METHOMYL JMPR 1975
IDENTITY
Chemical name
1-(methylthio)ethylideneamino methylcarbamate
Synonyms
S-methyl-N-[(methylcarbamoyl)oxy]thioacetimidate, LannateR,
NudrinR, Dupont 1179
Structural formula
O
"
CH3-C=N-O-C -NH-CH3 C5H10N2O2S
'
S-CH3
Other information on identity and properties
Molecular weight: 162.2
Physical state: white crystalline solid
Melting point: 78-79°C
Specific gravity: 1.2946 25°/4°
Odour: slightly sulfurous
Vapour pressure: 5 × 10-5 mm Hg at 25°C
1.6 × 10-4 mm Hg at 40°C
Solubility: (grams/100 grams solvent):
water 5.8, methanol 100,
acetone 73, ethanol 42,
isopropanol 22, toluene 3.
Stability
Stable in solid form. Aqueous solutions in closed systems
decompose slowly. Aeration, sunlight, alkalinity, and higher
temperatures increase the rate of decomposition in water.
Purity of technical material
Technical methomyl contains a minimum of 95% methomyl, typically
97-99%.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Methomyl, an insecticide with systemic properties, is toxic to
insects both by direct contact and ingestion. It provides broad
spectrum control of insects in many vegetables and field crops,
certain fruit crops, and ornamentals (commercial plantings).
Methomyl is effective against pests such as beetles, aphids,
thrips, leaf hoppers and caterpillars and particularly loopers, beet
armyworm and corn earworm (Harvey et al., 1973).
The registered and recommended uses of methomyl in the United
States of America are summarized in Table 1. Available information on
the use patterns of methomyl in several other countries is summarized
in Table 2.
The use of methomyl in glasshouse tests against the greenhouse
whitefly was reported by Krueger et al. (1973).
Methomyl is marketed on a world-wide basis and products based on
it are used in nearly 100 countries (du Pont de Nemours, 1975).
Formulations produced include LannateR methomyl insecticide, a 90%
active water-soluble powder, and LannateRL methomyl insecticide, a
24% w/w water-miscible solution. A 25% wettable powder is used in
Europe and in some other areas. A 45% water-soluble powder is favoured
in Japan. Granules and dust formulations are used in certain areas.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Residue data are available from supervised trials on a variety of
fruits, vegetables and field crops (du Pont de Nemours, 1975). A
summary of much of this information appears in Table 3, together with
information on rates of application, number of applications and
pre-harvest intervals used. These data are almost exclusively from the
United States of America except for a few trials on wheat and barley
from Canadian locations.
Residue data from supervised trials in several other countries
were reported to the Meeting. These are summarized in Table 4.
Methomyl residues were detected on most above-ground crops at the time
of harvest. Higher residues occurred on leafy vegetables, e.g.
lettuce, spinach, celery and cabbage with generally low levels on root
crops, cucurbits and grain crops. High residues were detected in
alfalfa, pea, bean and peanut foliage and straw of wheat, oats and
barley. The residue level diminishes with time after application. The
amount of insecticide applied, time interval between last application
and harvest, surface area, weight and surface structure of the crop
are factors that affect the level of the residue. The amounts of
residues resulting from the use of the powder and liquid formulations
are nearly identical when an equal amount of active ingredient is
applied (du Pont de Nemours, 1975).
TABLE 1. Registered and recommended uses of methomyl in the United States of America
Last application days
To livestock
Crops Insects kg/ha To harvest grazing/feeding
Alfalfa Beet Armyworm, Lygus Bugs 1/2-1 7
Alfalfa - Beet Armyworm 1/4-1/2
Calif. & Ariz. Alfalfa Caterpillar 1/3-1/2 7
Aphids 1/2-1
Beans (snap) Leafhoppers
Mexican Bean Beetle 1/4-1 1 for 1/4-1/2 kg/ha 3 (vines)
Beet Armyworm, Cabbage Looper,
Corn Earworm 1/2-1 3 for 1/2-1 kg/ha 7 (hay)
Broccoli, Cauliflower Cabbage Looper, Imp. Cabbageworm,
Diamondback Moth 1/4-1 3
Brussels Sprouts Cabbage Looper, Imp. Cabbageworm 1/2-1 3
Cabbage Cabbage Looper, Imp. Cabbageworm,
Diamondback Moth 1/4-1 1
Celery Cabbage Looper 1 14
Beet Armyworm 1/2-1 14
Citrus (oranges, Citrus Thrip 1/2-1 1 10
lemons, grapefruit,
tangelos)
Corn (sweet) Earworm - Whorl as needed 1/3-1/2
Earworm - Ears 1-3 days or
as needed 1/4-1/2 0 (ears) 3 (forage)
Fall Armyworm, European Corn
Borer - Ears 1-3 days as needed 1/2
TABLE 1. (Cont'd.)
Last application days
To livestock
Crops Insects kg/ha To harvest grazing/feeding
Cotton Bollworm, Tobacco Budworm -
Do not apply more than 1/2-3/4 15 Do not graze or
3 applications feed treated cotton
Cucumber Cabbage Looper 1/2-1 3
Lettuce (head) Cabbage & Alfalfa Loopers 1/4-1/2 7
Beet Armyworm 1/2-1 10
Melons Cabbage Looper 1/2-1 3
Nectarines Thrips 1/2-1 1 10
Peanuts Corn Earworm, Beet Armyworm -
Up to 3 applications as needed 1/4-1 21 Do not feed treated vines
Peppers Green Peach Aphid 1/2 10
Potato Tuberworm, Cabbage Looper 1/2
Aphids 1/2-1
Leafhoppers ) 14
Flea Beetles) East of Miss River 1/2
Soybeans Soybean Looper, Green Cloverworm,
Mexican Bean Beetle, Corn
Earworm, Beet Armyworm, 1/4-1/2 14 3 (forage)
Velvetbean Caterpillar - Up to 7 (hay)
2 applications
TABLE 1. (Cont'd.)
Last application days
To livestock
Crops Insects kg/ha To harvest grazing/feeding
Spinach Cabbage Looper, Beet Armyworm -
Do not apply when mininum daily
temperature is 32°F or lower. 1/2-1 7
Do not apply to seedlings less
than 3" in diameter
Squash (summer) Cabbage Looper
Melonworm ) 1/2-1 3
Pickleworm) Southeast only
Tomato Tomato Fruitworm, Aphids, 1/2 1
Cabbage Looper, Beet Armyworm over 1/2-1 2
Tobacco (except shade) Flea Beetle, Hornworm 1/4-1/2 7 (flue cured)
Budworm (2-3 applications before
flower buds open), Cabbage 1/2 14 (air or fire cured)
Looper, Aphids
Chrysanthemums Cabbage Looper, Corn Earworm, 1/4-1/2 lb
Beet Armyworm, Thrips (weekly) per 100 gals.
