PESTICIDE RESIDUES IN FOOD - 1981
Sponsored jointly by FAO and WHO
EVALUATIONS 1981
Food and Agriculture Organization of the United Nations
Rome
FAO PLANT PRODUCTION AND PROTECTION PAPER 42
pesticide residues in food:
1981 evaluations
the monographs
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, 23 November-2 December 1981
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome 1982
PHENTHOATE
Explanation
The compound was evaluated by the 1980 Joint Meeting*. Temporary
maximum residue limits were recommended for citrus fruits, carcass
meat of cattle, milk and eggs. Some additional data on supervised
trials have been provided since then, which are summarized in this
evaluation.
RESIDUES IN FOOD
USE PATTERN
In addition to the uses reported in the previous evaluation, the
registered uses of phenthoate in Italy and Japan on rice, vegetables
and on some other crops were reported to this Meeting. The data are
summarized in Table 1.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Citrus fruit
Orange, lemon and grapefruit trees were treated at a rate of
3.36-10.1 kg a.i./ha, in dilute sprays or at low volume. The
phenthoate and its oxygen analogue were analysed separately in the
rind and pulp. Phenthoate residues found in the rind of fruits are
summarized in Table 2. No residue was detectable in the fruit pulp at
any rate or time (<0.03 mg/kg). Phenthoate oxon was in the range of
0.04-0.07 mg/kg in the rind of orange (Iwata 1979).
Lemon trees were treated 3 to 5 times, at intervals of 5 days,
and at rate of 3 kg a.i./ha, in Japan. Samples were taken 7, 14 and 21
days after the last applications (Nissani 1981). Phenthoate residues
were analysed only in the pulp using a method with the limit of
determination of 0.002 mg/kg. Residues detected are summarized in
Table 3.
The residues for whole fruit basis can be calculated taking
into account the weight ratio of rind and whole fruit, which were
0.187 ± 0.063 for orange, 0.23 ± 0.32 for grapefruit and 0.3 ± 0.085
for lemon. The residues calculated for whole fruit basis support the
previously recommended TMRL of 1 mg/kg.
* See Annex II for FAO and WHO documentation
TABLE 1. Registered uses of phenthoate, Italy and Japan
Application
Crop Pest No. Dose % a.i.
(kg a.i./ha) in spray
Cabbage Large white butterfly 1-2 0.3-0.5 0.05
Cauliflower
Chinese cabbage up to 4 0.5 0.025-0.05
Radish Common white
Turnip Aphids
Spinach Thrips
Lettuce Diamondback moth
Celery Tobacco cutworm
Tomato Cabbage armyworm
Green pepper Cabbage sawfly
Eggplant Striped flea beetle
Curcurbits Cabbage webworm
Pumpkin 28 spotted ladybird
beetle
Green onion Greenhouse whitefly
Onion Lima bean pod borer
Potato Soybean pod borer
Dasheen Japanese butter bur
borer
Sweet potato Bindweed leaf miner
Carrot Sweet potato leaf
worm
Great burdock European corn borer
Soybean
Kidney bean
Azuki bean
Garden pea
Broad bean
Sweet corn
Kaki persimmon Japanese wisteria
mealybug up to 4 1.5 0.05
Persimmon fruit
moth bugs
Japanese
chestnut Peach pyralid moth up to 4 1.5 0.05
Tea Smaller tea tortrix 1-2 2 0.05
Tea tussock moth
White peach scale
TABLE 2. Residues resulting from supervised trials in citrus fruit
Application Residues (mg/kg) at intervals (days) after application2
Crop Country Year Rate
No. (kg a.i./ha) Formulation 3 10 19 34-39 59
Orange USA 1978 1 3.26 4 EC 0.68 0.41 0.23
rind California 1 6.72 4 EC 2.1 1.5 0.73
1 6.721 4 EC 4.5 2.4 1.6
1979 1 4.2 4 EC 2.9 2.3 1.5 0.58 0.23
8.4 4 EC 4 3 2.1 0.85 0.35
8.41 4 EC 6.3 4.2 3 1.4 0.38
Lemon 1978 1 4.2 4 EC 1.5 0.9 0.47
rind California 8.4 4 EC 2.8 1.7 0.78
8.41 4 EC 3.8 3.3 2.2
1979 1 5.04 4 EC 3.7 2.7 1.1
10.1 4 EC 7 4.5 1.9
10.11 4 EC 14 11 5.7
TABLE 2. (con't)
Application Residues (mg/kg) at intervals (days) after application2
Crop Country Year Rate
No. (kg a.i./ha) Formulation 3 10 19 34-39 59
Grapefruit 19782 1 3.36 4 EC 0.94 0.77 0.48
rind California 6.72 4 EC 2.1 1.6 0.87
6.721 4 EC 3.9 2.5 1.4
1979 1 0.05% 4 EC 0.9 0.5 0.31
0.1% 4 EC 1.8 0.77 0.59
Notes: 1 Low volume application at 454 l/ha; 2 The fruits were washed prior to analysis in this study.
