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    PHOSMET        JMPR 1976

    IDENTITY

    Chemical name

         OO-Dimethyl S-phthalimidomethyl phosphorodithioate or (in
         Chemical Abstracts usage)

         S-[(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)methyl]
         O,O-dimethyl phosphorodithioate [732-11-6]

         (Also referred to [eg in US Federal Register] as
         N-(Mercaptomethyl)phthalimide
         S-(O,O-dimethylphos-phorodithioate)

    Synonyms

         Phthalophos (USSR), PMP (Japan), IMIDANR PROLATER

    Structural formula

    CHEMICAL STRUCTURE 1


    Other information on identity and properties

    Molecular weight:             317.3

    State:                        white crystalline solid

    Melting point:                72.0-72.7C

    Vapour pressure:              1 x 10-3 mm Hg at 50C
                                  (decomposes below its boiling point)

    Solubility                    25 ppm in water (at 25C), and more than
                                  10 per cent in acetone, dichloromethane,
                                  mesityl oxide, butanone and xylene.

         Phosmet is hydrolyzed fairly rapidly in aqueous solution,
    especially when the solution is neutral or alkaline. Buffered
    aqueous solutions of 20g per ml concentration at room temperature
    were 50% hydrolyzed in 13 days at pH 4.5, in 5 hours at pH 7 and in
    3 hours at pH 8.3.

         The products of hydrolysis are phthalimide, 00-dimethyl
    phosphorodithioate and formaldehyde. Oxidising agents can also
    cause breakdown of phosmet. It is compatible with other pesticides
    except under alkaline conditions, and is slightly corrosive.

         Storage of formulations above 45C may lead to decomposition.

         The technical product is of 95 to 98 per cent purity and has
    melting point 66.5 to 69.5C. The principal impurities are
    OOS-Trimethyl phosphorodithioate (1-2%) and
    N-chloromethylphthalimide (1-2%). It is formulated as
    emulsifiable concentrates, wettable powders, granules and: dusts at
    a variety of active ingredient-concentrations.

         A mixture of phosmet with carbophenothion is marketed under
    the name TRIMIDANR", and the synergistic effects of styryl
    phosphorothioates (Large and Pitt, 1975) and acephate (Nakatomi and
    Ishibe, 1975) with phosmet have been reported recently, as has that
    of 4-phenyl-1,3-dioxan (Uetani et al., 1974).

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

         In the absence of relevant data, toxicological evaluation of
    this compound was postponed.

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

         Phosmet is effective in controlling a variety of insect and
    mite pests which attack livestock, pasture, fruit and field crops.

         It is used as a systemic insecticide and acaricide against a
    range of ectoparasites of animals, and may be applied as a dilute
    aqueous spray containing up to 0.5 per cent a.i., as a ready-to-use
    "pour on" formulation containing up to 4% a.i. and applied at up to
    40 mg/kg body weight, as a dust containing 1 to 2 percent a.i. or
    it may be administered orally.

         Phosmet is non-systemic in plants, and at the concentrations
    normally used is relatively harmless to a number of predators of
    plant mites and insect pests. It is, therefore, used frequently in
    integrated control programmes against crop pests. The crops on
    which it is used include pome and stone fruits, cereals, forage
    crops, pasture and pasture seed crops, nuts and green and root
    vegetables.

    In animals

    Cattle

         Phosmet is used to control cattle ticks (e.g. Boophilus
    microplus  and B. annulatus), cattle grubs (larvae of the bot
    flies, Hypoderma lineatum and H. bovis), and the blood
    sucking horn flies (Haematobia irritans), and is registered for
    these uses in the U.S.A. (Anon, 1971d and 1974). Effective control
    of cattle ticks has been obtained with a 0.03% spray (Drummond et
    al., 1972).

         It is officially recommended in Australia for use against
    cattle lice and cattle ticks, and was reported to give effective
    control of am acaricide-susceptible strain of B. microplus,
    when used as a pour-on formulation (Loomis et al., 1862). The
    maximum recommended application rate for use against lice on beef
    and dairy cattle in Australia is 10 mg/kg. Sprayed onto cattle in
    a finely divided dust, it was found to be effective against all
    stages of a resistant strain of B. microplus (Thomas and
    Taylor, 1971).

         In the USSR, phosmet has been found to be effective against
    ixoid ticks on cattle (Nepoklonov et al., 1969; Omarov, 1974), for
    control of the mites causing cattle psoroptosis (Surorov, 1970),
    and for protection of cattle against stable flies (Stomoxys
    calcitrans) and other blood-sucking flies (Ruzimuradov et al.,
    1973).

    Sheep

         Phosmet is used to control the sheep ked (Melophagus ovinus)
    in the U.S.A. (Pfadt et al., 1975), and has been found effective in
    the USSR against mites causing psoroptosis (Andrichuk, 1971 a,b).

    Fowls

         Effective control of fowl ectoparasites with phosmet in the
    USSR has been reported (Frolov, 1970).


    In plants, preharvest

    Apples

         Phosmet is used in the U.S.A. against a number of pests of
    apple trees, including the plum curculio, Conotrachelus
    nenuphar (Forsythe and Hall, 1972), and the codling moth
    (Laspeyresia pomonella). For control of the latter, phosmet is
    often used as part of an integrated control programme in which other
    insecticides, sanitation measures, reliance on natural predators for
    control of other pests (eg, the European red mite) and sterile moth
    releases, may play a part (eg, Butt et al., 1973, Holdsworth, 1973).

         In the USSR, phosmet is effective against the caterpillars of
    the leaf-miner moth, Stigmella malella (Gribkova, 1973) and
    against spider mites, hawthorn mites and soft scale insects.

         In the U.K., phosmet has been found to be particularly
    effective against the apple sucker, Psylla mali, and to give
    control of other pre-blossom pests (Vernon and Gould, 1972).

         Other apple pests controlled include San Jose Oystershell
    scale insects, e.g. as part of an integrated control programme in
    Canada (Wilde, 1973), woolly aphids, leaf roller moth (New Zealand
    and Netherlands), winter moth, apple weevil in Poland (Witkowska
    and Wojnarowska, 1971), and Aphis pomi in Spain.

    Pears

         Phosmet is used in the U.S.A. to control the pear psylla
    (Psylla pyricola) as well as the codling moth. In the USSR it
    gave control of Grapholitha molesta on pear trees when used as
    0.1 per cent spray on  six occasions at 14-day intervals (Omelyuta,
    1972), and it is also used on a small scale on pears in the
    Netherlands.

         The recommended period between treatment and harvest is 3
    weeks for both apples and pears in the Netherlands and in
    Australia, and the application rate for pome fruit is usually 0.75
    9 a.i/l (0.075%).

    Stone fruit

         In the U.S.A., phosmet is used on plums, cherries, peaches,
    apricots and nectarines, and it has been found to give control of
    Grapholitha molesta on peaches and apricots in the USSR. Its
    use on peaches has been reported in Turkey, and it is used on
    canning varieties of peaches in Australia against the oriental
    fruit moth at 0.5 g a.i./l, with a pre-harvest withdrawal period of
    3 weeks.

    Other fruits

         The use of phosmet against Patynota stultana on grapes in
    the U.S.A. has been reported (Ali Niazee and Stafford, 1973). It is
    also used against the grape berry moth and various gnawing pests of
    grapes in the USSR. On citrus crops it has been used against the
    citrus white fly; and the control of Zophodia convolutella on
    gooseberries (Shapovalova et al., 1970) and of caterpillars on fig
    trees (Popov, 1973) with phosmet have been reported in the USSR.

         In New Zealand, phosmet is used on grapefruit, Kiwifruit and
    Feijoas.

    Potatoes

         Phosmet is used to control the Colorado Beetle on potatoes in
    Spain (Del Rivero et al., 1971), East Germany (Klunker, 1974), and
    in the Netherlands, where the recommended pre-harvest interval is
    4 weeks. It is recommended in Australia for control of the
    red-legged earth mite in potato crops.

    Other root crops

         Phosmet is officially recommended in Australia for the control
    of globular springtail on beet and carrots, and the red-legged
    earth mite on carrots.

         In the USSR it is used on sugar beet against a variety of
    pests including Bothynoderes punctiventris (Nesterenko, 1970,
    1973).

    Green vegetables

         The use of phosmet against lepidopterous pests of cabbage has
    been reported in Spain, and it is officially recommended in
    Australia for control of the red-legged earth mite and other pests
    in beans, peas, crucifers and lettuce.

