FAO/PL:1967/M/11/1 WHO/Food Add./68.30 1967 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD THE MONOGRAPHS The content of this document is the result of the deliberations of the Joint Meeting of the FAO Working Party of Experts and the WHO Expert Committee on Pesticide Residues, which met in Rome, 4 - 11 December, 1967. (FAO/WHO, 1968) FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS WORLD HEALTH ORGANIZATION Rome, 1968 DIAZINON This pesticide was evaluated for acceptable daily intake by the 1965 Joint Meeting of the FAO Committee on Pesticides in Agriculture and the WHO Expert Committee on Pesticide Residues (FAO/WHO, 1965). As no additional toxicological data has become available since the previous publication, the following monograph addendum is confined to : EVALUATION FOR TOLERANCES USE PATTERN The following information was obtained from : Geigy Chemical Corp., Pesticide petitions submitted to the U.S. Food and Drug Administration 1956 to 1967; U.S. Dept. of Agriculture Handbook No. 331; U.S. Dept. of Agriculture Summary of Registered Agricultural Pesticide Chemical Uses, 1964 to 1967. Pre-harvest treatments Diazinon is used as a dust or spray formulation on over 60 food and feed crops including most fruits, vegetables, forages and hays. Table I summarizes typical dosages and pre-harvest periods for the various crop categories. Diazinon has been found effective in controlling over 100 species of food crop pests such as mites, aphids, thrips, maggots, fruitflies, worms, beetles, grasshoppers, leaf miners, etc. Seed furrow soil treatments are used for several root vegetable crops. Dermal applications are made on sheep and cattle to control horn flies, ticks and lice. TABLE I Crop Actual Dosage Pre-harvest Period, days Tree fruits 0.5 lb/100 gal (full coverage) 10-20 Caneberries 1.0 lb/acre (full coverage) 7 Citrus 0.5 lb/100 gal (full coverage) 7-21 Leafy vegetables 0.5-1.0 lb/acre 5-21 Root vegetables 0.5-1.2 lb/acre 10 Others 0.25-1.0 lb/acre 0-7 TABLE I (cont'd) Crop Actual Dosage Pre-harvest Period, days Forages and Hays 0.5-1.0 lb/acre No grazing limitations 4-10 days before cutting hay Cattle and Sheep 1.0-2.3 gal of 0.03-0.05% 14 pre-slaughter period spray per animal Post-harvest treatments There is no commercial post-harvest use of diazinon. Other uses Diazinon is recommended for fly control in dairy barns and other farm buildings as well as in food processing plants; however, this is becoming less important because of resistance. It is commonly used in households as a mothproofing agent to control carpet beetles and clothes moths, and is also used in home gardens and in public buildings to combat ants, cockroaches, firebrats, etc. RESIDUES RESULTING FROM SUPERVISED TRIALS In numerous experiments conducted in the U.S.A., Canada and several other countries residues were determined at various time intervals after multiple applications of varying amounts of diazinon on over 60 crops. For example, in the controlled experiments for apples, 16 varieties of apples were treated in 15 states in the U.S.A. using 1/2 to 1 lb/100 gal (full coverage sprays) on various spray schedules and in combination with other pesticides and fungicides. A summary of the numerous data (mostly unpublished material) obtained from the rates of application shown in Table I is given in Table II. TABLE II Typical Residues Crops Initial Pre-harvest at Pre-harvest Entimated Residues Period Period Indicated Half-life ppm days ppm days Tree Fruits Apples 0.6-0.8 14 0.1 5 TABLE II (cont'd) Typical Residues Crops Initial Pre-harvest at Pre-harvest Entimated Residues Period Period Indicated Half-life ppm days ppm days Pears 0.6-0.7 14 0.1-0.3 5 Cherries 3-7 10 0.1-0.3 3 Peaches 2-6 20 0.1-0.6 3-6 Apricots 1-2 10 0.1 2 Nectarines 1-2 10 0.2 3-4 Plums 2-4 10 0.1-0.2 2 Figs 0.5 10 <0.1 3 Citrus Oranges 3-5 21 0.1-0.4 4 Lemons 4.0 21 0.6-0.7 6-7 Grapefruit 0.3 7 0.1-0.2 7 Caneberries and Small Fruit Strawberries 0.9-1.4 5 0.2-0.4 2-4 Grapes 1-8 18 0.1-0.3 3 Cranberries 9 7 <0.1 1 Blueberries 1-4 7 0.1-0.3 1-2 Blackberries ) Boysenberries) 