FAO/PL:1969/M/17/1 WHO/FOOD ADD./70.38 1969 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD THE MONOGRAPHS Issued jointly by FAO and WHO 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 Group on Pesticide Residues, which met in Rome, 8 - 15 December 1969. FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS WORLD HEALTH ORGANIZATION Rome, 1970 2-PHENYLPHENOL AND ITS SODIUM SALT IDENTITY Chemical names 2-phenylphenol; sodium 2-phenylphenate Synonyms for the free phenol; o-hydroxydiphenyl Structural formulaeOther relevant chemical properties The free phenol is a white, crystalline, free-flowing powder, molecular weight 170.2. Mild phenolic odour. Less than 0.1g is soluble in 1 ml of water. Freely soluble in ethanol, soluble in fats and oils. It is dissolved or dispersed in wax formulations. The sodium salt is a buff coloured solid. Molecular weight 264.3. Very soluble in water and ethanol; practically insoluble in oils. Used as water solution. Purity Specifications for purity of both compounds have been published by the European Economic Community (E.E.C., 1967): E231 2-phenylphenol melting point 56 - 58°C content not less than 99% biphenylether not more than 0.3% p-phenylphenol not more than 0.1% alpha-naphthol not more than 0.01% sulphate after ashing not more than 0.05% E232 sodium orthophenylphenate melting point of 2-phenylphenol precipitated by acidification of sodium salt, not recrystallized and dried over sulphuric acid 56 - 58°C ph 2% water solution must be between pH 11.1 and 11.8 content not less than 95% C12H ONa.4H2.0 biphenylether not more than 0.3% p-phenylphenol not more than 0.1% x-naphthol not more than 0.01% EVALUATION FOR ACCEPTABLE DAILY INTAKE The biological data available on this compound have been evaluated by the Joint FAO/WHO Expert Committee on Food Additives, and a monograph entitled "Sodium o-phenylphenol" is included in the Sixth Report of this Committee (FAO/WHO, 1962). A summary of the data then considered as well as some limited additional information which has recently become available is included below. BIOCHEMICAL ASPECTS Absorption, distribution and excretion Tissue examination of rats which had received 2-phenylphenol orally for two years revealed little tendency for storage of the compound. The kidney was the only organ containing detectable amounts of the compound; average values of 220 mg/kg tissue were found in the kidneys of rats fed 20,000 ppm in the diet, and approximately 10 mg/kg tissue in the kidneys of rats fed 2000 ppm (Hodge et al., 1952). After administration to rabbits, 2-phenylphenol is highly conjugated with glucuronic acid but it is not known whether it is converted to an ethereal sulphate in this species. The glucuronide has been isolated from rabbit urine and characterized by conversion to the triacetylmethyl ester (Williams, 1959; Dodgson et al., 1948; Kamil et al., 1951). When administered orally to rats, 2-phenylphenol is partly converted to 2,5-dihydroxybiphenyl which, like 2-phenylphenol, is excreted in the urine as a glucuronide and ethereal sulphate. The total output of 2-phenylphenol within 48 hours amounted to about 70 percent as conjugates of 2-phenylphenol and 2,5-dihydroxyphenol (Ernst, 1965). TOXICOLOGICAL STUDIES Special studies on carcinogenicity Groups of 18 mice of each sex from two hybrid strains of mice were given 2-phenylphenol for 18 months. The dose of 100 mg/kg was given to the mice by gavage from the seventh day of age to the time of weaning at four weeks of age and thereafter the chemical was added to the diet in a corresponding amount of 280 ppm. There was no significant increase in the incidence of tumours (Innes et al., 1969). Acute toxicity LD50 mg/kg Animal Route body-weight References Rat oral 2700-3000 (approx.) MacIntosh, 1945 Hodge et al., 1952 Cat oral 500 (approx.) MacIntosh, 1945 Short-term studies Dog A preliminary study demonstrated that when daily doses of 1,000 mg/kg body-weight of 2-phenylphenol were fed to two dogs, both died within a month. Groups of two dogs each were then fed 2-phenylphenol for a period of one year in daily amounts of 0, 20, 200, and 500 mg/kg body weight. No effect related to the