    Pasture and forage crops

         Phosmet is used in the U.S.A. to control the alfalfa weevil
    (Hypera postica), and the clover head weevil. It has also been
    found effective against the alfalfa weevil in the USSR when applied
    at 0.75 kg/ha at the beginning of the egg-laying period. In
    addition, it is effective against Phytonomus variabilis on
    alfalfa (Marzhanyan et al., 1973). In Australia it is officially
    recommended for use on cruciferous forage crops, lucerne, pasture,
    and pasture seed crops to control the lucerne flea, the red-legged
    earth mite and the blue oat mite, the application rate on pastures
    being 0.0350.05 kg/ha with a withholding period of 7 days.

    Cereal crops

         In Australia satisfactory control of the blue oat mite on
    wheat was achieved with the ULV application of phosmet at 0.5 oz
    a.i. per acre (New South Wales Department of Agriculture, 1969  and

    phosmet is officially recommended for control of this pest as well
    as the lucerne flea and the redlegged earth mite in cereal crops.

    Cotton

         Applied at 3-5 kg/ha in cotton plantings in the USSR, phosmet
    has been found very effective against cutworm moths (Nikiforov and
    Mamaev, 1972). It is also reported to control other cotton pests.

    Post-harvest treatments

         The existence of a U.S. tolerance of 10 mg/kg for phosmet
    residues on sweet potatoes from post-harvest applications (Anon,
    1973), suggests that phosmet is used for the protection of this
    crop in storage in the U.S.A.

         Phosmet showed considerable promise in evaluation trials in
    the U.S.A. against stored products insects such as the red flour
    beetle, Tribolium castaneum (Herbst), (Speirs and Lang, 1970),
    but it is not known whether it has been adopted for the protection
    of stored grain, flour, etc.

    Other uses

         Phosmet has found some applications in forestry, particularly
    for the protection of conifers against such pests as the pine tip
    moth and the pine looper.

         In the USSR, dipping sheep in 0.5 per cent emulsions of
    phosmet kept the sheep free of Ixodes mites for 7 months
    (Sevost'yanov and Ushakova, 1971).

         Phosmet has also been found to be effective against several
    pests of tobacco, including the flea beetle (Mistric and Smith,
    1970). In Australia it is recommended for control of the lucerne
    flea on tobacco seed beds.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    In animals

    Cattle

         In a trial in the U.S.A. during 1964/5, five steers were
    sprayed with phosmet at 0.25% a.i., and one was slaughtered on each
    of days 3, 7, 14, 28 and 59 after treatment. Residues were
    determined in fat, liver and muscle, with the results indicated in
    Table 1 (Rogoff et al., 1967).

         Several trials involving the determination of phosmet residues
    in the fat of cattle at various intervals after treatment have been
    carried out in Australia (Snelson, 1976). The treatments have
    included spray and pour-on applications, and in one case the

    animals were sprayed 3 times. The application rates and residue
    results are shown in Table 1, along with the results of a trial in
    the U.K. using pour-on application.

         At the University of California, cattle were fed phosmet at
    approximately 1 mg/kg/day for 8 weeks, and at 2 mg/kg/day for an
    additional 8 weeks. The animals were killed and autopsied on days
    zero, 3, 7, and 14 following the completion of feeding. The phosmet
    residues in fat were all below the detection limit of 0.09 mg/kg, and
    in liver, kidney and muscle they were all below the detection limit of
    0.04 mg/kg with the exception of one zero day muscle sample.

         There have been several studies involving the determination of
    phosmet residues in the milk of dairy cows. In one of these (Johnson
    and Bowman, 1968), milk from 4 dairy cows ingesting phosmet in silage
    at a daily average rate of 0.22 mg/kg body weight was found to contain
    less than 0.002 ppm of phosmet or its oxygen analogue. In another
    (Woodard Research Corporation, 1963), 2 groups of dairy cows were
    treated with phosmet by spraying 3 times at weekly intervals at 0.25%
    or 0.5% a.i., whilst a further three groups were fed phosmet for 4
    weeks at levels of 20, 45 and 100 ppm in the diet. Milk samples were
    taken at frequent intervals from all five groups and analysed for both
    phosmet and its 0-analogue. The average apparent phosmet residue for
    all milk samples from treated cows was 0.016 mg/kg compared to
    0.015 mg/kg for control samples.

         Results for residues in milk and cream from further trials in
    Australia and the U.K. are given in Table 2.

    Goats

         A goat given a single oral dose of phosmet (70 mg per kg,
    administered in gelatine capsules) was milked dry at 8, 24 and 48
    hours after treatment (Bowman and Beroza, 1967). The milk was
    extracted with a 1:1 mixture of hexane and diethyl ether and the
    extracts were analysed by gas chromatography using a flame photometric
    detector in the sulphur mode. 0.38 mg/kg of phosmet was found in the 8
    hour sample, but none was detected in the subsequent samples.

    Pigs

         In Bulgaria, phosmet applied externally to pigs at 1.5% a.i. was
    found to penetrate through the skin in 2 to 5 days. The highest
    residues (10 mg/kg) accumulated in the subcutaneous fat. The meat
    accumulated approximately 8 ppm and some xylene derivatives were
    detected as metabolites of phosmet (Ionova et al., 1974).

    Fowls

         In the USSR (Chirikashvili et al., 1970), phosmet was
    administered to hens as a single oral dose of 300 mg/kg. The compound
    was detectable by thin layer chromatography in various organs and

    tissues, especially the lungs, heart and intestines, for 5 days after
    treatment, and was present in some of the eggs at a level of about
    2 mg/kg.
    In plants

         The available residue data from crop spraying trials are
    summarised in Table 3.

    Apples

         In two Stauffer Chemical Company trials in the Netherlands in
    1970, phosmet was applied as a spray containing 0.15% a.i. and at a
    rate of 2000 l/ha. The residue disappearance curves from these trials
    are reproduced as Figures 1 and 2. The oxygen analogue was measured as
    well as unchanged phosmet, and residues were determined in samples of
    fruit harvested at weekly intervals up to 4 weeks from treatment. The
    total residue after the recommended 3 week interval from treatment to
    harvest averaged 0.5 mg/kg, as against a national tolerance in the
    Netherlands of 1 mg/kg, even though the concentration of the spray was
    double that normally recommended.

         In two similar trials in New Zealand, phosmet was applied 9 times
    as a spray containing 0.15% a.i., and residues were determined over
    periods of 23 and 28 days respectively. The mean residues found after
    the recommended 14 day waiting period were in the range 1-3 mg/kg, as
    against a New Zealand national tolerance of 10 mg/kg. The normal
    application rate is 0.075-0.1% a.i.

         In a trial in Australia using two application rates (1.75 and 2.0
    g a.i./l) and carried out for the Stauffer Chemical Company, residues
    had fallen to below 1 ppm after 3 weeks (King and Best, 1971).

         In trials in the USSR (not included in Table 3), apple trees were
    sprayed with phosmet at the rate of 10 litres per tree of 0.2% spray.
    Residues were found to have disappeared from the apples 20 days after
    treatment (Adeishvili, 1973), but the detection limit of the method
    used is not known.

    Stone fruit

         Trials on two varieties of peaches were carried out by ICI in
    Australia. In one, phosmet was applied at 1.0 g a.i./l and peaches
    were sampled at 0, 7, 14 and 21 days after treatment. In the other
    phosmet was applied at 2.0 or 1.0 g a.i./l and samples of peaches for
    each application rate were taken at 1, 3, 5, 7 and 14 days after
    treatment. For the 1.0 g a.i./l application rate, residues had fallen
    to 1.1-1.5 ppm after 14 days, and to 0.5 ppm after 21 days (Snelson,
    1976).

         In Turkey, peaches of the Hale variety were treated 3 times in a
    period of 30 days with a 0.15% spray. Samples were taken over a 3-week
    period, and the residue found 21 days after the last treatment was 3.3
    ppm (Otaci et al., 1972).
 

   
    TABLE 1. Residues of phosmet in tissues of cattle slaughtered at various intervals after treatment

                                                                                                             

                                 Application                                Post
                                                                            treatment
    Country                         Rate                                    interval    Residues mg/kg
    (reference)       Method        (g a.i./l)   No.    Tissue              (days)      mean (range)
                                                                                                             

    U.S.A.            spray         2.5          1      Omental fat            3            0.40
    (Rogoff et al                                                              7            <0.2
    1967)                                                                     14            <0.2
                                                                              28            <0.2
                                                                              59            <0.2

                                                        Peri-renal             3            0.59
                                                        fat                    7            <0.2
                                                                              14            <0.2
                                                                              28            <0.2
                                                                              59            <0.2

                                                        Sub-cutaneous          3            0.67
                                                        fat                    7            <0.2
                                                                              14            <0.2
                                                                              28            <0.2
                                                                              59            <0.2

                                                        Liver                  3            0.10
                                                                               7            0.09
                                                                              14            0.08
                                                                              28            0.06
                                                                              59            0.08

    U.S.A.                                              muscle                 3            0.06
                                                                               7            <0.04
                                                                              14            <0.04
                                                                              28            <0.04
                                                                              59            <0.04

    TABLE 1. (Cont'd.)

