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Administrative data

Description of key information

In rats and mice, repeated inhalation exposure to propylene oxide for 2 years produced chronic irritation of the nasal epithelium, with such effects being only marginal in nature at 30 ppm. However, concentrations of 100 ppm and above produced epithelial damage. In a 4 -week study in rats, small and reversible increases in nasal epithelium irritation occurred at 525 ppm propylene oxide. There is some evidence to indicate neurotoxicity in rats at a relatively high exposure level of 1,500 ppm after 7 weeks of exposure. No signs of neurotoxicity were observed in rats exposed to 300 ppm for 24 weeks.
Repeated oral administration caused reduced body weight gain and gastric irritation, seen microscopically as reactive changes in the squamous epithelium of the fore stomach. No data are available on the toxicity of propylene oxide following repeated dermal exposure. The absence of significant toxic sequelae distant from the site of application following inhalation or oral administration suggests that concerns about target organ toxicity can be focused almost exclusively on tissues at the sites of initial contact. No additional classification for repeated exposure via inhalation, oral or dermal exposure is warranted.

Key value for chemical safety assessment

Mode of Action Analysis / Human Relevance Framework

Additional information

Justification for classification or non-classification