RESPIRATORY TRACT EFFECTS OF REPEATED EXPOSURES TO ISOPRENE/OZONE REACTION PRODUCTS IN MICE

摘要

Upper airway irritation and airflow limitation have been reported in mice during single exposures to the oxidation products (OPs) of isoprene, a hemiterpene emitted by humans and vegetation. This study evaluated the respiratory effects of repeated exposures to isoprene OPs. Male mice of 6 strains were exposed to a reaction mixture comprised of 3227 +-157 ppm isoprene and 1080 +-155 ppm ozone 3 hours/day for 4 consecutive days, and respiratory parameters were monitored via head-out plethysmography. Endpoints evaluated were sensory irritation, pulmonary irritation, airflow limitation, and airway responsiveness. Marked enhancement of the sensory irritation and airflow limitation effects was observed with repeated exposures, and pulmonary irritation developed in several strains. A reduction in airway responsiveness occurred in most strains, which may reflect airway mucous hypersecretion. The cumulative effects observed with repeated OP exposures have important implications for non-industrial indoor environments in which exposure may occur over many years.