                                                                                                             

                                    Application                             Post
                                                                            treatment
    Country                         Rate                                    interval    Residues mg/kg
    (reference)       Method        (g a.i./l)   No.    Tissue              (days)      mean (range)
                                                                                                             

    Australia         Spray         0.75         3      Omental                1            1.03 (0.91-1.14)
    (Snelson, 1976)                                     fat                    4            0.34 (0.28-0.40)
                                                                               8            0.0

                                                        Subcutaneous           1            0.60 (0.40-0.80)
                                                        fat                    4            0.06 (0.02-0.09)

                                                 1      Omental                1            0.77 (0.74-0.80)
                                                        fat                    4            0.07 (0.01-0.13)
                                                                               8            0.06 (0.02-0.09)

                                                        Subcutaneous           1            0.21 (0.21-0.21)
                                                        fat                    4            0.01 (0-0.2)
                      Spray (2      0.75         1      Omental                1            0.79 (0.52-0.93)
                      gallons =                         fat                    2            0.34 (0.25-0.40)
                      6.8 grams                                                3            0.24 (0.16-0.37)
                      technical                                                7            0.16 (0.11-0.21)
                      per beast)

    Australia                                           Peri-renal             1            0.24 (0.17-0.37)
                                                        fat                    2            0.18 (0.15-0.24)
                                                                               3            0.10 (0.09-0.11)
                                                                               7            0.07 (0.05-0.10)

    U.K.              Pour-on                    1      Omental                1            2.75 (1.64-3.7)
                      (40 mg/kg)                        fat                    2            1.73 (1.68-1.8)
                                                                               3            1.33 (0.92-1.9)
                                                                               7            0.58 (0.49-0.69)
                                                                              10            0.26 (0.15-0.36)

    TABLE 1. (Cont'd.)

                                                                                                             

                                    Application                             Post
                                                                            treatment
    Country                         Rate                                    interval    Residues mg/kg
    (reference)       Method        (g a.i./l)   No.    Tissue              (days)      mean (range)
                                                                                                             

                                                        Peri-renal             1            1.78 (1.20-2.19)
                                                        fat                    2            1.47 (1.42-1.5)
                                                                               3            1.05 (0.90-1.3)
                                                                               7            0.73 (0.40-1.1)
                                                                              10            0.37 (0.26-0.43)
                                                                                                             


    TABLE 2. Residues of phosmet in the milk of lactating dairy cows at various intervals after treatment
                                                                                                         
                    Method            Application                  Post-treatment    Residues mg/kg mean
    Country         of                rate          No. of         interval                   (max)
    (reference)     application       (g. a.i./l    applications   (days)            whole milk    cream
                                                                                                         
    Australia       Spray             0.75          1              1/6               0.08          0.84
    (King and       (1 3/4 gallons                                 2/3               <0.02         0.10
    Ferguson        = 6.0 grams                                    1                 0.02          0.10
    1971)           technical                                      2                 <0.02         0.02
                    per beast)                                     3                 <0.02         <0.02
                                                                   4                 <0.02         <0.02
                                                    2              1/6               0.03          -
                                                                   2/3               0.05          -
                                                                   1                 <0.02         -
                                                                   2                 <0.02         -
                                                                   3                 <0.02         -
                                                                   4                 <0.02         -

    U.K.            Pour-on           -             1              1/4               (0.07)        (0.77)
    (Snelson;       (20 mg/kg)
    1976
                                                                                                         

    


    FIGURE 1

    FIGURE 2



        TABLE 3. Residues of phosmet in various crops from supervised spraying trials

                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

    Apples       Netherlands               1.5                    1               0          1.8(1.3-2.1      0
                 (var. Lombertscalville)   (2000 1/ha)                            7          0.9(0.7-1.2)     0
                                                                                  14         0.6(0.3-0.9      0
                                                                                  21         0.5(0.3-0.6)     0
                                                                                  28         0.2(0.1-0.2)     0

                 Netherlands               1.5                    1               0          2.4(1.5-3.4)     0.04(0.01-0.07)
                 (var.                     (2000 l/ha)                            7          2.0(1.7-2.3)     0.06(0.04-0.09)
                 Goudreinette)                                                    14         1.4(0.6-2.0)     0.06(0.03-0.07)
                                                                                  21         0.4(0.2-0.6)     0.03(0-0.06)
                                                                                  28         0.6(0.2-0.7)     0.02(0.01-0.03)

    Apples       New Zealand               1.5                    9               2          2.0
                                                                                  9          1.7
                                                                                  15         1.1
                                                                                  23         0.7

                                           1.5                    9               1          4.3
                                                                                  3          3.6
                                                                                  7          4.0
                                                                                  14         2.9
                                                                                  21         3.0
                                                                                  28         2.1

    Apples       Australia                 1.75                   ?               0          2.2
                 (King & Best,                                                    1          1.5
                 1971)                                                            7          0.7
                                                                                  14         0.8
                                                                                  21         0.6

    TABLE 3. (Cont'd.)

                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

                                           2.0                    ?               0          2.8
                                                                                  1          1.5
                                                                                  7          1.6
                                                                                  14         1.0
                                                                                  21         0.7

    Peaches      Australia                 1.0                    1               0          3.8
                 (var. Golden                                                     7          3.6
                 Queen)                                                           14         1.1
                                                                                  21         0.5

                 Australia                 1.0                    1               1          3.4
                 (var.Maygold)                                                    3          2.5
                                                                                  5          1.3
                                                                                  7          3.1
                                                                                  14         1.5

    Peaches      Australia                 2.0                    1               1          5.3
                 (var. Maygold)                                                   3          6.2
                                                                                  5          4.2
                                                                                  7          3.9
                                                                                  14         6.2

    Peaches      Turkey                    1.5                    3               0          5.39
                                                                                  3          5.44
                                                                                  7          4.65
                                                                                  14         3.48
                                                                                  21         3.30

    TABLE 3. (Cont'd.)

                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

    Kiwifruit    New Zealand               1.1                    2               1          10.0
                                                                                  7          9.6
                                                                                  14         5.8
                                                                                  21         5.1
                                                                                  28         3.6
                                                                                  35         3.1
                                                                                  42         3.0

                                           1.12                   2               10         9.5
                                                                                             7.7
                                                                                             5.8
                                                                                             7.1

                                           1.12                   7               10         25.0
                                                                                             16.0
                                                                                             8.4
                                                                                             7.2

                                           0.75                   7               10         8.8
                                                                                             4.8
                                                                                             7.1
                                                                                             6.4

    Grapefruit   New Zealand               1.12                   4               1          0.65
                                                                                  7          0.57
                                                                                  14         0.3
                                                                                  21         0.26
                                                                                  28         0.38
                                                                                  42         0.22

    TABLE 3. (Cont'd.)

                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

    Potatoes     Netherlands               0.56 kg a.i./          2               22         0.004            0
                 (var.                     ha(as 50% w.p.)                                   (0.002-0.006)
                 Burmania)

                 Netherlands               "                      2               20         0.001            0
                 (var. Bintje)                                                               (0-0.003

                 Netherlands               "                      2               21         0.001            0
                 (var.                                                                       (0.001-0.002)
                 Eigenheimer)


    Alfalfa      U.S.A.                    1.1 kg a.i./           1               1          43.5
                 (Shaw et al.              ha(36% ec)                             8          2.09
                 1966)                                                            14         0.84
                                                                                  21         0.31
                                                                                  controls   0.18-0.44

    Alfalfa      U.S.A.                    0.56 kg a.i.           1               0          33.86
                 (Miller et al.            /ha(50% wp)                            5          3.58
                 1969)                                                            10         2.27
                                                                                  15         0.34
                                                                                  21         0.04

                                           1.1 kg a.i.            1               0          57.11
                                           /ha(50% wp)                            5          10.74
                                                                                  10         3.42
                                                                                  15         1.52
                                                                                  21         0.00

    TABLE 3. (Cont'd.)
                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

                                           0.56 kg a.i.           1               0          20.95
                                           /ha(36% ec)                            5          3.87
                                                                                  10         2.09
                                                                                  15         0.94
                                                                                  21         0.00

    Alfalfa      U.S.A.                    1.1 kg a.i.            1               0          44.42
                                           /ha (36% ec)                           5          9.87
                                                                                  10         5.06
                                                                                  15         2.00
                                                                                  21         0.37

    Coastal      U.S.A.                    0.84 kg a.i.           1               0          37.93
    bermuda      (Dorough et               /ha                                    1          32.66
    grass        al, 1965)                                                        3          23.89
                                                                                  7          15.79
                                                                                  14         8.31

