A Risk Assessment Concerning the Fate and Effects of Tributyltins in the Aquatic Environment

A qualitative assessment of the risk posed by tributyltins (TBT) to the aquatic environment is presented in this paper. It is based on reviews of the literature concerning the aquatic fate and effects of TBT. Sorption to particulate matter and assimilation by aquatic organisms appear to be the most important pathways for removal of TBT from the water column, followed by aerobic metabolism via a variety of organisms, and photolysis. There appears to be minor hydrolysis and volatilization of TBT. TBT is highly toxic to aquatic life, and provisional water quality criteria proposed for this class of chemicals range from 0.064 ppb in saltwater to protect against chronic toxicity to 0.303 ppb in freshwater protecting against acute toxicity. TBT has been shown to reach toxic concentrations in situ in some areas, but decisions concerning effects await answers to questions about bioavailability, duration of exposure, and the spatial dimensions of exposure.