MEVINPHOS                                       JMPR1972


    This pesticide was evaluated toxicologically by the 1965 JointMeeting
    (FAO/WHO, 1965). Since this evaluation the results of someadditional
    experimental work have been reported.


    Chemical name

         dimethyl 2-methoxycarbonyl-1-methylvinyl phosphate


         2-carbomethoxy-1-methylvinyl dimethyl phosphate, alpha isomer;

         1-methoxycarbonyl-1-propen-2-yl dimethyl phosphate

         Phosdrin insecticide(R), Phosdrin(R), OS-2046

         In the reports provided to the Meeting several other chemical
         names are used for this compound, slightly different fromthose
         mentioned above.

    Structural formula


             Mevinphos is comprised of two geometric isomeric forms. Thecis
         isomer possesses higher insecticidal activity than thetrans
         isomer. At least 60% of cis-isomer is in the technical

    Other information on identity and properties

    Analysis of a typical sample of technical mevinphos(Phosdrin(R)) gave
    the following results:

                                                 % w

         cis-mevinphos                            62

         trans-mevinphos                          28

         methyl aceto acetate                      2

         methyl-2-chloro aceto acetate             2

         dimethyl methyl phosphonate               2

         others (less than 1% w each)              4

    Physical and chemical properties of technical mevinphos(Phosdrin(R))

         Physical state:     liquid

         colour:             pale yellow

         Boiling range       99-103° C at 0.3 mm Hg

         Vapour pressure:    1.24 x 10-4 mm Hg at 20° C

         Solubility:         miscible with water, acetone, carbon
                             tetrachloride, chloroform, ethyl-,
                             isopropyl- and methyl alcohols, benzene,
                             toluene, xylene and other highly aromatic
                             petroleum fractions. Slightly soluble in
                             carbon disulfide and kerosene.

         Stability:          stable under normal storage conditions.
                             Decomposed at high temperatures.

         Hydrolysis:         mevinphos is hydrolysed in aqueous                             The rate of hydrolosis is increased in
                             alkaline solutions. At room temperatureand
                             pH 8 the half-life of mevinphos is 21 days,
                             at pH 11 only 1.4 hours.

         Compatibility:      mevinphos is compatible with mostpesticides.



    Absorption and distribution

    Mevinphos is rapidly excreted by cattle. Milk from a cow dosed with 2
    mg/kg (32P) mevinphos (80% cis, 20% trans isomer)contained 0.06
    ppm after 6 hours and only 0.007 ppm after 96 hours. Milk from a cow
    receiving 1 mg/kg/day for 7 days produced milk containing
    approximately 0.05 ppm up to 14 days after dosage; this probably
    consisted mainly of the trans isomer. Milk and tissues from
    cattle receiving up to 20 ppm mevinphos in the diet for 12 weeks
    contained less than 0.03 ppm (Casida et al., 1958).


    The main metabolite of both isomers in plants is dimethylphosphate,
    although this is formed less rapidly from the trans- than from
    the cis- isomer (Casida et al., 1956; Spencer and Robinson,1960).
    Trans- mevinphos is degraded faster than the cis- isomer by mouse
    liver homogenates; this was shown to be due to involvement of two
    enzyme systems (Morello et al., 1968). The cis- isomer is
    0-demethylated by a glutathione-dependent soluble enzyme, whereasthe
    trans- isomer is hydrolysed at the P-O bond by a 
    non-glutathione- dependent enzyme (Morello et al., 1967; Hutson
    et al.,1972). Cis- desmethyl-mevinphos and dimethyl phosphate
    were identified in mouse liver as the main metabolites of the
    cis-  and trans- isomers, respectively (Morello et al., 1967;

    Effects on enzymes and other biochemical parameters

    The cis form is about 100 times more active than the transform in
    inhibiting bovine RBC and mouse brain cholinesterases (Morello
    et al., 1967).


    Special studies on reproduction

    In a three-generation study, groups of 10 male and 20 female rats
    received diets providing 0, 0.06 and 1.2 mg/kg body-weight/day
    approximately of mevinphos (60% iso-isomer, 40%trans-isomer).
    Each generation was bred twice. No effects were noted on fertility,
    gestation, lactation and viability of young at the 0.06 level. In the
    1.2 mg/kg group the lactation index was reduced. No gross
    abnormalities were observed in the pups of these litters examined
    (Estep et al., 1967).

    Special studies on neurotoxicity

    Technical mevinphos was administered by gavage to groups of six hens
    pre-medicated with atropine sulphate and protopam sulphate. The test
    group received 7.5 mg/kg on two occasions, each dose separated by an
    interval of three weeks. A positive control group received
    triorthophenyl phosphate (0.5 mg/kg). No signs of neurotoxicactivity
    were evident in test and negative control groups. Positive controls
    developed ataxia and the histological examination of the sciatic
    nerve showed swollen oxons, myelin degeneration and fragmentation of
    the axis cylinders (Natoff et al., 1972).

    Acute toxicity

    Acute toxicity of mevinphos has been studied in the rat, (Simpson
    et al., 1972). Results of these studies are summarized in
    Table 1.

    TABLE 1

    Acute toxicity of mevinphos in the rat


    Material          Species        LD50         References

    Technical         Rat            1.4            Simpson et al.,
    mevinphos                                       1972.

    Cis-mevinphos     Rat            1.4            Ibid.

    Trans-mevinphos   Rat            81.8           Ibid.

    Short-term studies

    Rat (technical mevinphos)

    Groups of 12 male and 12 female rats received technical mevinphos in
    the diet at 0, 0.1 and 12.5 ppm for 13 weeks. Reduction of plasma, RBC
    and brain cholinesterase activities occurred in the 12.5 ppm female
    group and of plasma and RBC cholinesterase activities in the male
    group of the same dietary level. The male rats of this group also
    exhibited slightly reduced body-weights. At the 0.1 ppm level the
    exposed and control animals did not differ in relation to body-weight,
    food intake, organ weights, pathology, haematology and clinical
    chemistry tests (Simpson et al., 1972).

