Gastropods endocrine disruption

Returning to the question of endocrine disruption, it is now known that over 100 species of gastropods worldwide suffer from a condition described as imposex, the development of male characteristics by females. It has already been established for some species (e.g., dog whelk) that TBT is the cause of this, and it is suspected that organotin compounds account for most cases of imposex worldwide (Matthiessen and Gibbs 1998). Some examples of masculinization of female gastropods caused by tributyltin are given in Table 8.4. 

Aqueous and sedimentary TBT and TFT cause chronic and acute effects in algae, zooplankton, Crustacea, mollusks, fish, and animals. These effects have been local in nature, occurring mostly in harbors near industrialized lands. TBT is bioaccumulated in many species, which is unfortunate as it is a potent endocrine disrupter. The enrichment factor in mussels, snails, and oysters ranges from 10,000 to 60,000. As mentioned in Section 28.7.1, TBT induces imposex in marine gastropods. 

Chapter 5 illustrates a site-specific impact assessment of TBT originating from antifouling paint and present in marine as well as harbour sediments. TBT is an endocrine-disrupting chemical and extremely toxic to marine life such as gastropod species where it causes intersex and population decline. 

Tributyltin (TBT) is one of the best-studied endocrine disrupting compounds in invertebrates (Oberdorster and Cheek 2000). Concentrations as low as 1 ng/1 of TBT can lead to the development of male sex organs in female snails. This imposex response has been identified in approximately 150 species of gastropods and is clearly due to an interference with some part of the molluskan endocrine system. The toxicity of TBT to gastopods has caused its regulation. 

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