A Nova Scotia scientist who is being sent to study the cleanup of a massive U.S. oil spill says the effect on fish of chemical dispersants being used to break down the oil remains largely unknown, despite their low toxicity.
"I tell people low toxicity is not no toxicity," said Kenneth Lee, executive director of the Centre for Offshore Oil and Gas Research for Fisheries and Oceans Canada.
"We're still looking at the science of what are the effects of dispersants. And we're not only looking at the effects of whether it kills the fish, we're looking at what does it do to the health of the fish."
Lee and two other experts from the Bedford Institute of Oceanography, a federal research facility in Halifax, were scheduled to arrive Thursday in Louisiana to begin assessing the efficiency and safety of cleanup methods. Lee was unsure how long the team would be in the U.S.
A blown-out well has been spewing hundreds of thousands of litres a day into the Gulf of Mexico since an offshore drilling rig exploded and sank last month.
Lee, who's been studying cleanup and habitat recovery for nearly three decades, said this spill presents a challenge because the oil is mixing with sea water at the surface and becoming thick.
"This type of material may have the consistency of something like mayonnaise, it's very difficult to clean up," he told reporters a couple of hours before catching a flight to New Orleans.
Lee said the team will study the use of chemical oil dispersants in the Gulf, which he likened to a dishwashing detergent.
Dispersants break down an oil slick into tiny droplets in hopes of diluting it with tides and currents.
"You actually dilute the concentration of oil so low that it's below the level where you have toxic effects," he said.
Dispersants also keep diluted oil away from shores and help protect sea birds by getting the oil slick off the sea surface.
Experts have had success in the Gulf with applying dispersants on the surface, said Lee.
Now they're looking at injecting dispersants at the origin of the leak before the oil has a chance to mix with water.
Lee's team will measure the effectiveness of the sub-surface injection and find out where the dispersed oil is going.
While the use of dispersants isn't new, Lee said they have become more effective when used to clean up thicker oil.
He said the Bedford Institute is also researching how to speed up the process of using bacteria found in the ocean to break down oil naturally.