METHOMYL        JMPR 1976


         Methomyl was evaluated in 1975 by the Joint Meeting on
    Pesticide Residues. Complete toxicological data were not made
    available to the Meeting and an ADI could not be allocated. In the
    absence of an ADI no recommendations could be made for maximum
    residue limits, but guideline levels were recommended for various
    commodities and are summarized in Annex 1 of the Report of the 1975
    Meeting (FAO/WHO, 1976). Further work required by the 1975 Meeting
    included development of a suitable regulatory method and residue
    data from countries other than the U.S.A. The U.S. manufacturer
    submitted information for evaluation by the 1976 Meeting on
    residues, analytical methods, maximum residue limits and labelling
    (Dupont, 1976). Country statements were received from the
    Netherlands and Australia.

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



         In addition to information on new use patterns submitted by
    the basic manufacturer (Dupont, 1976), country statements
    describing national use patterns were received from Australia and
    the Netherlands. Table 1 summarizes the new use patterns called to
    the attention of the 1976 Meeting.


         New residue data from Australia, the Netherlands and the
    U.S.A. were made available to the Meeting. Data from the
    Netherlands were on tomatoes and peppers. Australia submitted data
    on maize, sweet corn, tomatoes, cauliflower, cabbage, peaches,
    apples, and cherries. The U.S. dossier included collards, hops,
    tobacco and garden vegetables (the latter from W. Germany). The new
    data generally support the 1975 guideline levels. The residue
    studies supporting changes in or additions to the 1975 guideline
    levels are detailed in this monograph. All residue values are
    expressed as methomyl but the analytical method determines total
    residues of methomyl plus the oxime metabolite S-methyl
    thioacethydroximate (1-(methylthio) acetaldehyde oxime).


         The available data on asparagus are from trials at 10
    locations in the U.S.A. (Dupont, 1975). Registered uses in that
    country permit a dosage of 1 kg a.i./ha, repeated as necessary,
    with a 1 day pre-harvest interval (PHI). The Meeting has not

    received any information on use patterns in other countries.
    Initial deposits from the permitted dosage are in the range 1-2
    mg/kg. Residues on the following day are usually < 1 mg/kg but
    occasionally exceed this level. The unique harvesting practice for
    asparagus involves cutting emerging spears every 2 or 3 days and
    thus requires a short (1 day) PHI. A guideline level of 2 mg/kg
    would be adequate.


         The only available data are from 11 locations in the U.S.
    (Dupont, 1975) and show residues in the range 0.4 to 4.8 mg/kg on
    harvested grapes treated under the registered use pattern (1 kg
    a.i./ha - 1 day PHI). Australia requires a 2 day PHI. The data
    indicate a need for a 5 mg/kg guideline level.

         Peaches, nectarines

         A guideline level of 1 mg/kg for nectarines was recommended by
    the 1975 Joint Meeting (FAO/WHO, 1976). Apparently a guideline level
    for peaches was inadvertently omitted. Approved Australian practice
    provides for use on peaches and nectarines at a spray concentration of
    22.5 g a.i./100l with a 1 day waiting period. Australian data made
    available to the 1976 Meeting show initial residues of 0.93 and 1.3
    mg/kg from the recommended (1x) and 2x application rates in "flesh of
    peaches". U.S. data indicate residue levels of 6 to 7 mg/kg on whole
    fruit one day after a 1/2x treatment and residues of the order of 5
    mg/kg persisting into the fourth day. Nectarines exhibited a similar
    residue pattern in the U.S. data (Dupont 1975). On the basis of
    residues on the whole raw commodity it was concluded that a guideline
    level of 5 mg/kg would be appropriate for both peaches and nectarines.
    This level is based on a 4 day pre-harvest interval.

         Green peas

         The only available residue data are from U.S. field trials.
    Methomyl is used on peas in the U.S. at the rate of 1 kg a.i./ha, 2
    applications, with a 1 day waiting period for pea harvest, 5 days for
    vines being fed to livestock, and 10 days for pea vine hay. In
    Australia the use of sprays at 0.025 - 0.05% with a 1 day waiting
    period is permitted. Supervised trials in the U.S. show residues of
    0.02 to 0.4 mg/kg in shelled peas and 0.12 to 4.6 mg/kg in filled pods
    at the specified 1 day PHI and recommended dosages. This suggests that
    separate guideline levels of 0.5 mg/kg for shelled green peas and 5.0
    mg/kg for peas in the pod would be adequate.

