Tributyltin contamination around an oil terminal in Sullom Voe (Shetland)

This report provides clear evidence of tributyltin (TBT) contamination of coastal waters close to an oil terminal handling large tankers. Dogwhelk populations from Sullom Voe, Shetland, have been examined for the development by females of certain male sexual characteristics (e.g. a penis and vas deferens). This condition, termed imposex, is a response to exposure to tributylin compounds, and can be quantified by use of the relative penis size index (RPSI). Dogwhelk populations throughout Sullom Voe were strongly affected by TBT (RPSI 34 to 81%), and up to 90% of the females in the oil terminal area were sterile. Queen scallops collected in the Voe contained enhanced concentrations of tin in adductor muscle and gonad tissue (0.02 to 0.23 mg kg(-1) wet weight), but it is considered unlikely that their growth and development is adversely affected. Tin was rarely detected in scallops, queens, or dogwhelks outside the Voe, although the development of a vas deferens in many of the female dogwhelks indicated a degree of contamination of the open waters of Yell Sound. TBT was detectable (2 ng litre(-1) as tin) in only two sea water samples taken from the terminal area.