« Return to this article

Know the West

Dispersing the toxicity


It's every coastal community's nightmare. An off-shore oil rig explodes, a tanker runs aground, and the name of their town -- Homer, Alaska, say -- becomes synonymous with the latest disaster of our oil-besotted age.

When such a disaster does happen, oil spill responders are faced with many choices about how to contain the spill and clean it up. In the Deepwater Horizon blowout, BP chose to apply chemical dispersants to break up the oil gushing out into the Gulf of Mexico.

Yet as a recent study in the journal Environmental Pollution reported, this dispersant, Corexit 9500A, when mixed with oil, made the oil it dispersed 52 times more toxic to a small marine organism called a rotifer, which is a key food source for many larger organisms in the ocean, including shrimp and crabs. While the effects of the dispersant are still playing out in the Gulf, researchers believe the loss of "fish food" could ripple up the marine food chain.


But the fact remains -- as long as we use oil, there will be spills, and we'll need ways to mop them up. This study, however, highlights the fact that the methods used to control oil spills can have their own negative impacts. Many coastal communities are worried that those impacts are understudied and underweighted when companies make decisions about how to respond to spills.

That's why, in 2010, Cook Inletkeeper, Alaska Community Action on Toxics, and other environmental nonprofits, along with Earthjustice, notified the EPA of their intent to sue the agency for its failure to properly evaluate the effects of dispersants, including testing their toxicity in coastal environments.

These communities know that use of dispersants, which break oil up into small droplets, is basically a tradeoff between protecting some animals and some parts of ecosystems versus possibly harming organisms sensitive to dispersants' effects.  Bob Shavelson, of Cook Inletkeeper, in Homer, puts it this way: "Industry would prefer (the oil) out of sight and out of mind…they just don't want bad public relations with oiled seals or birds on the front page of the newspaper."

The extent of that tradeoff, though, has not been quantified by the EPA. If it were known, these groups argue, oil spill responders might make different decisions about how to clean up after a disaster.

Dispersants, though understandably popular, aren't always a must-use option. Oil spill responders can plug leaks and use mechanical controls to sweep up spilled oil. They can wait and let oil naturally disperse. A lot of dispersants' effectiveness also depends on environmental conditions, like what type of oil was spilled, the wave height, amount and type of dispersant used, and salt content of the water the oil was spilled in. In some cases, depending on the type of oil spilled and the local ecology, dispersants might not be the best choice.

As Earthjustice attorney Hannah Chang explained to me, the Clean Water Act requires EPA to keep something called a product schedule that lists the chemical dispersants allowed to be used on oil spills. The schedule is also supposed to list the specific waters dispersants can be used in, and the quantity allowed to be used, in hopes of limiting toxic spillover effects like the one in the Gulf. To date, though, the EPA hasn't updated the schedule to do that. So, in August 2012, after waiting for EPA to respond to their notice for two years, the groups filed a formal lawsuit to force the EPA to evaluate the toxicity of these chemicals, in what quantity they should be used, and where they are appropriate.

The lawsuit is still ongoing. On its website, EPA says it plans to release a revised rule that includes evaluation of dispersant effectiveness and toxicity testing this month.

While he waits for the agency to do this, Cook Inletkeeper's Shavelson is nervously watching "a new wave of oil and gas drilling" in his neck of the woods. He hopes the EPA clarifies the potential harms and approved uses of dispersants before there's another spill in Alaska. He also points out, of course, that oil companies, particularly those renewing their efforts to drill in Arctic waters, should be focusing on prevention and safe drilling as a top priority:

"The first thing you should do is not spill the oil."

Stephanie Paige Ogburn is the online editor at High Country News.

Image of spilled oil on an Alabama beach courtesy Shutterstock.

Image of bird killed by oil spill courtesy Shutterstock.