Regional Comparisons of Coastal Sediment Contamination Detected by a Biomarker (P450 HRGS; EPA Method 4425)

Pollution investigations by the Center for Coastal Monitoring and Assessment of the National Oceanic and Atmospheric Administration (NOAA) have been conducted since 1984 and have incorporated extensive biological and chemical analyses. Since 1993, one of the biological tests utilized in these studies has been the biomarker P450HRGS, which is more recently described as EPA Method 4425. Extracts of sediments are applied to a human cell line with a reporter gene (firefly luciferase) at the CYP1A1 site. Light produced by the extracts is a function of the concentrations and potencies of those compounds with an affinity for Ah-receptor (certain polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and dioxins/furans). These compounds are carcinogenic and can produce chronic toxicity, and those containing chlorine are persistent and bioaccumulated. Nineteen coastal regions and 1309 samples from the three U.S. coasts have been evaluated as part of the NOAA investigations. The stratified random sampling approach used by NOAA provides estimates of the areas (km2) of each region containing levels of the compounds above thresholds. From analysis of the database, sediments with concentrations at or below 11 μg benzo[a]pyrene equivalents (B[a]PEq)/g would not be expected to produce effects on the benthos. At 32 μg B[a]PEq/g and above there is the potential for impacts on the biota, and above 60 μg/g, the degradation of the benthic community has been observed. Several of the regional surveys found no samples at or above 60 μg B[a]PEq/g, but 60% of the samples from New York Harbor (280 km2) were above this level. Analyses of data from Puget Sound and Chesapeake Bay demonstrate an increase in samples above 32 μg B[a]PEq/g in more populated and industrial regions. Method 4425 serves as both a biomarker, simulating the response of an organism (with CYP1A) exposed to inducing compounds, and as a bioanalytical technique measuring the levels of these chemicals in the samples. A targeted investigation of the distribution of the three important classes of compounds identified by Method 4425 would be more cost-effective by first screening samples by this method before expending substantial funds in the detailed chemical analysis of all samples.