PREDICTIVE TESTING OF ENVIRONMENTAL CARCINOGENS.

摘要

Two research approaches are presented which address different aspects of predictive testing for environmental carcinogens. In Part I, a well-known microbial assay is used to determine the presence of carcinogens in an environmental sample of suspected hazard. In Part II, a single chemical carcinogen is chosen to demonstrate the utility of three-phase microcosms for prediction of transport and transformations pathways in a reservoir ecosystem.; The Ames/Salmonella mutagenicity assay was used to screen processed oil shale extracts for potentially carcinogenic chemicals. Positive mutagenic activity was detected in organic solvent extracts of all four spent shales tested. This result combined with the fact that most carcinogens (90 percent) have been detected as mutagens in the Ames test, indicates that these extracts contain carcinogens.; Problems which might limit application of the Ames assay were explored. The results of assays of one-to-one mixtures of two mutagens which exhibited different dose response curves when assayed separately indicated the response to the mixture was non-additive. Furthermore, the response to the mixture was determined to be statistically indistinguishable (chi-square analysis) from the dose response curve of one of the mutagens in the majority of cases. This masking effect was found to persist for one strong mutagen (benzo(a)pyrene) even when it composed only 10 percent of the mixture. The effect of various non-toxic solvents on the mutagenic response of certain mutagens was also determined. The present study showed that the choice of solvent (ethanol, methanol, dimethylsulfoxide, p-dioxane) can significantly alter the magnitude of the mutagenic response.; Three-phase microcosms were used to study the aquatic fate and effect of a polycyclic aromatic hydrocarbon (PAH), benz(a)anthracene. In a series of experiments techniques were established for monitoring the behavior and for assessing the biological response to the pollutant. Results indicated that the three-phase microcosms used had limited application in the examination of biological response to chronic, low-dose exposure of non-toxic, relatively insoluble pollutant. On the other hand, the structurally simple microcosm was appropriate for a mass balance determination of the fate of the compound.