Says Dr. A Murugan, Senior Lecturer of Suganthi Devadson Marine Research Institute, Tuticorin: "The paints are usually used to curb attachment of fungi, bacteria and other organisms to the submerged hulls of ship.
"The toxic effect of paints containing biocide like Tributyltin (TBT) has been well established. It is considered as the most toxic compound ever deliberately introduced into the natural environment", he warns. "Tributyltin an endocrine disruptor in mollusks, causes imposex universally at very low concentrations. Imposex is prevalent in places close to ports, shipyards and mariculture facilities where TBT is used in these paints," he adds.
At the same time, Murugan says that monitoring of occurrence of imposex along Southern coast of India has been carried out under the Ministry of Environment and Forests funded projects.
Imposex, in India has been recorded in molluscs like Cronia konkanensis from Marmagoa harbor, Thais and Ocenebra species from Gujarat on the west coast and Thais biserialis and Chicoreus virgineus from Tuticorin harbour on the east coast, says Murugan.
Imposex has also been recorded in seashells like Babylonia spirata, Babyloni zeylanica, mollusks like Chicoreus virgineus, shells like Thais bufo, Hemifusus pugilinus and Lambis lambis along Chennai, Valinokkam and Tuticorin areas of Tamil Nadu coast. Murugan explains that imposex has been reported in over 118 species in 63 genera of marine life worldwide.
What are the consequences of imposex? In extreme cases, the development of male sexual characters in female snails can lead to the genital pore being closed. This brings about sterility in females and at times premature mortality due to rupture of the capsule gland.
Yet Dr. Murugan sounds hopeful as he says:" In view of the threat to the marine environment, the International Maritime Organization (IMO) has proposed phasing out of TBT by 2008."