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    PIRIMIPHOS-METHYL      JMPR 1976

    Explanation

         Pirimiphos-methyl was first evaluated at the 1974 Joint
    FAO/WHO Meeting on Pesticide Residues (FAO/WHO, 1975). A temporary
    acceptable daily intake for man was established.

         Additional toxicological and residue studies on this compound
    have become available and are summarized in this addendum.

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    BIOCHEMICAL ASPECTS

    Absorption, distribution and excretion

         Additional data are presented on the concentration of
    pirimiphos-methyl and metabolites in rat tissues and on the blood
    profile following a single oral dose.

         When rats were given a single oral dose of 2-14C-labelled
    pirimiphos-methyl at 7.5 mg/kg the uptake of radioactivity into
    blood and its subsequent disappearance from the blood stream were
    both very rapid. More than 50% of the radioactivity present in the
    blood 30 minutes after dosing had disappeared at 1 hour after
    dosing. Total radioactive residues in the blood 24 hours after
    dosing (generally 0.2-0.3 mg/l pirimiphos-methyl equivalents) did
    not increase following daily dosing of 2-14C-labelled
    pirimiphos-methyl for a further 3 days. Unchanged pirimiphos-methyl
    normally represented less than 10% of the total residue in the
    blood 24 hours after dosing.

         When 2-14C-labelled pirimiphos-methyl was administered orally
    to rats at 7.5 mg/kg/day for four days, total radioactive residues
    in the liver, kidney and fat did not normally exceed 2 mg/kg
    pirimiphos-methyl equivalents. Levels of unchanged
    pirimiphos-methyl where detected were very small and did not exceed
    0.15 mg/kg in fat or 0.1 mg/kg in liver and kidneys. There is no
    evidence to show that either pirimiphos-methyl or its metabolites
    accumulated in the liver, kidney or adipose tissue of rats
    following daily dosing with the insecticide over 4 days (Mills,
    1976).

    TOXICOLOGICAL STUDIES

    Special studies on mutagenicity

         Pirimiphos-methyl was tested for dominant lethal mutagenic
    activity in mice. Male animals were given orally 15, 80 or 150
    mg/kg body weight for 5 days before mating. Groups receiving
    ethylmethanesulphonate (EMS) and cyclophosphamide were used as
    positive controls. Mating was carried out during 8 consecutive

    weeks, each week with new virgin females (2 females per male).
    These were killed 15 or 16 days after caging and examined for live
    implantations and early and late foetal deaths. The ovaries were
    examined for the number of corpora lutea.

         Pregnancy frequency was statistically significantly lower in
    the 150 mg/kg group. No other effects were noted in the
    pirimiphos-methyl groups which give an indication of any mutagenic
    activity. Such effects were amply demonstrated in the positive
    control groups (McGregor, 1975).

         Pirimiphos-methyl has shown evidence of mutagenic activity in
    Salmonella typhimurium but not in Escherichia coli. No
    metabolic activation was used in this study (Hanna and Dyer, 1975).

    Special studies on neurotoxicity

         Pirimiphos-methyl was tested for neurotoxicity in the hen. Two
    groups of five hens were given single oral doses of 50 and 60 mg/kg
    (dose rates for LD50) respectively. They were observed for 21 days.
    Four birds survived in the first group and 2 birds in the second
    group.

         On day 21 of the study one additional bird was added to the
    group dosed with 50 mg/kg and three to the group dosed with 60
    mg/kg. The birds were protected with intramuscular injections of
    atropine and pralidoxime and then re-dosed at 50 or 60 mg/kg. No
    neurotoxic symptoms were observed on clinical assessment or during
    histological examination after a further 21 days. Tri-o-tolyl
    phosphate (500 mg/kg) was used as a positive control compound and
    all birds showed signs of ataxia and significant neuropathological
    changes. It is concluded that pirimiphosmethyl is not neurotoxic
    (Ross et al., 1975)

    Special studies on potentiation

         A test for potentiation of the acute toxicity of a combination
    of pirimiphos-methyl and bioresmethrin was conducted by
    administration of a suspension of the two compounds mixed in the
    ratio of their LD50 values. The degree of potentiation was assessed
    by finding the ratio between the expected toxicity and the observed
    toxicity of the mixture. The results obtained suggested that
    potentiation between pirimiphos-methyl and bioresmethrin does occur
    (ratio of expected to observed) but the extent does not appear
    sufficient to be of practical significance (Parkinson, 1975).

    Special studies on reproduction

         In an assessment of the effect of pirimiphos-methyl on
    reproductive functions of the rat, dietary concentration of 5, 10
    and 100 ppm were fed continuously to three generations of rats.
    There were no consistent dose-related effects on parent animals in
    respect of signs of reaction, mortalities, food consumption,

    bodyweight change, mating performance, pregnancy rate or duration
    of gestation.

         There were no consistent dosage related effects on values for
    litter size, pup mortality rates, litter weight, mean pup weight or
    the incidence of anomalies. Terminal observations of the F3
    generation showed no conclusive differences in organ weight. The
    only differences to attain statistical significance related to the
    higher absolute liver weight of males at 10 ppm and the lower
    absolute thyroid weight of males at 100 ppm. However, the
    significance of these differences was not maintained following
    adjustment for differences in body weight.

         For both sexes depression of both plasma and erythrocyte
    cholinesterase activity in excess of 20%, considered biologically
    significant, was recorded at 100 ppm in each generation, but not at
    5 and 10 ppm levels.

         Pirimiphos-methyl at 100 ppm has no significant effect on
    growth and reproductive functions of the rat (Palmer and Hill,
    1976).

    Special studies on egg production and hatchability

         The study was designed to assess the effect of dietary
    inclusion of pirimiphos-methyl on body weight and food consumption
    of laying hens and on their egg production and hatchability.

         Groups of 35 hens and 4 cockerels were fed doses of 0, 4, 12
    and 40 ppm pirimiphos-methyl for 28 days and then allowed a 14 day
    recovery experimental period. The effect of pirimiphos-methyl on
    number of eggs laid, egg quality, fertility and hatchability, chick
    body weight and mortality was examined, together with body weight
    and food consumption of parent birds.

         At all levels tested pirimiphos-methyl had no significant
    effect on egg quality, production, hatchability, or any other
    effect that could be observed on any of the parameters measured.

         This study was undertaken in view of the large number of
    chicks dead in the shell found in a previous experiment, the
    validity of which was doubted when a fault was discovered in the
    incubator.

         In addition, samples of egg, liver and mixed flesh were
    analysed for pirimiphos-methyl and two of its metabolites. Values
    were below the level of detection in egg yolk following the 7 day
    withdrawal period. Except in the mixed flesh from samples taken on
    day 21 of the study all samples were below detection (Ross et al.,
    1975a,b).

    Acute toxicity

         2-ethylamino-4-hydroxy-6-methylpyrimidine (I) and
    2-amino-4-hydroxy-6-methylpyrimidine (II) have both been identified
    as degradation products of pirimiphos-methyl in animals, in plants
    and in stored products. Their acute oral mammalian toxicity has
    been assessed and found of low order.