TABLE 2. Use patterns of methomyl in some countries other than the United States of America
Pre-harvest
Application No. of interval
Country Crop Formulation rate applications (days)
Australia beans 22.5% water 100 ml/100 4 (bean fly), as 1
miscible liquid litres necessary (been
thrips)
leafy vegetables - cauliflower, broccoli, " as necessary -
cabbage 5-14 day intervals 3
peaches, nectarines " as necessary 1
tobacco " as necessary -
Canada lettuce 21.6% water 0.4-0.8 kg/ha as necessary - 7
broccoli, Brussels sprouts, cauliflower, soluble liquid 0.25-0.5 kg/ha 5-7 day intervals
cabbage (maximum limit " 7, 1
of active (cabbage)
rutabaga ingredient 0.9 kg/ha 1 14
pea content of 34%) 0.5 kg/ha as necessary - 1
5-7 day intervals
potato " " 3
tomato 0.25-0.5 kg/ha " 1
corn (sweet and field) " as necessary - 3
2-5 day intervals
rapeseed 0.2-0.3 kg/ha 8
flax 0.25-0.3 kg/ha 30
Malaysia vegetables, tobacco, soybeans, rice, maize, 90% water 0.25-0.5 kg/ha as necessary - 7
grapes, tomatoes, citrus, lichee soluble powder 5-7 day intervals
TABLE 2. (Cont'd.)
Pre-harvest
Application No. of interval
Country Crop Formulation rate applications (days)
Mexico cotton, tobacco, potato, tomato, maize, 90% water 0.25-0.4 kg/ha
sorghum, safflower, alfalfa, soybean, soluble powder
peppers, broccoli, cabbage, cauliflower,
lettuce, cucumbers, melons, pumpkins, beans
Netherlands tomatoes, peppers (glasshouse) 25% water 3
soluble powder
New Zealand cereals, pasture, maize, lettuce, brassicas, 90% water 0.27-0.36 kg/ha 7
tobacco soluble powder
tomatoes, beans " 7
canefruit 0.022 kg/100 2
litres
grapes 0.022-0.36 kg/ 7
100 litres
Central Cotton, rice, okra, citrus, peppers, beans, 90% water 0.25-0.5 kg/ha 1-7
America leafy vegetables, maize, peanuts, potatoes, soluble powder
tomatoes, sorghum, soybeans, tobacco,
ornamental plants
France grapes, fruits, vegetables, ornamentals 25% wettable 125-200 g/100 as necessary
powder litres
Germany, leafy vegetables except cabbage, root 25% wettable 100-150 g/100 14, 21
Federal vegetables powder litres (glasshouse)
Republic of 7, 14
cabbage, onion (glasshouse)
TABLE 2. (Cont'd.)
Pre-harvest
Application No. of interval
Country Crop Formulation rate applications (days)
leek 14
fruits except cucumbers, tomatoes 7, 10
(glasshouse)
cucumber, tomatoes 3
hops 14
grapes 28
Japan, rice 45% wettable 0.45-0.75 kg/ha 3 21
Far East cabbage powder " 3 3
tea " 2 20
tobacco " - -
chinese cabbage " 2 14
radish 0.6-0.9 kg/ha 3 7
pepper 0.45-0.75 kg/ha 4 7
sweet potato, sugarbeet " 5 7
South citrus 90% water 0.02-0.03 kg/ha 2 (>0.02 kg/
Africa soluble powder 100 litres)
28 (>0.02 kg/
100 litres)
TABLE 2. (Cont'd.)
Pre-harvest
Application No. of interval
Country Crop Formulation rate applications (days)
peaches 0.05 kg/100
litres 16
sorghum, maize 0.165 kg/ha 7
tobacco 0.225 kg/ha 7 (ovendried)
14 (airdried)
tomatoes 0.05 kg/100 2
litres
potatoes 0.33-0.45 kg/ha 3
green beans 0.225 kg/ha 3 3
cauliflower, cabbage 0.025-0.05 kg/ 4
100 litres
Spain tomatoes, citrus fruits, olives, cotton, 25% wettable 0.125-0.2 kg/ 7
sugarbeet, tobacco, ornamentals powder 100 litres
United hops 25% wettable 0.25-0.8 kg/ha as necessary -
Kingdom powder 1-12 day Intervals
Methomyl residues were not detected in rape seeds (limit of
detection 0.03 mg/kg) harvested 19-28 days after spraying at the rate
of 0.21-0.28 kg/ha (Mendoza et al., 1974). Six trials were carried out
at different locations. Methomyl residues in rapeseed pods decreased
from 9.06 mg/kg one day after spraying at the rate of 0.25 kg/ha to
2.3 mg/kg on day 14 (Cochrane, 1975).
The residual behaviour of methomyl in peppermint and spearmint
hay and oil is summarized in Table 5 (Kiigemagi et al., 1973).
Residues of methomyl were not detected in the oil even at hay residues
as high as 3.54 mg/kg.
Methomyl residues determined on flue-cured and cigar-wrapper
tobaccos are shown in Table 6 (Tappan et al., 1973). Residues were
higher on cigar-wrapper than on flue-cured tobacco. There appeared to
be only minimal loss of residue from cigar-wrapper tobacco because of
relatively low temperatures during the curing and fermentation
processes. In one experiment (du Pont de Nemours, 1975) residues in
green tobacco harvested 1, 3 and 7 days after last treatment with
methomyl were 9.6, 10.0 and 0.92 mg/kg, respectively. After flue
curing the residues were 3.8, 2.9 and 0.52 mg/kg representing a 44-72%
reduction in methomyl residues.
Glasshouse trials on tomatoes were reported (Krueger et al.,
1973) and the data are shown in Table 7. Residues were higher and more
persistent than the field trials reported in Tables 3 and 4.
Residues of methomyl were not detected in milk from two cows fed
the compound at 2 and 20 mg/kg in the ration for 30 days (du Pont de
Nemours, 1975). Samples were collected and analysed every two days
during the experimental period. At the end of the 30 day period the
cows were killed. Residues of methomyl were not detected in samples of
lean muscle, subcutaneous fat, liver or kidney. The method was
sensitive to 0.02 mg/kg.