    Coastal      U.S.A.                    0.28 kg a.i.           1               0          12.3             0.06
    bermuda      (Leuck and                /ha                                    1          6.86             0.06
    grass        Bowman, 1968)                                                    3          1.11             0.00
                                                                                  4          0.96             0.00
                                                                                  7          0.72             0.00
                                                                                  15         0.13             0.00

                                           0.56 kg a.i.           1               0          27.0             0.13
                                           /ha                                    1          16.4             0.13
                                                                                  3          2.82             0.02
                                                                                  4          2.30             0.02
                                                                                  7          1.78             0.00
                                                                                  15         0.36             0.00

    TABLE 3. (Cont'd.)
                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

    Coastal      U.S.A.                    1.1 kg a.i./ha         1               0          52.9             0.36
    Bermuda                                                                       1          36.8             0.40
    grass                                                                         3          7.02             0.07
                                                                                  4          6.34             0.06
                                                                                  7          3.72             0.02
                                                                                  15         0.57             0.00

    Maize        U.S.A.                    0.28 kg a.i./ha        1               0          2.67             0.00
    plants       (Leuck and                                                       1          1.00             0.00
    (green       Bowman, 1968)                                                    2          0.39             0.00
    weight                                                                        4          0.20             0.00
    basis)                                                                        7          0.09             0.00

                                           0.56 kg a.i./ha        1               0          7.07             0.01
                                                                                  1          Not sampled owing to rain
                                                                                  2          0.99             0.00
                                                                                  4          0.46             0.00
                                                                                  7          0.26             0.00

                                           1.1 kg a.i./ha         1               0          10.9             0.02
                                                                                  1          Not sampled owing to rain
                                                                                  2          2.89             0.00
                                                                                  4          1.16             0.00
                                                                                  7          0.63             0.00

    Soybean      U.S.A.                    0.28 kg ai./           1               0          31.2             0.03
    plants       (Leuck and                ha                                     1          21.1             0.02
    (green       Bowman, 1968)                                                    2          15.0             0.01
    weight                                                                        4          2.45             0.00
    basis)                                                                        7          0.48             0.00
                                                                                  15         0.10             0.00
    TABLE 3. (Cont'd.)

                                                                                                                              

                                           Application
                                           rate
                                           g a.i./l           No. of          Pre-harvest       Residues at harvest
                                           unless otherwise   Applications    interval           mean (range) mg/kg
    Crop         Country                   stated                             (days)         Phosmet          0-analogue
                                                                                                                              

                                           0.56 kg a.i./ha        1               0          55.4             0.07
                                                                                  1          30.2             0.03
                                                                                  2          27.6             0.02
                                                                                  4          6.27             0.00
                                                                                  7          1.24             0.00
                                                                                  15         0.28             0.00

                                           1.1 kg a.i./ha         1               0          82.2             0.11
                                                                                  1          55.4             0.07
                                                                                  2          43.8             0.04
                                                                                  4          14.7             0.01
                                                                                  7          2.62             0.00
                                                                                  15         0.76             0.00

                                                                                                                              

    

    Other fruits

         Trials in New Zealand on Kiwifruit and grapefruit yielded the
    residue data given in Table 3. In most cases the spray concentration
    was slightly above the recommended upper limit of 0.1% a.i., but only
    for the highest rate of application to Kiwifruit (7 applications of
    0.112% a.i.) were residues in the whole fruit found to be above the
    national tolerance of 10 mg/kg after the recommended 10-day waiting
    period. Separate analyses of the skin and flesh revealed that the
    residues were mainly concentrated in the skin. Four applications of
    0.112% a.i. spray to grapefruit resulted in a residue of only 0.3
    mg/kg in the whole fruit (0.05 mg/kg in the flesh) after the
    recommended 14 day interval.

    Alfalfa

         In 1965, experiments were conducted in the United States to
    determine the rate of disappearance of phosmet from alfalfa. An ec
    formulation containing 36% a.i., w/v, was applied at the rate of 1.1
    kg a.i./ha. Residues were determined by the anthranilic acid
    colorimetric method over a period of 3 weeks after application. The
    results are given in Table 3, and show that the phosmet residues had
    declined to the levels found in untreated control samples after 21
    days (Shaw et al., 1966).

         In a subsequent trial on alfalfa (Miller et al., 1969), the
    disappearance rates of phosmet after application in two different
    formulations (the 36% ec and a 50% wp) were compared. Each formulation
    was applied at the rate of 0.5 and 1 lb a.i./acre in a dilute spray
    used at 100 gallons per acre. Each treatment was replicated twice, and
    the crop was sampled over a 3 week period after treatment. The results
    are summarised in Table 3.

         In the USSR, the feeding of rabbits with alfalfa gathered 10 days
    after it had been sprinkled with phosmet produced some depression of
    cholinesterase activity. When the alfalfa was gathered 15 days after
    treatment no depression was observed, and the residue level had
    declined to 1/6 of that found 11 days after treatment and 1/15 of that
    found 6 days after treatment (Semerdzhyan, 1972).

    Other forage crops

         Trials were conducted in the U.S.A. in which maize (for silage),
    soybean plants, and coastal Bermuda grass were each sprayed at rates
    of 0.28, 0.56 and 1.1 kg of phosmet per ha. Residues of phosmet and
    its oxygenanalogue were determined in samples taken over a 15 day
    period following treatment (Leuck and Bowman, 1968). The results are
    given in Table 3, and indicate that in all cases the residues had
    declined to under 1 mg/kg in 15 days or less. On the other hand, in a
    trial on Coastal Bermuda grass at the Texas Agricultural Experiment
    Station, in which phosmet was applied at 0.84 kg/ha, residues of about
    8 mg/kg were found after 14 days (Dorough et al., 1965).

         Leuck and Bowman analysed the concentrate used in their trial,
    and found that it contained a trace of the oxygen-analogue equivalent
    to 0.12% of the phosmet content. Thus some, at least, of the
    0-analogue residues found probably originated from the spray liquor
    rather than from environmental oxidation of phosmet.

    FATE OF RESIDUES

    General comments

         The results presented in the foregoing section indicate that both
    phosmet and its oxygen analogue are of low persistence in plants and
    animals. The photochemistry of phosmet in diethyl ether solution was
    studied by Tanabe et al. (1974), using a 450 watt UV lamp. They
    isolated N-methylphthalimide and N-methoxymethylphthalimide as
    photolysis products in low yield. Neither of these was insecticidally
    active. No photoproduct containing P or S could be isolated from the
    many minor components. Using UV radiation in the range 250-400 nm,
    Klisenko and Pis'mennaya (1973) found a half-life of 70 minutes for
    phosmet, and identified phthalimide, N-methoxymethylphthalimide and
    phthalic acid as photolysis products, in addition to P-O analogues.

    In animals

         The metabolism of carbonyl-14C-labelled phosmet in rats
    following oral administration was investigated by McBain et al.
    (1968). Metabolites were excreted in the urine in the following
    amounts (expressed as percentages of the administered dose): phthalic
    acid 21.0%, phthalamic acid 40.7% and five minor metabolites
    containing the phthaloyl moiety 10.9%. Not more than 0.04% of the dose
    administered was excreted in the urine as unchanged phosmet or its
    oxygen analogue. This study supported other evidence that phosmet is
    rapidly metabolised in mammals, mainly to innocuous water soluble
    compounds. For example, Chamberlain (1965) studied the fate of
    14C-labelled phosmet following dermal application to a steer. It was
    moderately absorbed by the skin of the animal, since 9.6% of the
    applied dose was recovered in the excreta (nearly 8% in the urine)
    within 7 days. It appeared that the compound was rapidly broken down
    in the blood, and that the primary degradation occurred at the
    nitrogen atom, resulting in the almost exclusive production of
    phthalic and phthalamic acids.

         Johnson and Bowman (1968) found no detectable residues of phosmet
    or its oxygen analogue in the milk, urine or faeces of lactating dairy
    cows fed with silage containing phosmet at a level providing 0.22
    mg/kg/ day. Detection limits were 0.002 mg/kg for milk and urine, and
    0.004 mg/kg for faeces.

         Tests under laboratory conditions in the USSR (Vrochinskii, 1971)
    showed that phosmet was stored only briefly by fish.

    In plants

         Trials on apples, peaches, lemons and potatoes showed that
    neither phosmet nor its oxygen analogue is translocated from treated
    to untreated portions of plants. Residues tend to remain on plant
    surfaces and are easily brushed or washed off. They are degraded quite
    rapidly by weathering.

         Phosmet is hydrolysed in plant tissues and converted to phthalic
    acid and/or phthalamic acid which is translocated in the plant,
    decarboxylated, apparently by enzyme action, and further metabolised
    to possible benzoic acid derivatives.

