EVALUATION OF RESPIRATORY EFFECTS OF THERMAL-DECOMPOSITION PRODUCTS FOLLOWING SINGLE AND REPEATED EXPOSURES OF GUINEA-PIGS

Groups of guinea pigs were exposed to the thermal decomposition produc ts (TDP) released from acrylonit rile butadiene styrene (ABS), polypro pylene-polyethylene copolymer (CP), polypropylene homopolymer (HP), or plasticized polyvinyl chloride (PVC). In single 50-min exposures to t he TDP, guinea pigs exhibited sensory irritation, coughing, and airway s constriction. Significant decreases in respiratory frequency (f) occ urred during TDP exposure which were magnified during CO2 challenge co nducted immediately post-exposure. For each resin, it was possible to demonstrate a linear relationship between the logarithm of heated mass and the percent decrease in f during CO2 challenge. From these relati onships, the mass of each resin producing a 50% decrease in f during C O2 challenge (RD(50) mass) was obtained. RD(50) masses of 2744, 25.2, 16.0, and 6.7 g were obtained for ABS, CP, HP, and PVC, respectively. Thus, the relative potency of their TDP was PVC > CP approximate to: H P >> ABS. Using the RD(50) mass of each resin, guinea pigs were expose d to TDP for 50 min/day on 5 consecutive days. These repeated exposure s also resulted in sensory irritation, coughing, and airways constrict ion. However, deaths occurred during exposures, and there was evidence of cumulative respiratory effects, and slower recoveries among surviv ors. Data obtained in guinea pigs were compared to a previous study wi th mice exposed to the TDP of the same four resins (Schaper et al. 199 4). On the basis of heated mass, mice were 20-500 times more sensitive to the acute respiratory effects of TDP than guinea pigs. Thus, the e xposure limits of 0.63, 0.11, 0.08, and 0.35 mg/m(3) proposed by Schap er et al. (1994) on the basis of particulates released from ABS, CP, H P and PVC should prevent not only irritation, but also possible coughi ng, and airways constriction in workers.