IPCS INCHEM Home


    PESTICIDE RESIDUES IN FOOD - 1983


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1983





    Data and recommendations of the joint meeting
    of the FAO Panel of Experts on Pesticide Residues
    in Food and the Environment and the
    WHO Expert Group on Pesticide Residues
    Geneva, 5 - 14 December 1983

    Food and Agriculture Organization of the United Nations
    Rome 1985

    OXAMYL

    RESIDUES

    Explanation

    Oxamyl was evaluated by the Meeting in 1980.1/ Several maximum
    residue limits (MRLs) were assigned, some of which were temporary
    because of the lack of approved uses or inadequate data on residue in
    harvested crops.

    Further work or information required was the following:

    1. Identification of animal tissue residues.

    2. Clarification of the no-effect level in the rat, especially in
    relation to the marginal effect of 50 mg/kg on the body weight in
    several studies.

    3. Further data on beans, maize and soybeans for reconsideration of
    the temporary recommendations.

    4. Additional data on materials used for animal feedstuffs, e.g.,
    sugarbeet leaves, maize fodder and bean fodder.

    5. Approved use information on those items for which only proposed
    uses were available.

    In addition, several items of information were considered desirable.
    Some of the information requested has been provided and is reviewed in
    this evaluation.

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

    Registered use patterns of oxamyl were reported from several
    countries. The additional new information is summarized in Table 1.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    The residues reported are the sum of oxamyl and its oxime expressed as
    oxamyl, as the method used converts the parent compound to oxime and
    determines the two compounds together.



              

    1/ See Annex 2 for FAO and WHO documentation.


        Table 1   Registered Uses for Oxamyl

                                                                                                                                                 

    Crop                Country             Rate                Formulation    No. of         Preharvest          Mode of application
                                            (a.i.kg/ha)                        treatments     interval
                                                                                              (days)
                                                                                                                                                 

    Banana              Central American    5-10 cu cm/plant    L                             7                   soil and foliar
                        countries           + foliar 3-4
                                            times per year

                        Greece              20-30 g/tree        G                                                 around trees

    Beans, french       The Netherlands     2.5                 G              1              14                  shortly before planting, at
    (glasshouse)                            0.5-1               L              2                                  planting and between rows 3-4
                                                                                                                  weeks after planting

    Cabbage1            The Netherlands     5                   C,L            1              14                  shortly before planting

    Coffee              Guatemala           0.48-0.72           L              4                                  foliar treatment at 2-3 week
                        El Salvador                                                                               intervals
                        Honduras
                        Nicaragua
                        Costa Rica

    Fruiting            The Netherlands     2.5                 G              1              14                  shortly before planting, at
    vegetables2                             0.5-1               L              2                                  planting and between rows 3-4
                                                                                                                  weeks after planting (drench)

    Lettuce             The Netherlands     2.5                 L,G            1              14                  shortly before planting
    (glasshouse)

    Maize               Thailand            25-37               L              1                                  incorporated in the soil foliar
                                            0.5-1%              L                                                 treatment
                        United States       0.3-0.6             L              1                                  in furrow or band treatment
                                            2 - 4               L
                                                                                                                                                 

    Table 1 (continued)

                                                                                                                                                 

    Crop                Country             Rate                Formulation    No. of         Preharvest          Mode of application
                                            (a.i.kg/ha)                        treatments     interval
                                                                                              (days)
                                                                                                                                                 

    Melon               Spain               1.4 - 2             L
                                            4 - 10              G

    Peanuts             Taiwan (Prov.       0.3-0.45            L
                        of China)
                        United States       2-6                 L              1                                  band treatment, immediate
                                                                                                                  incorporation
                                            2-3                 L              2                                  3 weeks apart

    Peppers             Spain               1.4 - 2             L
                                            4 - 10              G

    Pineapple           South Africa        1 - 2               L              6                                  at 4-week intervals incorporated
                        Thailand            26 - 40             L              1                                  in soil broad cast to soil,
                        United States       10 - 20                                                               immediate incorporation

                                            2 - 20                             monthly
                                                                               bimonthly                          foliar trea%ment

