The Toxicology of Polycyclic Organic Matter from Exhaust Gases

Abstract

The assessment of the potential toxic effects of polycyclic organic matter from exhaust gases can be approached in a variety of ways using short-term in vitro studies, whole animal studies testing total exhaust emissions or fractions thereof, and epidemiologic studies. Each of these approaches has its own problems of interpretation and extrapolation. Many of the experimental methods available today are claimed to yield results related to or predictive of human carcinogenesis. These same methods are not claimed to be predictors of non-neoplastic disease. These test systems are often used to evaluate fractions of the exhaust emissions or pure compounds which have been identified in the total exhaust. Caution is necessary in the interpretation of such results as many examples are known where results differ when compounds are tested alone or as components of a mixture. The majority of the in vitro tests monitor the initiation phase of carcinogenesis, whereas we know that cancer is a multistage process with a multifactorial etiology. The efforts of dissecting the emissions with the intention of identification and removal of toxic components to produce a higher quality emission must be weighed against simply reducing the quantity of total emissions.