    Rat (cis-mevinphos)

    Groups of 12 males and 12 females received cis-mevinphos in the diet
    at 0, 0.1 and 12.5 ppm for 13 weeks. Significant reductions of the
    cholinesterase activity were found in the plasma, RBC and brain of
    male and female rats receiving 12.5 ppm. The plasma cholinesterase
    level was also reduced at 0.1 ppm, in the females only. Other
    parameters were similar in the exposed and control animals (Simpson
    et al., 1972).

    Rat (trans-mevinphos)

    Groups of 12 males and 12 females received trans-mevinphos in the
    diet at 0, 10, 50, 250 and 1 250 ppm for 13 weeks. Cholinesterase
    activity was significantly reduced in the plasma, RBC and brain of
    females at all treatment levels, and in the males of the 250 and 1 250
    ppm groups. Erythrocyte cholinesterase was also inhibited at 50 ppm in
    the males. In the 10 ppm males no reductions in cholinesterase
    activity were found. Body-weights and haemoglobin levels of males and
    females exposed to 250 and 1 250 ppm were significantly reduced. At 1
    250 ppm, food intake, organ weights and serum protein levels were

    reduced, and the blood urea level and serum alkaline phosphatase
    activity were increased in both sexes. Eight males and six females fed
    1 250 ppm died during the test. SGPT activity was elevated at 1 250
    ppm in the females only. Females at 250 ppm were found to have
    increased blood urea levels and increased SGPT (Simpson et al.,

    In another experiment, groups of ten males and ten females received
    trans-mevinphos in the diet at 1, 5, 10, 25 and 50 ppm. Erythrocyte
    cholinesterase activity was reduced in the 5, 10, 25 and 50 ppm males
    and the 10, 25 and 50 ppm females. Brain cholinesterase activity was
    reduced only in the 50 ppm female group. No significant changes in
    plasma cholinesterase activity was found in either males or females
    (Simpson et al., 1972).


    Groups of four male and four female dogs received daily oral doses of
    0, 0.025, 0.075, 0.25 and 0.75 mg of mevinphos/kg/body-weight for two
    years. Vomiting occurred in several of the animals receiving 0.25 and
    0.75 mg/kg dosages; two males in the 0.75 mg/kg group were killed
    after 27 and 83 weeks dosing because of continuing vomiting and
    anorexia. The general health and growth rates of the other dogs
    remained unaffected throughout the study. No morphological changes
    attributable to mevinphos were found in the tissue of the dogs. Plasma
    and RBC cholinesterase depression were observed at 0.075 mg/kg and
    higher dosages, but not at 0.025 mg/kg. After two years dosing,
    inhibition of brain cholinesterase activity occurred in the 0.25 and
    0.75 mg/kg females and the 0.75 mg/kg males, but not at lower dosages
    (Wilson et al., 1971).

    Long-term studies


    Groups of 24 male and 24 female rats were given diets containing 0.37,
    1.11, 3.71 and 11.14 ppm of mevinphos (60% cis-isomer) for two
    years. A group of 48 male and 48 female rats acted as controls. No
    differences were noted in general health, behaviour or mortality
    between exposed and control animals. Transient reductions in
    body-weight occurred at two higher dosage levels during the first six
    months of the test. No differences in organ weight or morphological
    changes occurred which could be attributed to treatment; the
    haematological picture was unaltered. Experimental groups showed no
    differences from controls in the number or types of tumours developing
    during the two-year period. Erythrocyte and brain cholinesterase
    activities were reduced at the 3.71 and 11.14 ppm levels,
    respectively; lower levels did not affect the enzymes. No effects were
    found on the plasma cholinesterase in the 0.37 ppm group (Simpson
    et al., 1971).


    The effect of mevinphos on plasma and red blood cell cholinesterase
    was observed in groups of volunteers (five test and two control).
    Mevinphos was diluted in corn oil and administered in capsules at
    dosage levels of 1.0, 1.5, 2.0 or 2.5 mg/man/day. Baseline plasma and
    RBC cholinesterase levels were measured twice weekly during a
    pretreatment period followed by a 30-day test period during which the
    test dose was administered daily. Borderline depression (20%) in RBC
    cholinesterase occurred with dose levels of 1.5 and 2.0 mg/man/day and
    the highest dose produced a 24% decrease. Plasma cholinesterase was
    not significantly affected at any dose level (Rider et al., 1972).


    The data requested by the 1965 Joint Meeting has now been supplied.
    Mevinphos, a mixture of cis and trans isomers is rapidly
    metabolized in plants and animals. In plants, the cis isomer
    disappears more rapidly than the trans isomer. The cis isomer is
    more slowly degraded in animals.

    In a reproduction study in rats, a reduced lactation index was
    observed at 1.2 mg/kg/day, with no indications of teratogenic effects.

    Studies in rats with technical, cis and trans mevinphos indicated
    that the no effects for cholinesterase activity at 0.37 ppm is less
    than 0.1 ppm and 1 ppm, respectively. Results showed no evidence of

    A two-year study in dogs indicated a no-effect level based upon
    cholinesterase depression to be 0.025 mg/kg.

    Studies in humans indicated a reduction of cholinesterase activity at
    levels exceeding 1 mg/man/day.


    Level causing no toxicological effect

         Rat:      0.37 ppm in the diet, equivalent to 0.02 mg/kg

         Dog:      0.025 mg/kg body-weight/day

         Man:      1 mg/man/day, equivalent to 0.014 mg/kg body-weight/day


         0 - 0.0015 mg/kg body-weight



    Mevinphos is a systemic organo-phosphorous insecticide with a
    relatively short action; the material has both contact and systemic
    activity. It is recommended particularly for the control of a wide
    range of vegetable pests, especially when applications shortly before
    harvest are necessary, and for the control of aphids, leafrollers and
    mites in fruit.

