A report issued by the National Academies of Sciences, Engineering, and Medicine concludes that chemical dispersants can be effective in limiting the effects of a major marine oil spill but cautions that knowledge of dispersants’ effects on human health is limited. Dispersants are chemicals that reduce the amount of floating oil by causing the formation of small droplets that become entrained in the water column. The effect of dispersants is to hasten the dilution and dissolution of oil. The report notes that while the health hazards of the primary constituents of oil are well characterized, few studies have examined the potential health hazards of dispersants. Studies of workers who participated in the 2010 Deepwater Horizon oil spill response and cleanup in the Gulf of Mexico were inconclusive regarding the health effects of dispersants, according to NAS, and the studies’ limitations reveal the need to improve the gathering of information about workers’ illnesses and injuries during oil spill responses. The report recommends that this information clearly indicate whether workers were exposed to dispersants. Leaders of responses to and cleanup of future oil spills will need to weigh the potential health effects of dispersants against the known health effects of exposure to oil, the report says.  A free PDF of the report is available from the NAS website.