         The acute oral LD50 of compound (I) in the female rat is 2093
    mg/kg. 95% confidence limits: 1841-2380 mg/kg. Toxic symptoms set
    in rapidly and were of short duration. They included urinary
    incontinence and salivation. Deaths occurred within 24 hours and
    surviving animals were fully recovered within four days.

         No deaths and no toxic symptoms were observed after the
    administration of compound (II) to the tested female rat at 4000
    mg/kg (Parkinson, 1974).



    CHEMICAL STRUCTURE 1




    Short-term studies

    Rat

         Pirimiphos-methyl was administered to young rats at doses of
    0, 5, 8, 10 and 50 ppm in the diet for a period of 28 days in order
    to determine the no-effect level on plasma cholinesterase activity
    and body weight gain. Plasma cholinesterase activity was inhibited
    at the 50 ppm level throughout the dosing period by 30% and 50% in
    male and female animals respectively. No effect on erythrocyte
    cholinesterase activity was detected. There was a tendency towards
    poorer food utilization in the group but there was no effect on
    body weight gain.

         There were sporadic instances of statistically significant
    depressions of plasma cholinesterase activity at the 8 and 10 ppm
    levels but less than 25% and not dose related. The "no effect"
    level for pirimiphos-methyl in the young rat was 10 ppm in the diet
    administered for a period of 28 days. This is also the no-effect
    level established for pirimiphos-methyl in the rat over two years
    (FAO/WHO, 1975; Berry and Gore, 1975).

    Dog

         In order to examine the potential hepatic effect of
    pirimiphos-methyl in the dog, ten more dogs were given 25 mg/kg/day
    with six dogs acting as controls. Three of the dogs were killed
    after four weeks dosing for histopathological examination. The
    remaining animals were maintained at the same dose level for a
    total period of 13 weeks except for two dogs whose dose was raised
    progressively to 50 mg/kg/day from week eight onwards.

         Slight bile duct proliferation was present in two dogs given
    25 mg/kg pirimiphos-methyl for 13 weeks. None of the other dosed
    animals showed this effect even when the dose was increased to 50
    mg pirimiphos-methyl/kg/day in two other dogs.

         The effects in the dog liver characterised by bile duct
    proliferation in a certain number of dogs given 25 mg/kg/day was
    confirmed. However the changes appear to be small and dependent
    upon individual animal sensitivity and reversible; the mode of
    action could not be ascertained. Focal inflammation was present in
    the livers of control and dosed animals. Liver changes were shown
    in the rat at levels of 300-600 ppm in the diet and in dogs dosed
    at 10 mg/kg/day for two years (Garuti et al., 1976).

    Long-term studies

    Mouse

         Four groups of 52 male and 52 female mice of the CFLP strain
    were fed 0, 5, 250 and 500 ppm pirimiphos-methyl in the diet for 80
    weeks. Three extra groups of 12 male and 12 female mice were fed 0,
    5 and 500 ppm and were used for the investigation of cholinesterase
    levels.

         There were no significant differences in mortality between
    control and treated groups. Macroscopic examination of descendants
    gave no indication of treatment-related change. Efficiency of food
    utilization and overall body weight gain were not affected. Food
    consumption was reduced slightly among females receiving 500 ppm
    only. No changes ascribable to the administration of pirimiphos-
    methyl were seen during gross and histological examination at
    autopsy.

         Changes in the kidneys, namely foci of lymphocytic
    infiltration in the interstitium, or minimal perivascular or
    peribronchiolar lymphoid aggregations in the lung and abscesses and
    small haemorrhages in ovaries and other morphological changes in
    various tissues were seen in a proportion of animals of all groups
    including controls and were considered to be of no toxicological
    significance. Similarly the liver tumour incidence was comparable
    to that of the controls.

         There was no evidence to suggest that treatment with
    pirimiphos-methyl altered the tumour profile of the CFLP mouse at
    levels up to 500 ppm. However, animals of both sexes showed marked
    inhibition of plasma and erythrocyte cholinesterase activities at
    the 500 ppm dietary inclusion level. When corrected for differences
    prevailing between groups at the start of the study, differences in
    erythrocyte cholinesterase activity between the control and 5 ppm
    pirimiphos-methyl groups were normally less than 20% and
    consistently less than 25%. Plasma cholinesterase activities in
    both untreated and 5 ppm dietary inclusion level groups followed
    similar, slightly fluctuating patterns during the study, although
    levels in both sexes in the treated group appeared inhibited by
    comparison with controls. However there was no evidence of
    progressive inhibition during treatment and differences between the
    control and 5 ppm groups were considered to be of borderline
    biological significance (Hunter et al., 1976). A "no-effect" level
    at 5 ppm in the diet, equivalent to approximately 0.5 mg/kg/day was
    established over an 80 week period.

    OBSERVATIONS IN MAN

         A group of seven healthy volunteers, consisting of three males
    and four females, was given orally a dose of 0.25 mg
    pirimiphos-methyl/kg bw, in capsule form for a period of 56 days.
    No effect due to the administration of pirimiphos-methyl was seen
    on liver function tests, blood count or erythrocyte or plasma
    cholinesterase activity (Howard and Gore, 1976).

    COMMENTS

         Results of studies on the effect of pirimiphos-methyl on rat
    reproduction in a three generation test, on avian-egg production
    and hatchability and of special tests on mutagenicity were
    negative.

         Hydronephrosis incidence noted in a previous test has been
    shown to be well within the limits of control values pertaining to
    the same species.

         Two studies were performed to investigate the potential
    hepatotoxicity of pirimiphos-methyl. In an 80 week mouse study the
    tumour incidence (including that in liver) was comparable in test
    and control groups. In a three month dog study slight bile duct
    proliferation was observed in animals dosed at 25 mg/kg/day,

    however the effect was absent at 50 mg/kg/day. Focal inflammation
    occurred equally in the livers of control and dosed animals. In a
    56 day human study, 0.25 mg/kg/day did not induce any changes in
    liver function tests, blood count or erythrocyte or plasma
    cholinesterase activity. Additional biochemical data presented
    established that the substance is very rapidly absorbed,
    metabolised and excreted.

         The Meeting agreed that the previously indicated further
    studies have been carried out satisfactorily, and there is no
    objection to estimating a permanent acceptable daily intake.

    TOXICOLOGICAL EVALUATION

    Levels causing no toxicological effects

         Mouse     5 ppm in the diet equivalent to 0.5 mg/kg bw/day

         Rat       10 ppm in the diet equivalent to 0.5 mg/kg bw/day

         Man       0.25 mg/kg bw/day

    ESTIMATE OF ACCEPTABLE DAILY INTAKE FOR MAN

         0 -  0.01 mg/kg bw/day

    RESIDUES IN FOOD AND THEIR EVALUATION

         The 1974 evaluation of pirimiphos-methyl (FAO/WHO, 1975) was
    principally in relation to its use as a treatment of stored grains.
    However the insecticide is also used on growing crops, in public
    health and in industrial outlets. Therefore, arising out of the
    list of requirements in the report of the 1974 Joint Meeting, the
    following additional data are now presented.

    1.   Information on pre-harvest use patterns and residues in fruit
         and vegetables.

    2.   Information on residues in peanuts and other stored products.

    3.   Further information on the level and fate of residues at the
         point of consumption following the use of pirimiphos-methyl
         for the control of various stored product pests.

