Multi‐organ carcinogenicity by inhalation exposure to 2‐Bromopropane in rats

OBJECTIVE: The purpose of this study was to investigate the carcinogenicity of 2‐bromopropane (2‐BP) in rats. METHODS: Male and female F344 rats were exposed by whole body inhalation to 2‐BP vapor at concentrations of 0, 67, 200, and 600 ppm for 6 h/day, 5 days/week for 2 years. RESULTS: All rats of both sexes exposed to 600 ppm died or became moribund within 85 weeks. Death/moribundity was caused by 2‐BP induced tumors. In males, significantly increased tumors were malignant Zymbal's gland tumors; sebaceous adenoma and basal cell carcinoma of the skin/appendage; adenocarcinoma of the small/large intestine; follicular cell adenoma of the thyroid; fibroma of the subcutis, and malignant lymphoma of the lymph node. In addition, an increased trend in tumor incidence was found in the preputial gland, lung, forestomach, pancreas islet, brain, and spleen. In females, significantly increased tumors were adenocarcinoma and fibroadenoma of the mammary gland, squamous cell papilloma of the vagina, and large granular lymphocytic leukemia of the spleen. In addition, an increased trend in tumor incidence was found in Zymbal's gland, the clitoral gland, skin, large intestine, pancreas islet, uterus, and subcutis. Particularly, malignant Zymbal's gland tumors were induced even in males exposed to the lowest concentration, 67 ppm. CONCLUSION: Two‐year inhalation exposure to 2‐BP resulted in multi‐organ carcinogenicity in rats. Based on sufficient evidence of carcinogenicity in this study, 2‐BP has the potential to be a human carcinogen.