Aquatic ecological risks posed by tributyltin in US surface waters: pre-1989–1997 data

Risks to aquatic life from exposure to tributyltin (TBT) in surface waters were assessed probabilistically using 9 years of monitoring data. Ambient TBT concentrations were compared to acute and chronic effect thresholds to estimate risks for each year, source of TBT, and region. Sources of TBT comprised commercial harbors, shipyards, marinas, and fish/shellfish habitats proximate to these commercial areas. No risks of acute toxicity have been suggested since 1994. Chronic risks have remained highest in marinas compared to other sources, but have declined from a risk involving 25% of the species to one involving 4% of the species in 1997. Risks associated with commercial harbors and shipyards have been similar (4–6%) since 1994. Chronic risks have been 1% in fish and shellfish habitats sampled <1–2 km from TBT sources. Risks in Galveston Bay (1–19%) have been greater than in the other regions ( 9%).