Evaluation of the pulmonary toxicity of plasticized polyvinyl chloride thermal decomposition products in guinea pigs by repeated CO2 challenges.

Male guinea pigs were exposed to thermal decomposition products of plasticized polyvinyl chloride (PVC-A) at different concentrations up to levels inducing acute lethality. Several groups exposed at sublethal levels were then evaluated for pulmonary performance for a period of 57 days following exposure. Pulmonary performance was evaluated by challenging each animal with a mixture containing 10% CO2, 20% O2, and 70% N2. In control animals, this mixture induced an increase in both tidal volume and respiratory frequency. This hyperventilatory response was greatly depressed during the first 3 days following exposure and gradually returned to normal during the following weeks with the exception of the highest exposure group which still showed a diminished response 57 days after exposure. The pulmonary toxicity induced by thermal decomposition products of PVC-A is probably related to the very large amount of HCl released during thermal decomposition. The CO2 response test, a nonintrusive and noninvasive method to evaluate pulmonary performance in guinea pigs, is easily performed and appears to be a very promising type of pulmonary function test for toxicological evaluations.