    Potatoes            Fed. Rep. Germany   0.72-1.2            L              1              7
                        The Netherlands     5                   G, L           1                                  broadcast soil application
                        Sweden              3.5 - 5             G              1              100                 incorporated in soil
                        Finland             3 - 5               L              1
                        Spain               1.4 - 2             L              1
                                            4 - 10              G

    Soybeans            Hungary             0.2- 0.24           L                                                 foliar at 10-12 days apart
                        Thailand            26 - 40             L              1                                  incorporated in soil
                                            0.5 - 1%                                                              foliar
                        United States       1.2 - 2.4           L              1                                  in furrow band treatment
                                                                                                                  at planting broadcast

                                                                                                                                                 

    Table 1 (continued)

                                                                                                                                                 

    Crop                Country             Rate                Formulation    No. of         Preharvest          Mode of application
                                            (a.i.kg/ha)                        treatments     interval
                                                                                              (days)
                                                                                                                                                 

    Sugarbeet           Fed. Rep. Germany   1.2                 L              2                                  land treatment
                        The Netherlands     0.75-2.5            G              1                                  at sowing
                        Poland              2.5 -3              G                                                 in furrow at sowing
                        Romania             1.5                 G                                                 in furrow at sowing

    Sugarcane           South Africa        2.8                 L              1                                  at 6-8 leaf stage
                        Thailand            26 - 40             L              1                                  in furrow

    Tomatoes            Spain               1.4-2               L              1
                                            4 - 10              G
                                                                                                                                                 

    1 Cabbage includes Brussels sprouts, cauliflower, headed cabbage (red and white) and savoy cabbage.
    2 Fruiting vegetables, glasshouse crops include bell pepper, eggplant, zucchini, cucumbers, gherkins, melons and tomatoes.
    3 Proposed use.
    4 L = 240 or 250 g a.i./1 E.C.; G = 100 g/kg granular formulation.
        Banana

    Supervised trials were carried out at various locations in Central 
    America according to the registered use patterns or, at increased 
    rates, either a 50% overdose (3.6 ml/a.i./plant) was applied or an 
    increased number of applications (six instead of four were used). 
    The results are summarized in Table 2.

    The residue levels were somewhat lower in pulp than in whole fruits. 
    The concentration of the second major plant metabolite (DMCF:N, 
    N-dimethyl-1-cyanoformamide) was always below 0.02 mg/kg, the limit 
    of determination (DuPont 1983).

    Coffee

    Vydate L was applied at the recommended rate (0.5-0.75 kg a.i./ha) 
    and higher rates (up to 40 kg a.i./ha) from one to five times. A 
    large number of samples were analysed in supervised trials carried
    out in the United States, Guatemala and Costa Rica. The oxamyl 
    residue was below the limit of determination (0.02 mg/kg) in most
    of the samples treated at registered rates, but others contained 
    residues up to 0.08 mg/kg regardless of the time between last 
    application and sampling. The residue exceeded 0.1 mg/kg only in 
    samples that had received a higher dosage than the recommended 
    one. Two sets of samples contained residue up to 1.2 mg/kg but 
    these results are considered atypical. The dried beans contained
    approximately 40-50 percent higher residue than those from which 
    they were derived. No DMCF residue was detected in any of the 
    samples (DuPont 1983).

    Maize

    Vydate 10 G and Vydate L were applied as soil treatments at 
    various rates up to 9 kg a.i./ha in 10 states of the United States
    between 1976 and 1981. The residues were analysed in more than 
    200 samples. The oxamyl residues in the mature grain was always 
    below 0.02 mg/kg, the limit of determination. No residue was 
    generally detectable in the ears and stalks; however, in a few 
    cases residues were up to O.03 mg/kg in ears and 0.1 mg/kg in 
    stalks. No DMFC was detectable in these samples. Green forage 
    treated at rates of 1 and 2 kg a.i./ha oxamyl residues in the 
    ranges of 0.26-2.6 mg/kg and 0.02-0.08 mg/kg 28-30 and 56-60 days
    after treatments, respectively. DMFC residue was present in 
    concentrations of 0.02 to 0.06 mg/kg in some forage samples taken 
    at a one-month interval (DuPont 1983).