    USE PATTERN

    Pre-harvest

         Pirimiphos-methyl is a fast-acting broad-spectrum
    organophosphorus insecticide with both contact and fumigant
    actions. It is effective against a wide range of flying and
    crawling insects, including aphids, scales, mealy bugs, whiteflies,

    bugs, thrips, beetles, caterpillars, moths and ants. It also has
    acaricidal activity. It controls both adult and immature stages of
    insects such as whiteflies, and is effective against strains of
    insects which have developed resistance to malathion.

         Because it has only limited biological persistence on leaf
    surfaces, pirimiphos-methyl is particularly attractive for uses in
    which a broad spectrum of insecticidal activity is required for a
    short period. e.g. pre-harvest clean-up of vegetables. Rates of
    0.5-1.0 kg a.i./ha "low volume" or 0.05-0.1% a.i. "high volume" are
    normally recommended. 0.5-0.75 kg a.i./ha (or 20-30 mg a.i. per
    m3) is normally effective in controlling greenhouse whiteflies by
    fogging. A fogging rate of 40 mg per m3 is used to control
    mushroom flies.

         The principal formulation is a 50% emulsifiable concentrate.
    A 50% oil-based formulation is available for ultra-low volume
    application to outdoor crops and a 10% oil-based formulation is
    used for whitefly control under glass. An 8% emulsifiable
    concentrate is sold to the amateur gardener. Dust and aerosol
    formulations are under development for crop uses.

         A pre-harvest withholding interval of four days is normally
    recommended after spraying. No pre-harvest withholding interval is
    normally recommended after the use of a fog to control

    1.   whiteflies on greenhouse tomatoes, cucumbers and peppers.

    2.   mushroom flies.

         Pirimiphos-methyl is not generally recommended for use on
    celery.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Pre-harvest uses

         Data reviewed by the 1974 Joint Meeting showed that
    pirimiphos-methyl is rapidly lost from leaf surfaces during the
    first 2-3 days after spraying, mainly by volatilisation. Levels of
    the parent insecticide and the major degradation product, compound
    II (Figure 1), represent less than 10% of the applied material
    after two to three days. After foliar treatment the hydroxy-
    pyrimidine IV, formed by hydrolysis of the insecticide, is unlikely
    to be a significant residue - the compound is usually present only
    in trace amounts and is degraded photochemically and bound to plant
    material.

         Photochemical degradation of pirimiphos-methyl on leaf
    surfaces leads to the formation of compound II which is not
    accumulated.

         When applied to water in which rice seedlings were growing,
    pirimiphos-methyl was not translocated significantly into the
    foliage; in these conditions the hydrolysis product IV is likely to
    represent the predominant pyrimidine residue. Compounds V and VI
    occur only in trace amounts.

         The new data show that pirimiphos-methyl residues on growing
    crops decline rapidly during the first few days after spraying.

         Bullock (1972) has studied extensively residues of
    pirimiphos-methyl in crops grown world-wide. Samples were analysed
    for residues of pirimiphos-methyl and of the phosphorus-containing
    metabolites II and III. However significant amounts of the
    metabolites did not appear and so were not reported.

         The highest initial residues are found in leafy vegetables.
    However, pirimiphos-methyl residues decline very quickly on these
    crops so that after four days levels on vegetables generally are
    below 2 mg/kg except on celery and occasionally on lettuce, spinach
    or Brussels sprouts where they may be higher (Table 1). Residues on
    tree fruits are normally less than 2 mg/kg after four days, while
    on soft fruits (currants and berries) they are generally below 1
    mg/kg (Table 2). There was good agreement between the results
    obtained by Bullock and those obtained by a second laboratory on a
    set of apple samples from Japan.

         The residues which Bullock found in rice in husk (up to 0.21
    mg/kg), in dehusked rice and in maize (<0.01 mg/kg in both cases)
    following pre-harvest spray uses are all within the temporary
    tolerance levels recommended by the 1974 Joint Meeting for
    post-harvest uses on these commodities.

         The use of fogs to control whiteflies under glass results in
    initial residues of 0.3 mg/kg or less in cucumbers, tomatoes and
    peppers (Table 3). Although treatments for whitefly control may
    need to be made every 3-5 days, the available data (ICI Plant
    Protection Division, 1973) indicate that no accumulation of
    pirimiphos-methyl residues occur in these fruits on repeated
    application.

         There is also no accumulation of residues in mushrooms
    following multiple applications of a fog (Table 3). Initial
    residues of up to 2.5 mg/kg were found to decline rapidly to below
    0.5 mg/kg after two days (Bullock and Stephens, 1974).

         The new aerosol and dust formulations yield residues (Table 4)
    similar to those observed previously with sprays of the
    emulsifiable concentrate formulations on lettuce and blackcurrants
    (Boxwell and Bullock, 1976). Residues on tomatoes were marginally
    higher than after fogging but were still below 1 mg/kg immediately
    after application at normal rates.

    FIGURE 1

    Stored product uses

         In contrast to its short persistence on growing crops,
    pirimiphos-methyl possesses exceptional stability on stored
    products such as grains. Although high temperatures and high
    moisture levels in grain reduce the life of the deposit, the effect
    of these influences is much less than with other grain protectants
    approved or evaluated to date (FAO/WHO, 1975).

         During degradation, residues of pirimiphos-methyl on wheat
    grains are degraded by hydrolysis of the phosphorus-ester side
    chain, to give principally the parent hydroxy-pyrimidine IV (Figure
    1) and also the related compounds V and VI. Levels of compound II
    are always extremely low (approximately 0.05 mg/kg over a period of
    32 weeks in wheat grain treated at 4 mg/kg). No residues of the
    chemically unstable oxygen analogue III have been detected. The
    limit of detection for compound III is 0.01 mg/kg. Residues of the
    hydroxypyrimidine IV in stored grains are normally below 0.5 mg/kg.

    Peanuts

         Pirimiphos-methyl residues in undecorticated peanuts treated at
    the intended rate of 20 mg/kg did not exceed 5.0 mg/kg. Two trials
    were conducted in the U.S.A. in 1971-2 in which pirimiphos-methyl was
    applied at 20 and 50 mg/kg to undecorticated peanuts. Analytical
    results indicated that the target rates of treatment were achieved.
    Very little change occurred in the level of residues during the first
    month following application. Even at the end of three months
    substantially all of the deposit remained. The data suggest that the
    half-life is of the order of 5 months from the time of application.
    Twelve months after application the residue in the whole
    undecorticated nuts was approximately 20-25% of the original amount
    applied. These data have recently been published (Redlinger, 1976).

         A larger scale trial was conducted in the U.S.A. during 1972-73
    (Ussary, 1975). Pirimiphos-methyl was applied at 10, 20 and 30 mg/kg
    as an admixture treatment to undecorticated peanuts. Analytical
    results again indicated that the target rate of treatment was
    achieved. 20-50% of the initial residue was present on the
    undecorticated peanuts after twelve months storage, compared with 10%
    in the case of malathion. During four commercial scale trials in the
    U.S.A. in 1973-74, in which pirimiphos-methyl was applied at the
    proposed commercial application rate of 20 mg/kg, 30-60% of the
    initial residue was present at bin emptying, that is after 4 -6
    months storage (Ussary, 1975).


