By Janet Raloff
From New Orleans, at a meeting of the Society of Toxicology
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2005/03/4887.jpg?resize=150%2C67&ssl=1)
Ocean corals around the world are ill or dead for reasons that remain mysterious. One of the first signs of sickness is bleaching, in which reef-building animals lose the symbiotic algae that give them color and nutrients (SN: 1/30/99, p. 72: https://www.sciencenews.org/pages/sn_arc99/1_30_99/bob1.htm). New laboratory experiments indicate that one contributor to coral decline may be the paint additive tributyl tin (TBT).