        Table 2  Oxamyl Residues in Banana Samples Derived from Supervised Trials

                                                                                                                                           

                                         Application *                  Residues (mg/kg) at intervals (days) after application
                     Country/                                                                                                            
    Sample           location      Year   No.    Rate
                                                (ml a.i./       4-7       13-14     21        28-35     48-58     67-73     84
                                                plant
                                                                                                                                           

    Whole fruit      St Lucia      1981   12    0.6                       <0.021              <0.021
                                                1.2                       <0.021              <0.021
                                                2.4                       <0.021              <0.021
    Whole fruit                                                 0.12
    Pulp             Jamaica       1981   12    1.2             0.02
    Whole fruit                                 2.4             0.14
    Pulp             Jamaica                                    0.03
    Whole fruit                                 3.6             0.26
    Pulp             Jamaica                                    0.04
    Whole fruit      Jamaica              12    2.4             <0.021
    Whole fruit      Jamaica              12    3.6             <0.021

    Whole fruit      Puerto Rico   1982   33    1.2             0.07      0.08      0.08
    Pulp                                                        0.05      0.06      0.06

    Whole fruit      St Mary       1981   12    2.4             <0.02
                                                3.6             <0.02

    Whole fruit4     Costa Rica    1981   23    1.2                                 <0.01-              0.01-               <0.01-
                                                                                    0.04                0.03                0.01
                                          43    1.2                                           <0.01-                        <0.01
                                                                                              0.26
                                          63    1.2             <0.01                         <0.01-              0.02
                                                                                              0.21                0.14
                                                                                                                                           

    Table 2 (continued)

                                                                                                                                           

                                         Application *                  Residues (mg/kg) at intervals (days) after application
                     Country/                                                                                                            
    Sample           location      Year   No.    Rate
                                                (ml a.i./       4-7       13-14     21        28-35     48-58     67-73     84
                                                plant
                                                                                                                                           

    Whole fruit4     Costa Rica    1981   2     2.4             <0.01-,             0.03-     <0.01-    0.01-     0.04-     <0.01-
                                                                0.035,7             0.097     0.037     0.133     0.013     0.023
                                          43    2.4                                           <0.01-    <0.01               <0.01
                                                                                              0.08
                                          63    2.4             <0.01                         <0.01-
                                                                                              0.02
                                          26    3.6                                 0.01-               <0.01-              <0.01-
                                                                                    0.17                0.09                0.04
                                          43    3.6                                           0.01-                         <0.01
                                                                                              0.1
                                                                                                                                           

    * All applications made with a formulation of 240 or 250 g a.i./1 E.C.
    1 No residue was detected in the pulp.
    2 The previous treatments were not recorded.
    3 The last treatments were made approximately one month apart.
    4 Residues listed are the range of minimum to maximum values in four samples.
    5 Three days after last application.
    6 Treatments were made seven weeks apart.
    7 The last treatments were made three months apart.
    
    Soybeans

    Experimental plots were treated with Vydate 10 G and Vydate L in
    various states of the United States. The compound was applied to soil
    in furrow, band or broadcast and for foliar treatment at rates up to
    45 kg a.i./ha. Thirty seed samples were analysed of which three,
    treated at recommended rates, contained detectable residues (0.03,
    0.03 and 0.05 mg/kg). In one case, 150 days after treatment at a rate
    of 5.6 kg a.i./ha, the residue was 0.18 mg/kg in beans. All the other
    samples, including straw, processed oil and meal contained
    nondetectable residues only. No DMCF was detected (Du Pont 1983).

    Sugarbeet

    Vydate 10 g was applied in the row at planting at a rate of 1.1 kg
    a.i./ha in the U.K. The young plants contained 0.48 to 0.64 mg/kg
    oxamyl residue at the two to six leaf stages. Sugarbeet tops and roots
    (six samples)contained residues of 0.03-0.04 mg/kg at 113 to 131 days
    after treatment. Similar levels were also observed in control samples.