TABLE 3. Phenthoate residues in citrus pulp
Application Residues (mg/kg) at intervals
(days) after application
Rate
No. (kg a.i./ha) Formulation 7 14 21
3 3 50 EC 0.012 0.008 0.004
3 3 50 EC 0.018 0.005 0.008
5 3 50 EC 0.01 0.009 0.009
5 3 50 EC 0.015 0.006 0.004
Maize
Supervised trials were carried out applying a 50 EC formulation
of phenthoate 4 times, 14 days apart, at rates from 0.5 kg a.i./ha to
4 kg a.i./ha (Nissan 1981). Samples were taken 7 and 14 days after the
last application and the grains were anlaysed. None of the samples
contained detectable residues (<0.004 mg/kg).
Rice
Paddy rice was treated with a 50 EC formulation of phenthoate at
various times and rates (Nissan 1981). The husked rice and straw were
analysed, and the results are summarized in Table 4.
Other crops
Lettuce, onion, radish, spinach, tea, tobacco and tomato were
treated with phenthoate in supervised trials carried out in Japan
(Nissan 1981). The details of treatments and the results are
summarized in Table 5.
Infusion of tea leaves obtained from supervised trials referred
to in Table 5 (6 g leaves in 360 cm3 water at 100°C for 5 minutes)
did not give rise to residues above the limit of determination
(0.04 mg/kg) in potable tea.
TABLE 4. Residues of phenthoate in paddy rice
Application Residues (mg/kg) at intervals (days) after application
Crop No Rate (kg a.i./ha) and
intervals (days) Formulation 7 14 18-21 41 102
Rice, paddy 5 1.28 (7) 50 EC 0.035 0.028 0.03
husked 41 3.31 2.11
5 1.42 (7) 50 EC <0.04 <0.04
1.91 0.871
6 1.42 (7) 50 EC <0.04
2.061
1 0.5 50 EC <0.005
<0.011
1 0.5 50 EC <0.005
<0.011
2 0.5 (32) 50 EC 0.012
0.541
2 0.5 (32) 50 EC <0.005
0.241
1 0.5 (30) 50 EC 0.0052
0.321
0.281
1 In straw of rice; 2 Two sets of experiments.
TABLE 5. Residues resulting from supervised trials in Japan
Application Residues (mg/kg) at intervals (days) after application
Crop No. Rate
(kg a.i./ha) and Formulation
intervals (days) 3-4 7 10 14 20-21 24 27-34
Lettuce 2 1 (7 days 50 EC 0.08 0.08 0.02
4 apart) 0.06 0.05 0.009
Onion 2 0.75 (7 days 50 EC <0.01
apart)
(14 days <0.01
apart)
4 0.75 (7 days 50 EC <0.01
apart)
4 0.75 " " 50 EC <0.01
7 0.75 " " 50 EC <0.01
Radish 2 0.8 " " 50 EC <0.005
0.8 " " 50 EC 0.073
0.8 " " 50 EC <0.0051
0.8 " " 50 EC <0.0052
Spinach 2 0.75 " " 50 EC 0.015
0.75 " " 50 EC 0.005 <0.005
0.75 " " 50 EC 0.018
0.75 " " 50 EC 0.006 <0.005
Tea 2 1 " " 50 EC 0.009
3 1 " " 50 EC 0.047
2 1.5 " " 50 EC 0.039
3 1.5 " " 50 EC 0.044
TABLE 5. (con't)