         On apples, pears and peaches, the average half-life of phosmet
    appears to be less than two weeks. The disappearance of residual
    phosmet from standing corn plants was found to be rapid, but after
    ensiling, the loss of phosmet was slow (about 50% loss in 92 days).
    The acid conditions in the silage stack probably protected the phosmet
    against spontaneous hydrolysis.

         Kovac et al. (1968) reported the rapid decomposition of phosmet
    to non-toxic substances in fruit and vegetables. After treatment with
    a 0.25% phosmet spray, residue levels declined to 0.75 mg/kg in 1-12
    days. In experiments on beet, carrots and tomatoes grown on a loamy
    soil in the USSR, Boiko and Popova (1970) found no residues of phosmet
    30-35 days after treatment with sprays of up to 0.6% a.i.
    concentration.

    In soils

         Phosmet and its oxygen analogue are rapidly degraded in soils.
    Degradation is favoured by increasing alkalinity and moisture content
    and is less in autoclaved soil samples, indicating that hydrolysis of
    phosmet is not dependent on moisture alone, but is due in some degree
    to microbial action. The time for 50% degradation varied from 3 days
    in a non-autoclaved loamy soil containing 10% moisture, to 19 days in
    the same soil with only 2% moisture. It is stated that the phthalic
    acid produced is readily metabolised and utilised by micro-organisms
    so that phosmet represents a totally biodegradable pesticide leaving
    no unmetabolisable residues in the environment (Snelson, 1976). The
    vapour pressure of phosmet is fairly high, and under laboratory
    conditions it has been shown to evaporate rapidly from peat soils, but
    not from sandy soils (Zatserkovskaya, 1974).

    In storage and processing

         The effect of the washing, blanching and sterilisation operations
    used in the canning industry on phosmet deliberately added to apples,
    plums, cabbage, pears, green peas and red beet (by dipping them in a
    0.4% aqueous dispersion of phosmet) has been studied in the USSR
    (Gorelik et al., 1973a). Washing with 5 parts of a 0.5% NaOH solution
    to one part of fruit reduced the phosmet content of apples and plums

    by 50-55%. Blanching at 80C with a liquid/fruit ratio of 5:1 removed
    55% and 81% respectively of the initial phosmet loading of plums and
    apples. The rate of phosmet destruction by sterilisation varied from
    60% to 100% in a range of commodities, and about 38% in cabbage. No
    phosmet residues were detected in canned apples and plums after
    storage at 20C for 12 months.

         Similar studies were made of the effect of such processing on
    phosmet residues in apples used for production of canned apple puree
    as a baby food (Gorelik et al., 1973b). Blanching, crushing and
    sterilisation reduced the residue level by 51%, 28% and 16-25%
    respectively. The same workers studied the effects of deep freezing on
    the residue dynamics of phosmet in carrots, cabbage and beet. It was
    found that even prolonged deep freezing resulted in negligible
    reductions of phosmet residues, and it was concluded that vegetables
    containing phosmet in excess of the USSR tolerance of 0.25 mg/kg
    should not be frozen prior to processing.

    Evidence of residues in food in commerce or at consumption

    No data were available.

    METHODS OF RESIDUE ANALYSIS

    Colorimetric methods

         Much of the earlier work on residues resulting from supervised
    trials was carried out using colorimetric procedures which determine
    either the phthalimide moiety after conversion to anthranilic acid or
    the phosphorodithioate moiety after conversion to phosphomolybdate.
    The anthranilic acid method (Batchelder and Patchett, 1965) is the
    more sensitive and specific of the two. Both methods are described in
    detail by Batchelder et al.(1967), who also give typical figures for
    the recovery of phosmet by these methods from various crops and animal
    tissues. The anthranilic acid method is claimed to detect 2 micrograms
    of phosmet reliably (giving a detection limit of 0.04 mg/kg for a 50
    gram sample), and is applicable to animal or plant tissues. It will
    also detect the oxygen analogue but is susceptible to interference
    from folpet or azinphos-methyl. These compounds do not interfere with
    the phosphomolybdate method, which includes a selective hydrolysis
    step.

         An alternative colorimetric procedure for determining the
    phosphorodithioate moiety (Sharova and Kozhemyakin, 1973) involves the
    formation of a yellow complex with copper sulphate, and has been
    applied to the determination of phosmet residues in the tissues of
    birds, with a detection limit of 0.5 mg/kg.

         A method involving the liberation of formaldehyde by acid
    hydrolysis of phosmet, and colour development with chromotropic acid,
    has been applied to the measurement of phosmet residues in water, with

    a detection limit of 0.01 mg/l (Novikova and Varlamova, 1973), and in
    apples, with a detection limit of 0.5 mg/kg (Novikova et al., 1969).

    Thin-layer chromatographic methods

         Phosmet can be determined at the residue level by several of the
    methods involving in situ fluorimetry on thin-layer chromatograms
    which have been evolved for organophosphorus pesticides. For example,
    Frei and Mallet (1971) used a chelate spray reagent consisting of a
    1:2 mixture of salicyl-2-aldehyde-2-quinolylhydrazone and manganese
    (II) chloride, which was applied after exposure of the plate to
    bromine. They claim a visual detection limit of 0.04 g phosmet.
    Bidleman et al. (1972) used fluorescence quenched solutions of
    palladium (II) - calcein and palladium(II)-calcein blue as sensitive
    spray reagents for the in situ fluorometric determination of
    organophosphorus pesticides including phosmet, and reported that as
    little as 10.50 ng of a phosphorodithioate could be detected.

         Methods have also been described in which thin-layer
    chromatography is used as a clean-up procedure for phosmet residues
    extracted from foods prior to determination of the eluted pesticide by
    one of the colorimetric procedures referred to above. An example is
    the method of Novikova and Mel'tser (1972), which uses the chromotopic
    acid procedure after clean-up on silica gel plates. This method had a
    detection limit of 0.6 mg/kg for phosmet residues in foods of plant
    origin. Alternatively, the phosmet spot could be visualised on the
    plate by spraying with bromophenol blue and silver nitrate, giving a
    visual detection limit of 0.3 mg/kg.

         Phosmet is also detectable on TLC plates by enzyme inhibition
    methods. For example, Schutzmann and Barthel (1969) reported detection
    limits of 0.5 g and 0.05 g for phosmet and its oxygen analogue
    respectively, using horse serum cholinesterase with indoxyl acetate as
    substrate. Schutzmann (1970) reported that the sensitivity of the
    method could be improved by using either the acetate or butyrate of
    N-methyl indoxol as substrate. Ackermann and Engst (1970) used beef
    liver esterase with 1-napthyl acetate and Fast Blue B on silica gel G
    plates to detect organophosphorus residues in rat foetal tissues. They
    were able to detect 0.025 mg/kg of phosmet and 0.005 mg/kg of its
    0-analogue by this method.

    Gas chromatographic methods

         Some early gas chromatographic determinations of phosmet residues
    made use of the electron capture detector (ECD). For example, Bowman
    and Beroza (1965) were able to determine phosmet (but not the
    0-analogue) in milk and sweet corn by using the ECD, and Gutenmann et
    al. (1965) applied it to the determination of phosmet (detection limit
    0.1 mg/kg) and the O-analogue (0.2 mg/kg) in apples, potatoes, grapes
    and alfalfa following a TLC clean-up.

         Later methods have made use of either an alkali flame ionisation
    detector (AFID) giving selective detection of phosphorus compounds, or
    a flame photometric detector (FPD) operated in either the phosphorus
    or the sulphur mode. Bowman and Beroza (1966) used the FPD with a
    526 nm phosphorus filter to determine phosmet (detection limit 0.002
    mg/kg) and the 0-analogue (0.004 mg/kg) in sweet corn, following
    clean-up and separation on a silica gel column. The glc column packing
    was 10% DC 200 on 80/100 mesh Gas Chrom Q. The column was operated at
    200C, and required conditioning with repeated injections of phosmet
    and corn extract to obtain a constant response to the insecticide. The
    same column packing was used by Watts and Storherr (1967) in
    conjunction with an AFID for the determination of phosmet and other
    organophosphorus insecticide residues in milk after a sweep
    codistillation clean-up. They too found the need for thorough column
    conditioning. Storherr et al. (1967) used essentially the same
    procedure to determine organophosphorus pesticides including phosmet
    in fortified samples of edible oils. The average recovery for phosmet
    was 96%, and the method detected apparent levels in unfortified
    samples ranging from less than 0.01 to 0.04 mg/kg.

         Bowman and Beroza (1967) were able to determine phosmet extracted
    from milk (in hexane/ether) without clean-up by using the FPD with a
    394 nm sulphur filter. Bowman et al. (1968) investigated several
    alternative extraction procedures for removing OP residues (including
    phosmet and its O-analogue) from field treated crops, and found the
    most efficient method to be soxhlet extraction for 4 hours with 10%
    methanol in chloroform. Determination was by gas chromatography with
    flame photometric detection using a phosphorus filter.

