Nearly five years have passed since the explosion of the Deepwater Horizon oil rig set off one of the largest oil-spill disasters in U.S. history. The April 2010 blast killed 11 workers and discharged millions of gallons of oil into the Gulf of Mexico. In response to the spill, about 750,000 gal of dispersants were injected underwater into oil gushing from the well. Another 1 million gal were sprayed from airplanes onto oil slicks.
A mixture of surfactants and solvents, dispersants break oil into smaller droplets that microbes are able to degrade. They’re used to minimize harm to natural resources from oil spills. But after the disaster in the Gulf, scientists, environmental activists, and others raised questions about the efficacy and ecological impact of pouring more than a million gallons of dispersants into water.
“For a lot of people, the idea of adding more chemicals to an already big chemical spill is probably counterintuitive,” says Christopher M. Reddy, a marine geochemist at Woods Hole Oceanographic Institution. In presentations and discussions that he’s had since the accident, Reddy has gotten more questions about dispersants than about the oil in the Gulf spill, he adds.
To answer some of these queries, the Environmental Protection Agency is proposing to require manufacturers to provide more detailed information about their dispersant products.
EPA’s proposal would revise its existing regulation on the use of dispersants and other chemical and biological agents on oil spills in U.S. waters. It would require manufacturers to provide detailed toxicity and efficacy data for any dispersant that the agency deems acceptable for use on oil spills. The proposal under the Oil Pollution Act of 1990 also would clarify the criteria EPA will use when adding products to its list of acceptable dispersants. The agency says it hopes the proposed changes will create an incentive for the development of dispersant products that are less toxic.
In addition, the proposed rule would require manufacturers of dispersants to supply comprehensive instructions for dispersant use by emergency responders. It also would require monitoring when dispersants are used on major spills.
While chemical industry trade groups say they are reviewing the proposal, which was issued in January, environmental groups are applauding EPA’s move.
“We’re glad to see the EPA taking this problem seriously,” says Miyoko Sakashita, a program director at the Center for Biological Diversity. “We’ve got to step back and fully understand what happens when we release these chemicals into our waters. Otherwise we’re just adding insult to injury during an oil spill.”
Three environmental groups, including the Center for Biological Diversity, sued EPA and the U.S. Coast Guard in 2012 for authorizing the use of dispersants in U.S. waters without knowing the effects on endangered wildlife. In a 2013 settlement filed in federal court, EPA agreed to further investigate the safety of oil dispersants. The proposed regulatory change stems in part from that suit.