Aerial spraying of rape fields with methomyl (0.25 kg/ha)
resulted in the death of bees (Greenhalgh, 1975). Dead bees were
collected 1.5, 3 and 24 hours after spraying. Methomyl residues were
2.03, 0.46 and 0.65 mg/kg, respectively. Dead bees (3 hours after
spraying) from an individual hive contained 0.42 mg/kg methomyl.
Samples of nectar, collected from this hive 8 to 10 hours after
spraying, did not contain detectable methomyl residues. Two samples of
dead bees were stored for one year at 0° and reanalysed. Residue
levels had dropped from 2.03 and 0.65 mg/kg to 0.4 and 0.04 mg/kg,
respectively.
Soil studies indicated the loss of 50-75% of applied methomyl
after 30 days, with only trace quantities remaining after 90 days and
no detectable residue within one year (du Pont de Nemours, 1975;
Harvey & Pease, 1973).
TABLE 3. Methomyl residues in crops from supervised trials in the United States of America
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Cabbage 0.25-0.38 6-10 0.03-0.40 (2) <0.02-0.35 (3) <02-0.02 (2) <0.02 (2)
0.5 1-8 0.04-3.0 (9) <0.02-0.44 (7) <0.02-0.16 (9) <0.02-0.15 (4) <0.02-0.02 (3) <0.02 (2)
1.0 1-7 0.15-16 (7) 0.16-1.1 (4) <0.02-0.92 (5) <0.02-0.56 (4) <0.02-0.02 (2) <0.02 (2)
Lettuce, 0.25 2-3 6.2 (1) <0.02-5.7 (3) <0.02-3.6 (6) <0.02 (1) <0.02-0.60 (4)
head 0.45-0.5 3-6 0.80-17 (7) 0.06-17 (12) <0.02-7.1 (23) 0.06-1.6 (5) <0.02-0.68 (12) <0.02 (1)
0.9-1.0 3-5 10-40 (3) 0.07-19 (8) <0.02-15 (15) 0.60-0.88 (2) <0.02-1.4 (7) <0.02 (1)
1.8 4 48 (1) 3.6 (1) 3.2 (1) 2.5 (1)
Lettuce, 0.25 3 2.0 (1) 0.52-1.3 (2) 0.02 (1)
leaf 0.50 3 9.2 (1) 1.0-9.2 (2) 0.48 (1)
1.0 3 34 (1) 4.2-29 (2) 0.76 (1)
Spinach 0.3-0.6 1-7 8.8-32 (3) 1.7-7.4 (7) 0.07-6.9 (15) 0.04-1.2 (3) <0.02-0.13 (5) 0.60 (1)
0.9-1.2 1-9 0.06-96 (4) 0.51-16 (11) 0.07-5.7 (14) 0.22-1.3 (3) 0.03-0.13 (5) 0.56 (1)
Tomatoes 0.25 4-5 0.02 (2) <0.02 (1) <0.02 (2) <0.02 (2) <0.02 (1)
0.45-0.5 3-16 0.03-0.24 (6) <0.02-0.09 (8) <0.02-0.04 (16) <0.02 (4) <0.02 (1)
0.9-1.0 1-8 <0.02-1.34 (16) <0.02-0.13 (10) <0.02-0.04 (5)
1.8-2.0 5-8 0.37 (1) <0.02 (1) <0.02 (1)
Peppers 0.45-0.67 1-9 0.06-0.34 (6) 0.02-0.39 (10) 0.02-0.38 (9) 0.05-0.07 (2)
0.9-1.0 1-8 0.11-3.2 (12) 0.03-0.44 (12) 0.03-0.74 (7) 0.03-0.10 (3) 0.19-0.24 (2)
1.8-2.0 1-8 0.43-2.2 (2) 0.15-0.46 (2) 0.44 (1) 0.19 (1)
Eggplants 0.5 2-9 0.05-0.10 (3) <0.02-0.11 (5) 0.02 (1)
1.0 6 0.30 (1) 0.11 (1) 0.15 (1)
TABLE 3. (Cont'd.)
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Cucumber 0.5-0.75 2-8 0.03-0.07 (2) 0.04-0.07 (3) 0.02 (1)
1.0 6-8 0.04 (1) <0.02 (1) 0.04 (1)
Squash, 0.5 1 0.03 (1) 0.02 (1) <0.02 (1)
summer 1.0 1 0.07 (1) 0.05 (1) <0.02 (1)
Cantaloupe 0.5-0.75 1-8 0.02-0.17 (4) 0.03-0.07 (3)
1.0 3-8 0.10-0.12 (3) 0.09-0.16 (3)
Melons - 0.5-1.0 1-2 0.03-0.15 (3) <0.02 (3) <0.02-0.09 (2)
honeydew,
crenshaw,
casaba
Watermelon 0.5-1.0 1-7 <0.02-0.07 (6) <0.02 (4) <0.02 (1)
Asparagus 0.45-0.5 1-5 <0.04-0.76 (11) <0.02-0.21 (11) <0.04 (4)
0.9-1.0 1-5 <0.04-1.1 (19) <0.02-0.52 (15) <0.02-0.12 (8) <0.02 (4)
1.8 2-5 0.26-2.5 (8) 0.07-0.17 (4)
Celery 0.45 1-6 4.6-7.4 (12) 0.09-2.7 (6) <0.02-1.4 (6) <0.02 (1) <0.02-0.06 (14)
0.75-0.9 1-11 1.6-22 (2) 0.25-6.9 (8) <0.02-3.7 (11) <0.02-0.13 (3) <0.02-0.17 (11)
1.5-1.8 3-11 2.9 (1) 0.64-7.4 (3) 0.28-4.3 (3) 0.14 (1)
TABLE 3. (Cont'd.)