administration of 2-phenylphenol was observed. Haematological values, urinary sugar and protein values, organ weights and histopathological examination of the various tissues did not differ from the normal range (Hodge et al., 1952). Rat Groups, each comprising 15 male rats, were fed 2-phenylphenol in daily doses of 0, 2, 20, or 200 mg/kg body-weight for 32 days. There were no toxic symptoms attributable to feeding 2-phenylphenol. The mean growth-rate and the haemoglobin and white blood cell levels in all groups were comparable to the controls (MacIntosh, 1945). Five male and five female rats in each group were given by stomach tube doses of 0, 50, 100, 200, and 500 mg/kg body-weight for five days a week over a period of six months. The only abnormality observed was a slight increase in average liver and kidney weights in the animals fed the 500 mg/kg dose level (Hodge et al., 1952). When diets containing 0, 1,000, 3,000, 10,000, or 20,000 ppm of 2-phenylphenol were fed for three months to groups of rats comprising 12 males and 12 females, slight retardation of growth was observed in the 20,000 ppm group. There was no significant difference between the mortality of control and test animals. There were doubtful increases in weight of liver, kidney, and spleen of certain rats of the 10,000 and 20,000 ppm groups. No tissue changes were observed (Hodge et al., 1952) Long-term studies Rat Male and female rats (25 of each sex per group) were maintained for two years on diets containing 0, 200, 2,000 and 20,000 ppm of 2-phenylphenol. The animals fed 200 and 2000 ppm showed no adverse effects when compared with the controls, as judged by growth, mortality, gross appearance, haematology, urinary sugar and protein values, organ-weights, tissue content of 2-phenylphenol, and histopathological examination of various tissues. The group fed 20,000 ppm of 2-phenylphenol differed from the controls by exhibiting slight retardation of growth, histological kidney changes (marked tubular dilation), and the presence of small amounts of 2-phenylphenol in the kidney tissues (Hodge et al., 1952). OBSERVATION IN MAN A 5.0 percent solution of 2-phenylphenol in sesame oil and a 0.1 percent aqueous solution of the sodium salt tested on 200 subjects caused neither primary skin irritation nor skin sensitization. The sodium salt is slightly irritating in 0.5 percent aqueous solution and decidedly irritating in 1.0 percent and 5.0 percent solutions (Hodge et al., 1952). COMMENT The short and long-term studies in rats are sufficient to be taken as a basis for the evaluation of 2-phenylphenol. The dog study was not considered adequate. In addition, the studies on metabolism are incomplete and there are no studies on reproduction. However, the Meeting considered that the toxicological studies were adequate to reaffirm the previous acceptable daily intake established by the Joint FAO/WHO Expert Committee on Food Additives in its Sixth Report (FAO/WHO, 1962). TOXICOLOGICAL EVALUATION Level causing no significant toxicological effect Dog: 500 mg/kg body-weight/day Rat: 2000 ppm in the diet, equivalent to 100 mg/kg body-weight/day ESTIMATE OF ACCEPTABLE DAILY INTAKE FOR MAN 0 - 1.0 mg/kg body-weight (based upon the previous adi. - FAO/WHO, 1962) RESIDUES IN FOOD AND THEIR EVALUATION USE PATTERN Pre-harvest treatments In Great Britain a dormant paint application to apple trees is approved for control of canker. Post-harvest treatments 2-phenylphenol has been used broadly for over 40 years in many countries for its general antimicrobial properties. Due to its broad spectrum bactericidal and fungistatic effect, and commercial availability it is widely used. It is employed as a household disinfectant, preservative in oil-water emulsions used in the textile and metal industries, as well as a post-harvest treatment for fruits and vegetables to prevent losses due to rots and moulds in storage and transport of these foods. The sodium salt is used as a preservative for protein-based and other adhesives, as well as for the post-harvest use in fruits and vegetables. Principal formulations in the U.S.A. are: 2-phenylphenol: 5% liquid; 98% wettable powder; 2% in wax. Wax