2.5-5 7 0.1-0.3 2 Loganberries ) Raspberries ) Leafy Vegetables Cabbage 1-2.5 7 0.3-0.7 4-6 Celery 7-9 10 <0.1-0.3 2 Cauliflower 0.8 5 0.4-0.5 7 Broccoli 1-2 5 0.5 3 Lettuce 6-17 10 0.3-0.5 1-2 Spinach 5-8 10 <0.1-0.2 2 Endive 3 10 0.1 2 Collards 3 12 <0.1 2 Kale 10-24 12 0.1-0.2 1 Parsley 1-6 12 0.1 2 Swiss Chard 2 12 <0.1 2 Turnip Greens 4-15 12 <0.1 2 Vegetable Root Beets <0.1 0 Onions 7-13 (green) 10 (green) 0.4-0.6 (green) 2 2-3 (dry) 10 (dry) 0.2-0.3 (dry) 2 TABLE II (cont'd) Typical Residues Crops Initial Pre-harvest at Pre-harvest Entimated Residues Period Period Indicated Half-life ppm days ppm days Carrots 1-2 10 0.1-0.3 2-3 Parsnips 0.7 10 0.3 6 Radishes 0.2-0.4 10 <0.1 4 Turnips 0.5 10 0.4-0.5 21 Vegetables (Others) Peppers 0.6-0.8 5 0.1-0.2 2-3 Cucumbers 1.0-2.5 7 <0.1 2 Green beans 1-2 7 <0.1 2 Lima beans 0.2-1.0 7 <0.1-0.2 2 Squash 0.1-0.2 3 <0.1-0.2 2 Corn (ears only) <0.1 0 <0.1 - Peas (plus pod) <0.1 0 <0.1 - Miscellaneous Tomatoes 0.1-0.4 3 <0.1-0.2 2 Melons 0.1-0.7 3 <0.1-0.2 2-3 Olives 1-6 75 <0.2-0.6 ca 25 Hops (cones) 3-11 14 0.1-0.3 3 Sorghum (grain) 0.5 7 < 0.1 2 Pre-slaughter Meat Period Lamb fat 1-3 14 0.1-0.5 5 Beef fat 1-3 14 <0.1-0.2 3 Pre-grazing Initial residue Residue Forages interval Cutting Time In forage at cutting Half-life days days ppm ppm days Alfalfa 0 7 12-24 0.2-0.5 2 Clover 0 7 4-14 1.0-4.0 2-3 Range/Pasture grass 0 21 9 4.0-7.2 2-3 30 54 (oil formulation) Pea/Bean 0 4 5-10 2.0-5.0 2 Corn 0 0 12-21 - 2 RESIDUES IN FOOD MOVING IN COMMERCE Of some 14,800 randomly selected samples of raw agricultural products examined by the U.S. Food and Drug Administration from June 1965 through 1966, only 32 samples showed any detectable residue of diazinon. FATE OF RESIDUES In soils Since diazinon is used to some degree as a soil treatment, the fate in soil is important with respect to root crops grown in those soils even though there is no reported systemic action for diazinon. Laygo and Schulz (1963) studied the persistence of organo-phosphorus insecticides in the microfauna in soils. Using Drosophila melanogaster assays, diazinon disappeared from the top soil layers within 9 days. Getzin and Rosefield (1966) treated four soil types with diazinon-14C under laboratory conditions and conducted a field trial with 5-6 lbs per acre soil treatment. Results indicated that 50 per cent of the initial residue remained after 4 weeks. Dissipation progressed more slowly after 8 weeks with 10 per cent or 0.2 ppm diazinon remaining after 24 weeks. In plants It can be seen from the data in Table II that diazinon does not persist long as a residue on most food plants as determined by the sulfide and the phosphorus procedures. It was generally considered that the sulfide procedure was the most reliable measure of residues of diazinon in plants; however, to make sure that no significant anticholinesterase phosphate derivatives (such as oxo-diazinon, the P=0 oxygen analog which contains no sulfur) remained, some residue data were acquired in 1956 by the anticholinesterase method. These data showed that no significant residues of oxodiazinon remained on the products tested (Geigy, 1956). It was not until fairly recently that a more comprehensive study was made on the nature of residues on plants. Coffin and McKinely (1964) reported on the metabolism and persistence of diazinon on field sprayed lettuce. Diazinon residues decreased from 8.1 ppm to 0.3 ppm from 4 hours to 7 days after spraying, and detectable quantities of diazinon were present at 10 and 14 days. No significant amount of oxodiazinon or other metabolites were found by the paper chromatographic detection system. Ralls, et al. (1966) studied the fate of 35S-labelled diazinon on field grown crops and found a rapid decrease in diazinon residues. The metabolite identified from field samples was oxodiazinon. Three thin-layer chromatographic systems showed the presence of this metabolite on spinach at 0.005 to 0.01 ppm 5 days after spraying. Paper chromatography of snap bean extracts harvested 7 days after treatment showed an increase in