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Sweet corn 0.25-0.5 2-12 <0.02-0.03 (9) <0.02 (5) <0.02 (3) <0.02 (2)
0.75-1.5 2-14 <0.02-0.03 (3) <0.02-0.07 (6) 0.03 (1) <0.02-0.02 (2)
Potatoes 0.04-0.6 3-10 <0.02 (1) <0.02 (1) <0.02 (5)
1.0-10 1-7 <0.02 (1) <0.02 (6)
Onions, 0.25-0.5 1-2 <0.02-0.28 (5) 0.36 (1) <0.02-0.11 (7) <0.02-
green 0.28 (12)
0.9-1.8 1-2 <0.02-0.26 (4)
Onions, dry 0.45-0.9 1-4 0.05-0.08 (2) <0.02-0.06 (5) <0.02-0.1 (4) <0.02 (3)
Sugarbeets - 0.5-1.0 1-3 <0.02 (4) <0.02 (2) <0.02 (7)
roots 4-12 1-4 <0.02 (2) <0.02 (4)
Sugarbeets - 0.5-1.0 1-3 0.72-2.1 (4) <0.02-0.84 (6) <0.02 (7)
tops 4-12 1-4 2.8-5.7 (2) 0.12 (1) <0.02-
1.4 (5)
Peas, green 0.45-0.5 1-3 <0.02-0.12 (3) <0.02 (1)
0.9-1.0 1-3 0.09-0.52 (3) <0.02 (1)
2.0 1-2 1.1 (1) <0.02 (1) <0.02 (1)
Peas, green- 0.45-0.5 1-3 0.06-4.0 (5) 0.07-1.1 (4) <0.02-0.17 (5) <0.02 (1)
filled pods 0.9-1.0 1-3 0.20-4.6 (6) 0.19-1.4 (6) 0.04-0.27 (5)
2.0 1-2 2.2 (1) 0.64-0.93 (2) <0.02 (1) 0.02 (1)
Peas, green- 0.45-0.5 1-3 1.3-15 (5) 0.11-5.8 (2) <0.02-3.1 (6) 0.02 (1)
forage 0.9-1.0 1-3 4.2-33 (5) 3.7-4.3 (2) 0.12-7.6 (6)
2.0 1-2 27-48 (2) 10-14 (2) 0.06-4.9 (2) 0.30 (1)
TABLE 3. (Cont'd.)
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Snap beans 0.2-0.5 2-7 <0.02-1.0 (4) <0.02-0.30 (9) <0.02-0.44 (10) <0.02 (1)
1.0 2-6 0.06-1.4 (3) 0.03-0.30 (3) <0.02-0.62 (5)
Lima beans 0.5-1.0 6-11 0.68 (1) <0.02-0.05 (2) 0.03 (1)
Dry beans 0.45-0.5 1-2 <0.02 (4) <0.02 (9) <0.02 (1)
0.9-1.0 1 <0.02 (4) <0.02 (6) <0.02 (9) <0.02 (4) <0.02 (1)
Soybeans 0.5-1.0 1-4 <0.02 (2) <0.02 (13)
2.0-4.0 1-4 <0.02 (2)
Soybean 0.5 1-4 0.60 (1) <0.02-5.1 (5) 0.03-0.80 (3) 0.12 (1) 0.07-0.15 (2)
forage 1.0-2.0 1-4 0.02-8.0 (4) 3.7 (1) 0.88 (1) 0.08-0.40 (3)
Peanuts 0.45-1.8 1-4 <0.02 (2) <0.02 (1) <0.02 (4)
Peanut hulls 0.45-1.8 1-4 <0.02 (2) <0.02 (1) <0.02 (4)
Peanut 0.45-0.5 1-4 20 (1) 14 (1) <0.02-1.8 (2) 0.43 (1) <0.02 (1) <0.02-
foliage 0.34 (7)
0.9-1.0 1-4 13-48 (5) 7.1-31 (5) 1.3-20 (6) 1.4 (1) 0.23 (1) 0.04-
0.99 (8)
1.8-2.0 3 >100 (1) 48 (1) 16 (1) 0.14-
3.8 (2)
Cottonseed 0.25-0.5 2-9 2.1-2.2 (2) <0.02 (3) <0.02 (6)
1.0-2.0 1-9 0.1 (1) <0.02 (2) <0.02-
0.21 (8)
TABLE 3. (Cont'd.)
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Wheat 0.22-0.5 1-7 <0.02-0.09 (7) <0.02-0.07 (8) <0.02-0.30 (10) <0.02-0.12 (2) 0.09 (1)
0.9-1.0 2-5 0.17-0.21 (2) 0.24-0.33 (2) 0.02 (1)
Wheat, green 0.45-0.5 2 22-48 (2) 12-18 (2) 0.12-4.9 (7) 0.37-0.59 (2) 0.03-0.16 (6)
forage 0.9-1.0 2-4 36-46 (2) 30-34 (2) 0.32-12 (5) 0.12-0.34 (3)
Wheat straw 0.22-0.5 1-5 23-26 (2) 0.90-20 (3) 0.07-11 (10) 2.0-4.0 (2) 0.09-0.16 (2) 1.0-2.7 (2)
0.9-1.0 4-5 34-55 (2) 1.8-15 (3) 0.08 (1)
Barley 0.22-0.45 1-4 <0.02-0.72 (5) <0.02-0.21 (4) <0.02 (1)
0.9 4 0.14-1.11 (2) <0.02-0.04 (2)
Barley, 0.45 2 14-16 (2) 11 (1) 0.02-0.15 (2)
green forage 0.9 2 38-45 (2) 14-18 (2) 0.06-0.47 (2)
Barley straw 0.22-0.45 1-4 0.05-3.1 (5) <0.02-0.28 (4) <0.05 (1)
0.9 4 4.8-6.8 (2) <0.02-0.16 (2)
Oats 0.45-0.9 4 <0.02 (4)
Oats, green 0.45-0.9 2 0.05-0.27 (4)
forage
Oats straw 0.45-0.9 4 1.7-7.1 (4) <0.05 (4)
Sorghum 0.33-0.5 1 0.09 (2) <0.02-
0.07 (7)
0.75-2.0 1-2 0.36 (1) <0.02-0.08 (4) <0.02 (5)
TABLE 3. (Cont'd.)
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Sorghum 0.33-0.5 1 0.56-1.4 (2) <0.05-
foliage 0.59 (7)
0.75-2.0 1-2 1.8 (1) 0.12-0.38 (2) <0.05 (6)
Apples 0.75-1.0 5-9 0.43-3.2 (5) 0.22-1.7 (2) 0.07-0.6 (4) 0.21-0.32 (2) 0.06 (1) <0.02-
0.12 (8)
1.5 8 8.7-9.7 (2) 4.2-5.1 (2) 0.68-1.2 (2) 0.31-0.52 (2)
2.0-2.5 5-12 0.12-0.64 (2) <0.02-0.06 (2) 0.32-
0.72 (4)
Peach 0.5 7-8 5.6-6.9 (2) 1.1-4.0 (2) 0.69-3.1 (2)
Nectarine 0.5 1 0.21-0.70 (2)
1.0 1 0.36-4.1 (2) 0.49 (1) 0.17 (1) <0.02 (1)
2.0 1 1.5-13.5 (2) 0.08 (1) 0.07 (1)
Grapes 0.33-0.67 1-2 0.04-0.28 (4) <0.02 (1) <0.02-0.40 (7) <0.02 (1) <0.02 (1)
1.0-2.0 1-2 0.4-4.2 (8) 0.11-1.7 (8) 0.22-2.1 (9) 0.24-0.60 (3) 0.14 (1)
Pineapple 2.5-5.0 6 <0.02 (2)
10-20 1-6 <0.02-
0.10 (11)
Grapefruit 0.5-1.0 1 0.25-0.33 (2) 0.02-0.07 (2)
Oranges 0.75-1.5 1-5 0.16-0.70 (4) 0.05-0.07 (3) <0.02-0.07 (6) 0.02-0.04 (2)
2.0-4.0 1 0.28 (1) 0.13-1.6 (2) 0.05 (1)
Lemon 1.0-4.0 1 <0.02-0.22 (4) 0.04-0.18 (3) <0.02 (3) <0.02 (1)
TABLE 3. (Cont'd.)
