Accumulation of butyltin compounds in finless porpoises (Neophocaena asiaeorientalis) from Korean coast: Tracking the effectiveness of TBT regulation over time

► BTs were detected in all livers of finless porpoises from Korean coastal waters. ► BT levels in porpoises were generally greater than the threshold value. ► Significant age-dependent accumulation of BTs was found. ► BT levels decreased between the sampling years of 2003 and 2010. ► The effectiveness on TBT ban has reached to marine mammals in Korean coastal waters.