DETERMINATION OF MUTAGENICITY IN SEDIMENTS OF THE ABERJONA WATERSHED USING HUMAN LYMPHOBLAST AND SALMONELLA-TYPHIMURIUM MUTATION ASSAYS

Organic and inorganic chemical wastes from tanneries and insecticide and other industries have been released into the Aberjona watershed in eastern Massachusetts since before the midnineteenth century. In recent studies of the environmental fate of these waste chemicals, it has been shown that sediments in many parts of the watershed contain high concentrations of toxic metals and organic pollutants. We were concerned that exposure to these or other as yet uncharacterized pollutants in sediments might pose risks to human health. Thus, we collected 32 surface sediment samples downstream of major stream forks, from sediment deposition areas, and near known hazardous waste sites and tested their ability to mutate the bacterium Salmonella typhimurium and human lymphoblastoid cells. Dichloromethane-methanol extracts of 20 of the 32 samples were mutagenic to the bacteria, but only two were mutagenic to the human cells. This general lack of correlation between the two species' responses is consistent with wide differences in sensitivities we have observed with pure chemical mutagens. We note with interest, however, that sediment mutagenicity was not significantly correlated with proximity to known hazardous waste sites, to present or former industrial sites, or with toxic metals concentrations. This may reflect either basin-wide redistribution of mutagenic chemicals or an origin not associated with identified industrial releases. The discovery of a potent mutagenic mixture in large quantity permits us to continue our study with the goal of identifying the primary mutagens, locating their sources, and evaluating the risks to human health.