    According to the information available, mevinphos is officially
    registered and/or approved for use in

    Argentina           Dem. Rep. of Germany          Norway
    Australia           Fed. Rep. of Germany          Peru
    Austria             Greece                        Philippines
    Belgium             Hungary                       Portugal
    Brazil              Italy                         South Africa
    Bulgaria            Jugoslavia                    Sweden
    Canada              Mexico                        Switzerland
    Colombia            Morocco                       Tunisia
    Czechoslovakia      Netherlands                   United Kingdom
    Denmark             New Zealand                   United States
    Finland             Nicaragua                     Uruguay
    France              Nigeria

    Use recommendations

    Typical application rates for mevinphos are in the range 0.125 - 0.50
    kg a.i./ha. In the United States, up to 1.0 kg a.i./ha is registered.
    The recommended period between treatment and harvest varies from
    country to country, but is typically between 1 and 7 days for outdoor
    crops, and 7 to 14 days for glasshouse crops.

    Multiple applications of mevinphos can be made, depending on pest
    incidence, and use recommendations allow for these treatments.

    The detailed use recommendations are given in Table 2.

        TABLE 2  Recommended applications of mevinphos to crop foliage
                                                                                 Dosage rate
    Crop                             Pest(s)                                     (kg a.i/ha)


    Pome fruit (apples, pears)       aphids, mites1, scale insects               0.125 - 0.25
                                     caterpillars, fruit flies,

    TABLE 2  (Cont'd.)
                                                                                 Dosage rate
    Crop                             Pest(s)                                     (kg a.i/ha)

    Stone fruit (peaches,            lygus bugs, grasshoppers, mealybugs,        0.25 - 0.50
    apricots, cherries)              leafrollers and psyllids

    Citrus (oranges, grapefruit,     aphids                                      0.125 - 0.25
    lemons)                          leafrollers, mites, mealybugs,
                                     woolly whitefly2, orange tortrix3,
                                     caterpillars, scale insects, cutworms       0.25 - 0.50

    Grapes                           aphids                                      0.25 - 0.50
                                     mites, caterpillars, leafrollers,
                                     leafhoppers, lygus bugs                     0.25 - 1.0

    Strawberries                     aphids, spider mites                        0.125 - 0.25
                                     grasshoppers, strawberry leafrollers,
                                     salt marsh caterpillares4                   0.25 - 1.0


    Brassicas (broccoli, cabbage,    aphids                                      0.125 - 0.25
    cauliflower, collards,           caterpillars, bugs, mites, leafhoppers,
    Brussels sprouts)                leafminers, beetles, thrips                 0.25 - 1.0

    Spinach, lettuce                 aphids                                      0.125 - 0.25
                                     caterpillars, mites, bugs, leafhoppers,
                                     leafminers                                  0.25 - 1.0

    Peas, beans                      aphids                                      1.125 - 0.25
                                     beetles, weevils, mites, pea moth,          0.25 - 0.50

    Cucurbits (melons,               aphids                                      0.125 - 0.25
    cucumbers)                       mites, caterpillars, bugs, thrips,
                                     beetles, leafminers, leafhoppers            0.25 - 0.50

    Root, tuber and bulbous          aphids                                      0.125 - 0.25
    vegetables                       thrips, cutworms, caterpillars,
    (carrots, potatoes, turnips      mites, bugs, leafhoppers, leafminers,       0.25 - 0.50
    and onions                       mealybugs

    Tomatoes                         aphids, whitefly5                           0.125 - 0.25
                                     mites, fruit flies, mealybugs,              0.25 - 0.50
    1  Mites are principally Tetranychidae, Tarsonemidae and Eriophyidae.
    2  Aleurothrixus floccosus

    3  Argyrotaenia citrana
    4  Estigmene acrea
    5  Trialeurodes vaporariorum and Bemisia spp.
    Officially approved pre-harvest intervals

    Officially approved pre-harvest intervals have been established in a
    number of countries. The situation in each country is described in
    Table 3. The information has been obtained principally from the
    Regulatory Authorities. Every attempt has been made to have these data
    current, but since legislation and regulations do change, some of
    these changes may not yet be known.

    With regard to pre-harvest intervals, these normally refer to an upper
    application rate of 0.5 kg/ha, but since official recommendations in
    some countries, especially in the case of tree fruits, are on the
    basis of spray concentrations rather than rate per hectare, this upper
    rate may not always be precise. At a typical spray volume in tree
    fruits of 1 000 l/ha, 0.05% a.i. w/w would be equivalent to 0.5 kg
    a.i./ha. In the United States, an upper rate of 1 kg/ha is now
    sometimes recommended for certain row crops attacked by resistant
    pests. In this case, approved pre-harvest intervals are lengthened
    accordingly, as shown in Table 3. Only crops likely to be of
    importance in international trade are included.



    CROP                          COUNTRY                       PHI

    General classes

    All                           Hungary                       5
                                  Portugal                      4
                                  Sweden                        4

    Outdoor                       Denmark                       4

    Glasshouse                    Denmark                       7

    Fruit                         Argentina                     1
                                  Austria                       14
                                  Belgium                       7
                                  Canada                        1
                                  Canada (high rate)            3
                                  Italy                         5
                                  Netherlands                   7
                                  Norway                        7
                                  United Kingdom                3

    TABLE 3  (Cont'd.)


    CROP                          COUNTRY                       PHI

    Pome fruit                    Australia                     2
                                  Switzerland                   21

    Stone fruit                   Australia                     2
                                  Switzerland                   21

    Vegetables                    Argentina                     3
                                  Australia                     2
                                  Austria                       4
                                  Belgium                       7
                                  Brazil                        4
                                  Canada                        1
                                  Canada (high rate)            3
                                  Colombia                      10
                                  Mexico                        4
                                  Netherlands                   7
                                  Norway                        7
                                  S. Africa                     4
                                  Switzerland                   10
                                  United Kingdom                3
                                  Uruguay                       1-4

    Leafy vegetables              Netherlands                   7-14

    Specific crops


    Apples                        U.S.A. - 0.25-05 kg/ha        1
    Cherries                        "        "  "  "  "         2
    Citrus                        Colombia                      15
                                  U.S.A. - 0.25-05 kg/ha        1
    Grapes                        Switzerland                   21
                                  U.S.A. - 0.25-05 kg/ha        2
    Peaches                       U.S.A. - 0.25-05 kg/ha        1
    Peers                         U.S.A. - 0.25-05 kg/ha        1
    Strawberries                  U.S.A. - 0.25-05 kg/ha        1
                                  U.S.A. - 1 kg/ha              2


    Beans                         Mexico                        1
                                  U.S.A. - 0.25-05 kg/ha        1

    TABLE 3  (Cont'd.)


