246. Parathion-methyl (WHO Pesticide Residues Series 2)

PARATHION-METHYL JMPR 1972

Explanation

This pesticide was evaluated by the 1968 Joint Meeting and several
items of information were required before 30 June 1972 (FAO/WHO,
1969). Data concerning some of the questions became available and are
discussed.

RESIDUES IN FOOD AND THEIR EVALUATION

1. Data on metabolites in plants and animal products

No new data available.

2. Data from other countries than the Federal Republic of Germany
and U.S.A.

Extensive information was obtained on use patterns in many
countries and areas of the world, dosage rates and frequencies of
application (see Table 1). However, no information became
available on residue levels resulting from supervised trials on
uses corresponding with the recommended uses in these areas.

Furthermore, since the 1968 Joint Meeting the use pattern, for
example in the USA, has been changed and also expanded; national
tolerances have been established for many crops, which differ
from the tolerance levels proposed by the 1968 Joint Meeting. No
data which could support any changes in levels were available for
evaluation at this time.

3. Data on rice

The only new data available on rice are given in Table 1.

4. Residues in food moving in commerce

Residue analysis carried out in the Federal Republic of Germany
between 1965 and 1968 on domestic and imported fruit and
vegetables showed that out of a total of 228 samples, six samples
of apples contained parathion-methyl ranging between <0.1 and
0.5 ppm and one apple contained <0.01 ppm, whereas one sample of
apricots and one sample of lettuce contained <0.01 and <0.1
ppm, respectively (Krause and Kirchhoff, 1969).

In a study on pesticide residue levels in food in the U.S.A.
(July 1963 - July 1969), residues of parathion-methyl could only
be determined in leaf and stem vegetables and in root vegetables,
and not in the other 10 of 12 separate food classes.

TABLE 1 Use patterns of parathion-methyl¹

Crops Dosage rates Countries PHI Applications
(kg a.i./ha, or or areas (weeks) (no.)
as % a.i. w/v)

Fruits
pome and stone 0.025 - 0.05% Eur., Ocean. 2-3 1-3
fruits

citrus fruits 0.025 - 0.075% Asia, Amer.(S) 2 1-2

grapes 0.025 - 0.075% Amer.(S), Eur. 2-3 2-3

pineapple 0.05 - 0.075% Afr., Amer. (C.,S.) - 2-4
Asia

Vegetables

beans, brassicas,
cucumbers, onions 0.025 - 0.05% Afr., Amer(C.,S.) 2-3 2-4
potatoes, tomatoes Asia, Eur., Ocean.

Field crops
cereals (including
maize, excluding 0.025% Amer.(S) early 2
rice) growing
stage

Rice 0.4 - 0.8.kg/ha Amer.(S), Asia 3 2-3
(E.,S.)

Cotton 0.5 - 2 kg/ha Afr., Amer.(S), Asia 2-6
(SE)

0.5 - 2 kg/ha Amer (C) - 6-12

TABLE 1 (Cont'd.)

Crops Dosage rates Countries PHI Applications
(kg a.i./ha, or or areas (weeks) (no.)
as % a.i. w/v)

Peanut 0.025 - 0.05% Amer:(S), Asia - 1-2

Sugarcane 0.05% Asia early growing 1-3
stage

Coffee 0.025 - 0.075% Afr., Amer(C.,S.) 2 1-2
Asia

Tobacco 0.025 - 0.05% Amer.(C.,S.), Asia - 1-4

¹ Abbreviations used: PHI = pre-harvest intervals. Afr. Africa.
Amer.(C.,S.) = Central, South America
Asia (S,E,SE) = resp. South, East and South-East Asia.
Eur. = Europe
Ocean. = Oceania: Australia, New Zealand, etc.

Residue incidence reported by Duggan et al., (1971) is given in
Table 2.

TABLE 2

Parathion-methyl residues in vegetables (1963-1969)

Samples analysed Incidence (%)
(no.)