        TABLE 1. Residues of pirimiphos-methyl resulting from supervised spray trials on leafy vegetables and root crops (EC formulations)

                                                                                                                                 

                                                                    No. of          Residues (mg/kg) at intervals (days)
                                                    Rate a.i.       applications    after last application
    Crop            Country         Formulation     % or kg/ha                      0               4               7
                                                                                                                                 

    Beans           West Germany    50% EC          0.15 kg/ha           1          0.15-0.25       <0.01-0.07      <0.01-0.01
    (Bush)                                          0.3 kg/ha            1          0.05-0.47       <0.01-0.08      <0.01-0.04

    (French)        U.K.            50% EC or       0.05%                1          0.06-0.07       0.01-0.03       <0.01-0.01
                                    8% EC           0.1%                 1          0.08-0.14       0.10-0.14       <0.01-0.06
                                                    0.2%                 1          -               0.26            0.14

    Peas            U.K.            50% EC          0.1 %                1          -               -               <0.01
                                                    0.2 %                1-2        -               <0.01           <0.01

    Lettuce         U.K.            50% EC or       0.025%               3          0.19-0.73       0.07-0.13       0.30-0.12
                                    25% EC          0.05%                1-3        11-18           0.60-1.8        0.37-0.88
                                                    0.1%                 1-3        19-39           1.8-2.9         0.63-2.1

                    West Germany    50% EC          0.025%               1          2.6-2.7         0.23            0.07-0.13
                                                    0.05%                1          3.4-7.3         0.52            0.14-0.71
                                                    0.1%                            4.7             -               0.52

                    West Germany    25% EC          (0.15 kg/ha          1          4.6-8.1         0.02-0.24       0.02-0.19
                                                    0.3 kg/ha            1          6-13            0.05-0.50       0.01-0.11

    Spinach         West Germany    25% EC          0.025%               1          3.2-6.7         0.35-1.0        0.22
                                                    0.05%                1          12-14           1.5-1.6         0.19-0.43
                                                    0.1%                 1          21              3.4             0.75

    Cabbage         U.K.            25% EC          1.0 kg/ha            1          -               0.30-0.50**     <0.02-0.28
                                                    2.0 kg/ha            1          -               0.31-1.8        0.09-0.40

                    West Germany    25% EC          0.15 kg/ha           1          0.13-1.4        0.05-0.18       <0.01-0.09
                                                    0.3 kg/ha            1          0.57-4.6        <0.01-0.69      <0.01-0.40
                                                    0.6 kg/ha            1          4.1             1.5             0.18

    TABLE 1. (Cont'd.)

                                                                                                                                 

                                                                    No. of          Residues (mg/kg) at intervals (days)
                                                    Rate a.i.       applications    after last application
    Crop            Country         Formulation     % or kg/ha                      0               4               7
                                                                                                                                 

    Cabbage         Malaysia        25% EC          1.0 kg/ha            18         -               -               0.01***
                                                    2.0 kg/ha            18         -               -               0.01-0.02***

    Cauliflower     U.K.            50% EC or       0.1%                 1          0.20-2.0        0.01-0.11       <0.01
                                    8% EC
    (Hearts)                                        0.2%                 1          0.15-1.4        0.04-0.24       <0.01-0.04

    (leaves)                        50% EC or       0.1%                 1          0.66-12         0.50-1.3        0.02-0.35
                                    8% EC           0.2%                 1          1.5-13          0.65-1.1        0.04-2.2

    Brussels        U.K.            50% EC          1.4 kg/ha            3          1.7-3.3         0.30-1.7        0.28-0.66
    sprouts                                         (0.1%)
                    (buttons)                       2.28 kg/ha           3          2.9-6.8         0.96-4.5        0.67-2.3
                                                    (0.2%)

    Brussels        Netherlands     50% EC          0.5 kg/ha            1          0.26*           0.14**          0.07

    sprouts                                         (0.05 %)
    (buttons)                                       0.75 kg/ha           1          0.49*           0.39**          0.21
                                                    (0.075%)

    Spring          U.K.            50% EC or       0.05%                1          0.28-1.6        <0.01-0.07      <0.01-0.08
    onions                          8% EC           0.1%                 1          2.3-4.2         0.04-0.49       <0.01-0.46

    Celery          U.K.            8% EC           0.05%                1          18-34           3.1-8.8         1.2-2.7
                                                    0.1%                 1          26-69           5.1-14          3.70-8.0

    Carrots         U.K.            50% EC          1.14 kg/ha           1          0.32-0.95       0.09-0.16       0.10-0.22
                                                    (0.1%)

                                                    2.28 kg/ha           1          0.57-2.2        0.17-0.48       0.12-0.50
                                                    (0.2%)

    TABLE 1. (Cont'd.)

                                                                                                                                 

                                                                    No. of          Residues (mg/kg) at intervals (days)
                                                    Rate a.i.       applications    after last application
    Crop            Country         Formulation     % or kg/ha                      0               4               7
                                                                                                                                 

    Potatoes        U.K.            50% EC          0.1%                 2          <0.01           <0.01
                                                    0.2%                 2          <0.01           <0.01           <0.01-0.02

    Sugar           West Germany    25% EC          0.05%                1          18              -               1.7
    beets                                           (0.3 kg/ha)

                                                    0.1%                 1          38              -               3.1
                                                    (0.6 kg/ha)
                                                                                                                                 

    *   Samples taken after 1 day
    **  Samples taken after 3 days
    *** Samples taken after 9-15 days

    TABLE 2 Residues of pirimiphos-methyl resulting from supervised spray trials on tree and sort fruits (EC and ULV formulations

                                                                                                                                         
                                                      No. of         Residues (mg/kg) at intervals after last application
                            Formulation  Rate a.i.,   Application
    Crop          Country                % or kg/ha                  0 days       4 days       7 days                   Other
                                                                                                                                         

    Apples        U.K.      50% EC or    0.1 %            3          0.51-1.3     0.25-0.67    0.10-0.80
                            8 %          0.05%            1
                                         0.2 %            3          0.76-2.8     0.58-1.9     0.16-1.5
                                         0.1%             1

                  France    50% EC       0.075%           6          -            -            -             2 weeks:    0.32

                  Japan     50% EC       0.1 %            1-3        -            -            -             10 days:    0.15-1.4

    Pears         Spain     50% EC       0.1 %            1          -            -            -             12 weeks:   <0.01

    Plums         U.K.      50% EC       0.1 %            2          0.47-0.96    0.24-0.55    0.02-0.25
                                         0.2 %            2          1.6-2.2      1.3-1.5      0.06-0.55

    Lemons        Italy     25% EC       0.05 %           1          -            -            -             9 weeks:    0.25 in peel
                                                                                                                         0.03 in flesh

                                         0.075%           1          -            -            -                         0.75 in peel
                                                                                                                         0.03 in flesh

                                         0.01 %           -          -            0.27-0.35    -                         -
                                                                                  in peel

                                                                                  0.02-0.03
                                                                                  in flesh

    Oranges       Australia 25% EC       0.075%           2          -            -            -             4 months:  0.69 in peel
                                                                                                                         <0.01 in flesh

                                         0.1              2          -            -            -                         0.92 in peel
                                                                                                                         <0.01 in flesh

    TABLE 2 (Cont'd.)

