Effects on Animals:
Vinyl acetate is an irritant to the eyes and respiratory system in experimental animals and may be an animal carcinogen. Instillation of 470 mg of undiluted vinyl acetate into the rabbit eye caused severe irritation. The dermal LD(50) in rabbits is 2,335 mg/kg. The oral LD(50) in rats is 2,920 mg/kg. The 2-hour LC(50) in rats is 4,000 ppm. The primary toxic effect associated with inhalation of vinyl acetate is irritation of the pulmonary tract and eyes. In one study, mice and rats were exposed to 50, 200 or 1,000 ppm for 6 hours/day, 5 days/week for 3 months. Pulmonary irritation was observed at 1,000 ppm for rats and at both 200 and 1,000 ppm for mice. At a concentration 1,000 ppm, reduced body weight gain, increased pulmonary congestion, and histopathological changes in the respiratory tract of mice were observed. The no-observed-effect-level (NOEL) during this study was 50 ppm for the mice and 200 ppm for the rats. Although there are reports that vinyl acetate can affect the liver (reduced absolute and relative liver weight) and central nervous system (decreased or increased excitability), these effects have not been replicated in other studies. Pathological lesions have not been observed in studies that reported central nervous system or liver effects. In a two generation reproductive study, rats were exposed to 200, 1,000, or 5,000 ppm vinyl acetate in the drinking water. No adverse effects on reproductive function were observed. Vinyl acetate was genotoxic in both in vivo and in vitro studies on mammalian cells; it was inactive in the Ames bacterial mutagenicity assay. In a chronic exposure study rats and mice were exposed to 0, 50, 200, and 600 ppm vinyl acetate by inhalation for two years. Reduced weight gain was observed in high dose animals, but no systemic toxicity was observed at any dose in either species. Treatment pathology was limited to changes indicating chronic irritation of the respiratory tract in intermediate and high dose animals and only the high dose animals had frank signs of injury. An increased incidence of nasal tumors was observed in high dose rats. The International Agency for Research on Cancer (IARC) has concluded that there is inadequate evidence for the carcinogenicity of vinyl acetate in experimental animals. However, the IARC evaluation was made prior to completion of the carcinogenicity study cited in ACGIH.

Effects on Humans:
Vinyl acetate is an irritant to the eyes and respiratory tract in humans. Vinyl acetate vapors were irritating to the eyes at a concentration of 21.6 ppm, but no irritation was noted at a concentration of 10 ppm. Dermal contact with vinyl acetate may produce irritation with blister formation. Volunteers exposed to concentrations ranging from 19.5 to 71.5 ppm vinyl acetate for 0.5 to 4 hours reported respiratory tract irritation. IARC has concluded that in the absence of adequate epidemiological data, no evaluation of the carcinogenicity of vinyl acetate to humans could be made.