Leafy and stem vegetables

domestic 13 864 6.1
imported 153 -

Root vegetables

domestic 13 561 1.3
imported 533 1.2

In the period 1966 -1969 the residue levels of parathion-methyl in
leaf and stem vegetables and in root vegetables showed distribution
given in Table 3.

TABLE 3 Parathion-methyl residues in vegetables (1966-1969)

Samples Trace % of samples in ranges (ppm)
analysed (0.03) 0.04-0.1 0.1-1 >1
(no.)

Leaf and stem 9 813 2.34 1.47 2.25 0.05
vegetables

Root vegetables 8 243 0.23 0.12 0.20 -

5. Data on residue levels in total diet studies

Results from a total diet study carried out in U.S.A. (June 1968
- April 1970) (Duggan and Corneliussen, 1972) showed that only
the leafy vegetable class of the twelve separate food classes
examined contained parathion-methyl and that it was present only
in trace amounts, i.e., <0.001 mg/day.

Corneliussen (1972) showed in a subsequent report (June 1969 -
April 1970) the occurrence of parathion-methyl in 6 out of 360
total diet composites ranging from 0.003 - 0.023 ppm.

Similarly, Smith (1972) reported that in a total diet study
carried out in Canada in 1970 parathion-methyl was only
determined in the leafy vegetable class of 12 separate food
classes. Residues in 40 g of prepared leafy vegetable composite
per day were 0.010 ppm in the second quarter of 1970 (average of
1970 0.005 ppm). It was not detected in a total diet survey in
England and Wales (Abbott et al., 1970).

6. Methods of residue analysis

For the determination of parathion-methyl in food products,
Camoni et al., (1968) used a combined Hyflo-Supercel, Florisil
and animal charcoal column clean-up. The residues were detected
by TLC and colorimetric techniques, followed by a GLC
determination. Rippel and Kovac (1968) determined residues of
parathion-methyl in citrus fruit juices by extraction from a
mixed sample/silica gel column, separation on TLC and
colorimetric determination; the limit of detection was 0.2 ppm.
Residues of parathion-methyl in rats and chickens have been
detected by TLC (Beck and Sherman, 1968). Acetonitrile extracts
were developed on silica gel G plates with a chloroform/carbon
tetrachloride mixture and visualized with ethanolic sodium
hydroxide. This method was proposed as a quantitative screening
procedure supplementary to cholinesterase activity estimation.
Gas chromatography with several different detectors has been
reported for the determination of residues. For residues in rats,
Gabica et al. (1971) used the flame photometric detector for
levels as low as 0.003 ppm. Suzuki et al. (1968) analyzed rice
grains containing 0.1 - 10 ppm of parathion-methyl using the
electron capture detector. Residues in the range 0.2 - 40.0 ppm
present in green and cured alfalfa were determined using a
thermionic detector (Waldron and Goleman, 1969). The multiresidue
procedures described by Abbott et al. (1970) for total diet
samples are also applicable to parathion-methyl residues.

Specifications for the parathion-methyl formulated products most
commonly used are developed and are available (FAO, 1971).

APPRAISAL

Because of the lack of relevant data on residue levels from supervised
trials, as mentioned above, the Meeting was not able to propose any
changes in the tolerance figures established in the 1968 Meeting or to
propose tolerance figures for other crops or commodities.

The data on which the temporary ADI for parathion-methyl were based
were re-evaluated, and it was decided to extend the temporary ADI for
a further three-year period.

FURTHER WORK OR INFORMATION

REQUIRED (by 30 June 1975)

1. Data on supervised trials in various areas, including the
currently recommended rates of application and pre-harvest
intervals on those crops for which insufficient information is
available.

2. Data on residues in food moving in commerce.

REFERENCES

Abbott, D.C., Crisp, S., Tarrant, K.R. and Tatton, J. O'G. (1970)
Pesticide residues in the total diet in England and Wales, 1966-1967.
III - Organophosphorus pesticide residues in the total diet. Pestic.
Sci., 1: 10-13.