formulations are applied by commercial application equipment in tandem with sorting and washing facilities. These are specifically designed for the crop concerned as to technology of use, formulation strength, time of immersion in the bath and monitoring of the process to ensure maintenance of treatment criteria for effectiveness without damage to the crop. Wax strength formulations vary, e.g. carrots 0.5%, citrus 0.8%, cucumbers 2.5%, nectarines 0.2%, peaches 0.2%; peppers 2.5%, plums 2%, tomatoes 2.5%. A 5% liquid dip is used for crates, field boxes, hampers, lugs and wood containers for fruits and vegetables (U.S.D.A., 1967). sodium o-phenyl phenate: 97% wettable powder, solutions ranging from 1.5% to 40%, wax emulsion from 0.7% to 2.0%. The strength of solution used varies with the crop concerned and the time of immersion to obtain protection and avoid phytotoxic reactions in fruits or vegetables. The times of immersion will vary from a few seconds to several minutes, but are precisely prescribed and monitoring is required for each formulation and crop. Examples includes apples 0.45% - 1.4% solution, bananas 2% applied to cut stem area of crown of head area (no residue in fruit or skin), cantaloups 1.5%, carrots 0.1%, cherries 1.0% with wetting agent, citrus 0.5% wax emulsion to 3% in water (plus caustic and hexamine), cucumbers 1% - 2%, nectarines 1%, peaches 0.05 - 0.6%, pears 0.23% to 1.45%, peppers 1%, pineapple 1.25% (1% in wax), plums 0.1%, sweet potatoes 0.37% - 0.5% solution or 0.7% wax emulsion, tomatoes 1% (U.S.D.A., 1967). These use patterns were available from the U.S.A. only. RESIDUES RESULTING FROM SUPERVISED TRIALS As mentioned above, the technology for use of these compounds has been developed under commercial conditions requiring accurate control of time of treatment which may be from as brief as 10 seconds (apples and pears) to 15-18 minutes (peaches), at specified temperatures, pH etc. The data pertaining to the conditions of these trials were collected from several locations in the U.S.A. They are unpublished. They have been collated and submitted with full details to FAO by the Dow Chemical Company (Dow, 1969). A review of several abstract journals revealed no published literature bearing on this subject from other countries. It is known that both compounds are used by several citrus exporting countries, but these have not been identified, nor were use patterns, technology of use or data on residues resulting from supervised trials supplied for evaluation from other than the U.S.A. The results of U.S.A. trials are summarized in Tables 1 and 2 (Dow, 1969). TABLE I Residues resulting from supervised trials with 2-phenylphenol Percent 2-phenylphenol Range of residues as Fruit or vegetable in wax* ppm o-phenylphenol Not rinsed Carrots 0.5 17.0 Cucumbers 0.5-2 4.2-5.6 Peppers 2 0.1-1.0 Plums 2 2.5-12.8 Sweet potatoes 1 4.0-5.7 Tomatoes 2-3 0.1-7.7 *Concentration varies according to crop and/or contact time TABLE 2 Residues resulting from supervised trials with Sodium o-phenylphenate Percent sodium o-phenylphenate Range of residues as Fruit or vegetable in water* ppm o-phenylphenol Rinsed Not rinsed Apples 0.42-0.77 0.2-14.0 Cantaloups 1.5 edible portion 1.0-6.0 whole fruit 42.0-117.0 Carrots 0.1 2.8-11.0 Cherries 0.65-1.08 0.3-2 Citrus 2.0 5.5-9.3 Cucumbers 1.0 1.3-7.7 Nectarines 0.75-1.2 0.4-1.4 Peaches 0.1-0.12 9.0-15.0 Pears 0.4-0.99 1.0-25.0 1.0-22.0 Peppers 1.0 4.2-7.1 Pineapples 1.25 3.8-7.1 Plums 0.4 0.8-1.3 Sweet potatoes 0.5-1.0 0.5-11.0 1.7-3.4 Tomatoes 0.9 0.5-1.4 *Concentration varies according to crop and/or contact time FATE OF RESIDUES Carrots treated with 0.1% sodium o-phenylphenate, stored and steam or abrasion peeled prior to canning in a commercial manner contained no residues in the canned product. In cantaloups the residue is mostly in the unedible portion (42.0-117 ppm in whole fruit, 2.8-11.0 ppm in edible portion) (Dow, 1969). The value of OPP residues found in peel of oranges varies slightly with variety. Shamoute oranges peel varied between 5.9-23 ppm; Valencias between 8.8 and 21.3 ppm; grapefruit peel 7.0-26.1 ppm; lemons 5.4-15.6 ppm in peel. The quantities of OPP in pulp of