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The screening of complex atmospheric mixtures for potential biological hazard presents special problems in sampling, analysis, and interpretation. Recent efforts emphasize a close coupling of chemical (fractionation) and biological (bioassay) techniques. Most of these studies have been performed on air particulate samples; far less attention has been directed toward vapor-phase and gas-phase samples. The most commonly employed short-term test has been the Ames Salmonella/microsome assay.
Current studies on particulate components favor a combination of size-selective sampling with chemical analysis and bioassay, to provide a more direct relationship between the data obtained and the potential inhalation hazard. When possible, multiple agents are identified and bioassayed in carefully defined chemical fractions. Iterative application of bioassay and chemical fractionation thus facilitates identification of individual chemical species that display biological activity.
In the area of quantification and interpretation, complex atmospheric mixtures present additional challenges, including the possible masking of mutagenic activity by toxicants contained within the mixture, differential metabolic activation, and detoxification. Important concerns to be addressed in estimating a sample's toxicity include questions of biological availability and dosimetry. Answers to such questions determine our ability to estrapolate in vitro results to the in vivo situation.
short-term bioassays, atmospheric pollutants, complex mixtures, particulates, atmosphere, vapors, gases, biological availability, dosimetry, organics, toxic organics
Director, Genetic Toxicology Division, Health Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, N.C.