#imposex

Tributyltin (TBT) is a highly toxic biocide that has been used extensively to prevent the growth of marine organisms on the hulls of large ships. It is a problem in the aquatic environment because it is extremely toxic to non-target organisms, is linked to immuno-supression and imposex (development of male characteristics in females) in snails and bivalves, and can be persistent.

But as the chemical began to leach off the ships and accumulate in marine environments, especially around shipping ports, scientists started seeing negative effects on aquatic plants and animals.

Shellfish and sea snail populations were hit especially hard. Female whelks, for example, started growing penises and vas deferens (the tubes that directs sperm from the testes). This left the snails sterile—a condition called “imposex.” In Australia in 2004, for example, between 43 and 100 percent of snails studied were found to be imposex.

Even with its ban in 2008, TBT presents a danger to the environment. One of the most problematic aspects of TBT is its accumulation in sediments and its long half life of about 2 years. TBT often bonds to suspended material and sediments to the bottom, where it can remain and be released for up to 30 years.