citrus is very low. In many cases none could be detected, but when peel contained the higher levels, OPP residues from trace to 0.4 ppm were found in pulp (Rajzman and Apfelbaum, 1968). There is no information available on possible chemical alteration of the nature of the residue. All residue analysis methods to date rely on expressing the residue as 2-phenylphenol. Evidence of residues in food in commerce or at consumption Information on the residue content of food in commerce is rare. Only one published paper has a bearing on this subject (Rajzman and Apfelbaum, 1968). Citrus fruit treated in 22 packing houses in Israel were collected, sampled and analysed. The residues in whole fruit range from 1.8 to 8.3 ppm with 80% of the samples containing less than 5 ppm. The authors conclude that in view of the small number of samples used, their finding of a maximum of 8.3 ppm should not be considered as the maximum quantity which can occur in citrus treated in the manner described. There is no information available with regard to residues in food at the time of consumption. It can be assumed there will be little loss of residue in wax-treated fruits and vegetables. Since the treatment is by post-harvest application, the amounts in wax-treated food reaching the consumer can be considered as those reported as resulting from supervised trials. Possibly slightly lower levels will remain in food treated with water formulations. METHODS OF RESIDUE ANALYSIS Colorimetric procedures have most often been proposed for the determination of residues of 2-phenylphenol. Tomkins and Isherwood (1945) used coupling with diazotized sulphanilic acid in determining residues in oranges and marmalade after a steam-distillation extraction, with acid-alkali treatment clean-up stages. Gottleib and Marsh (1946) suggested an aminophenazone procedure for the determination of several phenolic fungicides. The results of a collaborative study of this method as applied to the determination of residues of 2-phenylphenol in apples, pears and citrus fruit have been reported by Schiffman (1957); Hayward and Grierson (1960) used this method on oranges. A similar procedure has been officially recommended by the Communauté Economique Européene (van Elslande, 1967) for residues in fruits and this should be suitable for regulatory purposes at the present time. A modified steam-distillation extraction apparatus has been described by Leinbach and Brekke (1961) who used an indophenol colorimetric method for residues in purees of raspberry, strawberry, prunes, loganberry and fig and in orange juice. The coloration given by reacting 2-phenylphenol with titanium sulphate (Caulfield and Robinson, 1953) is not sufficiently sensitive for residue analysis. A spectrofluorometric procedure for the examination of single fruits was proposed by the Cotta-Ramusino and Stacchini (1966) which is sensitive to <0.1 mg of 2-phenylphenol for fruit, Gunther et al. (1963) reported a procedure for the routine examination of citrus fruits for biphenyl and 2-phenylphenol, determining the latter colorimetrically after coupling with p-nitrofluoroborate, and obtained recoveries ranging from 89 to 100 percent at the 0.5 to 10 ppm level. Chromatographic methods available include a gas chromatographic examination of concentrated orange juice (Thomas, 1960), applicable over the range 1 to 10 ppm on 1 ml of sample and a thin-layer chromatographic procedure for the detection of residues of biphenyl and 2-phenylphenol in lemons (Chioffi, 1965). Mestres and Chave, (1965) used extraction with cyclohexane in a Dean and Stark apparatus before separating and determining biphenyl and 2-phenylphenol by gas chromatography with flame-ionisation detection. These chromatographic techniques should be developed and evaluated for application as regulatory procedures. NATIONAL TOLERANCES Tolerance (ppm) Country Crop as 2-phenylphenol Canada Cherries, nectarines 5 Citrus fruits, cucumbers, pepper (bell), pineapple, tomatoes 10 Sweet potatoes 15 Carrots, peaches, plums 20 Apples, pears 25 Cantaloups 125 E.E.C. Citrus fruits 12 Netherlands Citrus fruits 10 United Kingdom Citrus fruit 70 Apples, pears, pineapples 10 Melons 