Integration of in vitro and in vivo bioassays for assessing the toxicity of complex PAH mixtures in freshwater sediments

Polycyclic aromatic hydrocarbon (PAH) mixtures are ubiquitous marine and freshwater sediment contaminants. However, little information is available that defines the toxicity, bioavailability, and bioaccumulation potential of sediment PAH mixtures to benthic and aquatic organisms. This research investigated an integrated triad approach, using chemical analyses and a battery of in vitro bioassays and in vivo biomarkers, to characterize the bioavailability and hazard of a complex PAH mixture in freshwater lake sediments adjacent to a former manufactured gas plant (MGP) facility.; The in vitro toxicity of sediment PAHs to benthic organisms was evaluated using Chironomus tentans, Hyalella azteca, and Vibrio fischeri. Genotoxicity of sediment PAHs was evaluated using the Salmonella/microsome assay. Substantial mortality (>90%) and growth inhibition were observed in the infaunal C. tentans, but the epifaunal H. azteca, and V. fischeri were relatively insensitive to sediment PAHs. Sediments from a nearby freshwater reference lake were negative in Salmonella , although 76% of MGP site lake sediments induced a positive genotoxic response in Salmonella. Sediment PAH concentrations were not correlated with in vitro benthic organism responses, but were correlated with Salmonella/microsome assay genotoxicity. Chemical characterization, and several of the in vitro bioassays, were useful in identifying contaminants of concern and impacted sediments, but could not be used alone in a successful in situ biomonitoring program.; The in vivo genotoxicity and bioavailability of sediment PAHs were assessed by flow cytometry, DNA adduct 32P-postlabeling, and erythrocyte micronuclei biomarkers in juvenile coho salmon (Oncorhynchus kisutch) caged in the water column. Significant PAH-induced genotoxicity was observed with flow cytometry and DNA adduct 32P-postlabeling, but not with erythrocyte micronuclei. Flow cytometry and DNA adduct levels are sensitive in vivo biomarkers and measures of sediment PAH genotoxicity in coho salmon.; An integrated triad protocol using chemical analyses, in vitro bioassays, and in vivo biomarkers would be useful in an in situ biomonitoring program for assessing sediment ecotoxicity: Future research should focus on this triad approach using selected in vitro bioassays and in situ studies with caged and feral species. This protocol has merit and implicated sediment PAHs as genotoxins in a salmon population.