Residues (mg/kg)1
Pre-harvest interval in days
Rate No. of
Crop kg/ha applications 0-1 2-3 4-7 8-10 11-14 >14
Tangelos 1.0 5 1.7 (1) 1.0 (1) 0.16 (1) 0.06 (1)
Alfalfa 0.25-0.5 1 7.8-20 (3) 2.0-6.5 (5) 0.30-10 (11) 0.20-0.78 (3)
1.0-2.0 1 18-100 (2) 26-62 (3) 1.5-6.8 (7) 0.87-2.3 (2)
Tobacco 0.5-1.0 2-4 9.1-16 (3) 0.39-10 (4) 0.02-0.92 (3) 0.24 (1) <0.02 (1)
(green) 12 1 0.06 (1)
8-16 mg/ 1 <0.02 (2)
plant
Tobacco 0.25-1.0 2-5 0.60-6.5 (7) 2.8 (1) 0.07-0.52 (6) 0.17 (1) 0.03-0.11 (4) <0.02-
0.10 (3)
(flue cured) 4.0 4 31 (1) 0.29 (1) 0.09 (1)
12-24 1 <0.02-
0.19 (5)
6-12 mg/ 1 <0.02 (3)
plant
1 Residues, mg/kg, at interval, days, after application. (Number of samples in parenthesis.)
TABLE 4. Methomyl residues in crops from supervised trials from various countries
Application Residues in mg/kg, at intervals (days) after application1
Rate kg
Crop Country No. a.i./ha Formulation 0-1 2-3 4-7 8-10 11-14 >14
Tomatoes Germany 1 0.225 25% wp <0.01 (1) 0.02 (1) <0.01- <0.01 (1) <0.01 (1)
South Africa 6-10 0.05 90% WP <0.02- 0.02 (2)
0.13 (4) <0.02 (2)
Tomatoes Germany 1 0.225 25% WP 0.19 (1) 0.07 (1) 0.02- 0.02 (1) 0.05 (1)
(glasshouse) Netherlands 1 0.075 25% WP 0.01- <0.01- 0.07 (2)
0.02 (2) 0.02 (2)
2 0.125 0.05- 0.02-
0.06 (2) 0.03 (2)
New Zealand 1 0.28 90% WP <0.01- <0.01- <0.01 (2) <0.01 (1)
0.08 (2) 0.02 (3)
1 0.56 0.04- <0.01- <0.01- <0.01 (1)
0.11 (2) 0.06 (3) 0.02 (2)
1 1.12 0.3 (1) 0.06- 0.05 (1)
0.13 (2)
Cabbage Germany 1 0.225 25% WP 0.38 (1) 0.02 (1) 0.01- 0.01 (1) <0.01 (1)
South Africa 1 45g/100l 90% WP 1.8-1.9 (2) 0.21 (1) 0.02 (2) 0.08 (1) 0.05 (1)
Far East 2-6 0.675 45% WP 0.21- 0.21-
0.80 (4) 0.33 (4)
Cauliflower Germany 1 0.225 25% WP 0.94 (1) 0.06 (1) 0.03- 0.01 (1) <0.01 (1)
0.04 (2)
South Africa 1 90g/100l 90% WP 0.62 (1) 0.95 (1) 0.23 (1) 0.05 (1) 0.06 (1)
Beans New Zealand 1 0.4-0.8 90% WP 0.10- 0.01- <0.01-
0.15 (2) 0.17 (4) 0.01 (4)
South Africa 3 0.225 90% WP 0.06- 0.03 (1) <0.03 (1)
0.69 (2)
TABLE 4. (Cont'd.)
Application Residues in mg/kg, at intervals (days) after application1
Rate kg
Crop Country No. a.i./ha Formulation 0-1 2-3 4-7 8-10 11-14 >14
Peaches South Africa 3 45g/100l 90% WP 2.0- 2.1 (1) 1.2 (1) 0.46- <0.1-
3.9 (2) 0.5 (2) 0.12 (2)
Carrots Germany 1 0.225 23% WP 0.09 (1) <0.02 (1) <0.02 (2) <0.02 (1) <0.02 (1)
Onions Germany 1 0.225 25% WP <0.01 (1) 0.01 (1) 0.02- <0.01 (1) <0.01 (1)
0.08 (2)
Far East 2-4 0.675 45% WP <0.01 (2) <0.01 (2) <0.01 (2) <0.01 (2)
Potatoes South Africa 10 0.45 90% WP <0.02 (1)
Sweet potatoes Far East 3-5 0.63 45% WP <0.01 (4) <0.01 (2) <0.01 (2)
Radish Germany 1 0.225 25% WP 0.46 (1) 0.16 (1) 0.08- 0.08 (1) 0.08 (1)
0.20 (2)
Radish Germany 1 0.225 25% WP 0.14 (1) 0.78 (1) 0.81- 1.06 (1) 0.22 (1)
(glasshouse) 0.98 (2)
Horse radish Far East 2-3 0.45 45% WP 0.06- 0.07 (1) 0.11- 0.16- 0.16- 0.17-
0.07 (2) 0.18 (2) 0.22 (2) 0.21 (2) 0.23 (2)
Peppers Far East 4-6 0.36 45% WP 0.51- 0.05- 0.01-
2.5 (4) 0.69 (4) 0.20 (4)
Grapes New Zealand 1 25-50g/100l 90% WP 1.01- 0.49- 0.05- 0.05 (4)
2.14 (4) 0.94 (4) 0.12 (4)
Apples Denmark 1 1.25 25% WP 1.92- 1.18- 0.96-
2.08 (2) 1.96 (2) 1.56 (4)
TABLE 4. (Cont'd.)