    CROP                          COUNTRY                       PHI
    Beet-roots                    West Germany                  14
    Broccoli, cabbage             West Germany                  7
                                  U.S.A. - 0.25-05 kg/ha        1
                                  U.S.A. - 1 kg/ha              3
    Brussels sprouts              West Germany                  14
                                  U.S.A. - 0.25-05 kg/ha        3
                                  U.S.A. - 1 kg/ha              3
    Carrots                       U.S.A. - 0.25-05 kg/ha        2
    Cauliflower                   U.S.A. - 1 kg/ha              3
    Celery                        Weet Germany                  14
                                  U.S.A. - 1 kg/ha              5
    Collards                      U.S.A. - 0.25-05 kg/ha        3
                                  U.S.A. - 1 kg/ha              7
    Cucumbers(outdoors)           West Germany                  3
                                  U.S.A. - 0.25-05 kg/ha        1
    Cucumbers(glasshouse)         Belgium                       3
                                  West Germany                  4
                                  Mexico                        3
                                  U.S.A. - 0.25-05 kg/ha        1
    Gherkins                      Belgium                       3
                                  Mexico                        3
    Lettuce (outdoors)            U.S.A. - 0.25-05 kg/ha        2
                                  U.S.A. - 1 kg/ha              4

    Lettuce (glasshouse)          Belgium                       7
                                  Netherlands                   7
                                  U.S.A. - 0.25-05 kg/ha        10
            (winter)              Belgium                       14
                                  Netherlands                   14
    Melons (outdoors)             Brazil                        4
                                  U.S.A. - 0.25-05 kg/ha        1
    Melons (glasshouse)           Belgium                       3
                                  Mexico                        3
    Onions                        West Germany                  14
                                  U.S.A. - 0.25-05 kg/ha        1
    Peas                          West Germany                  7
                                  Switzerland                   21
                                  U.S.A. - 0.25-05 kg/ha        1
    Peas for processing           Belgium                       4
                                  Netherlands                   4

    Potatoes                      West Germany                  7
                                  U.S.A. 0.25-05 kg/ha          1
    Spinach*                      U.S.A. 0.25-05 kg/ha          4

    TABLE 3  (Cont'd.)


    CROP                          COUNTRY                       PHI
    Tomatoes (outdoors)           Brazil                        4
                                  Colombia                      8
                                  West Germany                  3
                                  S. Africa                     2
                                  U.S.A. - 0.25-05 kg/ha        1
    Tomatoes (glasshouse)         Belgium                       3
                                  West Germany                  4
                                  Mexico                        3
    Turnips                       U.S.A. - 0.25-05 kg/ha        3

    * Netherlands - Leafy vegetables (lettuce endive), spinach,
      glasshouse summer (1 March - 1 Nov.) 7 days; winter 14 days.


    A substantial amount of data on the residues resulting from supervised
    trials was available. These trials were carried out in different
    countries on food crops, especially vegetables and fruit, grown under
    various conditions, using various pre-harvest intervals (PHI).

    Table 4 summarizes the range of residue levels which have been found
    when the product is used according to the conditions of "good
    agricultural practice".

        TABLE 4  Residues of mevinphos in crops following recommended foliage treatments


                        Maximum          Minimum                                  Range of
    Crop                recommended      pre-harvest                              results
                        rate             interval       Number of    Number of
                        (kg a.i./ha)     (days)         trials       results      (ppm)

    Brassicas1          0.5 - 1.0        1 - 7          18           45           <0.01 - 0.90

    Spinach             1.0              4              15           21           0.01 - 0.80

    Lettuce             0.5 - 1.0        2 - 14         21           22           <0.02 - 0.50

    Tomatoes            0.5              1              13           48           <0.02 - 0.20

    TABLE 4  (cont'd)


                        Maximum          Minimum                                  Range of
    Crop                recommended      pre-harvest                              results
                        rate             interval       Number of    Number of
                        (kg a.i./ha)     (days)         trials       results      (ppm)
    Cucumbers           0.5              1 - 3          10           26           <0.01 - 0.20

    Peas                0.5              2              5            10           <0.05

    Beans               0.5              2              7            13           <0.05 - 0.20

    Root vegetables     0.5              2              4            7            <0.05

    Onions              0.5              2              1            2            <0.05 - 0.10

    Apples              0.5              3              8            23           <0.05 - 0.45

    Pears               0.5              3              2            4            <0.02 - 0.12

    Peaches             0.5              3              4            9            0.03 - 0.29

    Apricots            0.5              3              2            5            <0.01 - 0.10

    Grapes              1.0              3              7            20           <0.02 - 0.27

    Citrus              1.0              1              6            13           <0.01 - 0.11

    Cherries            0.5              3              5            14           0.09 - 0.90

    Strawberries        1.0              1              8            22           <0.05 - 0.58

    Melons              0.5              1              5            6            <0.02 - 0.03

    1  Includes broccoli, cabbage, cauliflower, Brussels sprouts and collards.
    In most cases normal dosage rates were applied in accordance with
    label recommendations. However, in some experiments higher dosages are
    also included. Since local recommendations, particularly regarding the
    minimum pre-harvest interval, vary widely, the standard taken for
    stating the ranges in Table 4 is the minimum pre-harvest interval
    commonly used in practice.

    In U.S.A., where both recommendations and cropping conditions are
    sometimes rather different from those in other countries, ranges
    deriving from commonly employed practice have been estimated on the
    basis of data only from U.S.A. For guidance, the minimum pre-harvest
    intervals used for deriving the ranges from the data are stated
    briefly in the third column of the table. The variation in pre-harvest
    interval for some of the crops is due to variation in upper dosage
    rate, or whether the crops are grown under glass or not.

    Detailed mevinphos residue data, obtained from supervised trials with
    mevinphos on fruit and vegetables are given below. It should be noted

    (a)  All application rates refer to active ingredient; the sum of
         cis and trans mevinphos.

