Emerging methodologies for assessment of complex mixtures: application of bioassays in the Integrated Air Cancer Project.

The assessment of complex mixtures of environmental pollutants requires new interdisciplinary strategies. Integration of bioassay methodologies into these strategies is an important tool that provides direct evidence of the toxicity of a mixture. Short-term genetic bioassays are now widely used in the cancer assessment of complex mixtures. New and emerging interdisciplinary methodologies for assessing complex mixtures using bioassays are illustrated by the U.S. EPA's Integrated Air Cancer Project (IACP). The goals of this project are to identify the major airborne carcinogens and their emission sources and to improve the methodology and data available for human exposure and risk assessment from airborne carcinogens. The research effort is focused primarily on characterizing the impact of complex mixtures of products of incomplete combustion, including gaseous, semi-volatile, and particle-bound organic species. Short-term genetic bioassays have been integrated into several analysis strategies, including environmental biomonitoring; bioassay-directed fractionation/characterization; transformation studies; source apportionment; and exposure, dosimetry, and risk assessment.