                                                                                                                                           
                                                      No. of         Residues (mg/kg) at intervals after last application
                            Formulation  Rate a.i.,   Application
    Crop          Country                % or kg/ha                  0 days       4 days       7 days                   Other
                                                                                                                                           

    Oranges       South     25% EC       0.075%           1          -            -            -             2-8 months: <0.01-0.01 in peel
                  Africa                                                                                                 <0.01 in flesh

                                         0.01-0.125%      1          -            -            -                         <0.01-0.1 in peel
                                                                                                                         <0.01-0.1 in flesh

    Olives        Spain     50%ULV       0.25 kg/ha       2          -            -            0.46          9-20 days:  0.07-0.36
                                         0.5 kg/ha        2          -            -            -                         0.16-0.45
                                         1.0 kg/ha        2          -            -            -                         0.18-1.4

    Blackcurrants U.K.      8% EC        0.05 %           2          0.25-0.75    0.06-0.20    0.01-0.18
                                         0.1 %            2          0.86-2.3     0.25-0.62    0.08-0.34

    Raspberries   U.K.      50% EC or    0.05%            1-2        0.81         0.23         0.13          2-5 weeks:  <0.01-0.03
                            8% EC        0.01%            1-2        2.5          0.53         0.31                      <0.01-0.09
    Strawberries  U.K.      50% EC or    0.05%            1          0.14-0.79    0.17-0.39    0.04-0.16     4-7 weeks: <0.01-0.05
                            8%           0.1%             1          0.40-2.9     0.31-0.71    0.13-0.25                 <0.01-0.05

                                                                                                                                           

    TABLE 3. Levels of pirimiphos-methyl resulting from supervised residue trials on greenhouse crops and mushrooms using a 10% fogging
             formulation

                                                                                                                                     
                                                 Number of      Residues (mg/kg) at intervals after last application
    crop           Country        Rate (a.i.)    Applications   0 days         1 day          2 days         3 days         4 days
                                                                                                                                     

    Cucumbers      U.K.           0.75 kg/ha         1-4        0.06-0.30      0.03-0.11      0.02-0.11      0.01-0.04      <0.01
                                  (=20 mg/m3)

                   Netherlands    20 mg/m3           1-5        0.08-0.19      0.03-0.08      0.02           <0.01-0.02     0.02
                                  20 mg/m3           5
                                  +30mg/m3           1-5        -              0.04-0.20      -              0.01-0.08      0.02-0.03

    Tomatoes       U.K.           0.5 kg/ha          2          -              0.15           -              -              -
                                  (= 15 mg/m3)
                                  1 kg/ha or         1-4        -              0.16-0.62      0.16           0.12           -
                                  30 mg/m3

                   Netherlands    0.75 kg/ha         1-3        -              <0.01-0.12     <0.01-0.18     0.08           -
                                  (= 20 mg/m3)
                                  30 mg/m3           1-5        -              0.06-0.17      -              0.08-0.14      0.08-0.11
                                  (= 1 kg/ha)

    Peppers        U.K.           1 kg/ha            1          -              0.26           -              -              -

    Mushrooms      U.K.           40 mg/m3       1 and 6        0.99           0.19           0.12           -              0.14-0.16
                                                 (two trials)   -2.5           -1.4           -0.44          -              (4-5 days)

                                                                                                                                     

    TABLE 4. Residues of pirimiphos-methyl resulting from supervised trials in the U.K. using dust and aerosol
             formulations (single application date per trial)

                                                                                                            
                                                      Residues (mg/kg) at intervals after
    Crop                Formulation    Rate           0 days         2 days         4 days         7-8 days
                                                                                                            

    Lettuce             Dust           Normal         2.1-10         0.53-7.9       0.33-2.1       0.06-1.9
                                       Overdosed      8.3-47         2.2-19         1.1-5.6        0.32-5.2

                        Aerosol        Normal         1.6-21         0.53-11        0.34-2.8       0.16-1.8
                                       Overdosed      13-40          6.2-25         2.0-7.6        0.75-3.8

    Tomatoes            Dust           Normal         0.01-0.93      <0.01-0.15     0.07-0.09      0.04-0.07
                                       Overdosed      0.18-1.4       0.08-0.89      0.05-0.13      0.02-0.03

                        Aerosol        Normal         0.09-0.67      0.04-0.43      0.02-0.38      0.03-0.05
                                       Overdosed      0.03-4.1       0.01-1.3       0.02-0.46      0.01-0.03

    Blackcurrants       Dust           Normal         0.10-0.59      0.03-0.05      -              -
                                       Overdosed      0.44-1.4       0.08-0.22      -              -

                        Aerosol        Normal         <0.01-0.27     <0.01-0.04     -              -
                                       Overdosed      0.04-0.59      <0.01-0.29     -              -

                                                                                                            
    

         During these studies there were wide variations between different
    samples analysed from the same bin. These were probably caused by
    non-representative sampling. Dust, estimated to constitute up to 10%
    of the contents of the bins, settles into layers in the bins. It
    contains several hundred mg/kg pirimiphos-methyl and in large bins it
    was impossible to sample the dust in a representative manner. However,
    residues in individual samples of undecorticated peanuts in the U.S.A.
    trials were generally below 5.0 mg/kg during the period after
    treatment at the proposed recommended rate of 20 mg/kg.

         The walls of the four warehouses used in the commercial scale
    trials were sprayed with a 0.5% aqueous suspension of
    pirimiphos-methyl and probe samples were taken adjacent to the walls
    during the storage period. Residues in the undecorticated peanuts were
    similar to those from the bulk of the warehouse and it was concluded
    that there was no major transfer of pirimiphos-methyl from the walls
    to the peanuts (Ussary, 1975).

    Rice

         The 1974 Joint Meeting recommended temporary tolerances of 10
    mg/kg in rice (in husk), 20 mg/kg in rice bran, 2 mg/kg in dehusked
    rice and 1 mg/kg in polished rice.

    Cogburn (1976) in the U.S.A. found that an admixture treatment of
    pirimiphos-methyl at 10 mg/kg protected rice from all insect
    infestation for twelve months. At this rate residues in the rice in
    husk, bran, dehusked rice and polished rice were all within the
    temporary tolerance levels proposed by the 1974 Joint Meeting.

    Dates

         In supervised trials in Iraq, MacCallum, Deighton and Pascoe
    (1976) found that 500 mg pirimiphos-methyl per square metre sprayed
    onto packaging materials (cardboard or wooden boxes) was effective in
    protecting export dates from insect attack. A deposit of 125 mg per
    square metre was effective for the treatment of waxed paper liners. At
    these rates pirimiphos-methyl residues in the dates during the
    following six months were invariably small - i.e. less than 0.5 mg/kg.

    Cheese

         There is very little movement of pirimiphos-methyl into cheese
    stored on surfaces treated with the insecticide for mite control.