a cholinesterase inhibiting compound with an Rf value corresponding to oxodiazinon. Additional studies on the field incurred residue levels of diazinon (I), oxodiazinon (II) and 2-isopropyl-4-methyl-pyrimidin-6-ol (III) were made by Ralls and co-workers (1967) using diazinon-32P. A spinach sample analyzed one hour after spraying contained 31.7 ppm (I), 1.5 ppm (II) and 2.5 ppm (III). Analysis of a 4 day sample gave 1.8 ppm (I), 0.34 ppm (II) and 2.5 ppm (III). Although diazinon and its oxygen analog dissipated rapidly, compound (III), the result of further hydrolysis of oxodiazinon, persisted at the same level. The mammalian toxicity of this persistent compound is not known. Similar experiments with snap bean and tomato plants showed the same rapid disappearance of diazinon and oxodiazinon to levels greatly below 0.1 ppm after 4 days. Less than 0.1 ppm of compound (III) was found in all 4-day samples. Grasses and grains grown for forage which had been treated with diazinon were analyzed by the sulfide procedure. Maier-Bode (1963) found diminution of residues occured only in the uncut grasses. After cutting and while drying to hay, little of the diazinon was lost. In animals Robbins et al (1957) administered 32P-labeled diazinon orally to a cow at 20 mg/kg level. Much of the diazinon was rapidly metabolized and excreted. About 74 percent of the dose, excreted as polar degradation products, was accounted for in the urine 36 hours after treatment. The main 32P-labeled end products of diazinon metabolism in the cow were found to be diethyl phosphorothioic and diethyl phosphoric acid. From this extreme rate of administration residues of 0.09 to 0.56 ppm appeared in milk at from 6 to 24 hours after administration. No residues were found after 24 hours. Rai and Roan (1959) found no residues of diazinon in the milk of dairy animals given daily oral doses of diazinon at the rates of 1.06, 5.30 and 10.60 mg/kg of body weight over a 3 week feeding period. These administration rates are calculated to be 100, 500 and 1000 ppm on the basis of the grain fed, or 51, 290 and 500 ppm on the basis of hay consumed. Steers treated with 165 and 825 ppm in daily oral doses calculated on the bases of grain fed showed traces of diazinon in blood, urine, muscle, liver and brain. Only in fat was a significant residue found of 0.23 ppm at the maximum feeding level. These results were obtained by the use of three methods of analysis; a sulfide, an anticholinesterase and a bioassay method. Derbyshire and Murphy (1962) fed cows at the rate of 500 ppm calculated on dry matter intake and found no residue in milk. Diazinon residues in the fat of sprayed cows has been reported one and seven days after the last application, but none was present after a post-spray interval of 14 days. (Claborn et al., 1953). In storage and processing Residue levels of diazinon, oxodiazinon and 2-isopropyl-4-methyl-pyrimidin-6-ol were measured in snap beans, spinach and tomatoes subjected to washing, blanching and peeling (for tomatoes) under simulated commercial conditions (Ralls et al, 1967). Diazinon on spinach at harvest 4 days after spraying was present at 1.8 ppm and oxodiazinon at 0.34 ppm. A spray rinse did not significantly reduce residues. Detergent washing reduced diazinon to 0.77 ppm and oxodiazinon to 0.18 ppm, and steam blanching gave a total reduction to about 30 percent of the original residue. Only a water blanching process significantly reduced the level of pyrimidinol metabolite from 2.5 ppm to 0.1 ppm. Residues at harvest (8 days) on snap beans and tomatoes were less than 0.1 ppm. Subsequent commercially simulated treatment appeared to have little or no effect, except possibly the commercial peeling of tomatoes. No data is available on the effect of freezing, canning, etc. RESIDUES IN FOOD AT TIME OF CONSUMPTION Total diet studies conducted during 1965 and 1956 by the U.S. Food and Drug Administration revealed that 98 percent of the food samples contained no detectable residues of diazinon. The remaining 2 percent contained only trace quantities. A