    Sugarcane

    Sugarcane fields were treated in the USA, including Hawaii and Puerto
    Rico by application of Vydate L in the form of dripping irrigation or
    as foliar treatment one to five times at rates of 1.1 to 2.2 kg
    a.i./ha. The oxamyl residue was below 0.02 mg/kg in the majority of
    samples but it reached 0.1 mg/kg 14 days after foliar treatment and
    decreased to below 0.05 mg/kg after 28 days (DuPont 1983).

    In South Africa, sugarcane was treated twice at rates of 3 1/ha and 2
    1/ha 42 days apart. The initial residue on the leaves was about 225
    mg/kg and declined rapidly thereafter. The residue levels were around
    9.6, 1.5, 0.6 and<0.05 at 4, 16, 32 and 64 days, respectively, after
    the second application (South Africa 1983).

    Fruit and Vegetables

    Granular and liquid formulations of oxamyl were applied at recommended
    and double rates in Finland (1983), the Netherlands (1983) and Sweden
    (1983). The results of trials are summarized in Table 3. Potato fields
    were treated with Vydate granular and EC formulations at rates of 2.5
    kg a.i./ha to 5 kg a.i./ha in Finland and Sweden. Samples were taken
    from 17 experimental areas from 1977 to 1982. Residue levels were in
    the range of 0.01 to 0.11 mg/kg in new potatoes and were below 0.01
    mg/kg in the mature tuber.


        Table 3   Oxamyl Residues in Fruit and Vegetable Samples Derived from Supervised Trials

                                                                                                                                               

                                  Application          Formulation            Residues (mg/kg) at intervals (days) after application1
                                                                                                                                           
    Crop         Country       Year    No.  Rate                    1            3           7          10        14         45         67
                                        (a.i. kg/ha)
                                                                                                                                               

    Cucumber     Netherlands   1979    1    5          G                                                                     0.21
    glasshouse                                                                                                               (0.16-0.28)
                                       1    10         G                                                                     0.27
                                                                                                                             (0.20-0.33)
                                       2    5          L                                                          0.43
                                                                                                                  (0.37-0.45)
                 Finland       1980    1    0.12/100 l L                                                                     <0.03

    Cucumber     Netherlands   1981    1)3  10+        G            0.31         0.46        0.48
    glasshouse                         3)   2.5        L            (0.22-0.45) (0.32-0.59) (0.28-0.59)

    Gherkin                    1981    1    2.5        L                         0.04        0.06       0.06      0.05
    glasshouse                                                                   (0.04-0.04) (0.04-0.08) (0.05-0.07) (0.04-0.06)
                                       1    2.5        L                         <0.01       <0.01      <0.01     <0.01

    Tomato                     1979    11   5          G                                                                                0.06
    glasshouse                                                                                                                       (0.04-0.11)
                                       1    10         G                                                                                0.12
                                                                                                                                     (0.04-0.14)
                               1980    24   5          L                                                                     0.412
                                       1+)  10+        G            0.19         0.27        0.14
                                       4 )  2.5        L            (0.11-0.30) (0.12-0.62) (0.07-0.25)
                                                                                                                                               

    Table 3 (continued)

                                                                                                                                               

                                  Application          Formulation            Residues (mg/kg) at intervals (days) after application1
                                                                                                                                             
    Crop         Country       Year    No.  Rate                    58           62          72/73      125       148        197        365
                                        (a.i. kg/ha)
                                                                                                                                               

    Strawberry                 1977/78 1    2.5        L                                                                                <0.02
    outdoor                            1    5          L                                                                                <0.02
                               1979/80 1    5          G                                                                     0.03
                                                                                                                             (0.02-0.05)
    French beans 1980          1       5    G                       0.1
    glasshouse                                                                   (0.06-0.13)


    Brussels sprouts           1980    1    5          L                                                          <0.02
    outdoors                           1    10         G                                                <0.02

    Lettuce                    1980    1    2.5        G            0.27
    glasshouse                                                      (0.20-0.30)

    Onions                     1980    1    0.55                                             <0.01
                                       1    0.45                                             <0.01

    Onions       Finland       1980    1   0.12g/100 l L            <0.1
                               1980    1   0.12g/100 l L            <0.05
                               1982    1   0.12g/100 l L                                     <0.1
                                                                                                                                               

