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OVERVIEW OF THE MUTAGENICITY OF URBAN AIR
Citation:
CLAXTON, L. D., S. H. WARREN, P. P. MATTHEWS, G. M. WOODALL, S. T. BAGLEY, AND P. WHITE. OVERVIEW OF THE MUTAGENICITY OF URBAN AIR. Presented at The 9th International Conference on Environmental Mutagens, and the 36th Annual Meeting of the Environmental Mutagen Society, San Francisco, CA, September 03 - 08, 2005.
Description:
For the past 25 years, there has been great interest in the mutagenicity and carcinogenicity of ambient air and in the sources of those genotoxicants. Prior to the 1980's, the evaluation of airborne toxicants was done on a pollutant-by-pollutant basis. However, the assessment of carcinogenicity for multiple compounds and the modeling of risks for constantly changing chemical mixtures presented an enormous challenge. Also, it became apparent that chemical analysis could not effectively monitor all potentially airborne toxicants or for unknown toxicants. One simple approach was to measure the toxicological activity of total airborne masses. Therefore, the last quarter century has seen a number of studies in which researchers examined the toxicology of actual samples from ambient air and sources that pollute the air. For those interested in cancer, the genotoxicity assays have been used to compare genotoxic activity by location, meteorological conditions, sources, and by other modifying conditions. Additionally, mutation tests have been used for large, multi-site, and/or time series studies, for bioassay-directed fractionation studies, for identifying the presence of specific classes of mutagens, and for doing site- or source-comparisons for relative levels of airborne mutagens. The purpose of this presentation is to address how mutagenicity assays have provided a means to characterize the toxicology of ambient air affected by many sources under varying conditions. The factors that impact the mutagenic burden of ambient air and what is known about the identity of specific mutagens will be addressed. Moreover, future research needs and opportunities will be outlined. For example, although PAHs are prominent in most airborne emissions, PAHs generally do not account for the majority of the mutagenic activity detected. The majority of mutagenicity is usually associated with moderately polar and highly polar classes of compounds. The review makes it clear that a number of needs still exist to provide better characterization of airborne pollutants (e.g., identifying volatile and semi-volatile genotoxicants). Additionally, multi-national studies that examine the airborne mutagenicity of both volatiles and aerosols during different seasons of the year should be done, and source-apportionment studies need to be done in more complex air sheds that typify urban air sheds. Also, initial efforts at replacing historically-used assays with some emerging technologies (e.g., comparative microarrray analysis of tissues from exposed animals) should be initiated.