    TABLE 1. National use patterns for methomyl, 1976


                                            Application              Pre-harvest Interval     Other
    Country          Crop           Rate (a. i.)     Formulation             (days)           Restrictions

    Netherlands      tomatoes       0.1% spray       25% WP                  3
                     peppers        "                "                       3

    Australia        apples         35-45 g/100 l    25% sol.                1

                     nectarines     25 g/100 l       "                       1

                     peaches        25 g/100 l       "                       1

                     cherries                        "                       2

                     leafy veg.     250-500 g/ha     "                       none

                     potatoes       300-450 g/ha     "                       none

                     tomatoes       35-45 g/100 l    "                       none

                     lucerne                         "                       1

                     peppers                         "                       1

                     eggplant                        "                       1

                     beans          25 g/100 l       "                       1

                     soybeans       300 g/ha         "                       3

                     citrus                          "                       2

                     grapes                          "                       2

    TABLE 1. (Cont'd.)


                                            Application              Pre-harvest Interval     Other
    Country          Crop           Rate (a. i.)     Formulation             (days)           Restrictions

                     cottonseed                      25% sol.                -

                     rapeseed                        "                       2

                     peas           25-50 g/100 l    "                       1

    U.S.A.           asparagus      0.5-1.0 kg/ha    Water                   1
                                    (as needed)      sol.

                     field &        0.25-0.5         powder                                   Do not feed
                     popcorn        kg/ha            and                                      animals within
                                                     liq.sol.                                 3 days after

                     green peas     0.5-1.0 kg/ha    "                       1                livestock
                                    (2 applications)                                          feeding-3 days
                                                                                              vine, 14 days

                     sugar beets    8-1.0 kg/ha      "                       7                do not feed tops
                                    (3 applications)                                          to livestock

    New Zealand      cereals                                                 7

                     pasture                                                 7

                     tomatoes                                                2

                     beans                                                   2

                     cabbage,                                                7

    TABLE 1. (Cont'd.)


                                            Application              Pre-harvest Interval     Other
    Country          Crop           Rate (a. i.)     Formulation             (days)           Restrictions

    New Zealand      lettuce,
                     raspberries                                             2

    United           hops           0.3-0.8 kg/ha    25% WP                  none
    Kingdom                         (as needed)



         Snap beans

         The data on snap beans (succulent) show residues at harvest in
    the range 0.06 to 1.4 mg/kg one day after a treatment at 1.0 kg
    a.i./ha. Residues had decreased to 0.03 - 0.30 mg/kg by the second and
    third day. Information made available through country statements
    indicates that New Zealand requires a 2 day waiting period while
    Australia and the U.S. require 1 day. A guideline level of 2 mg/kg
    would accommodate all these use patterns.


         Data from trials at five locations in the United Kingdom were
    made available (Dupont, 1976). Multiple applications at exaggerated
    dosages resulted in residues ranging from < 0.02 to 1.2 mg/kg when
    the last application was made one week before harvest. The sample was
    presumably dried hops. The approved use in the U.K. permits repeated
    applications at 0.3 - 0.8 kg/ha.


         New data on collards (Dupont, 1976) showed some unusually high
    residue values, e.g. 123 mg/kg one day after a 1 kg/ha application; 56
    mg/kg after 7 days; 12 mg/kg at 10 days, and 5 mg/kg at 14 days. The
    residue values from the four trial sites exhibited no particular
    pattern, which may be typical for the broad leaf vegetables. A
    guideline level of 5 mg/kg would be consistent with the 1975
    recommendation on spinach. The data indicate the need for a 14 day

         Garden vegetables and vegetables under glass

         The results of a series of residue trials in Fed. Rep. of Germany
    were made available to the 1976 Meeting. They are summarized in Table


         The further development of available analytical methods for
    residues to make them suitable for regulatory use was required by the
    1975 Joint Meeting. The gaschromatographic method of Pease and
    Kirkland (1968), modified by the use of a flame photometric detector
    (Pease, 1969) has been used successfully for regulatory purposes in
    some laboratories but others have experienced difficulties. It was
    concluded that the method could not be recommended without reservation
    for regulatory purposes until these difficulties had been resolved.


         National tolerances or maximum residue limits reported to the
    Meeting are shown in Table 3.


         Toxicology data were not adequate to support an ADI when methomyl
    was evaluated by the Joint Meeting in 1975, but sufficient residue
    information was available to permit the Meeting to record guideline
    levels. The supplementary information submitted to the 1976 Meeting
    includes country statements from the Netherlands and Australia, as
    well as a dossier from the basic manufacturer (Dupont).