         A gas chromatographic method employing the AFID (with rubidium
    sulphate as alkali source) and a short, narrow bore column containing
    10% DC 200 on 100/120 mesh Gas Chrom Q has been described by Barney et
    al. (1972). For most crops, clean-up is achieved simply by shaking
    with charcoal followed by filtration through a Millipore filter.
    Cottonseed and cotton foliage require prior acetonitrile partition.
    The lower limit of detection is given as 0.05 mg/kg and the method has
    been successfully applied to a range of fruit, vegetable and fodder
    crops. The authors state that the FPD in either the P or S mode may be
    used instead of the AFID, but stress the importance of the small
    particle size of the solid support to ensure adequate resolution of
    the oxygen analogue from phosmet.

         Several multi-residue gas chromatographic procedures which
    include phosmet have been published recently. Some examples are:

    (a)  The method of Ripley et al. (1974) for OP residues in natural
         waters (using the FPD).

    (b)  The method of Luke et al. (1975) for OP and nitrogen containing
         pesticides in produce (using the AFID with a potassium chloride
         source).

    (c)  The method of Krijgsman and Van de Kamp (1976) which utilises a
         capillary column of SE-30 with a flame photometric detector.

    NATIONAL TOLERANCES REPORTED TO THE MEETING

         The national tolerances shown in Table 4 have been reported to
    the Meeting.

    
    TABLE 4. National tolerances reported to the Meeting

                                                                                      
                                             Pre-harvest
                                             interval,      Tolerance,
    Country        Crop                      days           mg/kg         Reference
                                                                                      

    Australia      Fat of meat of cattle                    1             Snelson
                   Milk and milk products                                 1976
                   (fat basis)                              0.2           "

                   Pome and stone fruit                     1             "

    Canada         Apples, peaches and
                   pears                                    10

                   Plums                                    5

    Netherlands    Apples, pears             21             1

                   Potatoes                  28             0.02

    New Zealand    Fruit                     14             10
                   (Kiwifruit                10)

    USA            Alfalfa                                  40            Anon, 1969

                   Apples, peaches & pears                  10            "

                   Meat & fat of cattle,
                     goats, hogs & sheep                    0.2           Anon, 1969

                   Grapes                                   10            Anon, 1971a

                   Cherries                                 10            Anon, 1971b

                   Apricots, nectarines
                     and plums                              5             "     "

    TABLE 4. (Cont'd.)

                                                                                      
                                             Pre-harvest
                                             interval,      Tolerance,
    Country        Crop                      days           mg/kg         Reference
                                                                                      
                   Potatoes                                 0.1           Anon, 1971c

                   Sweet potatoes (from
                     post-harvest application               10            Anon, 1973



                   Almond hulls, blue berries,
                     corn forage and fodder
                     (including sweet corn,
                     field corn and popcorn),
                     cranberries, pea forage
                     and hay                                10            Anon, 1975

                   Fresh corn, including sweet
                     corn (kernel and cob with
                     husk removed), corn grain
                     (including popcorn), and
                     peas                                   0.5           Anon, 1975

                   Meat, fat and meat by-products
                   of horses                                0.2           Anon, 1975

                   Nuts                                     0.1           Anon, 1975

    USSR           Vegetables                               0.25          Gorelik et
                                                                          al, 1973b

                   Figs                                     0.25          Popov, 1973
                                                                                      
    

    APPRAISAL

         As a systemic insecticide and acaricide against a range of
    ectoparasites of animals, phosmet may be applied as a dilute aqueous
    spray containing up to 0.5% a.i., as a ready-to-use "pour on"
    formulation containing up to 4% a.i. and applied at up to 40 mg per kg
    body weight, as a dust containing 1 to 2% a.i., or it may be
    administered orally.

         In plants, phosmet is used as a non-systemic pesticide and is
    applied to a variety of crops to protect against insects and mites. At
    the concentrations usually applied it can be effective without harming
    some useful predators and this makes it of value for integrated
    control programmes. On fruit, a 0.1% spray has been used on pasture
    and forage crops up to 0.75 kg/ha, and on cereal crops at 35 g/ha (ULV
    spray). It has been used at 3-5 kg/ha on cotton.

         Data available on residues in meat of cattle is not extensive,
    but would be in accord with a maximum level of 0.2 mg/kg. Applied as a
    spray to apples and peaches, residues are generally less than 1 mg/kg
    after a 3 weeks preharvest period. On forage crops, application of
    phosmet at 1 kg a.i./ha produced residues of the order of 50 mg/kg
    which declined to less than 5 mg/kg after 14 days. Because phosmet is
    not excreted in the milk, cattle can graze recently treated pastures.

         Both phosmet and its oxygen analogue are of low persistence in
    plants and animals. In mammals phosmet is rapidly metabolised, mainly
    to innocuous water-soluble compounds. The metabolites principally
    excreted are phthalic acid and phthalamic acid with only minute traces
    of phosmet or its oxygen analogue.

         Plants treated with phosmet tend to retain it on the surface
    where it is washed off or weathered. In plant tissues conversion to
    phthalic or phthalamic acid again takes place and these undergo
    further breakdown.

         Phosmet and its oxygen analogue are rapidly degraded in soils,
    degradation being favoured by increasing soil alkalinity and moisture
    content. Apart from simple chemical hydrolysis, metabolism by
    microorganisms also occurs and it has been stated that phosmet is
    totally biodegradable.

         Processing in the canning industry by washing with dilute alkali,
    bleaching or sterilising will remove at least 50% of the phosmet from
    fruit and vegetables.

         Several analytical methods suitable for regulatory purposes are
    available. These include a colorimetric method which determines the
    phthalimide moiety after conversion to anthranilic acid and gas
    chromatographic methods with either an alkali flame ionisation or a
    flame photometric detector. There is also an enzyme inhibition.

    REFERENCES

    Ackermann, H., and Engst, R. Occurrence of organophosphorus
    1970                insecticides in the foetus. Arch. Toxikol., 26:17.

    Adeishvili, L.G. Pesticide residues in apple fruits. Tr.
    1973                Nauchno-Issled. Inst. Zashch. Rast (Toflis),
                        25:3-5.

    Ali Niazee, M.T., and Stafford, E.M. Management of grape pests in
    1973                Central California vineyards. I. Cultural and
                        chemical control of Patynota stultana on
                        grapes. J. Econ. Entomol., 66 (1): 154-7

    Andrichuk, B.V. Phthalophos as an acaricide for the control of
    1971a               sheep psoroptosis. Tr. Yses. Nauch-Issled. Inst.
                        Vet. Sanit., 38: 264-70

    Andrichuk, B.V. Acaricidal dusts for the control of sheep
    1971b               psoroptosis. Tr. Vses. Nauch-Issled. Inst.Vet.
                        Sanit., 39: 363-8

    Anon. (Environmental Protection Agency, Washington, D.C.)
    1969                N-(mercaptomethyl) phthalimide S-(O,O
                        -dimethyl phosphorodithioate) and its oxygen
                        analog; tolerances for residues. Federal Register,
                        34 (63): 6041.

    1971a               Ibid., 36(59); 5690.

    1971b               Ibid., 36(132): 12898-9

    1971c               Ibid., 36 (152): 14471-2

    Anon. (Food Drug Administration, Washington, D.C.) New animal
    1971d               drugs for ophthalmic and topical use.
                        N-(mercaptomethyl) phthalimide S-(O,O-dimethyl
                        phosphorodithioate). Federal Register, 36(231):
                        22829.

    Anon. (Environmental Protection Agency, Washington, D.C.)
    1973                N-(mercaptomethyl) phthalimide
                        S-(O,O-dimethylphosphorodithioate) and
                        residues. Federal Register, 38(55): 7459-60.

    Anon. (Food Drug Administration, Washington, D.C.) New animal
    1974                drugs for ophthalmic and topical use.
                        N-(mercaptomethyl) phthalimide
                        S-(O,O-dimethylphosphorodithioate). Federal
                        Register, 39(172): 32025-6.

    Anon. (Environmental Protection Agency, Washington, D.C.)
    1975                N-(mercaptomethyl) phthalimide S.(O,O-
                        dimethyl-phosphorodithioate) and its oxygen
                        analog; tolerances for residues. Federal Register,
                        40(48): 11352-3.

    Barney, J.E., Ja, W.Y., and Shelman, D.L. Analytical method:
    1972                for pesticides, plant growth regulators and food
                        additives. (Academic Press, Ed. G. Zweig and J.
                        Sherma), Vol. VI, pp. 408.134

    Batchelder, G.H., and Patchett, G.G. American Chemical Society,
    1965                149th Meeting, Division of Agriculture and Food
                        Chemistry, Paper No. 37.

