Butyltins in shellfish, finfish, water and sediment from the Coos Bay estuary (Oregon, USA)

Butyltin was measured in tissue, water and sediment samples collected throughout Coos Bay estuary between 1986 and 1997. Butyltin-induced shell deformation in commercial oysters prompted this assessment. Butyltins are released from tributyltin oxide (TBTO)-containing boat paint. Clams from three sites contained tributyltin (TBT) levels ranging from 168 to 457 μg/kg in 1992–1994. Consequently, Oregon Health Division (OHD) issued a shellfish consumption advisory in 1995; it was rescinded in 1997 after US Environmental Protection Agency (EPA) revised the TBTO oral reference dose (RfD). The revised RfD changed the tissue screening level from 112 to 1120 μg TBT/kg. Fifty percent of sediment samples collected during 1991–1997 and analyzed for total butyltins (TotBT) exceeded the Puget Sound Dredge Disposal Analysis Screening Level (PSDDA SL) of 73 μg TBT/kg dw. TotBT at three shipyards selected for site assessment by EPA ranged from 24 to 68,613 μg/kg dw. Sediment and tissue butyltins have been decreasing in all but one area of the estuary.