Imposex

These pollutants cause female sea snails (marine gastropod molluscs) to develop male sex organs such as a penis and a vas deferens.

[3] Tributyltin is used as an anti-fouling agent for boats which affects females of the species Nucella lapillus (dog whelk), Voluta ebraea (the Hebrew volute),[4] Olivancillaria vesica,[5] Stramonita haemastoma[6] (red-mouthed rock shell) and more than 200 other marine gastropods.

Later stages of imposex lead to sterility and the premature death of the females of reproductive age, which can adversely affect the entire population.

[4] In 1993, Scientists from the Plymouth Marine Laboratory found a thriving dog-whelk population in the Dumpton Gap, near Ramsgate in the UK despite high levels of TBT in the water.

The imposex stages of female dog whelks and other molluscs (including Nucella lima) are used in the United Kingdom and worldwide to monitor levels of tributyltin.