Toxic Mist Unintended Dispersant Effect

Wednesday, March 21, 2018 @ 11:03 AM gHale

Dispersant chemicals used to clean up oil spills have the unintended effect of transforming crude oil into a toxic mist able to travel for miles and penetrate deep into human lungs, new research has found.

Dispersants used during the 2010 Deepwater Horizon disaster in the Gulf of Mexico and other large spills break down oil into particles so small they can easily take to the air, according to a study by Johns Hopkins University in Baltimore.

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Just agitate the oil-dispersant mixture with wind, some waves, or raindrops and the ultrafine particles can become airborne, researchers said.

“Once in the air they don’t come down easily, and they can travel quite far,” said Nima Afshar-Mohajer, an environmental health researcher with Johns Hopkins and the study’s lead author in a published report on NOLA.com. “Depending on wind directions, they can easily travel 50 miles away.”

If inhaled, the compounds – some of which can cause cancer – are drawn to the innermost parts of the lungs where they are quickly absorbed into the body. 

“The dispersant continues to disperse the crude oil in the lungs, and that helps the crude oil absorb into the cells,” said Afshar-Mohajer, whose research was published in the journal Atmospheric Environment last month.

BP, who used dispersants after the 2010 disaster, did not respond to requests for comment on the study.

The Deepwater Horizon oil rig was 41 miles off Louisiana’s coast when it spewed 200 million gallons of oil into the Gulf after an explosion that killed 11 and injured 17 workers. BP used two types of dispersant to break up the oil: Corexit 9500 and Corexit 9527, both manufactured by Nalco Environmental Solutions. About 770,000 gallons of dispersant injected directly into the damaged wellhead about a mile under water. BP sprayed another 1 million gallons on the massive slick on the water’s surface. Thousands of cleanup workers, Coast Guard members and coastal residents could have been within the potential range of airborne oil particles. 
The Johns Hopkins study didn’t investigate the toxicity of dispersants, only how dispersants amplify the spread of oil’s toxic compounds. Corexit’s ingredients are a trade secret, making testing difficult, Afshar-Mohajer said.

Afshar-Mohajar conducted his research with laboratory wave tanks filled with saltwater. Various wave types were simulated with Louisiana crude oil and Corexit dispersants on the water’s surface. Aerosol sensors measured and identified air particles inside the tank.
 
When dispersants were added, the concentration of airborne oil particles increased 10 to 100 times, Afshar-Mohajar found. 
 
He noted that airborne particles are different from the gases released by oil, which are also toxic.

Dispersants are designed to work much like dish soap on grease. They loosen the tension between oil and water, allowing the oil to break up into smaller droplets.



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