Oil Spill Clean-up and Chemical Dispersants: Does the Good Outweigh the Bad?

Stephen R. Humphrey, "Chemical Dispersants and Crude Oil - Efficacy and Toxicity," The Oil Drum, 7/14/2010.

"In the case of oil released underwater, dispersant reduces the amount of oil surfacing, hence reducing danger and toxicity for the topside workers trying to repair the damaged well and contain the spill. It also increases surface area and time for oil-droplet exposure to microorganisms in the water column. The microbes digest the oil into simpler and much less harmful chemicals."

"More than 200 genera of bacteria, cyanobacteria, fungi, and algae are known to degrade or transform hydrocarbons, using them for energy and carbon."

"The US National Research Council issued a report on dispersants in 2005. The report succinctly noted the tradeoffs involved in dispersant use: 'Dispersant application thus represents a conscious decision to increase the hydrocarbon load (resulting from a spill) on one component of the ecosystem (e.g., the water column) while reducing the load on another (e.g., coastal wetland). Decisions to use dispersants, therefore, involve trade-offs between decreasing the risk to water surface and shoreline habitats while increasing the potential risk to organisms in the water column and on the seafloor.'"

"Prolonging spilled crude oil's exposure to offshore sea life increases environmental harms in ways we don't understand very well, and these harms are probably much worse than we know. In my opinion there's no silver lining among the tradeoffs, only trading off one bad against other bads.

It’s remarkable to me how much people have discussed toxicity of dispersants, and how little people have discussed the toxicity of crude oil, which is high for people and many other organisms. We definitely need to learn whether dispersant allows the oil to degrade fast enough and in large enough quantities to offset damage done by spreading the oil through more of the environment for longer. But we also need a comparable public discussion of the toxicity of the oil to people, to habitats and animals along the shore, and to the myriad creatures of the Gulf of Mexico."

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