Recently an unusually high number of dolphins have been found dead of infectious diseases, and most of these had abnormally high tissue concentrations of certain compounds that, even in low concentrations, reduce dolphins' resistance to infection  The only source of these compounds in the dolphins' environment is boat paint
Ttherefore, since dolphins rid their bodies of the compounds rapidly once exposure ceases, their mortality rate should decline rapidly if such boat paints are banned
The compounds break down into harmless substances after a few months of exposure to water or air.