Application Residues in mg/kg, at intervals (days) after application1
Rate kg
Crop Country No. a.i./ha Formulation 0-1 2-3 4-7 8-10 11-14 >14
Cucumbers Denmark 1 0.25g/plant 25% WP 0.73- 0.11- 0.07-
0.97 (4) 0.46 (4) 0.14 (2)
(glasshouse) Germany 1 0.225 25% WP 0.15 (1) <0.01 (1) 0.02 (2) <0.01 (1) <0.01 (1)
Cucumbers Germany 1 0.225 25% WP 0.05 (1) 0.04 (1) <0.01 (2) <0.01 (1) <0.01 (1)
Oranges South Africa 1 18g/100l 90% WP 0.22- 0.03 (1) <0.02- <0.02 (1)
0.42 (2) 0.03 (3)
1 50g/100l 1.8 (1) 0.63 (1) 0.58 (1) 0.27 (1) 0.37 (1)
Blackcurrants Denmark 4 0.75 25% WP 1.06- 0.06-
1.20 (2) 0.23 (8)
Strawberries Denmark 1 0.5 25% WP <0.05 (8)
Raspberries New Zealand 1 22-45g/100l 90% WP 0.06- 0.01- <0.01 (2)
0.15 (2) 0.02 (2)
Spinach Germany 1 0.225 25% WP 9.06 (1) 0.86 (1) 0.16- 0.01 (1) 0.02 (1)
0.91 (2)
Lettuce Germany 1 0.225 25% wp 2.59 (1) 0.30 (1) 0.02- <0.01 (1) <0.01 (1)
0.08 (2)
Lettuce Germany 1 0.225 25% WP 3.20 (1) 2.73 (1) 1.80- 1.24 (1) 0.29 (1)
(glasshouse) 2.28 (2)
Sorghum South Africa 1 0.33 90% WP 1.9- <0.04 (2) <0.04 (2)
2.25 (2)
Maize South Africa 1 0.16 90% WP <0.02 (1) <0.02 (1)
TABLE 4. (Cont'd.)
Application Residues in mg/kg, at intervals (days) after application1
Rate kg
Crop Country No. a.i./ha Formulation 0-1 2-3 4-7 8-10 11-14 >14
Rice Far East 1-3 0.675 45% WP <0.01 (5)
Tea Far East 1-2 0.81 45% wp 0.08- 0.04- <0.01 (4)
0.40 (5) 0.33 (5)
Tobacco South Africa 4 0.225 45% WP 0.05 (1)
Far East 1 0.34-0.67 45% wp <0.01-
0.02 (6)
Turkey 1-3 0.25 0.15 (1) 0.49 (1) 0.51 (1)
Hops (dried) Germany 3-4 0.125-0.25 25% WP <0.02 (3) 0.02 (5)
United 5-9 0.06-0.10 20, 25% <0.02- <0.02 (1)
Kingdom water 0.20 (6)
soluble
liquid,
25% WP
4-6 0.125 <0.02-
0.96(4)
4-5 0.15-0.19 0.31-
1.20 (3)
1 Numbers in parenthesis are the number of samples.
TABLE 5. Methomyl residues in mint in supervised trials (Kiigemagi et al., 1973)
Rate No. of Pre-harvest Methomyl residues (mg/kg) in
kg/ha applications interval (days) fresh hay spent hay oil
Peppermint
0.28 1 13 0.09 <0.02 <0.04
0.56 1-2 0 2.13-10.1
3 1.53
7 <0.02-0.66
8 0.39 0.29 <0.04
14-26 <0.02-0.12 <0.02-0.08 <0.04
1.1 1-2 0 4.20-20.6
3 1.06-2.56
7 0.02-1.19
8 0.55 0.36 0.04
14-26 <0.02-0.17 <0.02-0.13 <0.04
2.2 1 0 28.0
3 1.64
7 0.55
26 0.22 0.03 <0.04
Spearmint
0.56 1-2 0 56.7
7 3.75
8 3.59 0.28 <0.04
14-22 0.23-1.51 0.11-0.12 <0.04
1.1 1-2 0 133
7 7.50
8 5.34 0.34 <0.04
14 0.16 0.17 <0.04
TABLE 6. Methomyl residues on cigar-wrapper and flue-cured tobaccos
(Tappan et al., 1973)
Rate No. of Pre-harvest Residues
kg/ha applications interval (days) (mg/kg)
Cigar-wrapper tobacco
0.95-1.1 3-6 0 22.17-100.3
1.17-1.04 4 1 30.2
1.07-0.95 6 7 8.36
1.07 6 14 3.87
Flue-cured tobacco
0.33-0.34 4-7 5 0.03-0.25
0.34 7 12 0.03
0.34 6 13 0.03
0.34 7 19 <0.02
TABLE 7. Methomyl residues in glasshouse tomatoes (Krueger et al., 1973)
Methomyl (mg/kg)1 at dosages of
Days after treatment 0.03 kg/ha 0.06 kg/ha
1st spray
0.5 0.61 0.99
1.5 0.22 0.77
3 0.20 0.71
6 0.11 0.53
2nd spray
0.5 0.97 2.11
7 0.18 0.65
3rd spray
7 0.35 0.59
1 Mean of 3 replicate experiments.
FATE OF RESIDUES
General comments
The metabolism of methomyl in plants and rats results in the
rapid complete degradation of the molecule to carbon dioxide and
acetonitrile as the major residual products.
In animals
Methomyl-14C was administered orally to rats (Harvey et al.,
1973; Baron, 1971). Essentially all the radio-labelled material was
rapidly eliminated from the body within 24 hours in the ratio of 1
part 14C-carbon dioxide, 2 parts 14C-acetonitrile and 1 part urinary
metabolites. Approximately 10% of the original dose was found in the
whole body and organs one day after treatment. The chemical identity
of the radio-labelled material excreted in the urine was not
determined. However, the absence of methomyl, S-methyl
N-hydroxythioacetimidate, the S-oxide and S,S-dioxide of methomyl and
conjugates thereof was demonstrated.
In plants
The metabolic fate of methomyl was investigated in tobacco, corn
and cabbage in the laboratory and greenhouse (Harvey & Reiser, 1973;
Baron, 1971). Plants treated with 14C-methomyl rapidly degraded the
compound to carbon dioxide and acetonitrile which volatilized from the
plant tissues. Analysis of the tissues of treated plants showed that
the remainder of the 14C activity had been reincorporated into
natural plant components after total decomposition of the methomyl
molecule. Radio-labelled lipids, Krebs cycle acids (glycolic,
tartaric), sugars, suspected amino acids and a multiplicity of 14C
products were identified or detected. The absence of the oxime
(S-methyl N-hydroxythioacetimidate), the S-oxide and S,S-dioxide of
methomyl was demonstrated. The only residue found was methomyl itself.
