Studies of the Effects of Hydrogen Chloride and Polyvinylchloride (PVC) Smoke in Rodents

Test methods for evaluating the toxicity of smoke generated by the combustion of materials have traditionally used the mouse or the rat as the animal model. Recently, the guinea pig was used to study the effects of combus tion gases and smoke atmospheres on respiratory function and incapacitation. The objective of this study was to compare the effects of HCl and PVC smoke in the mouse, the rat, and the guinea pig with those in the baboon to evaluate the utility of these rodents as predictive models for humans. Mice, rats and guinea pigs were exposed for 15 minutes to HCl, and the rats and guinea pigs were also exposed to nonflaming and flaming PVC smoke atmospheres containing targeted concentrations of HCl. In the rats and guinea pigs, respiratory re sponses and arterial blood gases were monitored during exposure, CO ₂ chal lenge response tests were conducted at 3 and 90 days following exposure, and the respiratory tracts were examined by'light microscopy at 90 days postexpo sure. The three rodent species were more sensitive than the baboon to the lethal effects of HCl and PVC smoke, with the mouse and guinea pig being more sensitive than the rat. The respiratory response of the rodents also dif fered from that of the primate. Anatomical differences in the respiratory tracts of rodents and primates may be responsible for these differences in sensitivity and response as well as for apparent differences in the severity and location of respiratory tract injury caused by HCl or PVC smoke. Although all three ro dent species have deficiencies as predictive models for the effects of irritant combustion atmospheres in humans, the mouse and the guinea pig have the most serious limitations.