         Thomas and Rowlands (1975) treated a wooden plank at 440 mg per
    square metre with 2-14C-labelled pirimiphos-methyl and then stored a
    22 kg Cheshire cheese, wrapped in a cloth, on it for fourteen weeks.
    The cheese was turned to stand on alternate ends weekly, as in normal
    storage practice. The radioactive residue was confined to the outer 4
    mm of the cheese in which there was no detectable breakdown of
    pirimiphos-methyl.


         Levels of pirimiphos-methyl were approximately 40 mg/kg in the
    outer 1 mm and 5-10 mg/kg in the outer 6 mm of the cheese. On a "whole
    cheese" basis, this represents a residue of approximately 0.4 mg/kg.

    FATE OF RESIDUES

    In animals

         Extensive data were evaluated by the 1974 Joint Meeting on the
    fate of pirimiphos-methyl in goats, cows, hens, their edible tissues
    and in foods of animal origin.

         When fed to these animals, pirimiphos-methyl is rapidly
    metabolised and the metabolites are excreted, principally in the
    urine. Only very small quantities are excreted into milk or eggs.
    Cattle receiving pirimiphos-methyl in their ration do not accumulate
    significant quantities in edible tissues, including fat. Such
    organophosphorus residues as are detectable are of the parent
    compound. No residues of the phosphorus-containing metabolites II and
    III could be detected in meat, milk, butter or eggs (limit of
    detection: 0.01 mg/kg or below).

         Since the 1974 Joint Meeting, data on the fate in pigs and
    additional data on the fate in hens have become available.

    Pigs

         Davis et al. (1976) maintained groups of pigs for 21 and 29 days
    on diets containing 3, 10 and 34 mg/kg pirimiphos-methyl. No residues
    of pirimiphos-methyl or of its phosphorus containing metabolites II or
    III were detected in the kidney, liver, lung, heart or muscle (limit
    of detection: 0.005 mg/kg in each case). Small residues of
    pirimiphos-methyl and compound II were found in the fat of pigs fed
    pirimiphos-methyl at 10 and 34 ppm in the diet (Table 15). No residues
    were detected in the fat of pigs returned for eight days to untreated
    diet prior to slaughter. No residues of the P=0 analogue (III) were
    detected in any fat tissues (limit of detection 0.005 mg/kg).

         No residues of the hydroxypyrimidines IV and V were found in any
    of the above-mentioned tissues (limits of detection 0.01 mg/kg for
    compound IV and 0.04 mg/kg for compound V).

    Hens

         Ross et al. (1975b) confirmed the low residue levels in eggs and
    meat previously reported by other authors (FAO/WHO, 1975).

         Groups of laying hens were maintained for 28 days on diets
    containing 0, 4, 12 and 40 ppm pirimiphos-methyl. At all but the
    highest dose level, pirimiphos-methyl levels in the eggs were below
    0.01 mg/kg. At the 40 ppm dietary inclusion level, pirimiphos-methyl
    levels in the egg yolk reached a plateau of 0.03-0.04 mg/kg after
    seven days. After the hens had been returned to untreated diet for

    seven days, pirimiphos-methyl residues in the yolks were below the
    limit of detection (i.e. less than 0.008 mg/kg). Residues in the
    albumen were negligible (less than 0.01 mg/kg).

         Residues of pirimiphos-methyl in meat tissues were below 0.01
    mg/kg at all dose levels.

         No residues of the phosphorus-containing metabolites II and III
    were detected in any samples of eggs or meat (limit of detection:
    0.006-0.02 mg/kg).

    In processing

         Initial data on the fate of pirimiphos-methyl residues or
    processing of stored products were reviewed by the 1974 Joint Meeting
    (FAO/WHO, 1975). Subsequent studies are described below.

    TABLE 5. Residues of pirimiphos-methyl and its desethyl metabolite
             in the fat of pigs fed pirimiphos-methyl in the diet

                                                                        

                                                              Desethyl
    Days           Level in diet      Pirimiphos-methyl       Metabolite
    on diet        (ppm)              (mg/kg)                 (mg/kg)
                                                                        

    21             control            ND                      ND
                   3                  ND                      ND
                   10                 0.008                   0.016
                   34                 0.034                   0.034

    29             3                  ND                      ND
                   10                 0.006                   0.009
                   34                 0.05                    0.036

    29             control            ND                      ND
    + 8 days       3                  ND                      ND
    recovery
                   3                  ND                      ND
                   10                 ND                      ND
                   10                 ND                      ND
                   34                 ND                      ND
                   34                 ND                      ND

                                                                        

    ND: Not detected, less than 0.005 mg/kg

    Wheat

         Residues of pirimiphos-methyl in flour are relatively stable to
    the conditions found during baking to bread and biscuits. However,
    because of the dilution which the flour undergoes during these
    processes flour initially containing 1 mg/kg pirimiphos-methyl is
    likely to yield bread/biscuits containing residues of the order of
    0.5 mg/kg.

         Bullock and co-workers (1976) have studied extensively the fate
    of pirimiphos-methyl during processing to bread and biscuits. In
    studies with the radiolabelled compound, flour was dosed with
    2-14C-labelled pirimiphos-methyl and baked to produce white bread,
    wholemeal bread and biscuits. Although pirimiphos-methyl is known to
    be a relatively volatile compound, there was no significant loss of
    radioactivity by volatilisation. Distribution of radioactivity
    throughout the bread was fairly uniform. Unchanged pirimiphos-methyl
    accounted for 75-90% of the radioactivity in the baked product. The
    major degradation products formed during baking were the
    hydroxypyrimidines IV and VI, which accounted for 3-10% of the
    radioactivity in the final product.

         Similar results were obtained by residue analysis in a second set
    of studies. After correction for the weight increase when flour is
    baked to bread, residues of pirimiphos-methyl fell by 11-18%.
    Likewise, residue analysis of biscuits showed average losses of 8%.
    However, owing to the dilution of the flour which occurs during
    baking, the residue level of pirimiphos-methyl in bread will be lower
    than that in the corresponding flour.

         During extensive residue studies Bullock et al.(1976) found that
    levels of pirimiphos-methyl in bread and biscuits are likely to be
    about 50% of those in the flour from which they were derived. These
    findings agree well with the earlier work of Bullock (1973, 1974)
    which was reviewed by the 1974 Joint Meeting. No residues of the
    phosphorus-containing compounds II and III were detected in bread
    baked from flour treated with pirimiphos-methyl at 1 mg/kg or in
    biscuits baked from flour treated at up to 5 mg/kg (limit of
    detection: 0.03 mg/kg)(Bullock et al., 1976).

         The hydroxypyrimidine IV also undergoes little degradation during
    the baking process. This compound has previously been shown to
    constitute a minor part (generally less than 0.5 mg/kg) of the residue
    in stored grains (FAO/WHO 1975). When bread was baked from flour
    containing 2-14C-labelled compound IV, the unchanged
    hydroxypyrimidine constituted more than 90% of the radioactive residue
    in the bread (Bullock et al., 1976). By analogy with pirimiphos-methyl
    residues, it can be concluded that residues of compound IV in baked
    products will not exceed 0.2 mg/kg and will normally be considerably
    lower.