The half-life of methomyl was of the order of 3-7 days. Repetitive
season-long treatment of cabbage and corn under field conditions
confirmed the results obtained with single treatments on young plants
in the laboratory.
In soil
Laboratory studies showed that methomyl was degraded rapidly by
microbial action in soil with carbon dioxide as the principal product
(Harvey & Pease, 1973). In soils treated with methomyl under field
conditions only trace residues of methomyl, its oxime and a polar
fraction remained after one month, and none was detected after one
year. Fractionation of the unextractable radioactivity remaining in
soil five months after treatment with 14C-methomyl showed that the
water-soluble residual radioactivity was distributed among the normal
soil organic fractions. This would be expected from reincorporation of
the 14CO2 or other small fragments formed from the complete
breakdown of 14C-methomyl. A run-off study with unlabelled methomyl
under farm use conditions showed that methomyl did not move laterally
into untreated areas with run-off water.
In storage and processing
Some data are available on the effect of cooking and field
trimming on residue levels of methomyl in some commodities (du Pont de
Nemours, 1975). Table 8 shows the data on the effect of cooking.
Residue reduction of about 70-90% was achieved for tomatoes, peas and
cabbage. Reductions of about 50-90% in methomyl residues resulted from
trimming celery (Table 9).
A study was carried out to follow the distribution of methomyl in
wheat spiked at 0.05, 0.10 and 0.20 mg/kg levels and processed through
laboratory simulated milling. The data from this study (Table 10) show
that approximately 20-35% of the methomyl is recovered with the major
portion in the flour fraction.
Residues in food in commerce or at consumption
Data were not available to the Meeting to indicate the level and
incidence of methomyl residues in food moving in commerce or in food
at the time of consumption.
METHODS OF RESIDUE ANALYSIS
Residues of methomyl can be determined by gas-chromatographic
methods. Pease & Kirkland (1968) described a method for determining
residues in animal and plant tissues and soil. Samples were extracted
with ethyl acetate followed by solvent-partitioning clean-up steps.
Methomyl was then hydrolysed to the corresponding oxime,
methyl-N-hydroxythioacetimidate, which was determined by
programmed-temperature gas chromatography with microcoulometric sulfur
detection. The limit of determination of the method was 0.02 mg/kg
based on a 25 g sample, with an average recovery of 93% for all
tissues investigated. Lower recoveries, averaging 63%, were obtained
with soils. Pease (1969) modified the method by using the flame
photometric detector in the sulfur mode, allowing the injection volume
to be reduced from 50 µl to 5 µl with the same limit of determination.
Certain crops (e.g., sweet corn, cabbages) contain troublesome
interferences and others such as cottonseed and tobacco cause emulsion
difficulties during the procedure.
Fung (1975) reported an adaptation of the Pease & Kirkland (1968)
method for determining methomyl residues in tobacco. The sensitivity
of the method was 0.01 mg/kg based on a 50 g sample, with an average
recovery for green and cured tobacco of 87%.
TABLE 8. Effect of cooking on residues of methomyl
Residue level
Original residue after cooking Reduction
Sample level (mg/kg) (mg/kg) %
Tomatoes 0.70 0.18* 74
Peas 1.1 0.09 92
Cabbage 16 1.1 93
Water 2.0 0.56 72
Water 10 3.7 63
* Cooking water contained 0.04 mg/kg methomyl.
TABLE 9. Effect of trimming on residues of methomyl in celery
Pre-harvest
No. of Rate interval Untrimmed Trimmed Reduction
applications kg/ha (days) mg/kg mg/kg %
3 0.45 3 2.3 0.27 88
3 0.45 7 1.4 0.25 82
3 1.8 3 7.4 0.64 91
3 1.8 7 4.3 0.53 88
1 0.45 3 2.7 0.8 70
1 0.9 3 3.4 0.8 77
1 0.45 2 1.1 0.09 92
1 0.9 2 3.2 0.25 93
6 0.9 3 6.9 3.9 44
6 0.9 5 3.7 1.5 60
6 0.9 7 1.8 1.0 45
TABLE 10. Effect of milling wheat on methomyl residues1
Methomyl found, µg Recovered (%)
Methomyl added, µg Bran Flour Bran Flour
5.0 N.D. 1.7 0 34
10 0.42 2.6 4 26
20 0.65 3.7 3 19
1 Whole wheat grain was "spiked" and then carried through the milling
process.
Mendoza et al. (1974) described a method for determining methomyl
using 1-fluoro-2,4-dinitrobenzene. Methomyl is hydrolysed to
methylamine and after reaction with 1-fluoro-2,4-dinitrobenzene, the
reaction product 2,4-dinitrophenylmethylamine is analysed by GLC with
electron capture detection. Recoveries of methomyl added to rapeseed
oil at 0.01-1 mg/kg averaged 97%. This method lacks specificity since
under the conditions used other methyl carbamate insecticides would
interfere.
Williams (1972) reported the direct gas-chromatographic
determination of methomyl with microcoulometric nitrogen detection but
did not apply it to samples. Reeves & Woodham (1974) described a
method for the analysis of methomyl in soil, sediment, water and
tobacco. Methomyl is extracted from soil, sediment and water with
dichloromethane and from tobacco with a mixture of dichloromethane and
benzene. Soil, sediment and water extracts are purified by elution
through a chromatographic column of activated Florisil, while tobacco
extracts are purified by a coagulation procedure. Determination is by
GLC with a sulfur flame photometric detector. The limit of
determination of the method is 0.05 mg/kg. Average recoveries of 75,
19, 80 and 78% were obtained for water, soil, sediment and tobacco,
respectively.
Methomyl can also be determined by a thin-layer
chromatographic-enzyme inhibition technique (Mendoza et al., 1974).
Rape seeds, oils and meals are extracted with ethyl acetate and
cleaned up by liquid-liquid partitioning. Quantitative recoveries are
obtained and the limits of detection are 0.01 mg/kg in rape oils and
meals and 0.03 mg/kg in seeds. McLeod et al. (1975) utilized the same
detection procedure to analyse fortified food samples. Estimated
recoveries from milk, eggs, beef, honey, butter, pork, peas and
cabbage were variable: 70-90% for samples fortified at 0.5 mg/kg and
40-90% for 0.05 mg/kg.
