7. Current Status of Contamination by Organotins and Imposex in Prosobranch Gastropods in Korea

Organotin compounds are considered to be dangerous chemicals because of their deleterious effects on non-target marine organisms. In 2003, the use of TBT-based antifouling paints was totally banned in Korea, and the International Maritime Organization (IMO) proposed to extend the ban to almost all ocean-going vessels. In this study, the concentrations of organotins in the coastal environment are analyzed to illustrate the differences of these analyzed items in the periods before and after the IMO and Korean regulations, focusing on organotins concentrations in molluscan soft tissues and the imposex phenomenon in the rock shell (Thais clavigera), a gastropod species sensitive to organotin compounds, collected from the Korean coasts from 1995 to 1997 and 2002, and from 2005 to 2009. TBT and TPhT were dominant organotins. Higher organotin concentrations were observed in areas with frequent shipping activities, including regions adjacent to harbors or shipyards, than in areas away from shipping activities. Concentrations of TBT, TPhT, and their metabolites in tissue, imposex frequency, and relative penis length index and sterility ratio of rock shell specimens collected from the southern coast after the regulations for TBT- and/or TPhT-based antifouling paints were in place showed lower values than those before the regulations. Because of the continued occurrence of imposex in the rock shell populations after the regulations were established, it is necessary to carry out further studies to monitor organotin concentrations in tissues and imposex frequency of rock shell specimens along with evaluations of the organotins residues in seawater and sediment in Korean coastal areas.