0>aIIJI<': ODd Can«< RlAk Ed H. vainlo, hi Sana &. A.J. McMichael Ju1CmB.l1onalAgencyfor 00 Cancer '", 1990 Genetic activity profiles - application in assessing potential carcinogenicity of complex environmental mixtures! M. D. Waters and L. D. Claxton u.s . Environmental Protection Agency, Health Effects Research Laboratory, Genetic Toxicology Division, Research Triangle Park, NC 27711 H. F. Stack Environmental Research and Testing, Inc ., Research Triangle Park, NC 27709 and T. E. Graedel AT&T Bell Laboratories, Murray Hill, NJ 07974 Summary . Some knowledge of the po tential genetic activity of a complex environ- mental mixture may be gained from an assessment of the genetic activity of its component chemicals . The expanded genetic activity profile (GAP) data-base provides a computer-generated graphic representation of genetic bioassay data as a function of dose of the substance tested. In addition, the atmospheric chemical compound (ACe) data-base contains information on chemical structures, pro- perties, detection methods and sources of chemicals found in ambient air. Using the combined data-bases, information on the quantity of an individual chemical present within a mixture or fraction of a mixture may be related to the quantity (lowest effective dose; LED) of the chemical required to demonstrate a positive response in one or more genetic bioassays . Alternatively, quantitative information on the carcinogenic potency of each individual compound (TD so value) may be related to the quantity present in the mixture or mixture fraction and used to calculate the percent human exposure doselrodent potency dose (HERP) for the chemical. Using an additivity assump- tion , a conservative estimate of potential carcinogenic hazard for the mixture may be calculated based on the HERP indices for its chemical components. This conceptual approach is limited by the relatively small number of chemicals identified in complex mixtures for which genetic toxicology and animal cancer data exist. This document bas been reviewed in accordance with U.S. Environmental Prote ction Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 75 I