicate that
    whole milk residues would reach a plateau of 0.04 times the residue in
    feed. Once ingestion stops, excretion in milk soon ceases (two to six
    weeks). Cottonseed cake for feed should have less than 0.1 ppm of
    endrin residues if the recommended practical residue limits for whole
    milk and milk products are not to be exceeded.

    Rice bran is used as a component of poultry feed; feeding studies on
    hens indicate that endrin residues in depot fat would reach about five
    times the level in feed; for eggs the ratio would be about 0.7 times.

    Calculations indicate that it is unlikely that significant endrin
    residues would be found in cooked poultry or eggs. The rice bran used
    as a constituent of poultry feeds should not contain residues greater
    than 1 ppm if the recommended practical residue limits for poultry and
    eggs are not to be exceeded.

    In the absence of experimental residue data at the recommended
    preharvest interval of 45 days or longer, the meeting did not
    recommend a tolerance for oats.

    Under field conditions, endrin is rapidly loot from plants through
    evaporation - 60-80 percent over six to 18 weeks, depending on the

    Endrin is metabolized by plants to delta-keto endrin, a rearrangement
    product, and to very hydrophilic metabolites; traces of the aldehyde
    (SD 7442) and alcohol have been reported. The parent compound appears
    to be the major residue at all times.

    The widespread use of endrin on cotton does not appear to give rise to
    measurable residues in the human diet. Dietary studies in the United
    States have revealed no endrin residues in finished cottonseed oils,
    milk, milk based infant foods, milk products, beef or meats and trace
    amounts in margarine and fats. Exceptionally, one diet composite
    sample in one sampling location in the United States contained 0.20
    ppm of endrin in oils, fats and shortening.


    The following tolerance and practical residue limits are to apply to
    raw agricultural products moving in commerce unless otherwise
    indicated. All figures include the sum of endrin and delta-keto


    Cottonseed, cottonseed oil (crude)                0.1

    Cottonseed oil (finished), maize
    (sweet), wheat, barley, sorghum,
    rice (brown or polished), apples                  0.02


    Milk and milk products (fat basis)                0.02
    Fat of poultry                                    1
    Eggs (shell-free)                                 0.2



    An adequate long-term study in a strain of mice of known tumour


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    See Also:
       Toxicological Abbreviations
       Endrin (EHC 130, 1992)
       Endrin (HSG 60, 1991)
       Endrin (ICSC)
       Endrin (FAO Meeting Report PL/1965/10/1)
       Endrin (WHO Pesticide Residues Series 4)
       Endrin (WHO Pesticide Residues Series 5)
       Endrin (IARC Summary & Evaluation, Volume 5, 1974)