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Push for chemical dispersants hard to explain

March 5, 2014

At the Enbridge Northern Gateway hearings, Living Oceans took a strong stand against the use of chemical dispersants in response to oil spills because they are toxic to certain marine life. However, both the Kinder Morgan TransMountain Pipeline application and the federal government’s recent Tanker Safety Report advocate their use.

Karen Wristen

“This push to use dispersants is hard to explain,” said Karen Wristen, Executive Director of Living Oceans. “There’s a growing body of evidence that the dispersant/oil mix is more toxic than the oil itself.”

Toxic effects from oil dispersed into the deeper levels of the ocean have been observed in fish, shellfish and dolphins. Humans exposed to dispersants during spill response have also suffered illnesses ranging from skin and respiratory irritation through to serious central nervous system disorders.

The idea behind using chemicals to break up an oil spill on the surface of the water is the protection of shorelines, seabirds and marine mammals; however, this protection comes at the cost of the life or health of other creatures living in the water column or on the ocean floor. Studies following the Exxon Valdez spill have now established that the oil/dispersant mix becomes more bioavailable to some species and is adept at holding highly toxic, heavy PAHs (polycyclic aromatic hydrocarbons) in the water column. Salmon and herring are particularly vulnerable to these PAHs, which are linked with long-term genetic damage.

“Dispersants are used because they make the oil appear to ‘go away’, which is good for public relations and restoring public confidence in tourism and seafood,” said Wristen. “No more oiled birds and otter pups—people are far less sympathetic toward zooplankton and sturgeon, and it’s harder for the TV cameras to capture impacts below the water’s surface.”

Based on the science that exists today, it is difficult to foresee a situation where dispersants would create a better result than mechanical or natural processes. It is also unclear that dispersants could be applied effectively to spills of tarsands diluted bitmen: oil must be on the surface of the water and able to mix with the dispersant in order for it to do any good.

Living Oceans’ evidence at the Northern Gateway hearings directly critiqued Enbridge’s studies, finding that for much of the year, conditions would not be right for using dispersants in any event.

“So many factors have to line up for these chemicals to do their job,” said Wristen. “Wind, temperature, wave height and the time oil has spent on the water all play a role in determining whether or not dispersants can work. We found that over half the time, wind conditions alone would prevent dispersants from being used.”

Weather buoy locations showing wind conditions.

Weather buoy locations showing wind conditions that make dispersant response possible.

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