    Batchelder, G.H., Patchett, G.G., and Menn, J.J. Analytical
    1967                methods for pesticides, plant growth regulators
                        and food additives (Academic Press, Ed. G. Zweig),
                        Vol. V, pp. 257-275.

    Bidleman, T.F., Nowlan, B., and Frei, R.W. Metallofluorescent
    1972                indicators as spray reagents for the in situ
                        determination of organophosphorus pesticides in
                        thin layer chromatograms. Anal. Chim. Acta, 60(1):
                        13-23.

    Boiko, I.B., and Popova, N.G. Effect of some organophosphorus
    1970                pesticides on the biological value of vegetable
                        crops. Med. Zh. Uzb., 9: 35-7.

    Bowman, M.C., and Beroza, M. Analysis of Imidan colorimetrically
    1965                and by electron-affinity gas chromatography. J.
                        Assoc. Offic. Anal. Chem., 48(5): 922-6.

    Bowman, M.C. and Beroza, M. Determination of Imidan and Imidoxon
    1966                in sweet corn by gas chromatography with flame
                        photometric detection. J. Assoc. Offic. Anal.
                        Chem., 49(6): 1154-1157.

    Bowman, M.C. and Beroza, M. Note on extraction of a polar insecticide
    1967                (Imidan) from milk. J. Assoc. Offic. Anal. Chem.,
                        50(4): 940-941.

    Bowman, M.C., Beroza, M., and Leuck, D.B. Procedures for extracting
    1968                residues of phosphorus insecticides and
                        metabolites from field treated crops. J. Agr. Food
                        Chem., 16(5): 796-80.

    Butt, B.A., White, L.D., Moffit, H.R., Hathaway, D.O., and
    1973                Schoenleber, L.G. Integration of sanitation,
                        insecticides, and sterile moth releases for
                        suppression of populations of codling moths in the
                        Wenas Valley of Washington. Environ. Entomol.,
                        2(2): 208-13.

    Chamberlain, W.F. A study of the dermal treatment of a 1965 steer
                        with C14-labelled Imidan. J. Econ. Entomol.,
                        58(1):51-55.

    Chirikashvili, R.V., Abbasov, T.G., and Frolov, B.A. Duration
    1970                of persistence of phthalophos in organs and
                        tissues of hens during oral administration. Tr.
                        Vses. Nauch-Issled. Inst. Vet. Sanit., 37: 175-8.

    Del Rivero, J.M., Lafuente, M., and Lazaro, E. New products
    1971                for control of the potato beetle, Leptinotarsa
                        decemlineata, resistant to chlorinated
                        insecticides. An. Inst. Nac. Invest. Agr. (Spain),
                        Ser. Prot. Veg. (1): 183-7.

    Dorough, H.W., Randolph, N.M., and Wimbish, G.H. Imidan, and
    1965                trichlorfon residues on Coastal bermudagrass.
                        Texas A&M University/Texas Agricultural Experiment
                        Station. Progress Report PR-2385.

    Drumond, R.O., Ernst, S.E., Trevino, J.L., Gladney, W.J., and
    1972                Graham, O.H. Boophilus annulatus and B.
                        microplus. Sprays and dips of insecticides for
                        control on cattle. J. Econ. Entomol., 65(5):
                        1354-7.

    Forsythe, H.Y., and Hall, F.R. Control of the plum Curculio in
    1972                Ohio. J. Econ. Entomol., 65(6): 1703-6.

    Frei, R.W., and Mallet, V. Quantitative thin-layer chromatography
    1971                of organothiophosphorus pesticides by in situ
                        fluorimetry. Intern. J. Environ. Anal. Chem., 1:
                        99.

    Frolov, B.A. Activity of some organo-phosphorus and carbamate
    1970                compounds for fowl ectoparasites. (Argas
                        persicus and Cimex lectularius) Tr., Vses.
                        Nauch-Issled. Inst. Vet. Sanit., 37: 334-43

    Gorelik, L.D., Kushchinskaya, In.N., and Nemets, S.M. Effect
    1973a               of technological conditions on the content of
                        phthalophos in canned food. Konserv. Ovoshchesush.
                        Prom. 4: 8-10.

    Gorelik, L.D., Kushchinskaya, I.N., and Sazonova, A.R. Lowering
    1973b               the phthalophos level during the preparation of
                        canned apple sauce. Konserv. Ovoshchesush. Prom.
                        7: 21-3.

    Gribkova, N.I. Effectiveness of insecticides against leaf-miner
    1973                moths. Khim. Sel. Khoz., 11(8):592-4.

    Gutenmann, W.H., Bache, C.A., and Lisk, D.J. Determination
    1965                of Imidan and Imidoxon in crops by preparative
                        thin layer and by gas chromatography. J. Gas
                        Chromat., 3: 350-52.

    Holdsworth, R.P. Realities of integrated insect control.
    1973                Proc. Ohio State Hort. Soc., 126: 89-92.

    Ionova, I., Zhecheva, G., and Dimitrov, K. Residual amounts
    1974                of Sevin, Neguvon, and Imidan in the meat of pigs
                        treated against ectoparasites. Vet-Med Nauki,
                        11(5): 28-34.

    Johnson, J.C., and Bowman, M.C. Fate of Bidrin and Imidan
    1968                when fed in silage to lactating dairy cows. J.
                        Dairy Science, 51(8): 1225-8.

    King, N.L., and Best, D.R. Unpublished report from Hawthorn Park
    1971                Research Laboratories Pty-Ltd. to Stauffer Chem.
                        Co. (Australia) Pty. Ltd.

    King, N.L., and Ferguson, A.B. Unpublished report from Hawthorn
    1971                Park Research laboratories Pty. Ltd. to Stauffer
                        Chem. Co. (Australia) Pty. Ltd.

    Klisenko, M.A., and Pis'mennaya, M.V. Effects of UV radiation
    1973                on dialkyldithiophosphate pesticides. Khim. Sel.
                        Khoz., 11(12): 916-8.

    Klunker, R. Current status of potato beetle control, especially
    1974                with respect to the resistance problem.
                        Nachrichtenbl. Pflanzenschutz DDR 28(9). 191-6.

    Kovac, J., Batora, V., Moracvik, J., and Benusova, M. Persistence
    1968                of O,O-dimethyl-S-(phthalimidomethyl)
                        dithiophosphate residues in vegetables and fruits.
                        Agrochimia (Bratislava), 8(3): 77-81.

    Krijgsman, W., and Van de Kamp. C.G. Analysis of organophosphorus
    1976                pesticides by capillary gas chromatography with
                        flame photometric detection. J. Chromat.,
                        117(1): 201-5.

    Large, G.B., and Pitt, L.S. Thiophosphate synergists. U.S. Patent
    1975                3, 886, 273, 27 May 1975, Stauffer Chemical Co.

    Leuck, D.B., and Bowman, M.C. Imidan insecticide residues
    1968                (Imidan and Imidoxon): their persistence in corn,
                        grass and soybeans. J. Econ. Entomol., 61(3).
                        705-7.

    Loomis, E.C., Noorderhaven, A., and Roulston, W.J. Control of
    1972                Southern cattle tick by pour-on animal systemic
                        insecticides. J. Econ. Entomol., 65: 1638-41.

    Luke, M.A., Froberg, J.E., and Masumoto, H.T. Extraction and
    1975                clean-up of organo-chlorine, organo-phosphorus,
                        organo-nitrogen and hydrocarbon pesticides in
                        produce for determination by gas-liquid
                        chromatography. J. Assoc. Offic. Anal. Chem.
                        58(5): 1020-6.

    Mardzhanyan, G.M., Semerdzhyan, O.G., Ust'yan, A.K. and Manukyan,
    1973                Z.S. Possibility of controlling Phytonomus with
                        organo-phosphorus insecticides. Izv. Sel'skokhoz.
                        Nauk, 16(11-12): 36-41.

    McBain, J.B., Menn, J.J., and Casida, J.E. Metabolism of
    1968                carbonyl-C14 labelled Imidan,
                        N-(Mercapto-methyl) phthalimide-
                        S-(O,O-dimethylphosphorodithioate), in rats
                        and cockroaches. J. Agr. Food Chem., 16(5):
                        813-820.

    Miller, M.C., Shaw, F.R., and Smith, C.T. The comparative residual
    1969                life of two formulations of Imidan on alfalfa. J.
                        Econ. Entomol., 62(3): 720-1.

    Mistric, W.J., and Smith, F.D. Organophosphorus and carbamate
    1970                insecticides as substitutes for DDT in controlling
                        the tobacco flea beetle on flue cured tobacco. J.
                        Econ. Entomol., 63: 509-11.