125 NATIONAL TOLERANCES (continued) Tolerance (ppm) Country Crop as 2-phenylphenol United States Cherries, nectarines 5 of America Citrus, citron, cucumbers, grapefruit, 10 kumquats, lemons, limes oranges, peppers (bell), pineapple, tangelos, tangerines, tomatoes Sweet potatoes 15 Carrots, peaches, plums (fresh prunes) 20 Apples, pears 25 Cantaloups, of which not more than 125 10 ppm shall be in the edible portion. APPRAISAL The antimicrobial properties of 2-phenylphenol have been utilized in many countries for over 40 years. Due to its broad spectrum fungicidal and bactericidal properties and commercial availability it has been used widely as a germicide. In addition to its current use as a post-harvest pesticide it has been used in household disinfectants, preservatives for water-oil emulsions in textile and metal industries. The sodium salt is also used as a preservative in water base paints and adhesives. The free phenol is used in the post-harvest treatment of fruits and vegetables in wax formulations as a protectant in shipment and storage. The sodium salt is dissolved in water and used as a post-harvest rinse for fruit and vegetables. The tree phenol is also used to treat harvesting containers, shipping and storage facilities, fruit handling machinery and shipping containers. The data on residues from supervised trials are based only on U.S.A. technology of use and on the two products as manufactured by Dow Chemical Company. These are proprietary compounds, manufactured by several companies in many countries. No information was provided on the use pattern or technology of use in other countries. The residues from both compounds are expressed as 2-phenylphenol. Highly specific methods of dipping and washing individual species of fruits and vegetables in the protective baths have been developed, with carefully prescribed times of immersion varying from as little as 10 seconds (apples and pears) to e.g. 6 minutes for citrus. A skilled technology and monitoring of wash solutions is required to maintain correct conditions for treatment. Consequently, amounts of residues vary depending upon the type of formulation used, the technology of treatment and the fruit or vegetable itself. Supervised trials in the U.S.A. carried out in several types of commercial scale fruit and vegetable handling facilities resulted in residues of (ppm) apples 0.2-14, cantaloups (whole fruit) 42-117, carrots 2.8-17 (removed by processing), cherries 0.3-2, citrus 5.5-9.3, cucumbers 1.3-7.7, nectarines 0.4-1.4, peaches 9-15, pears 1-22, peppers 4.2-7.1, pineapples 3.8-7.1, plums 0.8-12.8, sweet potatoes 0.5-5.7, tomatoes 0.5-7.7. Variations of conditions of treatment and contact time could presumably result in slightly higher residues. Methods of analysis for residues are available and they should be evaluated by collaborative studies. (This in not considered critical). In general all methods are based on determining the 2-phenylphenol content of an aqueous solution residue extract by colometric measurement after coupling with 4-aminoantipyrine. No data are available on residues on fruits and vegetables as consumed, but since these are post-harvest uses it would be a fair speculation to assume that the residues would be the average of the ranges outlined above. Since the technology of treatment is so critical, in approaching the recommendation of tolerances, some leeway should be provided for error in time of immersion, pH of bath and other factors in this technology. RECOMMENDATIONS FOR TOLERANCES, TEMPORARY TOLERANCES OR PRACTICAL RESIDUE LIMITS Cherries, nectarines 3 ) ) Citrus, cucumbers, peppers (bell), ) pineapples and tomatoes 10 ) ) Sweet potatoes 15 ) ) Apples, plums, (fresh prunes) 15 ) ppm as 2-phenylphenol ) Carrots, peaches 20 ) ) Pears 25 ) ) Cantaloups (whole fruit) 120 ) ) Cantaloups (edible portion) 10 ) FURTHER WORK OR INFORMATION DESIRABLE 1. A reproduction study in experimental animals. 2. Metabolic studies in experimental animals and man. 3. Long-term studies using a larger number of animals. 4. Data on residue levels in raw agricultural commodities moving in commerce. 5. Data on residues in food at the time of consumption. 