    (b)  Lbs/acre has been regarded as being essentially equivalent to


    Brassicas treated with Phosdrin according to the most extreme current
    practice (i.e., for 0.5 kg/ha, PHI one day for broccoli and cabbage
    and three days for cauliflower, collards and sprouts; for 1.0 kg/ha,
    PHI three days for broccoli, cabbage, sprouts and cauliflower and
    seven days for collards) contained residues of mevinphos in the range
    of less than 0.01 ppm to 0.9 ppm, the upper figure being estimated
    from the data for sprouts.


    Recommended applications of mevinphos (i.e., 0.5 kg a.i./ha, minimal
    PHI four days, up to 1 kg a.i./ha, minimal PHI seven days) resulted in
    residues not exceeding 0.5 ppm, four and seven days, respectively,
    after the final application.


    The basis for deriving the range of residues from non-U.S.A. data was
    that of current recommendations in the Netherlands, and U.S.A. data is
    that of current recommendations. On this basis the range of residue
    levels reported was from <0.02 - 0.50 ppm.

    Under all these conditions, it has been shown that the residues of
    mevinphos did not exceed 0.50 ppm, when label recommendations were
    followed, i.e. PHI for lettuce grown outdoors was 4-7 days and for
    glasshouse lettuce 7-14 days, depending on application rate and
    growing period. In winter, the longer PHI's are recommended.


    Residues of mevinphos did not exceed 0.05 ppm (maximum dosage rate of
    0.5 kg a.i./ha) when beans were treated with 0.5 kg/ha mevinphos and
    sampled two days later.


    Residues of mevinphos did not exceed 0.05 ppm in peas which had
    received recommended treatments of mevinphos (maximum of 0.5 kg
    a.i./ha), sampled two days after application.

    Root vegetables, bulbs and tubers

    With a final treatment to harvest interval of two days, mevinphos
    residues in carrots, turnips, onions and potatoes did not exceed 0.10
    ppm, following recommended applications of mevinphos (maximum dosage
    rate of 0.5 kg a.i./ha).


    At a dosage rate of up to 0.50 kg a.i./ha, and an interval between the
    final application and harvest of one day, residues of mevinphos ranged
    from less than 0.02 ppm to 0.08 ppm; at the double dosage rate, i.e.
    up to 1 kg a.i./ha, residues ranged from 0.05 - 0.2 ppm.


    In cucumbers grown under glass, three days after application of
    mevinphos at a maximum dose of 0.5 kg a.i./ha, residues did not exceed
    0.13 ppm. Similarly, in cucumbers grown outdoors, residues were less
    than 0.10 ppm one day after recommended applications.


    Residues of mevinphos in whole melons did not exceed 0.05 ppm one day
    after the final treatment at a maximum of 0.5 kg a.i./ha.


    After recommended applications at a maximum of 0.5 kg a.i./ha,
    residues did not exceed 0.1 ppm after a PHI of three days in gherkins
    grown under glass.

    Top fruit

    Studies with mevinphos on top fruit are summarized in Table 5.

    TABLE 5  Mevinphos residues on fruit


                        Maximum             Pre-harvest         Residues
    Fruit               treatment           interval            (ppm)
                        (kg a.i/ha)         (days)

    Apples              0.5                 3                   0.45

    Pears               0.5                 3                   0.14

    Peaches             0.5                 3                   0.29

    Apricots            0.5                 3                   0.10

    Cherries            0.5                 3                   0.90

    Citrus              1.0                 1                   0.11


    At an application rate of 1.0 kg a.i./ha and a PHI of three days, the
    maximum residue of mevinphos in grapes was 0.27 ppm.


    Following applications of mevinphos to strawberries grown outdoors at
    a maximum rate of 1.0 kg a.i./ha, with a minimum PHI of one day, the
    maximum residue was 0.14 ppm; at a slightly higher treatment level,
    i.e. 1.25 kg a.i./ha, the maximum residue was 0.45 ppm.


    General comments

    Mevinphos residues in crops decrease rapidly, partly due to
    volatilization and partly through degradation. The principal
    degradation products are dimethyl phosphate and acetoacetic acid.

    Provided mevinphos is used according to the conditions of good
    agricultural practice, detectable residues will not occur in meat,
    milk and milk products. Livestock is unlikely to be exposed to
    mevinphos residues in feed since crops used for animal feeds are
    rarely treated. Nevertheless, data are available to show that cattle
    eating feed containing high levels of mevinphos do not produce meat or
    milk containing appreciable residues.

    In animals

    Casida et al. (1958) conducted studies with mevinphos fed to cattle
    at levels of up to 20 ppm, expressed on the dry matter content (far in
    excess of levels which could occur in practice). From the results of
    these studies, the authors stated that mevinphos had no tendency to
    accumulate in any tissue, but was rapidly detoxified in the animal.

    Feeding of 32P-labelled mevinphos for seven consecutive days to a cow
    at a level of 40 ppm, in dry matter, did not lead to levels of
    mevinphos in whole milk above 0.06 ppm at any time during the study.
    Mevinphos residues in the tissues from this cow at autopsy at the end
    of the seven-day period were essentially found only in the liver (0.3
    ppm) and kidneys (0.04 ppm).

    In a more extensive experiment, 12 lactating cows were fed for a
    12-week period at levels of 1, 5 and 20 ppm on the total diet. Samples
    of milk were taken periodically and samples of fat, liver, kidney,
    muscle, heart and brain at the end of the feeding period from all
    treatments. All contained less than 0.03 ppm mevinphos (limit of
    determination of the analytical method).

    However, their experiments showed that in the case of the cis-isomer
    of mevinphos, dimethyl phosphate was the main degradation product
    together with very small amounts of mevinphos acid (the free
    carboxylic acid). In the case of the trans-isomer, the same products
    were found, although there was even less of the carboxylic acid.

    Desmethyl derivatives (where the methoxyl groups joined to the P atoms
    would have been hydrolysed to hydroxyl groups) were not detected.