         The pattern and levels of residues found in semolina and cooked
    pasta prepared from pirimiphos-methyl treated wheat are similar to
    those found in flour and bread/biscuits respectively. Unchanged
    pirimiphos-methyl constitutes the major proportion of the residue.

         Bullock and May (1976) studied the fate of residues in wheat on
    processing to semolina and pasta. White semolina prepared from Durum
    wheat treated at 10 mg/kg contained only 1.6 mg/kg pirimiphos-methyl.
    Pirimiphos-methyl levels in both white and wholemeal pasta were
    approximately 85-90% of those in the corresponding semolina.

         70% of the pirimiphos-methyl residue in semolina was transferred
    unchanged to cooked pasta. However the weight of pasta increases by
    100% on cooking so that the concentration of pirimiphos-methyl in
    cooked pasta is likely to be approximately 35% of that in the
    corresponding semolina.

    Peanuts

         Pirimiphos-methyl residues in peanuts are found mainly on the
    hulls. There is little transfer of residue to the kernels.
    Pirimiphos-methyl residues in processed fractions obtained from the
    kernel are normally very much smaller than in the whole raw
    agricultural commodity.

         Ussary (1975) has reviewed the available unpublished data for
    pirimiphos-methyl residues in peanut fractions. He concluded that
    residues in the kernels depend upon the degree of contamination by the
    hulls which occurs in the differing shelling processes. Nevertheless
    in the commercial scale trials in the U.S.A. during 1973-74, where
    peanuts were treated at 20 mg/kg by admixture, pirimiphos-methyl
    levels in the sound mature kernels were normally less than 5 mg/kg.

         Undecorticated peanuts containing a mean residue of 10 mg/kg
    pirimiphos-methyl yielded oil containing 9-14 mg/kg pirimiphos-methyl.

         In the 1972-3 trials in the U.S.A. undecorticated peanuts treated
    at 20 mg/kg yielded peanut butter containing mean residues of 3 mg/kg
    (Ussary, 1975).

         In the series of admixture trials in the U.S.A, pirimiphos-methyl
    residues in the peanut hulls were normally below 50 mg/kg (Ussary,
    1975).

    Residues in food in commerce

         Pirimiphos-methyl has not yet been widely used and therefore no
    information is available on residues in food moving in commerce.

    METHODS OF RESIDUE ANALYSIS

         The preferred method of residue analysis, by gas chromatography
    with a phosphorus detector, was reviewed by the 1974 Joint Meeting.
    The method was recently published (Zweig, 1976). It is suitable for
    the determination of residues of pirimiphos-methyl and the phosphorus-
    containing metabolites II and III in crops. The limit of determination
    is normally 0.01 mg/kg in each case.

    NATIONAL TOLERANCES

         The following national tolerances have been reported to the
    Meeting.

    Country             Commodity                         Tolerance, mg/kg

    France              Cereals                                 4
                        Fruit and vegetables                    2

    Netherlands         Cucumbers, courgettes,
                        peppers and tomatoes                    0.2

    West Germany        Cereals                                 4*
                        Grain parts                             2*

         In the UK, where tolerances are not normally specified,
    pirimiphos-methyl is registered for uniform admixture with small grain
    cereals at 4 mg/kg.

    APPRAISAL

         Pirimiphos-methyl was evaluated by the 1974 Joint Meeting when,
    in addition to the required toxicological information, further data
    were considered desirable on its use on stored products other than
    grain, on residues on fruit and vegetables following approved uses,
    and on terminal levels in various foods. These data have been
    provided.

         In use on outdoor and indoor crops, since pirimiphos-methyl has
    only a limited biological persistence on leaf surfaces it can be used
    where a broad spectrum of insecticidal activity is required for a
    short period, e.g., pre-harvest clean-up of vegetables. Rates of
    0.5-1.0 kg. a.i./ha "low volume" or 0.05 to 0.1% a.i. "high volume"
    are normally recommended. A fogging rate of 20-30 mg a.i./m3 is
    normally effective in controlling greenhouse whiteflies, and a fogging
    rate of 40 mg/m3 is used to control mushroom flies.

                 
    *Temporary tolerance.

         A pre-harvest withholding interval of four days is normally
    recommended after spraying. but 0 to 3 days after the use of a fog to
    control whiteflies on greenhouse tomatoes, cucumbers and peppers or
    mushroom flies.

         Pirimiphos-methyl residues on growing crops decline rapidly
    during the first few days after spraying. On the leaf surfaces and
    other aerial parts of the plant the compound is lost principally by
    volatilization; photochemical or other degradation also occurs.
    However, there are no significant amounts of the degradation compounds
    containing the intact phosphorus ester grouping and the
    phosphorus-containing residue can be expressed as the parent compound.

         Following treatment at recommended rates, levels on vegetables
    are normally less than 2 mg/kg after four days but higher applications
    can occasionally lead to residues on some green leafy vegetables
    (lettuce, spinach, Brussels sprouts) not exceeding 5 mg/kg. On celery,
    on which it is not generally recommended, residues my be higher than
    this.

         Residues on tree fruit are below 2 mg/kg after 4 days whilst on
    soft fruits they are below 1 mg/kg. When used for fogging under glass,
    initial levels are 0.3 mg/kg or less on cucumbers, tomatoes and
    peppers.

         Residues of pirimiphos-methyl are relatively stable in the
    conditions found during baking to bread and biscuits. Flour containing
    1 mg/kg of pirimiphos-methyl is likely to yield bread or biscuits
    containing about 0.5 mg/kg of the unchanged compound; the main
    degradation products do not contain phosphorus. Approximately similar
    changes occur when durum wheat is milled to white or whole meal
    semolina and this is subsequently made into pasta and cooked.
    Preparation of white semolina reduces the residue by about 80% (most
    of the pericarp is removed) but what is left is largely retained in
    pasta, even on cooking, although the proportion is halved in cooked
    pasta by uptake of water.

         These results, and the additional results obtained in stored
    rice, do not suggest a need for any alteration in the maximum residue
    levels proposed temporarily for wheat and wheat products and rice at
    the 1974 Joint Meeting and these are confirmed as maximum residue
    limits.

         Data evaluated by the 1974 Joint Meeting on the fate of
    pirimiphos-methyl in goats, cows, hens, their edible tissues and foods
    from them has now been supplemented by work with pigs which has shown
    no accumulation in the fat or meat of pigs maintained on diets
    containing pirimiphos-methyl at levels up to 34 mg/kg. Any residues of
    the parent compound or its phosphorus-containing metabolites were
    below the limit of detection (0.005 mg/kg) in muscle, kidney, liver,
    lung and heart, and very small in fat. When hens were fed for 28 days
    on diets containing up to 40 mg/kg of pirimiphos-methyl small residues

    (0.03 - 0.04 mg/kg) were found in eggs at the highest level of
    treatment. Residues of pirimiphos-methyl in meat tissues were below
    0.01 mg/kg at all doses, and neither the desethyl compound nor the
    oxon was detectable in any samples of eggs or meat.

    RECOMMENDATIONS

         As an ADI has now been established, the temporary tolerances
    recommended by the 1974 Meeting are converted to maximum residue
    limits. The following additional limits are recommended. They refer to
    the sum of pirimiphos-methyl, its oxygen analogue and N-desethyl-
    pirimiphos-methyl expressed as pirimiphos-methyl.

