SENSITIVITY OF CYTOCHROME-P450-1A1 INDUCTION IN FISH AS A BIOMARKER FOR DISTRIBUTION OF TCDD AND TCDF IN THE WILLAMETTE RIVER, OREGON

The sensitivity of a biomarker for environmental contamination with pe rsistent organochlorines and PAHs (cytochrome P450-1A1 induction in fe ral fish) was evaluated at six sites along 314 km of the Willamette Ri ver, Oregon. Whole-body contamination of Northern squaw-fish with appr oximately 2 pg/g of TCDD and 20 pg/g of TCDF in Portland Harbor was si gnificantly higher than upstream sites. Carp muscle TCDF and hepatic b iomarker response were also elevated at this site, as were sediment TC DD, TCDF, and PAHs concentrations. In July, cutthroat trout TCDD conce ntrations above and below a bleached kraft pulp mill were similar. In October cutthroat trout below the mill contained about 2-fold more TCD D than fish upstream. Similar hepatic biomarker profiles occurred in c utthroat trout above and below the mill at both times. Histopathologic al examination suggested existing organochlorine burdens in adult Will amette River fish were not overtly toxic at any site.