Beck, J. and Sherman, M. (1968) Detection by TLC of organophosphorus
insecticides in acutely poisoned rats and chickens. Acta Pharmacol.
Toxicol., 26: 35-40.

Camoni, I., Gandolfo, N., Ramelli, G.C., Sampaolo, A. and Binetti, L.
(1968) Analytical procedure for the detection and determination of
parathion and methyl-parathion in food products. Bollettino dei
Laboratori Chimica Provinciali. 19: 615-629.

Corneliussen, P.E. (1972) Pesticide residue samples in total diet
samples (VI). Pestic. Monit. J., 5: 313-321.

Duggan, R.E., Lipscomb, G.Q., Cox, E.L., Heatwole, R.E. and Kling,
R.C. (1971) Pesticide residue levels in foods in the United States
from July 1, 1963 to June 30, 1969. Pestic. Monit. J., 73-212.

Duggan, R.E. and Corneliussen, P.E. (1972) Dietary intake of pesticide
chemicals in the United States, III, June 1968 - April 1970. Pestic.
Monit. J., 5: 331-341.

FAO/WHO. (1965) Evaluation of the toxicity of pesticide residues in
food. FAO Meeting Report No. PL/1965/10/1; WHO/Food Add./27.65

FAO/WHO. (1968) 1967 evaluations of some pesticide residues in food.
FAO/PL: 1967/M/11/1; WHO/Food Add./68.30.

FAO (1971) Parathion-methyl. FAO specifications for plant protection
products. AGP:CP/33.

Gabica, J., Wyllie, J., Watson, M. and Benson, W.W. (1971) Example of
flame photometric analysis for methyl-parathion in rat whole blood and
brain tissue. Analyt. Chem., 43: 1102-1105.

Koen, J.G. and Huber, J.F.K. (1970) A rapid method for residue
analysis by column liquid chromatography with polarographic detection
- Application to the determination of parathion and methyl-parathion
on crops. Analytica Chim. Acta, 51: 303-307.

Krause, C. and Kirchhoff, J. (1969) Organophosphatrückstünde auf
Marktproben von Obst und Gemüse sowie auf Getreide erzeugnissen.
Nachrichlinblitt das Deutschen Pflanzenschutzdienstes, 21(6): 81-84.

Ott, D.E. and Gunther, F.A. (1968) Automated analysis of
organophosphorus insecticides by wet digestion - oxidation and
colorimetric determination of the derived orthophosphate. J. ass. off.
analyt. Chem., 51: 697-708.

Rippel, A. and Kovac, J. (1968) Determination of parathion-methyl in
citrus fruit juices. Nahrung, 12: 711-714 (in German).

Smith, D.C., Sandi, E. and Leduc, R. (1972) Pesticide residues in the
total diet in Canada. Pestic. Sci., 3: 207-211.

Suzuki, K., Goto, S. and Kashiwa, T. (1968) Residue analysis of
agricultural chemicals. I. Determination of parathion-methyl in rice
grains by gas chromatography with electron-capture detection. Japan
Analyst, 17: 187-191 (in Japanese).

Waldron, A.C. and Goleman, D.L. (1969) Ethyl and methyl-parathion
residues in green and cured alfalfa. J. Agr. Fd. Chem., 17: 1066-1069.

    See Also:
       Toxicological Abbreviations
       Parathion-methyl (FAO/PL:1968/M/9/1)
       Parathion-methyl (WHO Pesticide Residues Series 5)
       Parathion-methyl (Pesticide residues in food: 1978 evaluations)
       Parathion-methyl (Pesticide residues in food: 1979 evaluations)
       Parathion-methyl (Pesticide residues in food: 1980 evaluations)
       Parathion-methyl (Pesticide residues in food: 1984 evaluations)
       Parathion-methyl (Pesticide residues in food: 1995 evaluations Part II Toxicological & Environmental)