A BIOMARKER APPROACH TO ASSESSING XENOBIOTIC EXPOSURE IN ATLANTIC TOMCOD FROM THE NORTH-AMERICAN ATLANTIC COAST

We determined levels of hepatic cytochrome P4501A (CYP1A) mRNA, hepati c DNA adducts, and fluorescent aromatic compounds (FACs) in bile, a me asure of exposure to polyaromatic hydrocarbons, in Atlantic tomcod fro m six river systems ranging from highly polluted to relatively pristin e on the northeast North American coast (the Hudson River, New York; t he St. lawrence River, Quebec; the Miramichi River, New Brunswick; the Saco and Royal rivers, Maine; and the Margaree River, Nova Scotia). H udson River tomcod showed the greatest response for all parameters, an d tomcod from the Margaree River exhibited the least response. Tomcod from the Miramichi River exhibited marked induction of CYP1A mRNA but low levels of hepatic DNA adducts and biliary FACs, whereas fish from the St. Lawrence River showed no induction of CYP1A mrna and moderatel y elevated levels of DNA adducts and biliary FACs. In tomcod from the Hudson and Miramichi rivers, the levels of CYP1A mRNA were 28 times an d 14 times, respectively, as great as the levels in fish from the St. Lawrence, Saco/Royal, and Margaree rivers. Mean levels of DNA adducts varied from 120 nmol adducts/mol bases in hudson river tomcod to < 3 n mol adducts/mol bases in fish from the Miramichi and Margaree rivers. Concentrations of FACs in the bile of tomcod from the Hudson and St. L awrence rivers were 8 and 1.8 times, respectively, as great as the con centrations in tomcod from the Miramichi River and Margaree River. In tomcod from the Hudson River, all three biomarkers were markedly eleva ted; in the St Lawrence River two biomarkers were elevated, but no bio marker was substantially elevated in fish from the Saco/Royal and Marg aree rivers. Elevated levels of hepatic DNA adducts and biliary FACs i n tomcod from the Hudson River suggest increased exposure to PAHs, con sistent with previous studies.