    In plants

    Casida et al. (1956) reported that after applying mevinphos to
    vegetable crops as a foliar spray, 90% of the amount applied was lost
    within two days and 99% in four days. From experiments in which pea
    and bryophyllum plants absorbed 32P-labelled mevinphos through their
    roots, it may be concluded that within 12 hours after application
    losses occurred primarily through volatilization, whereas thereafter
    decomposition made the greater contribution. Using similar methods
    with labelled mevinphos applied to cucumber, maize, bean and pea
    seedlings, they reported that the cis-isomer declined more rapidly
    than the trans-isomer.

    Spencer and Robinson (1960) grew pea seedlings in gravel and applied
    32P-labelled mevinphos via the roots. Like Casida et al. (1956)
    they found that the trans-isomer degraded somewhat more slowly than
    the cis-one. This conclusion is further supported by those field
    residue studies by Shell where cis- and trans-isomers were
    analysed separately.

    When pea plants were exposed to labelled cis-mevinphos acid instead
    of mevinphos, degradation of the acid was somewhat slower than that of
    cis-mevinphos. Moreover, although dimethyl phosphate was still the
    main degradation product, desmethyl mevinphos acid was also formed.
    For these reasons, the main degradation pathway of mevinphos acid was
    also formed.

    For these reasons, the main degradation pathway of mevinphos must have
    been direct to the dimethyl phosphate and could not have been
    primarily via the carboxylic acid.

    In soil

    In soil, mevinphos appears to be decomposed primarily by chemical
    hydrolysis (Hindin, 1963). Getzin and Chapman (1959) studied the fate
    of 32P-labelled mevinphos in soil and the subsequent uptake in pea
    plants by an enzyme inhibition method. There is a positive correlation
    with organic matter content and base-exchange capacity.

    Most mevinphos was held by peat (127 mg/100 g soil) and least by sand
    (3-8 mg/100 g soil).

    In sand, the residues in peas reached 170 ppm after two days,
    decreasing to 8.5 ppm after 14 days; in muck soils, the residues in
    the pea plant were 0.82 ppm and 0.05 ppm, respectively, after the same

    Residues after harvest

    The comparatively rapid decline in mevinphos residues seen in the
    growing crop usually continues after harvest whilst the commodity is
    being stored or transported to the market. Thereafter, the various
    commercial and domestic processes reduce levels still further, often
    to below the limits of analytical determination. Consequently,
    residues at harvest bear little relation to residue levels in food
    when it is ready to eat. At the latter point, mevinphos residues often
    may not be detectable, even though residues near the proposed
    tolerance levels were present at harvest time.

    Residues in crops stored under ambient conditions

    Studies have been undertaken in which samples of fruit and vegetables
    have been stored at ambient temperatures for 2 - 9 days. Table 6
    summarizes typical figures for the decline in residues in cabbage,
    broccoli, cauliflower, lettuce and spinach stored in ambient
    conditions (Shell Research Ltd., 1957, 1971, 1972; Shell Chimie,

        TABLE 6  Decline of residues in leafy vegetables after harvest


    Time                          Residues of mevinphos (ppm)
    (days)         Red cabbage    Broccoli   Cauliflower   Lettuce         Spinach

    Harvest        0.2            0.27       0.06          0.15         0.35     8.7

    2              0.11           0.09       <0.02         0.10         0.30     5.2

    4              0.06           0.02       -             0.05         0.20     2.7

    6              0.02           -          -             -            -        1.1

    8              -              <0.02      -             -            -        -

    9              0.01           -          -             -            -        -
    Comparable data for fruits were also obtained and are summarized in
    Table 7.

    TABLE 7  Decline of residues in fruits after harvest


                               Residues of mevinphos (ppm)
    Time (days)          Apples            Peaches        Strawberries

    Harvest           0.72     1.29        2.9            0.34     0.11

    2                 -        -           -              0.25     0.04

    3                 -        -           2.7            -        -

    6                 0.07     -           -              -        -

    9                 -        0.21        -              -        -

    Effect of deep-freeze storage

    Laws (1959) studied the effect of deep-freeze storage on residues of
    mevinphos in cabbage; samples were taken after six weeks and six
    months of deep-freeze storage. Practically no decrease of mevinphos
    residues occurred during these storage periods.

    Effects of domestic processing

    The data shown in Table 8 are representative of those available for
    the effect of washing in cold water (Shell Research Ltd., 1972; Shell
    Development Co., 1962).

    TABLE 8  Mevinphos residues in leafy vegetables after washing

    Crop           Initial residues         Residues after washing
                   (ppm)                    (ppm)

    Spinach        1.10                     0.54
                   0.96                     0.66
                   0.50                     0.35

    Cabbage        0.11                     0.03
                   0.02                     <0.01

    Broccoli       1.60                     0.72
                   0.14                     0.10

    Cauliflower    1.00                     0.09
                   0.74                     0.52
                   0.09                     0.05

    In general, the lower initial residues were derived from produce which
    had been stored under ambient conditions. In some cases the
    proportionate loss after washing was less from crops containing lower
    than from those containing higher residue levels.

    A study by Wit (1972) demonstrated that household washing and
    subsequent cooking of endive resulted in a loss of 50% of the residue
    occurring in the crop at the retailer. In lettuce, household washing
    removed about 48% of the initial residue. Data are given in Table 9.

    TABLE 9  Mevinphos residues in vegetables after washing and cooking
    Vegetable      Average residue, 4 replicates (ppm)

                   initial residue     after washing       after cooking
    Endive         0.12(0.08-0.15)     0.10(0.02-0.16)     0.06(0.03-0.09)

    Lettuce        0.54(0.36-0.80)     0.28(0.24-0.30)

    Whilst the residue data used as the basis for proposing tolerances
    were based on the crops as picked, many crops, especially lettuce and
    brassicas, are trimmed before cooking. Table 10 gives data which show
    the difference between residues in the outer leaves and the trimmed
    produce and which are typical of all available data. In general outer
    leaves represent 10-20% of the weight of the untrimmed crop (Shell
    Research Ltd., 1957, 1960, 1971; Shell Chimie, 1971).

