Bioassay of allyl chloride for possible carcinogenicity.

A bioassay for possible carcinogenicity of technical-grade allyl chloride (3-chloropropene) was conducted using Osborne-Mendel rats and B6C3F1 mice. At initiation of the study the rats were approximately 6 weeks old and the mice approximately 5 weeks old. Allyl chloride in corn oil was administered by gavage to two groups of each species for 5 days a week for 78 weeks, followed by observation periods of 30 to 33 weeks for the rats and 14 weeks for the mice. The time-weighted average dosages were, respectively, 77 and 57 mg/kg/day for high and low dose male rats; 73 and 55 mg/kg/day for high and low dose female rats; 199 and 172 mg/kg/day for high and low dose male mice; and 258 and 129 mg/kg/day for high and low dose female mice. For each species, 20 animals of each sex were placed on test as vehicle controls. These animals were intubated with corn oil at the same time that dosed animals were gavaged with allyl chloride in corn oil. Twenty animals of each sex were placed on test as untreated controls for each species. These animals were not intubated. Survival of high dose male mice and high dose rats of both sexes was extremely poor. Fifty percent of the high dose male mice were dead by week 27; the 10 members of this group that survived past week 48 were sacrificed in week 56. Among the high dose rats, 50 percent of the males had died by week 14 and 50 percent of the females had died by week 38. Because of early mortality in these groups, the number of animals surviving long enough to be at risk from late-developing tumors was not adequate for meaningful statistical analysis. In this bioassay, squamous-cell carcinomas of the forestomach in male and female mice and squamous-cell papillomas of the forestomach in female mice occurred in incidences that were higher than in historical controls. No other neoplasms occurred in statistically significant increased incidences in dosed rats or mice Under the conditions of this bioassay no convincing evidence was presented for the carcinogenicity of allyl chloride in Osborne-Mendel rats of either sex. The results are suggestive that allyl chloride is carcinogenic in male and female B6C3F1 mice since the compound, when administered by gavage caused a low incidence of neoplastic and nonneoplastic lesions of the forestomach.