    1    Figures corrected for recovery except for gherkins, recovery for gherkins at level of 0.05 mg/kg 73-84% at level of 0.075 mg/kg, 
         91-93%. Ranges in parentheses.
    2    Residues after 31 days.
    3    Soil application at planting and three spray applications on plant and soil.
    4    Soil application at planting and four spray applications on plant and soil.
    5    Combination of 3.3% oxamyl and 6.7% chlorfenvinphos, as granules. L = 240 or 250 g a.i./l E.C.; G= 100 g/kg granular formulation.
        METHODS OF RESIDUE ANALYSIS

         Oxamyl residues were determined directly using a high pressure
    liquid chromatography technique (HPLC). The samples were extracted
    with ethylacetate (Thean et al. 1977) or methanol (Chiba et al.
    1983). After suitable clean-up, the concentrated extracts were
    analysed on reversed phases (C-18) and detected with a UV detector at
    240 and 250 nm or 254 nm, respectively. The recoveries were acceptable
    but the limits of determination for these methods were not stated.

         Krause (1980) reported a multi-residue procedure for the
    determination of seven carbamate insecticides, including oxamyl and
    four related carbamate metabolite residues, in fruits and vegetables
    in which reversed phase HPLC and post-column fluorometric detection
    were applied. In a comparison of acetonitrile, acetone and methanol,
    the latter was found to be the most efficient extracting agent for
    carbamate residues. The coextractives were removed using solvent
    partitioning and a charcoal-silanized celite column. The recovery
    averaged about 9 percent at both the 0.05 mg/kg and 1 mg/kg
    fortification levels, with standard deviations of 5% and 5.6%,
    respectively. The method is suitable for regulatory purposes.

    NATIONAL MAXIMUM RESIDUE LIMITS

         A summary of available information on national maximum residue
    limits (MRLs) reported to the Meeting is given in Table 4.

    APPRAISAL

         Oxamyl was first evaluated by the Meeting in 1980. Since then,
    additional data have been made available on use patterns and on
    residues deriving from supervised trials.

         When use recommendations were followed, residues ranged from less
    than 0.01 mg/kg to 0.14 mg/kg in whole banana and were somewhat lower
    in the pulp. Most of the coffee bean samples did not contain
    detectable residues. A measurable residue was found in only a few
    cases (maximum, 0.08 mg/kg). In dried coffee beans, the oxamyl residue
    was higher than in the corresponding green ones.

         No residue was detectable in mature maize. The green forage
    contained residue in the range of 0.26 to 2.6 mg/kg and below 0.1
    mg/kg four and eight weeks after treatment, respectively. Soybean
    samples contained a maximum residue of 0.05 mg/kg, while no residue
    was detectable in pressed oil and meal.

         Following soil treatment, the oxamyl residue was below 0.02 mg/kg
    in sugarcane at harvest.

    Table 4   National Maximum Residue Limits

                                                                    

    Country              Commodity                    MRL
                                                      (mg/kg)
                                                                    

    Australia            Cereals                      0.02
                         Meat                         0.02
                         Milk                         0.02

    Belgium              Onion                        0.02
                         Potatoes                     0.02

    Japan                Potatoes                     0.1

    The Netherlands      Eggplant                     1
                         Zucchini                     1
                         Cucumbers                    1
                         Gherkin                      1
                         Melon                        1
                         Paprika                      1
                         Tomatoes                     1

    South Africa         Sugarcane                    0.05

    Sweden               Bananas                      2.0

    Taiwan (Prov. of     Peanuts                      0.08
    China)               Sugarcane                    0.1
                         Tomato                       3.0

    United States        Apples                       2
                         Bananas                      0.1
                                                      (0.2 proposed)
                         Cantaloupe                   2.0
                         Celery                       3
                         Citrus fruits                3
                         Cottonseed                   2.0
                         Cucumbers                    2.0
                         Eggplant                     2.0
                         Honeydew melon               2.0
                         Maize, field corn,           0.2 (proposed)
                         fodder and forage
                         Maize, field corn grain      0.05 (proposed)
                         Peanuts                      0.2
                         Peanut, forage               2.0
                                                                    

    Table 4 (continued)

                                                                 

    Country              Commodity                    MRL
                                                      (mg/kg)
                                                                 

