PCB congener distribution in estuarine water,sediment and fish samples: implications for monitoring programs

Traditional analyses for PCBs in environmental matrices havefocused on commercial Aroclor mixtures with detection limits inthe 100 to 1000 part per trillion range. This approach hasrecently been supplanted by analyses for specific PCB compoundscalled congeners with detection limits less than 0.5 ppt. At thenational level, total PCB determinations based upon selected PCBcongeners typically characterize analyses of surface water,sediment and tissue. These federal efforts rely on a suite of 18to 20 congeners out of a total of 209 congeners to characterizetotal PCB. The present study compares total PCB estimates basedupon this subset of congeners with estimates based upon anexpanded list of 81 congeners from water, sediment and fishtissue collected from the Delaware Estuary.Analytical data from monitoring programs conducted in theDelaware Estuary by the Delaware River Basin Commission, NOAANational Ocean Service, U.S. Army Corps of Engineers and the U.S.Environmental Protection Agency from 1996 to 1998 were evaluated. Total PCB estimates derived from the different sets of congeners,including the adjustment factor of 2.0 used by NOAA, werecompared. This evaluation indicated that differences existbetween total PCB determinations based upon these approaches, andthat these differences vary depending on the matrix analyzed. The bias associated with using a smaller set of PCB congeners,and the implications for risk assessment are discussed.