Distribution of cytochrome P4501A1-inducing chemicals in sediments of the Delaware River-Bay system, USA.

The Delaware River-Bay system, USA, was the subject of a study by the National Oceanic and Atmospheric Administration that involved chemical and biological analyses, including the use of the biomarker P450 human reporter gene system (HRGS) to document the occurrence and distribution of cytochrome P450 (CYP) 1A1-inducing compounds. Sediment extracts from 81 locations along the Delaware River, Delaware Bay and immediate coastline were tested by utilizing HRGS as an inexpensive screening test, and were also analyzed for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls, with selected stations analyzed for dioxins and furans. Benthic community degradation has been observed when benzo[a]pyrene equivalents (BaPEq) exceeded 60 microg/g. The average levels of BaPEq for the largely industrialized upper, middle, and lower regions of the Delaware River were 107, 62, and 5 microg/g, respectively, excluding outliers. Tributaries leading into river averaged 21 microg/g BaPEq, whereas the central Bay and open coast had relatively low values (2.0 and 0.5 microg/g BaPEq, respectively). The HRGS values were highly correlated with total PAHs measured in the same sediment samples (r2 = 0.81). Overall, contamination levels consistently decreased from the upper and middle river sites as collection locations progressed down through the lower river and bay to the coast. Thus, despite the relatively high contaminant load in the river system, Delaware Bay and the immediate coastline seem to have relatively low levels of contaminants, and, therefore, impacts on the benthic organisms in the bay and coast would not be expected from these findings.