Canada's Department of Fisheries and Oceans says it will try again to secure samples of an oil spill dispersant for testing by government-funded researchers after the American manufacturer refused two requests in 2016.

The impasse surrounds research by fish biologist Craig Purchase of Memorial University of Newfoundland in St. John's.

Purchase was working on a $75,000 project funded by DFO comparing two types of oil dispersant products called Corexit on beach-spawning capelin.

Manufacturer refuses samples

"There is some concern that capelin are particularly prone to the adverse effects of an oil spill," Purchase says.

But he never got the chance to compare Corexit 9500 — an open ocean oil spill dispersant — with Corexit 9580, a surface agent used to clean beaches.

He was able to get a sample of the oil spill dispersant from DFO but the manufacturer, Nalco Environmental Solutions, refused to provide Purchase with a sample of the beach cleaning agent Corexit 9580 last April.

Nalco refused again when DFO asked for a sample on his behalf.

'We don't know the effects'

"I was a little surprised," said Purchase.

"DFO also seemed surprised as well, but we weren't able to proceed and make that comparison, so we don't know the effects, the potential benefits and the potential negative effects of that product.... It's unfortunate." 

DFO said it was told by Nalco that it will not provide samples to non-government agencies.

Back Story - BP Oil Spill - Children on beach

Children poke sticks into oil washed up on the shore in the aftermath of the BP oil spill along the U.S. Gulf Coast. (AP)

In a presentation to Nova Scotia fishing industry stakeholders last year, DFO spill expert Tom King quoted a letter from Nalco staff scientist Linda Russell refusing to participate in toxicity testing of Corexit.

"If the scope of the project can be reconsidered to remove these tests, we can restart the dialogue and process to obtain samples of Corexit."

Roman Blohoski, Nalco director of global communications, declined comment.

DFO not giving up

In June 2016 both Corexit 9500 and Corexit 9580 were approved for use in Canada on a case-by-case basis, provided authorities determine there is a net environmental benefit.

DFO spokesperson Vance Chow said the department will be contacting the company again in the next few weeks.

"The department is working towards the end goal of obtaining samples of Corexit so that government-funded researchers can conduct testing to determine the biological effects of the product on fish and other aquatic species," Chow said in an e-mailed statement to CBC News. 

Chow said the Canadian Coast Guard, Environment Canada and Natural Resources Canada are also involved.

Fishing industry weighs in

Leo Muise of the Nova Scotia Fish Packers Association said processors strongly want to see Nalco provide samples to DFO so the research can proceed.

"It would go a long way to building the trust between the seafood industry and the oil and gas industry," he said.