Application Residues (mg/kg) at intervals (days) after application
Crop No. Rate
(kg a.i./ha) and Formulation
intervals (days) 3-4 7 10 14 20-21 24 27-34
Tomato 3 1 " " 50 EC 0.42 0.034 <0.005
6 1 " " 50 EC 0.23 0.055 <0.005
Tobacco 2 0.8 (5 days) 50 EC 0.13 0.244
2 1.6 0.023 0.014
1 Two sets of experiments;
2 Four sets of experiments;
3 Cutters of tobacco;
4 Tips of tobacco.
FATE OF RESIDUES
Unwashed lemons were stored in paper bags for 2 and 7 days at
8°C. Rind residues for unstored fruit were 1.9 ± 0.2 mg/kg and
residues after 2 and 7 days of storage were 1.5 ± 0.1 mg/kg and
1.1 ± 0.1 mg/kg. Chopped lemon samples were frozen. Over a 5-week
interval, no changes in residue levels occurred from frozen storage;
also, phenthoate was stable in the acetone extract at 8°C (Iwata
1979).
NATIONAL MAXIMUM RESIDUE LIMITS REPORTED TO THE MEETING
Some additional maximum residue limits and pre-harvest intervals
registered in Japan were reported to the Meeting.
Crop Pre-harvest Intervals MRL
(days) (mg/kg)
Pumpkin 1 0.1
Cucurbits, eggplant,
green pepper, tomato 3 0.1
Azuki bean, broad bean, cabbage,
carrot, cauliflower, dasheen,
garden pea, great burdock 7 0.1
Kidney bean, onion, potato,
soybean, sweet potato
Apple, celery, Chinese cabbage,
lettuce, radish, spinach,
sweet corn, turnip 14 0.1
Tea 21 0.1
Kaki persimmon 30 0.1
Chestnut 0.1
EVALUATION
APPRAISAL
Since the compound was evaluated by the 1980 Joint Meeting,
additional data resulting from supervised trials have been made
available.
Residues resulting from the treatment of citrus fruits were
always less than 0.02 mg/kg in the pulp of citrus fruit and the
residues calculated on whole product basis were lower than 1 mg/kg.
The recent results support the temporary maximum residue limit (TMRL)
that was recommended by the 1980 JMPR.
Residues in husked rice were below 0.05 mg/kg, while the straw
contained up to 4 mg/kg phenthoate.
Residues in other crops were also low and unlikely to exceed
0.1 mg/kg in lettuce and radish; 0.05 mg/kg in tea; 0.02 mg/kg in
spinach; 0.01 mg/kg in maize and onion. In tomatoes the residues were
0.2-0.4 mg/kg at 3 days post-treatment, but declined rapidly to less
than 0.005 mg/kg in 14 days. These data were considered insufficient
to estimate maximum levels that could be used to propose MRLs. The
residue in frozen citrus rind was stable over a 5-week period and also
in the acetone extract at 8°C.
RECOMMENDATIONS OF RESIDUE LIMITS
The meeting recommends the following additional temporary MRL,
which refers to phenthoate alone.
Commodity Limit PHI on which recommendation
(mg/kg) is based (days)
Rice, hulled 0.05 7
FURTHER WORK OR INFORMATION
Desirable
Further data arising from supervised trials on lettuce, maize,
onion, tomato, radish, spinach and tea from more than one country.
REFERENCES
Iwata, Y., O'Neal, J.R., Barkley, J.H. and Gunther, F.A. Phenthoate
1979 applied to California citrus trees: Worker environment
research and residue levels on and in fruit. Department of
Entology, University of California, Riverside, U.S.A.
(Unpublished)
Nissan Chemican Industries Ltd. Residue analysis data on various
1981 crops in Japan. (Unpublished)
See Also:
Toxicological Abbreviations
Phenthoate (Pesticide residues in food: 1980 evaluations)
Phenthoate (Pesticide residues in food: 1984 evaluations)