6. Results of collaborative studies of chromatographic methods of analysis. REFERENCES Benger, H. (1968) Fluorimetsche bestimmung von o-phenyl-phenol in citrusfrüchten. Arch. Hyg. 152(3):225-30 Caulfield, P.H. and Robinson, R.J. (1953) Spectrophotometric determination of o-phenylphenol with titanium sulphate. Analyt. Chem. 25:982-3 Chioffi, V. (1965) Investigation of diphenyl and o-phenylphenol in lemons by thin-layer chromatography. Boll. Lab. Chim. Provinciali (Bologna), 16:366-76 Chem. Abs., 1966, 64:1254d. Cotta-Ramusino, F. and Stacchini, A. (1966) Spectrofluorometric determination of o-phenylphenol in citrus fruits. Fruits (Paris), 21:37-9; Chem. Abs., 64:14858h. Dodgson, K.S., Garton, G.A., Stubbs, A.L. and Williams, R.T. (1948) Studies on detoxication 15. On the glucuronides of stilboestrol, hexoestrol and dienoestrol. Biochem. J., 42:357-65 (cited in Williams 1959) Dow. (1969) Unpub. three-volume submission of data submitted by Dow Chemical Co., Midland, Mich., U.S.A. to FAO E.E.C. (1967) Amtsblatt der Europaischen Gemeinschaften, No. G1203B, 11 July 1967, 10. Jahrgang Nr. 148. Elslande van, R. (1967) Dosage des résidues d'orthophénylphénol et d'orthophénylphénate de sodium dans les agrumes. J. Offic. Communantés Européenes, 10: No.148, 7-9 (11.7.1967). Ernst, W. (1965) Umwandlung und Ausscheidung von 2-hydroxydiphenyl bei der Ratte. Arzneimittel. - Forsch., 15:632-6 FAO/WHO (1962) Evaluation of the toxicity of a number of antimicrobials and antioxidants. Sixth Report of the Joint FAO/WHO Expert Committee on Food Additives; FAO Nutrition Meetings Report Series No.31; Wld Hlth Org. techn. Rep. Ser. No.228, pp. 78-81 Gottleib, S. and Marsh, P.B. (1946) Quantitative determination of phenolic fungicides. Ind. Eng. Chem. Anal. Ed., 18:16-19 Gunther, F.A., Blinn, R.C. and Barkley, J.H. (1963) Procedure for routine determination of biphenyl and o-phenylphenol on and in citrus fruit. Analyst, 88:36-42 Hayward, F.W. and Grierson, W. (1960) Effects of treatment conditions on o-phenylphenol residues in oranges. J. Agr. Fd. Chem. 8.308-10 Hodge, H.C., Maynard, E.A., Blanchet, H.J. Jr., Spencer, H.C. and Rowe, V.K. (1952) Toxicological studies of orthophenylphenol (Dowicide I) J. Pharmacol. exp. Ther., 104:202-10 Innes, J.R.M., Ulland, B.M., Valerio, M.G., Petrucelli, L., Fishbein, L., Hart, E.R., Pallota, A.J., Bates, R.R., Falk, H.L., Gart, J.J., Klein, M., Mitchell, I. and Peters, J. (1969) Bioassay of pesticides and industrial chemicals for tumorigenicity in mice. A preliminary note. J. Nat. Cancer Inst. 42:1102-14 Kamil, I.A., Smith, J.N. and Williams, R.T. (1951) Studies in detoxication. 41. A study of the optical rotations of the amides and triacetyl methyl eaters of some biosynthetic substituted phenylglucuronides. Biochem. J. 50:235-40 (cited in Williams, 1959) Leinbach, L.R. and Brekke, J.E. (1961) A modified Gibbs method for the determination of 1 ppm or less of o-phenylphenol in fruits. J. Agr. Food Chem. 9:205-6 MacIntosh, F.C. (1945) The toxicity of diphenyl and o-phenyl-phenol. Analyst, 70:334 Mestres, R. and Chave, C. (1965) Determination of biphenyl and o-phenylphenol in citrus fruits. Trans. Soc. Pharm. Montpellier, 24:272-82. Chem. Abs., 63:15434g. Rajzman, A. and Apfelbaum, A. (1968) Survey of o-phenylphenol residues found in marketable citrus fruit. J. Sci. Fd. Agric. 19:740-4 Schiffman, C.D. (1957) Report on sodium orthophenylphenate residues on apples, pears and citrus fruits. J. Assoc. Offic. Agric. Chem., 40:238-42 Thomas, R. (1960) The detection and determination of diphenyl and o-phenylphenol in concentrated orange juice by gas chromatography. Analyst, 85:551-6 Tomkins, R.G. and Isherwood, F.A. (1945) The absorption of diphenyl and o-phenylphenol by oranges from treated wraps. Analyst, 70:330-3 U.S.D.A. (1967) Summary of registered agricultural pesticide chemical uses (2nd Edition), U.S. Department of Agriculture, Washington, D.C. pp. 647, 727-8(a) (1967) Williams, R.T. (1959) "Detoxication Mechanisms" London, Chapman and Hall, p. 308
See Also: Toxicological Abbreviations Phenylphenol, 2- (WHO Pesticide Residues Series 5) Phenylphenol, 2- (Pesticide residues in food: 1990 evaluations Toxicology)