multidetection gas chromatographic method using an electron capture detector and/or a thermionic detector specific for phosphorous was used for the analyses. The sensitivity of the method was about 0.05 ppm (Duggan et al. (1967)). METHODS OF RESIDUE ANALYSIS Most of the residue data summarized in this monograph were obtained using one or two of four different methods of analysis developed by Geigy Chemical Company (1956-1967). A sulfide procedure was considered the most accurate when spray history was known. In this procedure diazinon is extracted from crops with a solvent and from the solvent with 48 percent HBr. The 48 percent HBr treatment adds a high degree of selectivity for the determination of diazinon. Upon boiling the acid solution, diazinon sulfur is converted to H2S and distilled off. It is collected in zinc acetate solution and then converted to a methylene blue complex which is determined spectrophotometrically. Sensitivity of the sulfide procedure is about 0.1-0.2 ppm. Some crops such as kale had high natural sulfur blanks so these crops were analyzed by a phosphate method. Thiocarbamates such as ferbam also interfere and must be removed by an additional cleanup step. Some phosphorothioates are known to form relatively stable metabolic products containing no sulfur for which the method described above would not be applicable, so a cholinesterase inhibition method was utilized to validate the sulfide procedure. The method based on determining the phosphorous of diazinon and one based on the ultraviolet absorption properties of the pyrimidine portion of the molecule were fraught with high blank and cleanup problems. Sensitivity of these methods is about 0.3-0.4 ppm. None of these four methods were of adequate sensitivity or specificity for "total diet" samples. Such data were not possible until the GLC methods based on electron capture and thermionic detectors were used. The methods of Storherr and co-workers (1964 and 1965) using an ethyl acetate extraction and either a sweep co-distillation or celite column cleanup with gas chromatographic detection provide a rapid and adequately sensitive procedure for diazinon in most food commodities. J.R. Geigy S.A. has developed a gas chromatographic method which is applied following a shakeout with 48 percent HBr. The gas chromatographic methods are sensitive to about 0.01 ppm or better. A number of thin layer chromatographic procedures described in the literature will provide a confirmative test. RECOMMENDATIONS FOR TOLERANCES Temporary tolerances When diazinon is utilized in accordance with good agricultural practice to protect food, when necessary, against insect infestation, the treated product may have residues as high as those shown below : Peaches and citrus 0.7 ppm Other fruits 0.5 ppm Leafy vegetables 0.7 ppm Other vegetables 0.5 ppm Meat (fat basis) 0.5 ppm By no means will all samples of these products contain this amount of residue; in fact only a small, yet unknown, portion of each product in these categories is likely to be treated. Also there are some data available showing that a significant amount of reduction in residues will take place during washing and other preparation and processing of NATIONAL TOLERANCES Country Tolerance, ppm Crop Canada 0.25 melons, figs, cranberries and 7 vegetables 0.5 beans, Brussels sprouts, cucumbers, turnips 0.75 tree fruits including citrus, grapes, strawberries, and 16 vegetables. Germany (west) 0.5 on or in vegetables, fruits, root crops, legumes, grapes and hops. Hungary 5 food India 0 (proposed) cereals Italy 2 olive oil Netherlands 0.5 on or in 1) vegetables or parts thereof for consumption, including edible mushroome and edible roots, bulbs and tubers. 2) edible fruits of vegetables and fruit crops or parts thereof. Switzerland The Swiss intercantonal commission for toxic materials ("Commission Intercantonale des Toxiques") proposes a tolerance of 0.5 ppm. Federal regulations are in preparation. U.S.A. 0.75 ca 25 fruits and 25 vegetables, fat of meat and meat by-products of cattle and sheep. 