MALATHION JMPR 1975 Explanation Recommendations for maximum residue limits for malathion of 8 mg/kg in cereals and 2 mg/kg in whole meal and flour from rye and wheat were made at previous Joint Meetings (FAO/WHO 1967, 1969). In 1970, maximum residue limits were recommended for various fruits and vegetables (FAO/WHO, 1971). At the Eighth Session of the Codex Commission on Pesticide Residues (ALINORM 76/24 para. 144) it was pointed out that residues of malathion were highly persistent during long-term storage of grain at low temperature and low humidity and that milling of such grain resulted in residues in whole meal higher than the maximum residue limit of 2 mg/kg. In addition, it was indicated that new data from supervised trials on lettuce and apples would be submitted to the Joint Meeting. All governments were requested to provide residue data from supervised trials. Data and information on malathion residues in fruits and vegetables were made available to the Meeting. RESIDUES RESULTING FROM SUPERVISED TRIALS Data on malathion residues in apples and head lettuce from supervised trials in Canada were made available. The data summarized in Table 1 and 2, show the decline in malathion residues in both apples and lettuce with increasing pre-harvest intervals. The residue levels in lettuce were 40-80% lower than when the guard leaves were removed (Table 2). Malathion residues in apples from supervised trials in the United States of America (Yost, 1975) are shown in Table 3. Residues in pears ranged from 0.2-5.0 mg/kg (pre-harvest interval, 0 days) in seven trials in Washington, United States of America, following one application of malathion (25% WP or 57% EC) at rates of 0.57-1.9 kg/ha (Yost, 1975). Yost (1974) provided a summary of United States data on malathion residues in some crops (Table 3). RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION During 1973-1974 a total of 307 food commodity samples in the Netherlands were analysed for malathion residues. Some of the data are summarized in Table 4. In addition to these data, a total of 38 samples of swiss Chard, peas, beans, pears, red currants, raspberries, blackberries, parsley, radish, plums, carrots, grapes, cauliflower and chicory were analysed. Residues in 33 samples were below 0.01 mg/kg. Only five samples contained residues in the range 0.01-0.05 mg/kg. TABLE 1. Malathion residues in apples (supervised trials - Canada) Residues (mg/kg) at various locations1 Rate of application Pre-harvest Year kg a.i/ha Interval (days) St Jean Smithfield Kentville Summerland 1973 1.25 0 1.55 (1.28-2.00) 1.14 (1.00-1.41) 1 0.88 (0.74-0.98) 0.61 (0.37-0.85) 3 0.98 (0.86-1.18) 0.20 (0.16-0.23) 5 0.95 (0.79-1.14) 0.13 (0.08-0.17) 7 0.25 (0.22-0.30) 0.08 (0.04-0.10) 14 0.15 (0.14-0.16) 0.06 (0.04-0.07) 21 0.05 (0.04-0.06) 0.06 (0.06-0.07) 19742 1.25 3 0.52 (0.39-0.64) 0.11 (0.09-0.13) 1.57 (1.55-1.60) 1.82 (1.53-2.12) 7 0.21 (0.15-0.26) 0.05 (0.04-0.05) 0.54 (0.49-0.59) 1.38 (1.18-1.59) 14 0.03 (0.03-0.03) 0.34 (0.29-0.38) 1 In 1973 and 1974 samples were analysed in three and two laboratories, respectively. Averages and range of values determined (in parenthesis) are given. 2 Rate of application for Smithfield trials was 5 kg/ha. TABLE 2. Malathion residues in head lettuce (supervised trials - Canada) Residues (mg/kg) at various locations1 Rate of Pre-harvest With guard leaves Without guard leaves application interval Year kg a.i./ha (days) St Jean Lethbridge St Jean Lethbridge 1973 1.25 0 9.23 (6.45-11.5) 16.2 (13.3-18.8) 4.06 (3.73-4.25) 8.03 (7.57-8.74) (Lethbridge) 2.0 1 4.60 (4.25-4.87) 3.35 (2.80-3.93) 0.90 (0.69-1.06) 1.58 (1.30-1.73) (St Jean) 3 0.71 (0.68-0.74) 1.36 (1.26-1.48) 0.16 (0.11-0.20) 0.53 (0.40-0.63) 5 0.05 (0.05-0.06) 0.35 (0.32-0.38) 0.03 (0.02-0.04) 0.16 (0.13-0.21) 7 0.06 (0.05-0.07) 0.32 (0.28-0.35) 0.01 (0.01-0.01) 0.06 (0.05-0.07) 14 0.02 (<0.01-0.03) 0.02 (0.01-0.03) <0.01 0.01 (<0.01-0.01) 1 Samples were analysed in three