Testimony was presented concerning the establishment of an occupational exposure standard for acrylonitrile (107131) (AN) to which an estimated 125,000 workers were potentially exposed. Two year feeding and inhalation studies with animals indicated the chemical to be carcinogenic, producing tumors of the central nervous system (CNS), cerebral tumors, squamous cell neoplasms of the Zymbal gland, adenocarcinoma of the small intestine and large intestine, along with numerous benign tumors. Other findings included papillomata in the stomach, hemangioma of the kidney, fibroadenomas of the mammary gland, benign tumors of the uterus, and tumors of the ear canal. These animal studies have reinforced the findings of the Du Pont mortality study of workers exposed to AN which, though incomplete, strongly suggested that AN has carcinogenic properties for humans. Teratogenicity studies indicated increased incidence of fetal malformation. Concentrations of 0.05 milligrams/liter (the Soviet standard for exposure to AN) have demonstrated an inhibitory effect on CNS function, specifically in relation to the learning process. Cases of AN as an allergen causing contact dermatitis and ulcers have been widely documented. It was recommended that drugs essential to the treatment of acute intoxication from AN be kept in the medical facility of all facilities using AN, and that employers institute a respiratory protection program in accordance with requirements.