    In melons, 75-90% of mevinphos residues were found to be present in
    the rind. Peeling reduced levels in cucumbers and peaches by up to
    50%, in apples by up to 60% and in pears by between 50 and 75%. In
    citrus, residues were confined primarily to the peel, and where
    residues were reported in peel, they were usually below 0.01 ppm in
    the pulp (Shell Development Co. 1957, 1958; Shell Chimie, 1970; Shell
    Research Ltd., 1957, 1972; Shell Chemical Co., 1961).

    Cooking vegetables and fruits reduces residues as illustrated by the
    data given in Table 11 (Shell Research Ltd., 1960, 1972).

    TABLE 10  Residues of mevinphos in outer leaves and trimmed crop


    Crop                          External leaves     Trimmed crop
                                  (ppm)               (ppm)

    Lettuce                       0.50                0.40
                                  0.24                0.20
                                  0.17                0.12

    Cabbage                       0.59                <0.05
                                  0.50                0.08
                                  0.08                <0.02
                                  0.64                0.02
                                  0.22                0.02

    Brussels sprouts              0.63                0.08
                                  0.25                0.16
                                  0.02                <0.02

    TABLE 11  Mevinphos residues in crops after cooking
                                           Residues (ppm)
    Crop                          Before cooking      After cooking
    Broccoli                      0.09                0.02
    Cabbage                       0.03                0.01
    Spinach                       2.70                0.81
                                  1.10                0.36
    Beans                         15.01               7.40

    TABLE 11  (cont'd)
                                           Residues (ppm)
    Crop                          Before cooking      After cooking
    Apples                        1.10                0.59
                                  0.65                0.26
                                  0.60                0.43

    1  Spiked sample.

    Blanching and canning

    In the canning of fruit and vegetables, which involves considerable
    heat treatments, virtually all mevinphos residues are eliminated.

    A study by Dormal et al. (1959) demonstrated that blanching and
    canning spinach, peas and beans effectively removed all residues of
    mevinphos. Similar studies also showed the complete elimination by
    commercial canning of residues of mevinphos present at harvest on
    spinach and peaches; 40% of the residues of mevinphos present were
    removed from beans purely by the process of blanching, while this
    reduction was increased to 99% on subsequent bottling (Shell Research
    Ltd., 1960, 1971; Shell Chemical Co., 1957).

    Processing of wine

    Painter et al. (1959) added mevinphos to grape must, and residues of
    mevinphos were found in wine prepared from the must. Measurable
    amounts of mevinphos were also retained in the sediment.

    Mevinphos residues in certain crops after harvest

    Whilst canning effectively removes residues from treated crops, the
    effects of the milder domestic processes are variable and the
    available data are summarized under individual crop headings.

    Where possible an estimate is made of the level which could be
    expected in the food when ready to eat if the crop were at the
    proposed tolerance level at harvest. In the great majority of cases,
    harvest time levels will be well below the proposed tolerances, so
    that the estimate made here for residues at the point of consumption
    will in general be well above those occurring in practice.


    The combined effects of delay between harvest and marketing, washing,
    removal of outer leaves and cooking are likely to reduce harvest
    residues of about 1.0 ppm to a maximum of 0.05 ppm.


    The combined effects of washing, transport and cooking would be
    expected to reduce harvest residues of about 1.0 ppm to around 0.15

    Peas, beans, carrots, turnips and potatoes

    Residue levels observed at harvest where crops had been treated
    according to good agricultural practice were invariably less than 0.05
    ppm, and no processing work was undertaken in these crops.

    Apples, pears, peaches, apricots, cherries and strawberries

    The principal losses of residue in fruits occur during transport to
    the market. Such factors as peeling, washing and cooking are not
    always relevant and are not considered here. In estimating losses
    there are great variations in the times and conditions of transport.
    Thus, apples and pears from distant countries may experience shipment
    periods of several weeks whereas fruits such as cherries and
    strawberries may be eaten within a matter of days after harvest. Thus,
    in the case of apples it is probable that residues at the
    proposed-tolerance level could decline to below the limits of
    determination where long shipment periods are involved. In the case of
    strawberries which reach the market in two days, residues could
    decline to between 50% and 70% of their harvest values.

    Melons and citrus fruit

    These fruits are peeled before being eaten. Residues in melons of 0.05
    ppm at harvest would not be likely to contain detectable levels in the
    edible portion. The same is true of citrus fruit.


    Some reductions in residues will occur between harvest and consumption
    due to transport and removal of outer leaves. Washing will also have
    some effect (residues decline by washing about 50%). Precise figures
    of residue losses between harvest and the moment of consumption are
    difficult to estimate, especially in view of the widely varying
    conditions and times of transport from one country to another.


    Residues of mevinphos are best determined by gas-liquid
    chromatography. Alternatively, an enzyme inhibition cholinesterase
    method may be employed.

    Gas chromatographic methods

    Because of their accuracy, specificity, sensitivity and speed, gas
    chromatographic methods of analysis are the methods of choice.

    Mevinphos can be determined by using a flame photometric detector
    (Beroza and Bowman, 1968; Brody et al., 1966). A specific method for
    the analyses for residues of both the cis and trans isomers of
    mevinphos has been developed (Shell Research Ltd., 1957-72) and
    satisfactorily used on crops down to a general level of 0.01 ppm for
    each isomer. The crops are extracted by maceration with chloroform.
    Low water content crops are dampened with water before extraction.
    Co-extracted natural products can be removed by cleanup using a liquid
    - liquid chromatographic technique, followed by analysis of the
    mevinphos-containing extract  Using this procedure, mean recoveries of
    80-115% from crops at the 0.02 - 0.20 ppm level may be achieved for
    each isomer.

    A thermionic detector has also been employed in the analyses of crops
    for residues of mevinphos (Winterlin, 1970; Shell Chemical Co., 1969).
    The crops are extracted with either ethyl acetate or chloroform,
    followed by a column adsorption chromatographic cleanup, if required,
    and determination by GLC equipped with a thermionic flame detector.
    This provides a quick and sensitive means for the detection, as well
    as the separation of the two isomers of mevinphos. These thermionic
    detector methods are capable of detecting levels of mevinphos as low
    as 0.01 ppm, with recoveries in the range of 90% to 110%.

