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)