WHO/Food Add./24.65 FAO Nutrition Meetings Report Series No. 38A SPECIFICATIONS FOR IDENTITY AND PURITY AND TOXICOLOGICAL EVALUATION OF SOME ANTIMICROBIALS AND ANTIOXIDANTS The content of this document is the result of the deliberations of the Joint FAO/WHO Expert Committee on Food Additives which met 8-17 December 1964a a Eighth Report of the Joint FAO/WHO Expert Committee on Food Additives, Wld Hlth Org. techn. Rep. Ser., 1965, 309; FAO Nutrition Meetings Report Series 1965, 38. DIPHENYL CHEMICAL NAMES Biphenyl; phenylbenzene EMPIRICAL FORMULA C12H10 STRUCTURAL FORMULAMOLECULAR WEIGHT 154.21 USE As a fungistatic agent in wrapping material to inhibit growth of moulds on citrus fruits. DESCRIPTION White or pale yellow to amber, crystalline solid or leaflets having a characteristic odour. IDENTIFICATION TESTS A. Solubility: Water: Insoluble Ether: Soluble Ethanol: Soluble B. Melting point: About 69° C. Boiling point: About 225° PURITY TESTS Arsenic: Not more than 3 mg/kg. Lead: Not more than 10 mg/kg. Solidification point: Not below 68.5° Distillation range: It distils completely within a 2.5° range between 252.5° and 257.5°. ASSAY Required. Biological Data Biochemical aspects Diphenyl is metabolized in rats1,2 and rabbits2 to various phenolic compounds, mainly 4-hydroxydiphenyl which is excreted in the urine in both free and conjugated form (ethereal sulfate and glucuronate). This demonstration of a common mechanism in 2 species of animals suggests that human metabolism would follow similar paths, but no report of this has been found in the literature. Diphenyl was found to be less toxic when given with a diet containing a supplement of 1-cystine or dl-methionine, but diphenyl is not highly conjugated with cystine. Acute toxicity Animal Route LD50 References (mg/kg body-weight) Rat oral 3500-5000 3,4 Rabbit oral 2400 3 Short-term studies Rabbit. Five rabbits were each given doses of 1 g/kg body-weight by stomach tube in a 25% dilution in olive oil 2 or 3 times a week until they died. Deaths occurred within 5 to 20 weeks. The blood picture showed no significant change, but the gain in body-weight was less than in the controls, and retention of urea occurred near the terminal stage of intoxication.3 Rat. Eleven young female rats were fed for 32 days on a diet low in casein and containing 1% diphenyl. A marked growth retardation was observed. Histological examination of 2 animals showed the beginning of fatty changes in the liver and mild toxic changes in the kidney.1 In a small group of weanling rats fed with a diet containing 0.3% diphenyl, weight increase was less than in control animals.5 Administration of diphenyl to young rats for 4 weeks in doses of 2, 20 and 200 mg/kg body-weight per day induced neither growth retardation nor significant change in the blood picture.6 Oral administration of 0.3 mg/kg body-weight daily to 10 rats for 12 days did not induce growth retardation.7 Groups of young rats were fed for 3 months on rations containing 0%, 0.01% and 0.1% of diphenyl. No significant differences were observed in the growth rates, food efficiency, organ weights, blood urea or histology of tissues between treated and control rats. At the level of 0.1% only a slight polyuria was noted.8 Monkey. Small groups of monkeys were fed for a year on rations containing 0.01%, 0.1% and 1% diphenyl. The only significant change was a slight increase in weight of the liver at the intake level of 1%.8 Dog. Nine dogs divided into 3 groups received diphenyl in corn oil daily at the rate of 0, 2.5 and 25 mg/kg body-weight 5 days a week for 52 weeks. One dog on 2.5 mg/kg and 1 on 25 mg/kg lost about 1 kg in weight each. The other animals gained in weight. Blood and urine were unchanged. No gross or microscopic pathological changes were found in any of the tissues examined.9 Long-term studies Rat. A long-term feeding experiment with rats made use of dietary levels of 0.01%, 0.1% and 1% diphenyl for a 2-year period.8 Unfortunately this study failed to supply the desired information for two reasons: (a) a severe respiratory infection caused a