                         Peanut, hay                  2.0
                         Peanut, hulls                0.2
                         Pears                        2.0
                         Peppers, bell                3
                         Pineapple                    1
                         Pineapple, forage            10
                         Potatoes                     0.1
                         Root crop vegetables         0.1
                         Soybeans                     0.2
                         Soybeans, straw              0.2
                         Summer squash                2.0
                         Tomatoes                     2
                         Watermelon                   2.0
                         Winter squash                2.0

    Fed. Rep. Germany    Onions                       0.05
                         Pineapples                   0.05
                         Potatoes                     0.05
                         Sugarbeet                    0.05
                                                                 

         The range of the residue level did not decrease significantly
    in cucumber grown in a glasshouse during the first two weeks after
    foliar application.

         No DMCF residue was detected in any of the samples, except 
    green maize forage, in which the maximum level found was 0.02 
    mg/kg.

    RECOMMENDATIONS

        The Meeting examined the new data provided and concluded that 
    some of them were suitable for estimating MRLs for coffee beans, 
    sugarcane and onion. In addition, the temporary maximum levels 
    recommended by the 1980 Meeting for soybeans (0.05T), banana 
    (0.05T) cucumber (0.2T) have been changed.

        The results of trials on sugarbeet and tomato supported the 
    previous recommendations. Residue data on Brussels sprouts, French 
    beans, gherkins, lettuce and strawberry were insufficient for 
    making recommendations. The limits recommended refer to the sum of 
    oxamyl plus its oxime expressed as oxamyl.

                                                                

    Commodity               Limit               Preharvest
                            (mg/kg)             interval
                                                (days)
                                                                

    * coffee beans          0.1                 7
    * sugarcane             0.05**              28
    * onions                0.05**              56
    maize                   0.05**              90 changed from
                                                   temporary
    soybeans                0.1
    bananas                 0.2                 7
    cucumber                0.5                 14
                                                                

    *    New proposals.
    **   Residue at or about the limit of determination.


    FURTHER WORK OR INFORMATION

    Required (by 1984)

    1.   Further data on beans, for reconsideration of the temporary
         recommendation.

    2.   Additional data on materials used for animal feedstuffs, e.g.,
         sugarbeet leaves and bean fodder.

    Desirable

    1.   Additional residue data from trials reflecting good agricultural
         practice in additional countries, in particular, residue data on
         peas.

    2.   Information on residues in food in commerce and at consumption.

    3.   Information on the effect on oxamyl residues of cooking,
         processing or storage of raw agricultural commodities.

    4.   Crop rotation studies on additional commodities and under field
         conditions with applications of commercial formulations (both
         granular and liquid) according to maximum recommendations.

    REFERENCES - RESIDUES

    Chiba, M. Veres, D.F., Townshend, J.L. and Potter, J.W. Redistribution
    1983      of oxamyl from treated seeds to peach seedlings and soil as
              determined by high-performance liquid chromatography. J.
              Agric. Food. Chem. 31: 53-58.

    DuPont.  Residue reports of supervised trials. (Unpublished)
    1983

    Finland. Information on oxamyl submitted to FAO.
    1983

    Krause, R.T. Multiresidue method for determining N-methylcarbamate
    1980      insecticides in crops, using high performance liquid
              chromatography. J. Assoc. Off. Anal. Chem. 63:1114-1124.

    The Netherlands. Information on oxamyl submitted to FAO.
    1983

    South Africa. Information on oxamyl submitted to FAO.
    1983

    Sweden. Information on oxamyl submitted to FAO.
    1983

    Thean, J.E., Fong, W.G., Lorenz, D.R. and Stephens, T.L. High pressure
    1977      liquid chromatographic determination of methomyl and oxamyl
              on vegetable crops. J. Assoc. Off. Anal. Chem. 61:15-17.


    See Also:
       Toxicological Abbreviations
       Oxamyl (JMPR Evaluations 2002 Part II Toxicological)
       Oxamyl (Pesticide residues in food: 1980 evaluations)
       Oxamyl (Pesticide residues in food: 1984 evaluations)
       Oxamyl (Pesticide residues in food: 1985 evaluations Part II Toxicology)