    Nakotomi, K., and Ishibe, K. (Hokko Chemical Industry Co. Ltd.)
    1975                Insecticidal synergism with acephate
                        phosphorothioate mixtures. Japanese Patent 75 71,
                        838, 14 June 1975.

    Nepoklonov, A.A., Nepoklonova, M.I., and Pavlova, N.V. Acaricidal
    1969                properties of phthalophos.Tr., Vses. Nauch-Issled.
                        Inst. Vet. Sanit., 34: 348-50.

    Nesterenko, N.I. Organophosphorus preparations used to control sugar
    1970                beet pests. Khim. Sel. Khoz., 8: 382-3.

    1973                Ibid., 11(2): 113-6.

    New South Wales Department of Agriculture. Extracts from the 1966-7
    1969                annual report of the Entomology Branch. PANS, 15
                        (2): 225.

    Nikiforov, A.M., and Mamaev, K.A. Testing of new chemical
    1972                preparations (cotton pesticides). Khlopkovodstvo,
                        8: 31-2.

    Novikova, K.F., and Mel'tser, F.R. Chromatophotometric method
    1972                for determining residual amounts of phthalophos in
                        food products of plant origin. Probl. Anal. Khim.,
                        2: 95-99.

    Novikova, K.F., Mel'tser, F.R., Makarova, S.V., and Navmova, V.A.
    1969                Spectrophotometric determination of residual
                        phthalophos in apples. Gig. Primen. Toksikol.
                        Pestits. Klin. Otravi, 7: 595-601.

    Novikova, K.F., and Varlamova, T.A. Spectrophotometric
    1973                determination of microgram quantities of
                        phthalophos and phosalone in natural waters.
                        Metody Opred. Pestits. Vode, 1: 98-103.

    Omarov, L.M. Phthalophos and Sevin dusts to control mites.
    1974                Veterinarya. 4: 37-8.

    Omelyuta, V.P. Effectiveness of insecticides against Grapholitha
    1972                molesta. Khim. Sel. Khoz., 10(7): 516-7.

    Otaci, C., Turhan, K., and Barkin, S. Imidan residues on peaches.
    1972                Bitki Koruma Bul., 12(1): 45-8.

    Pfadt, R.E., Lloyd, J.E., and Spackman, E.W. Power dusting with
    1975                organo-phosphorus insecticides to control the
                        sheep ked. J. Econ. Entomol., 68(4): 468-70.

    Popov, P.F. Effectiveness of different preparations against
    1973                caterpillars of fig Glyphipterygidae. Khim. Sel.
                        Khoz., 11(8): 595-6.

    Ripley, B.D., Wilkinson, R.J., and Chau, A.S.Y. Multi-residue
    1974                analysis of 14 organo-phosphorus pesticides in
                        natural waters. J. Assoc. Offic. Anal. Chem.,
                        57(5): 1033-42.

    Rogoff, W.M., Brody, G., Roth, A.R., Batchelder, G.H., Meyding,
    1967                G.D., Bigley, W.S., Gretz, G.H., and Orchard, R.
                        Efficacy, cholinesterase inhibition and residue
                        persistence of Imidan for the control of cattle
                        grubs. J. Econ. Entomol., 60(3): 640-6.

    Ruzimuradov, A., Valiev, B., and Matchanov, S. Test of insecticides
    1973                against pasture ground stable flies and gnats.
                        Mater. Konf. Molodykh. Uch. Uzb. Sel'sk Khoz. 7th
                        1972: 60-2. (Published in Veterinarya, 1973, ed.
                        by Sh. A. Azimov et al).

    Schutzmann, R.L. Note on improved spray reagents for TLC
    1970                fluorogenic detection of cholinesterase
                        inhibitors. J.Assoc. Offic. Anal. Chem., 53(5):
                        1056-7.

    Schutzmann, R.L., and Barthel, W.F. Indoxyl acetate spray reagent
    1969                for fluorogenic detection of cholinesterase
                        inhibitors in environmental samples. J. Assoc.
                        Offic. Anal. Chem., 52(1): 151-6.

    Semerdzhyan, O.G. Poisoning of rabbits fed Phthalophos treated
    1972                alfalfa. Izv. Sel'skokhoz. Nauk. 15 (6): 77-9.

    Sevost'yanov, A.Z., and Ushakova, N.N. Acaricidal effectiveness of
    1971                some pesticides against Ixodes mites during tests
                        in samples of sheep wool. Tr. Stavropol
                        Sel'skokhoz. Inst., No. 34 (Vol 4): 74-6.

    Shapovalova, G.K., Sedykh, A.S., and Abelentseva, G.M.
    1970                Effectiveness of using phthalophos and
                        benzophosphate to combat gooseberry moth
                        (Zophodia convolutella), and insecticide
                        residues on the berries. Khim. Sel. Khoz. 8(8):
                        594-5.

    Sharova, V.M., and Kozhemyakin, N.D. Photoelectro-colorimetric
    1973                determination of metaphos and phthalophos in
                        tissues of experimentally poisoned birds. Khim.
                        Sel. Khoz, 11 (3): 229-30.

    Shaw, F.R., Callahan, R.A., and Miller, M.C. Rates of disappearance
    1966                of Zolone and Imidan from alfalfa. J. Econ.
                        Entomol., 59(6): 1524-5.

    Snelson, J.T. Private communication from Department of Primary
    1976                Industry, Australia.

    Speirs, R.D., and Lang, J.H. Contact, residue and vapour toxicity
    1970                of new insecticides to stored products insects.
                        II. USDA Agricultural Research Service, Marketing
                        Research Report No. 885.

    Storherr, R.W., Murray, E.J., Klein, I., and Rosenberg, L.A.
    1967                Sweep co-distillation clean-up of fortified edible
                        oils for determination of organo-phosphate and
                        chlorinated hydrocarbon pesticides. J. Assoc.
                        Offic. Anal. Chem., 50(3): 605-15.

    Surorov, P.S. Acaricidal effect of ciodrin, phthalophos and
    1970                chlorophos on cutaneous mites, cattle psoroptosis
                        causative agents. Tr., Vses. Nauch Issled. Inst.
                        Vet. Sanit., 35: 379-82.

    Tanabe, M., Dehn, R.L., and Bramhall, R.R. The photochemistry
    1974                of Imidan in diethyl ether. J. Agr. Food Chem.,
                        22(1): 54-6.

    Thomas, F.J.D., and Taylor, A.S. (ICI of Australia and New Zealand
    1971                Ltd.) Apparatus and compositions for controlling
                        cattle ticks. South African Patent 69 06, 036 22
                        February 1971.

    Uctani, T., Hirano, T., and Tsuchitate, M. (Kumiai Chem. Industry
    1974                Co. Ltd.) Acaricidal and insecticidal
                        compositions. Japanese Patent 74 15, 776, 17 April
                        1974.

    Van Cleave, H.V., and Anderson, A.L., Field control tests for pecan
    1971                insects. Proc. Tex. Pecan Grow. Ass.: 32-3

    Vernon, J.D.R., and Gould, H.J. Further trials on alternatives
    1972                to DDT for the control of pre-blossom pests on
                        apple and pear. Plant Pathol., 21(1). 1-9.

    Vrochinskii, K.K. Accumulation of pesticides in hydrobiocts
    1971                as a measure for evaluating experimental water
                        toxicology. Eksp. Vod. Toksikol. 149-63.

    Watts, R.R., and Storherr, R.W. Sweep do-distillation clean
    1967                up of milk for determination of organophosphate
                        and chlorinated hydrocarbon pesticides. 50(3):
                        581-5.

    Wilde, W.H.A. Low volume concentrate spraying and integrated 1973
                        control in some Ontario orchards. Proc. Ohio State
                        Hort. Soc. 126: 85-8.

    Witkowska, D., and Wojnarowska, P. Effectiveness of some chemical
    1971                preparations against Anthonomus pomorum (apple
                        weevil). Biol. Inst. Ochr. Rosl. (48): 357-66.

    Woodard Research Corporation. Unpublished report.
    1963

    Zatserkovskaya, G.A. Evaporation of insecticides from different
    1974                types of soils. Zashch. Rast (Kiev), 20: 61-6.
    


    See Also:
       Toxicological Abbreviations
       Phosmet (ICSC)
       Phosmet (JMPR Evaluations 2003 Part II Toxicological)
       Phosmet (Pesticide residues in food: 1978 evaluations)
       Phosmet (Pesticide residues in food: 1979 evaluations)
       Phosmet (Pesticide residues in food: 1981 evaluations)
       Phosmet (Pesticide residues in food: 1984 evaluations)
       Phosmet (Pesticide residues in food: 1994 evaluations Part II Toxicology)