high mortality among the controls; (b) rats receiving 0.1% and 1% diphenyl exhibited tubular dilatation of the kidneys, as did two of the control rats. Groups of 15 weanling rats of each sex were fed 0.001%, 0.005%, 0.01%, 0.05%, O.1%, O.5% and 1% diphenyl in the diet. Growth was inhibited particularly at the 0.5% and 1% levels, apparently because of decreased food consumption daring the first 100 days of the test. During 750 days there was a decrease in longevity in rats on the 0.5% and 1% diets. At the other levels there was no significant evidence of toxicity. With the diet containing 1% diphenyl, haemoglobin values of male end female rats were lower in comparison with controls when measured at 300 and 400 days respectively. The histopathological changes observed in the kidneys of rats on the 0.5% and 1% diets were irregular scarring, lymphocytic infiltration, tubular atrophy and patchy tubular dilatation to the point of cyst formation in association with hydronephrosis and sometimes albuminuria and haemoglobinuria. These phenomena did not occur at a concentration of O.1% diphenyl or less.10 In another long-term study, the onset end reversibility of kidney damage in rats on diets containing 0.1%, 0.25% and 0.5% diphenyl were investigated, and the findings quoted under reference 10 were confirmed.11 In one experiment on 13 rats fed daily with a diet containing 0.025% to 0.05% diphenyl, after 2 months 1 animal had squamous cell carcinoma and 2 had papillomas of the forestomach.4 Comment on experimental studies reported Most of the studies reported have been carried out in dogs and rats. The value of negative results of short-term studies in groups of 3 dogs at levels of 2.5 and 25 mg/kg body-weight is limited.9 Long-term studies in rats provide a basis for evaluation.10,11 Metabolic studies on 2 species reveal a common mechanism of detoxication, but no data are available on metabolism in man. Evaluation Level causing no significant toxicological effect in the rat From consideration of the long-term studies in rats, the level causing no significant toxicological effect when ingested over a period approximating to the life span nay be assessed at 0.1%. 0.05% (= 500 ppm) in the diet is equivalent to 25 mg/kg body-weight per day. Estimate of acceptable daily intakes for man mg/kg body-weight Unconditional acceptance 0-0.05 Conditional acceptance 0.05-0.25 Comment Diphenyl presents certain peculiar problems since it is primarily used as a treatment for wrappers for fruit. Nevertheless, diphenyl penetrates into the skin of the fruit and may consequently be included in food or drink prepared from it. Fruit drinks are commonly consumed in considerable quantities by children and by sick people. For these reasons caution should be exercised and the pattern of use should be closely studied. Further Work Considered Desirable 1. Long-term studies in a species other than the rat, with careful evaluation of tumour incidence. 2. Biochemical studies in man. References 1. West, H. D. (1940) Proc. Soc. exp. Biol. (N.Y.), 43, 373 2. West, H. D., Lawson, J. R., Miller, I. H. & Mathura, R. (1955) Fed. Proc., 140, 303 3. Deichmann, W. B., Kitzmiller, K. V., Dierker, M. & Witherup, S. (1947) J. industr. Hyg., 29, 1 4. Pecehiai, L. & Saffiotei, U. (1957) Med. d. lavoro, 48, 247 5. West, H. D. & Jefferson, N. C. (1942) J. Nutr., 23, 425 6. MacIntosh, F. C. (1945) Analyst 70, 334 7. Rogliani, E. & Procaccini, S. (1956) Biochim. appl., 3, 193 8. Newell, G. W. (1953) Toxicological study of diphenyl in citrus wraps (Report 1953 of the Standford Research Institute) 9. Hazleton. L. H., Kundzins, N., Howard, J. W. & Johnson, C. D. (1956) Studies on diphenyl in the dog. In: XXth International Physiological Congress, Brussels, July 29 - August 4, 1956. Abstracts of communications, p. 412 10. Ambrose, A. M., Booth, A. N., DeEds, F. & Cox, A. J. (1960) Food Res., 25, 328 11. Booth, A. N., Ambrose, A. M. & DeEds, F. (1956) Fed. Proc., 15, 403
See Also: Toxicological Abbreviations DIPHENYL (JECFA Evaluation) Diphenyl (FAO/PL:CP/15) Diphenyl (FAO/PL:1967/M/11/1)