Weight of evidence assessment of brown bullhead liver tumours in Canadian waters of the Detroit Rive

Session: Poster Session

Ken Drouillard, University of Windsor, Great Lakes Institute for Environmental Research, [email protected]
Mark McMaster, Environment and Climate Change Canada, [email protected]

Abstract

Liver tumours in brown bullheads from Canadian waters of the Detroit River were evaluated.  One hundred and fifty fish above age 3 were submitted for histopathology. Collections occurred in 2002 and 2016 across three locations: Peche Island (PI), Turkey Creek (TC) and Boise Blanc (BB).  One fish from BB (2002) contained a biliary neoplasm. Given that only 20 fish were collected at BB in 2002, this yielded a site- and time specific tumor frequency of 5%. A weight of evidence approach (WOE) was used to justify pooling fish across sites and years. Sediment chemistry studies indicated ?PAHs were significantly lower (p<0.001; ANOVA) at PI, but not different between TC and BB. There were no differences in sediment PAHs with time. Sediment PAHs were strongly correlated with PCBs indicating PCBs could be used as a surrogate measure of sediment exposures by fish. Bullhead PCBs, in contrast to sediments, showed no differences between locations. WOE exposure assessment indicated bullheads could be pooled between TC and BB and across time but were mixed for inclusion of PI fish. The combined TC and BB samples from 2002-2016 included 106 fish aged 3-12 years with a tumour frequency of 0.94%, less than the benchmark.