None of the methods discussed can be considered satisfactory for
regulatory purposes. The method of Pease & Kirkland (1968) requires
resolution of emulsion and interference problems. The method of Reeves
& Woodham (1974) has been tested on only soil, sediment, water and
tobacco and requires further validation. The thin-layer
chromatographic-enzyme inhibition method (Mendoza et al., 1974) is
semi-quantitative and the dinitrofluorobenzene method (Mendoza et al.,
1974) is non-specific.
NATIONAL TOLERANCES REPORTED TO THE MEETING
Some examples of national tolerances were reported to the Meeting
and are listed in Table 11.
TABLE 11. Examples of National tolerances for methomyl reported to
the Meeting
Tolerance
Country Commodity (mg/kg)
Australia Soybeans, grapes, rapeseed, citrus fruit,
cherries 2
Leafy vegetables, tomatoes, potatoes, peaches,
nectarines, apples, maize, peppers, beans,
eggplant 1
Canada Cabbages 5.0
Lettuce 2.0
Citrus fruits 1.0
Netherlands Peppers, tomatoes 0.05
New Zealand General 0.2
South Africa Cabbages, cauliflowers, citrus, green beans,
potatoes, peaches, sorghum, maize, tomatoes,
tobacco 0.2
United Alfalfa, bean forage, corn fodder and forage,
States pea vines, soybean forage 10
of America Spinach 6
Cabbage, endive (escarole), grapes, lettuce,
nectarines, peaches, peas 5
Broccoli, celery 3
TABLE 11. (Cont'd.)
Tolerance
Country Commodity (mg/kg)
Beans (succulent), Brussels sprouts,
cauliflower, grapefruit, lemons, oranges,
tangerines, mint hay 2
Apples, sorghum forage 1
Cucurbits, fruiting vegetables, leafy
vegetables (except broccoli, Brussels sprouts,
cabbage, cauliflower, celery, endive
(escarole), lettuce and spinach), root crop
vegetables, sorghum grain, soybeans 0.2*
Beans (dry), corn grain (including popcorn),
fresh corn including sweet corn (kernels plus
cob with husk removed), cottonseed, peanuts,
peanut hulls 0.1*
* Negligible residues.
APPRAISAL
Methomyl is a broad spectrum insecticide that is toxic to insects
both by direct contact and ingestion. It is used on a considerable
scale in many countries on a relatively wide range of crops. Methomyl
is effective against many pests such as beetles, aphids, thrips, leaf
hoppers and particularly caterpillars, loopers, beet armyworms and
corn earworms which damage many vegetables, field crops, certain fruit
crops and commercial plantings of ornamentals.
Methomyl is marketed in the form of water-soluble powder, water
miscible solution and wettable powder.
The rates of application vary depending on part and crop. Normal
application rates are 0.25-1 kg/ha.
Extensive residue data were available from the United States of
America with limited data from Canada, Denmark, Germany, the
Netherlands, New Zealand, South Africa and the Far East. Methomyl was
the only residue found. Limited data are available on the fate of
methomyl residues in storage and processing. No data were available to
indicate the level and incidence of methomyl residues in food moving
in commerce or in food at the time of consumption.
Information is available on the fate of methomyl residues in
plants, in rats and in soil. In plants the half-life of methomyl is of
the order of 3-7 days. Methomyl itself is the only residue detected.
The absence of the oxime (S-methyl N-hydroxythioacetimidate), the
S-oxide and the S,S-dioxide of methomyl has been demonstrated. The
molecule is degraded to carbon dioxide and acetonitrile as the major
residual products which volatilize from the plant tissues.
In rats methomyl is eliminated from the animal body within 24
hours in the ratio of 1 part carbon dioxide, 2 parts acetonitrile and
1 part urinary metabolites. Methomyl, S-methyl
N-hydroxythioacetimidate, the S-oxide and S,S-dioxide of methomyl and
conjugates thereof are not present in the urine. Methomyl degrades
rapidly in soil with carbon dioxide as the principal end product.
Available residue methods do not appear to be suitable for
regulatory purposes.
National tolerances have been established in a number of
countries.
RECOMMENDATIONS
The following guideline levels are recommended.
Pre-harvest
intervals
Guideline on which
level, recommendations
Commodity mg/kg are based (days)
Cabbage 5 1
Spinach 5 7
Lettuce 5 10
Celery 3 10
Citrus (oranges, lemons,
grapefruit, tangelos) 2 1
Apples 2 7
Snap beans, cauliflower,
tomatoes, peppers 1 3
Nectarines, grapes 1 7
Hops (dried), tobacco (flue-cured) 14
Cucumbers, eggplant 0.5 3
Green onions 0.5 10
Summer squash, cantaloupes,
melons, watermelons 0.2 3
Asparagus 0.2 5
Green peas 0.2 7
Dry onions, barley, sorghum 0.2 14
Pineapples 0.2 30
Pre-harvest
intervals
Guideline on which
level, recommendations
Commodity mg/kg are based (days)
Sweet corn 0.1 1
Potatoes, dry beans 0.1 3
Sugar beets 0.1 7
Cottonseed, soy beans, wheat, oats 0.1 14
Peanuts 0.1 21
Milk, meat 0.02*
Animal feedstuffs: alfalfa, pea
forage 10 7
Sorghum and soy bean forage,
wheat, oat and barley straw 10 14
Peanut forage 5 21
Mint hay 2 14
Peanut hulls 0.1 21
* At or about the limit of determination.
FURTHER WORK OR INFORMATION
REQUIRED
1. Full toxicological data (before an acceptable daily intake can be
recommended).
2. Modification or refinement of available methods of residue
analysis to make them suitable for regulatory purposes.
DESIRABLE
1. Further data on the disappearance of residues during storage and
processing.
2. Further residue data from countries other than the United States
of America.
REFERENCES
Baron, R. L. (1971) Toxicological considerations of metabolism of
carbamate insecticides: Methomyl and carbaryl. Pesticide Terminal
Residues, Tahori, A. S., ed., Butterworths, London, pp. 185-197
Cochrane, W. P. (1975) Canada Department of Agriculture, Ottawa
(unpublished report)
Du Pont de Nemours (1975) Information on methomyl insecticide. E. I.
Dupont de Nemours & Company (Inc.), Wilmington, Delaware, U.S.A.
(unpublished)
Fung, K. K. H. (1975) Determination and identification of S-methyl
N-((methyl-carbamoyl) oxy) thioacetimidate (methomyl) residues in
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See Also:
Toxicological Abbreviations
Methomyl (EHC 178, 1996)
Methomyl (HSG 97, 1995)
Methomyl (ICSC)
Methomyl (Pesticide residues in food: 1976 evaluations)
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)