    Commodity                                   Limit, mg/kg

    Peanut hulls, peanuts (whole)                       50

    Peanut oil                                          10

    Lettuce, mushroom, olives,
     peanuts (kernels), spinach                         5

    Apples, Brussels sprouts, cabbage,
    cauliflower, cherries, pears, plums                 2

    Blackcurrants, carrots, cucumber,
    gooseberries, peppers, raspberries,
    spring onions, strawberries, tomato                 1

    Beans with pod, cheese, citrus, dates               0.5

    Peas, potatoes                                      0.05*

    * At or about the limit of determination

    FURTHER WORK OR INFORMATION

    DESIRABLE

    1.   Results of studies now in progress on the residues in peanuts and
         peanut products.

    2.   Results from commercial trials on other commodities.

    REFERENCES

    Berry, D., and Gore, C.W. Pirimiphos-methyl (PP511): Determination
    1975                of no effect level during a 28 day rat feeding
                        study. Unpublished report received from ICI
                        Central Toxicology Laboratory. Submitted to the
                        World Health Organization by ICI.

    Boxwell, J.W., and Bullock, D.J.W. Pirimiphos-methyl: Residues on
    1976                crops following application of aerosol and dust
                        formulations (UK). ICI Plant Protection Division
                        Report No. TMJ1305A. (Unpublished)

    Bullock, D.J.W. Residue summary: Pirimiphos-methyl in crops. ICI
    1972                Plant Protection Ltd. Report No. TMJ595/1.
                        (Unpublished)

    Bullock, D.J.W., Harrison, P.J., and Day, S.R. Pirimiphos-methyl:
    1976                Degradation of residues in flour during baking.
                        ICI Plant Protection Division Report No. AR2666A.
                        (Unpublished)

    Bullock, D.J.W., and May, M.S. Pirimiphos-methyl: Residue transfer
    1976                from durum wheat to semolina and pasta. ICI Plant
                        Protection Division Report No. TMJ1345A.
                        (Unpublished).

    Bullock, D.J.W., and Stephens, P.P. Pirimiphos-methyl: Residues in
    1974                mushrooms following application of
                        pirimiphos-methyl by `Fumovap' gun and Swingfog
                        machine. ICI Plant Protection Ltd. Report No.
                        AR2543A. (Unpublished).

    Cogburn, R.G. Pirimiphos-methyl and a protectant for stored rough
    1976                rice: Small bin tests. J. Econ. Ent., 69(3): 369.

    Davis, J.A., Day, S.R., Hemingway, R.J., Jegatheeswaren, T.,
    1976                and Bullock, D.J.W. Pirimiphos-methyl: residue
                        transfer study with pigs. ICI Plant Protection
                        Division Report No. AR2665A. (Unpublished)

    FAO/WHO 1974 Evaluations of some pesticide residues in food. AGP:
    1975                1974/M/11; WHO Pesticide Residues Series No. 4.

    Garuti, A., Gore, C.W., Ishmael, J., and Kalinowski, A.E.
    1976                Pirimiphos-methyl (PP511): A study of hepatic
                        changes in the dog. Unpublished report from ICI.

    Hanna, P.J., and Dyer, K.F. Mutagenicity of organophosphorus
    1975                compounds. Mutat. Res., 28: 405.

    Hodge, M.C.E., and Moore, S. Pirimiphos-methyl (PP511) teratological
    1972                studies in the rat. Unpublished report from ICI
                        Industrial Hygiene Research Laboratories.

    Howard, S.K., and Gore, C.W. The human response to long-term
    1976                oral administration of low doses of
                        pirimiphos-methyl. Unpublished report from ICI.

    Hunter, B., Graham, C., Street, Ae., Offer, J.M., and Printice,
    1976                D.E. Long-term feeding of pirimiphos-methyl
                        (PP511) in mice. (Final report 0-80 weeks).
                        Unpublished report from Huntingdon Research Centre
                        No. ICI/34/7650, submitted by ICI.

    ICI Plant Protection Ltd. Pirimiphos-methyl: Residues data for fogging
    1973                use on cucumbers, tomatoes and peppers.
                        (Unpublished).

    MacCullum Deighton, J., and Pascoe, R. Pirimiphos-methyl: Protection
    1976                of stored dates: Trials in Iraq 1974/5. ICI
                        Plan-Protection Ltd. Report No. AR2642A.
                        (Unpublished)

    McGregor, D.B. Dominant lethal study in mice of pirimiphos methyl.
    1975                Unpublished report from Inveresk Research
                        International (No. 289).

    Mills, I.H. Pirimiphos-methyl: Blood concentrations and tissue
    1976                retention in the rat. ICI Central Toxicology
                        Report No. CTL/P/247.

    Palmer, A.K., and Hill, P.A. Effect of pirimiphos-methyl (PP511)
    1976                on reproductive functions of multiple generations
                        in the rat. Huntingdon Research Centre Report,
                        submitted by ICI.

    Parkinson, G.R. Pirimiphos-methyl metabolites (R4039 and R35510):
    1974                Acute oral toxicity. Unpublished report from ICI
                        Central Toxicology Laboratory No. CTL/P/137,
                        submitted by ICI.

    Parkinson, G.R. Pirimiphos-methyl potentiation studies with
    1975                bioresmethrin. Unpublished report from ICI Central
                        Toxicology Laboratory (No. CTL/P/166B). Submitted
                        by ICI.

    Redlinger, L.M. Pirimiphos-methyl as a protectant for farmers
    1976                stock peanuts. J.Econ. Ent., 69(3): 377.

    Ross, D.B., Burroughs, S.J., and Roberts, N.L. Examination of
    1975a               pirimiphos-methyl for neurotoxicity in the
                        domestic hen. Unpublished report from Huntingdon
                        Research Centre (No. ICI/49/75220) submitted by
                        ICI.

    Ross, D.B., Christopher, D.H., Cameron, D.M., Dollery, R.,
    1976                Almond, R.H., and Roberts, N.L. Egg production and
                        hatchability following inclusion of
                        pirimiphos-methyl at various levels in the diet of
                        the laying hen. Huntingdon Research Centre Report
                        No. ICI/31A/75924.

    Thomas, K.P., and Rowlands, D.G. The uptake and degradation of
    1975                pirimiphos-methyl by cheshire cheese. J. Stored
                        Prod. Res., 11: 53.

    Ussary, J.P. ActellicR residues in peanuts. ICI United States
    1975                Inc. Interim Report. (Unpublished)

    Zweig, G. Analytical methods for pesticides and plant growth
    1976                regulators. Academic Press, 8: 125.
    


    See Also:
       Toxicological Abbreviations
       Pirimiphos-methyl (WHO Pesticide Residues Series 4)
       Pirimiphos-methyl (Pesticide residues in food: 1977 evaluations)
       Pirimiphos-methyl (Pesticide residues in food: 1979 evaluations)
       Pirimiphos-methyl (Pesticide residues in food: 1983 evaluations)
       Pirimiphos-methyl (Pesticide residues in food: 1992 evaluations Part II Toxicology)