Skimming operations continue to help mitigate the effects of the Deepwater Horizon/BP oil spill Friday, June 25, 2010. (Credit: U.S. Coast Guard / Petty Officer 3rd Class Jaclyn Young)
According to data from the US Environmental Protection Agency (EPA) around seven million liters of dispersants were used to combat oil pollution in the Gulf of Mexico. Back in October, we reported on a study of the long-term Gulf oil spill effects on coastal marine life. Now, researchers from the Queen’s University at Kingston say that dispersants may not be as harmful to fish as first thought.
Dispersants are chemicals used to break down oil into smaller droplets that will mix more readily with water when oil spills into oceans. Dispersant use was heavily criticized as there were fears that interactions between dispersant and oil would increase the toxicity to marine life. However, while the research found the dispersant alone to be toxic, it wasn’t toxic when it was mixed with the oil.
“The toxicity of dispersed oil could be attributed entirely to the effects of oil, and not to synergistic interactions between dispersant toxicity and oil toxicity,” says Dr. Hodson.
The findings supply a new perspective on the 1.84 million US gallons of dispersant used in the 2010 spill. However, dispersants still need to be used with caution, as they can mean a higher concentration of oil in bodies of water that experience an oil spill.
“While dispersants do not change the toxicity of oil, they can increase the amount of oil mixed into water by 100-fold compared to undispersed oil floating on the surface,” says Dr. Hodson. “The use of dispersants should be restricted to brief applications in open waters where marine life is less abundant.”
This research was originally published online by Environmental Toxicology and Chemistry and was supported by contracts from the Department of Fisheries and Oceans (Canada) and Environment Canada.
Adams J., Sweezey M., & Hodson P.V. (2013). Oil and oil dispersant do not cause synergistic toxicity to fish embryos. Environmental toxicology and chemistry / SETAC PMID: 24115182
