Urinary excretion of mercapturic acids and thiocyanate in rats exposed to acrylonitrile: influence of dose and route of administration.

Adult male Sprague-Dawley rats were exposed acutely to acrylonitrile (ACN) according to 1 of 3 different routes of administration: inhalation (6 h), i.v., or i.p. Urinary metabolites measured 24 h after administration were 2-cyanoethylmercapturic acid (CMA), 2-hydroxyethylmercapturic acid (HMA) and thiocyanate (TCN). In all 3 series of experiments, the relationship between excretion of total urinary metabolites and the degree of exposure was reasonably linear. However, there was a marked influence of the route of administration on the pattern of metabolic excretion. For example, after i.p. and i.v. injection CMA was the most important metabolite while after inhalation it was TCN. Our results also indicate an important effect of the dose on the pattern of excretion for all types of administration.