FAO Nutrition Meetings Report Series No. 40A,B,C WHO/Food Add./67.29 TOXICOLOGICAL EVALUATION OF SOME ANTIMICROBIALS, ANTIOXIDANTS, EMULSIFIERS, STABILIZERS, FLOUR-TREATMENT AGENTS, ACIDS AND BASES The content of this document is the result of the deliberations of the Joint FAO/WHO Expert Committee on Food Additives which met at Rome, 13-20 December, 19651 Geneva, 11-18 October, 19662 1 Ninth Report of the Joint FAO/WHO Expert Committee on Food Additives, FAO Nutrition Meetings Report Series, 1966 No. 40; Wld Hlth Org. techn. Rep. Ser., 1966, 339 2 Tenth Report of the Joint FAO/WHO Expert Committee on Food Additives, FAO Nutrition Meetings Report Series, 1967, in press; Food and Agriculture Organization of the United Nations World Health Organization 1967 PROPYL p-HYDROXYBENZOATE Synonyms Propylparaben Chemical name Propyl p-hydroxybenzoate; n-propyl ester of p-hydroxybenzoic acid Empirical formula C10H12O3 Structural formulaMolecular weight 180.21 Definition Propyl p-hydroxybenzoate, after drying for 2 hours at 80°, contains not less than 99 per cent. of C10H12O3. Description Propyl p-hydroxybenzoate is a white, almost odourless, crystalline solid. Use As an antimicrobial agent. Biological Data This additive was evaluated by the Joint FAO/WHO Expert Committee on Food Additives in its Sixth Report (FAO/WHO, 1962). Since its publication some new experimental work has been carried out on these compounds. This and other work not included in the Sixth Report is presented and discussed in this monograph. Biochemical aspects Dogs fed 1000 mg/kg body-weight excreted 58 per cent. in the urine and dogs given 50 mg/kg body-weight i.v. excreted 94 per cent. The ester was detectable in the plasma only soon after administration (Sokol, 1952; Jones et al., 1956). Two grams propyl ester was given daily to human volunteers for 50 days. No unhydrolyzed ester could be detected in the urine (Sabalitschka & Neufeld-Crzellitzer, 1954). At high doses, propyl p-hydroxybenzoate was found to be a useful anaesthetic for frogs and tadpoles (Kopsch, 1949). Acute toxicity Animal Route LD50 References (mg/kg body-weight) Mouse oral 8 000 Sokol, 1952 Mouse (free ester) 400 Sokol, 1952 Short-term studies Rat. Feeding experiments with n mixture of 40 per cent. ethyl ester and 60 per cent. propyl ester were reported under ethyl p-hydroxybenzoate (Heyden, 1939; Heyden, 1940). Rats ware fed on a vitamin A deficient diet with a mixture of propyl ester and methyl ester added at various concentrations. No additional pathological effects were noted (Cremer, 1935). Guinea-pig. Mixed propyl and methyl esters were fed to animals on scorbutic diets. No additional pathological effects were noted (Cremer, 1935). For details see the methyl ester. Dog. Dogs were fed 0.7 g/kg body-weight for 90 days without ill effects or macroscopic changes (Ghirardi, 1940). Rabbit. 0.25-0.30 per cent. solutions had no local anaesthetic effect on the cornea (Adler-Hradecky & Kelentey, 1960). Man. The propyl ester has been used therapeutically at doses of 800 mg/kg body-weight over 3 days for the treatment of moniliasis (Rossier & Wegmann, 1953). Long-term studies Rat. Experiments were conducted with a mixture consisting of 40 per cent. ethyl ester and 60 per cent. propyl ester. For details and results see ethyl p-hydroxybenzoate. It was concluded that the mixture, when fed at a level of 1500 mg/kg body-weight, did not produce any pathological changes, with the exception of a significant decrease in growth rate from the 4th to the 8th month. No influence in weight gain was seen at the 150 mg/kg body-weight level (Heyden, 1942). Comments The long-term studies in rats are adequate for an assessment. However, further biochemical studies in man and animals are desirable and further studies on local anaesthetic activity should also be undertaken. Evaluation Applicable to the methyl, ethyl and propyl esters. Level causing no toxicological effect Rat. 20 000 ppm in the diet, equivalent to 1000 mg/kg body-weight/day Estimate of acceptable daily intake for man mg/kg body-weight1 Unconditional acceptance 0-2 Conditional acceptance 2-7 REFERENCES Adler-Hradecky, C. & Kelentey, B. (1960) Arch. int. Pharmacodyn., 128, 135 Cremer, H. (1935) Z. Lebensmitt-Untersuch., 70, 136 Ghirardi, G, E. (1940) Arch, ital. Sci. farmcol., 9., 282 Heyden, -. (1939) Unpublished report from Applied Research Incorporated Heyden, -. (1940) Unpublished report from Applied Research Incorporated Heyden, -. (1942) Unpublished report from Applied Research Incorporated 1 Sum of ethyl, methyl and propyl esters of p-hydroxybenzoic acid. Jones, P. S., Thigpen, D., Morrison, J. L. & Richardson, A. P. (1956) J. Amer. pharm. Ass,. sci. Ed., 45, 270 Kopsch, P. (1949) Anat. Anz.,97, 158 Rossier P. H. & Wegmann, T. (1953) Wien. Med. Wschr., 19/20, 358 Sabalitschka, T. & Neufeld-Crzellitzer, R. (1954) Arzneimittel- Forsch., 4, 575 Sokol, H. (1952) Drug Stand., 20, 89
See Also: Toxicological Abbreviations