laboratories. Averages and range of values determined (in parenthesis) are given. TABLE 3. Malathion residues in apples from supervised trials Rate of Pre-harvest application No. of interval (kg/ha) Formulation applications (days) Residues (mg/ha)* 0.5-1.15 25% WP or 1-4 0 1.4-21.1 (14) 57% EC 1 0.4-3.3 (6) 2 1.0 (1) 3 0.4-2.3 (7) * Figures in parenthesis are the number of samples. TABLE 4. Summary of United States data on malathion residues in some crops Recommended Residue at Initial residue pre-harvest interval pre-harvest interval Crop mg/kg (days) mg/kg Head lettuce 28-160 7 1-10 Endive 13-20 7 0.3-8 Cabbage 14-45 7 trace - 8 Spinach 10-167 7 2.5-6 Blackberries 2-10 1 2-7 Raspberries 4-12 1 1-6 Cherries 1.4-11.2 3 2.1-5.9 Peaches 2.2-18.8 7 0.8-4.8 Broccoli 26-106 3 0.2-5 TABLE 5. Survey data on malathion residues in the Netherlands, 1973-1974 Number of samples Residues (range mg/kg) Commodity Total No. <0.01 <0.01-0.05 <0.05-0.1 <0.1-1.0 Head lettuce 67 57 4 3 3 Cucumbers 38 36 2 - - Tomatoes 34 34 - - - Raw grain 27 11 5 4 71 Whole meal flour 12 6 3 1 2 Celery 22 22 - - - Apples 21 15 4 2 - Bell peppers 16 16 - - - Endive 11 7 2 2 - Strawberries 11 3 4 1 3 Brussels sprouts 10 10 - - - 1 One sample of raw grain contained residues between 1 and 2 mg/kg. APPRAISAL The Codex Commission on Pesticide Residues referred to the Joint Meeting a request that the maximum residue limits for malathion in fruits and vegetables and the maximum residue limit of 2 mg/kg for whole meal and flour from rye and wheat be re-evaluated in the light of data provided by governments. No data were available to the Meeting on the residues in whole meal, flour and bread following milling of grain from long-term storage at low temperature and low humidity to re-evaluate the maximum residue limit of 2 mg/kg. Data from supervised trials on fruits and vegetables in Canada and the United States of America were available. The Canadian data for apples and head lettuce indicated that for Canadian conditions a maximum residue limit of 2 mg/kg with a pre-harvest interval of three days would be acceptable. However, the data from the United States trials support the maximum residue limits for apples and lettuce recommended at the 1970 Joint Meeting (FAO/WHO, 1971). Additional United States data on endive, cabbage, spinach, blackberries, raspberries, cherries, peaches and broccoli support the maximum residue limit recommendation of the 1970 Joint Meeting. The data for malathion residues on pears was for the day of application only (the pre-harvest interval in the United States of America is one day) and no recommendation could be made. The Joint Meeting concluded that in the light of the available information the recommendations made at the 1970 Joint Meeting for maximum residue limits for malathion should be maintained. FURTHER WORK OR INFORMATION DESIRABLE 1. Further information on residues in stored grains resulting from good storage practice including storage at relatively low temperature and humidity and the effect of milling, cooking and baking on these residues. 2. Residue data from supervised trials in countries where malathion is used. REFERENCES Yost, J. F. (1974) American Cyanamid Company, Princeton, United States of America. (Unpublished data) Yost, J. F. (1975) American Cyanamid Company, Princeton, United States of America. (Unpublished data)
See Also: Toxicological Abbreviations Malathion (ICSC) Malathion (FAO Meeting Report PL/1965/10/1) Malathion (FAO/PL:CP/15) Malathion (FAO/PL:1967/M/11/1) Malathion (JMPR Evaluations 2003 Part II Toxicological) Malathion (FAO/PL:1968/M/9/1) Malathion (FAO/PL:1969/M/17/1) Malathion (AGP:1970/M/12/1) Malathion (WHO Pesticide Residues Series 3) Malathion (Pesticide residues in food: 1977 evaluations) Malathion (Pesticide residues in food: 1984 evaluations) Malathion (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental) Malathion (IARC Summary & Evaluation, Volume 30, 1983)