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)