Concentration and distribution of butyltin compounds in a heavy tanker route in the strait of Malacca and in Tokyo Bay

The distribution of butyltins was investigated in seawater at 20 stations (n=69) along the tanker route in the Strait of Malacca and in Tokyo Bay, areas of potential release of toxic organotin compounds to the aquatic environment from large vessels coated with antifouling paints containing tributyltin (TBT) compounds. Relatively high concentrations of butyltins were observed along the Strait of Malacca and Tokyo Bay, high enough to cause deleterious effects on aquatic organisms, such as imposex in gastropods. The high ratio of TBT/dibutyltin (DBT) observed in the Strait of Malacca suggests that recent inputs of TBT have occurred there. Lower ratios were observed in Tokyo Bay. The present study suggested that the release of TBT from large vessels is the major source of butyltins in seawater.