Chemicals used to disperse marine oil slicks may harm corals more than the oil itself does, according to a new study. The finding suggests that chemical dispersants should be used near reefs only as a last resort, when oil approaches a shoreline where it might devastate wildlife and plants for decades.
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2007/08/6985.jpg?resize=300%2C197&ssl=1)
In many cases, authorities first try to clean up oil spills mechanically (SN: 11/18/06, p. 325). If weather conditions are too rough or a slick threatens to wash up on shore, dispersants are usually the next option. Made up of surfactants and solvents, dispersants act as detergents, breaking up oil into droplets that mix into water, scatter with currents, and eventually degrade. However, the dispersed oil droplets readily sink and can lethally contaminate coral.