Tributyltin in Dutch marinas, 1990-2001
The levels of tributyltin in marinas have fallen faster in recent years but they are still higher than the Maximum Allowable Concentration.
Sharp fall in levels of tributyltin in marinas
Tributyltin (TBT) levels have fallen faster in recent years. Levels were so low at three of the six monitoring sites that it was not possible to measure any TBT (less than 3 ng/l). Nevertheless, the maximum allowable concentration (MAC) may have been exceeded, because the MAC is 1 ng/l. The MAC was certainly exceeded at the other three monitoring sites.
The highest concentrations in 2001 were measured in Scharrendijke (17 ng/l) and Harlingen (16 ng/l).
Tributyltin policy
The Maximum Allowable Concentration (MAC) for this substance is 1 ng/l. Since 1990, the use of paints containing TBT has been banned for boats less than 25 metres long. From 2003 onwards, it must not be used on longer vessels either.
Relevance
TBT is a substance used in antifouling paints on ships. It is released slowly from the sides of ships and it is toxic even in low concentrations. It also has an effect on organisms and in locations for which it is not intended. The most sensitive organisms are two salt-water organisms; that is why only salt-water marinas are shown here.
