Since the Deepwater Horizon oil rig exploded and sank, vast quantities of dispersant chemicals have been sprayed onto the resulting slick. The chemicals are an attempt to reduce the environmental damage of the oil by helping large globs of oil "disperse" into smaller pieces which are easier for sea-living microbes to break down. But there is a dearth of knowledge about the impact of dispersants, especially if used in the volumes now being applied in the Gulf.