The two million gallons of the chemical used to break up BP’s catastrophic oil spill in the Gulf of Mexico in 2010 may have made the oil more toxic to marine life than it already was. In a study published in the journal Environmental Pollution, the chemical dispersant called Corexit was mixed with oil taken from the BP spill. The chemical cocktail killed and reduced reproduction in rotifers, a tiny creature that forms part of the base of the Gulf food chain.

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“Dispersants are preapproved to help clean up oil spills and are widely used during disasters,” said study leader Roberto-Rico Martinez of the Universidad Autonoma de Aguascalientes in Mexico in a press release. “But we have a poor understanding of their toxicity. Our study indicates the increase in toxicity may have been greatly underestimated following the Macondo well explosion.”

When the oil was combined with the dispersant, the mix became up to 52 times more toxic than the oil alone, according to the study Martinex conducted at Georgia Tech. As little as 2.6 percent of the oil-dispersant mixture in sea water reduced rotifer egg viability by 50 percent. If the toxic soup had the same effect in the wild, it may have reduced the supply of rotifers on the menu for shrimp, crabs and young fish in the estuaries around the Gulf.

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“What remains to be determined is whether the benefits of dispersing the oil by using Corexit are outweighed by the substantial increase in toxicity of the mixture,” said Terry Snell, chair of biology at Georgia Tech, in a press release. “Perhaps we should allow the oil to naturally disperse. It might take longer, but it would have less toxic impact on marine ecosystems.”

Corexit and oil may be toxic to wildlife, but the health effects on humans are not going to be a legal problem for the chemical’s manufacturer, Nalco, which merged with Ecolab Inc. last year.

On November 28, U.S. District Judge Carl Barbier of New Orleans dismissed Nalco from multiple lawsuits filled by plaintiffs who say they were harmed by Corexit, reported the Houston Chronicle.

Ecolab’s stock rose slightly the next day.


The BP Deep Water Horizon disaster’s oil slick just off the Louisiana coast. (NASA Earth Observatory, Wikimedia Commons)

Air force C-130 airplane spraying chemical dispersants on the Gulf of Mexico oil spill in May 2010 (U.S. Air Force Photo by Tech. Sgt. Adrian Cadiz, Wikimedia Commons)