    TABLE 2. Methomyl residues resulting from 1 application of 225 g/ha (Fed. Rep. of

    Crop                       Residue, mg/kg, at interval, days, after treatment
                               0         3         5         7        10        14

    cauliflower (head)         0.94      0.06       0.04      0.03     0.01      <0.01

    " (leaves)                 2.38      0.29      0.03      0.02     <0.01     <0.01

    radishes                   0.46      0.16      0.08      0.20     0.08      0.08

    radishes, under glass      0.14      0.78      0.81      0.98     1.06      0.22

    cucumbers                  0.15      <0.01     0.02      0.02     0.01      <0.01

    tomatoes                   <0.01     0.02      0.02      <0.01    <0.01     <0.01

    tomatoes, under glass      0.19      0.07      0.07      0.02     0.02      0.05

    cabbage                    0.38      0.02      0.02      0.01     0.01      0.01

    lettuce (under glass)      3.20      2.7       1.8       2.3      1.2       0.29

    carrots                    0.09      <0.02     <0.02     <0.02    <0.02     <0.02

    onions                     <0.01     <0.01     0.02      0.08     <0.01     <0.01

    spinach                    9.06      0.86      0.91      0.16     0.01      0.02
    TABLE 3. National tolerances or maximum residue limits
             reported to the Meeting
    Country             Crop                Tolerance or maximum
                                            residue limit, mg/kg

    Netherlands         tomatoes                    0.05
                        peppers                     0.05

    Australia           apples                      1
                        nectarines                  1
                        peaches                     1
                        cherries                    1
                        leafy veg.                  1
                        potatoes                    1
                        tomatoes                    1
    Australia           lucerne                     exempt
                        peppers (1)                 1
                        eggplant (1)                1
                        beans (1)                   1
                        soybeans (1)                1
                        citrus (1)                  1
                        grapes (1)                  1
                        cottonseed (1)              0.2
                        rapeseed (1)                1

    U.S.A.              asparagus                   2
                        field & popcorn             0.1 (grain)
                        green peas                  10 (vines)
                                                    5 (peas)

    New Zealand         cereals                     0.2
                        pasture                     0.2
                        tomatoes                    0.2
                        beans                       0.2
                        cabbage,                    0.2
                        raspberries                 0.2
    (1) Provisional tolerances

         The new material includes useful information on national use
    patterns, national tolerances, and additional supervised trials from
    countries other than the U.S.A. This information was designated as
    "required" by the 1975 Meeting.

         A requirement for the development of an analytical method
    suitable for regulatory use has not been fully satisfied. It was

    concluded that the GC (flame photometric) method of Pease would serve
    this purpose in laboratories where it had been validated, but could
    not be recommended without reservation.

         Some data on the decline of residues in storage and processing
    were furnished in response to the request made in 1975.

         In the light of new information on national use patterns,
    tolerances and supervised residue trials, some revisions are made to
    the guideline levels recorded by the 1975 Meeting.


         The guideline levels recorded by the 1975 Meeting are reaffirmed
    or are amended as listed below. Several new guideline levels are also

                                                  Interval on which
    Commodity         Guideline level (mg/kg)     guideline is based

    Collards1/        5                             14

    Grapes            5                             2

    Nectarines        5                             4

    Peas (in pod)1/   5                             1

    Peaches1/         5                             4

    Asparagus         2                             1

    Snap beans        2                             1

    Peas (shelled)    0.5                           1

    1/Additional to 1975 levels.


    REQUIRED (before an acceptable daily intake can be allocated and
    maximum residue limits can be recommended)

    1.   Submission of full toxicological data.


    1.   Development of an improved analytical method for regulatory

    2.   Further information on the decline of methomyl residues in
         storage or in processing.

    3.   Further information on national use patterns and residue data
         from countries other than Australia, the Netherlands, and the


    Dupont Information on methomyl insecticide. E.I. DuPont de Nemours
    1975                & Co. (Inc.), Wilmington, Delaware, U.S.A.,
                        September, 1975.

    Dupont Information on methomyl insecticide. E.I. DuPont de Nemours
    1976                & Co. (Inc.), Wilmington, Delaware, U.S.A., July,

    FAO/WHO Pesticide residues in food. WHO Technical Report Series
    1976                No. 592; FAO Plant Production and Protection
                        Series No. 1.

    Pease, H.L. and Kirkland, J.J. Determination of methomyl residues
    1968                using microcoulometric gas chromatography. J. Agr.
                        Food Chem. 16:554-557.

    Pease, H.L. Modification of the published gas chromatographic
    1969                method for determination of methomyl residues: Use
                        of a flame photometric detector.

    See Also:
       Toxicological Abbreviations
       Methomyl (EHC 178, 1996)
       Methomyl (HSG 97, 1995)
       Methomyl (ICSC)
       Methomyl (WHO Pesticide Residues Series 5)
       Methomyl (Pesticide residues in food: 1977 evaluations)
       Methomyl (Pesticide residues in food: 1978 evaluations)
       Methomyl (Pesticide residues in food: 1986 evaluations Part II Toxicology)
       Methomyl (Pesticide residues in food: 1989 evaluations Part II Toxicology)
       Methomyl (JMPR Evaluations 2001 Part II Toxicological)