    Enzyme inhibition

    A specific enzymatic method for the detection and determination of
    mevinphos in crops and animal products has been developed (Shell
    Development Co., 1964). The samples for analysis are extracted with
    chloroform, transferred to water, and determination is effected by a
    standard enzyme inhibition spectrophotometric method. Using this
    procedure, the limit of determination of mevinphos is 0.02 ppm for
    crops, 0.01 ppm for milk and up to 0.10 ppm for animal tissue.
    Recoveries are in the range of 80% to 110%.

    Bioassay Methods

    Bioassay methods have been described but such techniques have now been
    largely superseded.


    Officially approved tolerances for mevinphos have been established in
    some countries. The information presented in the following table has
    been obtained principally from the regulatory authorities. Every
    attempt has been made to present the most recent data, but the
    following list is not a fully authentic one. The figures in table 12
    refer to the sum of cis and trans mevinphos.


    Mevinphos is a systemic, rather volatile organo-phosphorous
    insecticide, which is used on a considerable scale in many countries,
    especially on vegetables and fruit, for the control of a wide range of
    pests, such as aphids, leafrollers and spider mites. This pesticide is
    recommended, particularly when control of pests is necessary, a
    relatively short time prior to harvest.

    Technical mevinphos contains no less than 60% of the cis-isomer of
    mevinphos, and about 28% of trans-isomer. The former possesses
    considerable higher insecticidal activity than the latter.

    The principal impurities in the technical material are methyl
    acetoacetate, methyl-2-chloro acetoacetate and dimethyl methyl
    phosphonate (each of the components mentioned comprise about 2% by
    weight of the total technical mevinphos).

    Mevinphos is mainly used as an emulsifiable liquid. The concentration
    rates of use range from 0.125-0.5 kg a.i./ha., applied as a foliage
    spray; in U.S.A. up to 1 kg a.i./ha. is registered to accommodate
    extreme pest conditions.

    The residue data available were obtained from many countries with
    different climatic and growing conditions and those presented are,
    with a few exceptions, representative of levels likely to occur at
    harvest under conditions of good agricultural practice.

    Information is available on the fate of mevinphos residues in animals,
    in plants and in soil; residue data on animal tissues and products of
    animal origin, such as milk, show that residues occur only from
    feeding levels far in excess of those which are likely to occur in
    practice. Provided mevinphos is used according to conditions of good
    agricultural practice, no measurable amounts of residue will occur in
    meat, milk and milk products.

    TABLE 12  Examples of national tolerances reported to the meeting1


    Country          Crop(s)                                     Tolerance

    Argentina        peas, beans, cucumbers, citrus              0.25
                     lettuce, melons, apples, pears, grapes      0.5
                     brassicas, spinach, cherries, peaches       1.0
                     and plums

    Australia        fruits and vegetables                       0.25

    Belgium          spinach                                     0.3
                     other vegetables, fruit                     0.1

    Brazil           peas                                        0.25
                     lettuce                                     0.5
                     broccoli, spinach, turnips                  1.0

    Canada           all treated crops                           0.25

    Czechoslovakia   leafy vegetables, cabbage                   0.1

    Fed. Rep. of     spinach                                     0.3
    Germany          vegetables and top fruit                    0.1
                     other crops                                 0.05

    Hungary          all crops                                   0.1

    Yugoslavia       apples                                      0.5
                     crops other than apples                     0.1

    Netherlands      spinach                                     0.3
                     other vegetables, fruit                     0.1

    Switzerland      vegetables )
                     top fruit  )                                0.25
                     grapes     )

    South Africa     tolerances vary according to crop           0.25 - 1.0

    U.S.A.           citrus, peas, beans, cucumbers, root veg.   0.25
                     apples, pears, grapes, lettuce, melons      0.5
                     stone fruit, brassicas, strawberries        1.0

    1  Additional tolerances may exist in some countries for crops grown
       for local consumption. These tolerances do not appear.

    When mevinphos was applied to plants, it was shown that it decreased
    rapidly within 12 hours after application, primarily through
    volatilization; thereafter degradation was mainly responsible for
    decrease in residue levels, the principle degradation products being
    dimethyl phosphate and acetoacetic acid.

    Little information is available on mevinphos residues in foods in

    A number of methods for residue analysis based on gas chromatographic
    procedures are available for specific determination of mevinphos
    cis-and trans-isomers. The GLC methods of analysis are the methods
    of choice, based on accuracy, specificity, sensitivity and speed.
    Recommendations are given for the most appropriate extraction
    procedures for residues in crops. These procedures can be used and
    adapted for regulatory purposes as required.

    The limit of determination of the GLC methods mentioned is as low as
    0.01 ppm for both cis- and trans-mevinphos in crops, with
    recoveries in the range of 90 - 110%.

    Alternatively, an enzymatic method for the detection and determination
    of mevinphos residues may be used. The limit of determination of the
    latter method is 0.02 ppm of mevinphos (both isomers) for crops, 0.01
    ppm for milk and 0.1 ppm for animal tissue. Recoveries are in the
    range of 100 - 110%.

    Various rates of application and pre-harvest intervals occur in
    different countries. It has been demonstrated that considerable losses
    of residues available at harvest occur whilst the commodity is being
    stored or transported to market. Thereafter, various commercial and
    domestic processes reduce levels still further, often below the limits
    of determination. Consequently, residues at harvest bear little
    relation to residue levels in food at the time of consumption.


    TOLERANCES                                                  ppm

    Brassicas (broccoli, Brussels sprouts, cabbage,
    cauliflower, collards) cherries, strawberries.              1

    Lettuce, spinach, apples, grapes, peaches.                  0.5

    Cucumbers, tomatoes, apricots, citrus fruits, pears.        0.2

    Carrots, beans, onions, peas, potatoes, turnips             0.1 

    Melons                                                      0.05




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    See Also:
       Toxicological Abbreviations
       Mevinphos (FAO Meeting Report PL/1965/10/1)
       Mevinphos (Pesticide residues in food: 1996 evaluations Part II Toxicological)
       Mevinphos (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)