USE OF HISTORICAL PCB AROCLOR MEASUREMENTS - HUDSON RIVER FISH DATA

Modern analytical techniques allow the resolution of most individual p olychlorinated biphenyl (PCB) congeners; however, analysis of long-ter m trends in concentration and calibration of environmental fate and tr ansport models often must rely on older, packed-column quantitations a gainst Aroclor standards. These quantitations were often based on a li mited set of chromatogram peaks, and methods may have changed over tim e. It is essential to be wary of false signals in the historical recor d resulting from changes in analytical schemes. Using an extensive dat abase of historical packed-column quantitations relative to Aroclor st andards in Hudson River fish, coupled with recent capillary-column qua ntitations of PCB congeners, we demonstrate that certain apparent chan ges in the historical record of PCB Aroclor concentrations are, in fac t, partly attributable to changes in quantitation methods. We then off er techniques to ''translate'' reported Aroclor concentrations to a si ngle, consistent basis. These corrections are essential to a valid int erpretation of the historical record of PCB contamination in the Hudso n River.