There is particular concern about certain chemicals that can alter the development and functioning of the endocrine system at very low concentrations and affect reproduction. These chemicals are called “endocrine disruptors.” The first documented examples of endocrine disruption in estuarine environments were in dog whelks and mud snails, caused by the use of tributyltin (TBT) in antifouling paints used on boats. Antifouling paints are applied to boats to prevent algae, barnacles, etc. from attaching themselves to the boats and slowing their movement through the water; fouling can have great effects on the speed of a ship. 

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