1 olives and olive oil 3 almond hulls 10 5 hays NATIONAL TOLERANCES (cont'd) Country Tolerance, ppm Crop 25 bean and pea forage 40 alfalfa, clever and corn forage 60 pasture grasses food for consumption. Other data which give support to the above factors is that in the U.S.A. "total diet" samples diazinon is seldom found and when found it is at a low level. The meeting is convinced that under the conditions of practical use the above residues on products which need to be protected will not produce a total diet which will contain an amount of diazinon in excess of the ADI. Therefore, it is recommended that a temporary tolerance be adopted for a period ending December 31, 1970, for the residue values for the products shown above. FURTHER WORK Further work required before 30 June 1970 1. More data on the amount and persistence of the oxygen analog on food crops. 2. Further data on the effect of food preparation and processing on the reduction of residues. 3. Data on the amount and persistence of the pyrimidinol moiety of the compound. REFERENCES PERTINENT TO EVALUATION FOR TOLERANCES Claborn, H.V., Mann, R.D., Younger, R.L. and Radeleff, R.D. (1963) Diazinon residues in the fat of sprayed cattle. J Econ. Entomol. 56 (6): 858 - 9. Coffin, D.E. and McKinely, W.P. (1964) The metabolism and persistence of Systox, Diazinon and Phosdrin on field-sprayed lettuce. J. Assoc. Off. Agr. Chem. 47 (4): 632 - 40. Derbyshire, J.C. and Murphy, R.T. (1962) Diazinon residues in treated silage and milk of cows fed powdered diazinon. J. Agr. Food Chem. 10 (5): 384 - 6. Duggan, R.E., Berry, H.C. and Johnson, L.Y. (1967) Pesticide residues in total diet samples II. Pest. Monitor. J. 1 (2), 2 - 12 (1967). FAO/WHO. (1965) Evaluation of the toxicity of pesticide residues in food. FAO Meeting Report 1965/10/1; WHO/Food Add./27.65 Geigy Chemical Co. (1956 -1967) Unpublished data and methods of analysis in pesticide petitions submitted to the U.S. Food and Drug Administration. Geigy, J.R. Basle, Switzerland. Analytical method for determination of diazinon (unpublished). Getzin, L.W. and Rosefield, I. (1966) Persistence of diazinon and zinophos in soils. J. Econ. Entomol. 59 (3) : 512 - 16. Laygo, E.R. and Schulz, J.R. (1963) Persistence of organophosphate insecticides and their effects on microfauna in soils. Proc. N. Dakota Acad. Sci. 17: 64 - 6. Maier-Bode, H. (1963) Residues of insecticides on cover crops growing in orchards after application of organic phosphorus toxicants on the trees. Z. Pflanzenkrankh. Pflanzenschutz. 70 (80): 449 - 59. Rai, L. and Roan, C.C. (1959) Report included in Geigy Chemical Co. pesticide petition to the U.S. Food and Drug Administration. Ralls, J.W. Gilmore, D.R., and Cortes, A. (1966) Fate of radioactive 0,0--diethyl 0-(2-isopropyl-4-methylpyrimidin-6-yl) phosphorothioate on field grown experimental crops. J. Agr. Food Chem. 14 (4) : 387 - 92. Ralls, J.W. Gilmore, D.R. Cortes, A., Schutt, S.M. and Mercer, W.A. (1967) Residue levels of diazinon and its transformation products on tomatoes, spinach and beans. Food Technology 21: 92 - 4. Robbins, W.E., Hopkins, T.L. and Eddy, G.W. (1957) Metabolism and excretion of phosphorus-32-labeled diazinon in a cow. J. Agr. Food Chem. 5 (7); 509 - 13. Storherr, R.W., Getz, M.E., Watts, R.R., Friedman, S.J. Erwin, F., Giuffrida, L. and Ives, F. (1964) Identification and Analyses of five organophosphate pesticides: Recoveries from crops fortified at different levels. J. Assoc. Off. Agr. Chem. 47 (6): 1087 - 93. Storherr, R.W. and Watts, R.R. (1965) A sweep co-distillation cleanup method for organophosphate pesticides. J. Assoc. Off. Agr. Chem. 48 (6): 1154 - 60.
See Also: Toxicological Abbreviations Diazinon (EHC 198, 1998) Diazinon (ICSC) Diazinon (FAO Meeting Report PL/1965/10/1) Diazinon (FAO/PL:CP/15) Diazinon (FAO/PL:1968/M/9/1) Diazinon (AGP:1970/M/12/1) Diazinon (WHO Pesticide Residues Series 5) Diazinon (Pesticide residues in food: 1979 evaluations) Diazinon (Pesticide residues in food: 1993 evaluations Part II Toxicology) Diazinon (JMPR Evaluations 2001 Part II Toxicological)