Mercury poisoning near Grassy Narrows First Nation worsened by ongoing industrial pollution, study suggests

A new study from the University of Western Ontario suggests mercury contamination in northwestern Ontario's English-Wabigoon River has been made worse by ongoing industrial pollution.

Contamination of the river system dates back to the 1960s and 70s, when the pulp and paper mill dumped an estimated nine tonnes of mercury into the water.

The mercury has impacted generations of people living in Grassy Narrows First Nation, also known as Asubpeeschoseewagong Netum Anishinabek, and Wabaseemoong Independent Nation, a community about 150 kilometres from Dryden near the Ontario-Manitoba border. 

However, the new study, published Thursday, has found that discharge of wastewater from the Dryden Paper Mill, combined with existing mercury, has created high levels of methylmercury – an even more toxic compound.

"Other forms of mercury don't accumulate as strongly as methylmercury, but because it accumulates, it builds up to high levels in organisms, presenting that greater risk," said Brian Branfireun, a biology professor at the University of Western Ontario. "It's actually more serious than I even imagined."

The experiment was conducted by masters student Eric Grimm under Branfireun's supervision.

Dianne Loewen, communications and engagement co-ordinator for Dryden Fibre Canada, the owner of the Dryden Paper Mill, said in an email to CBC News on Wednesday that she could not comment on the study.

"Dryden Fibre Canada only recently acquired the mill from Domtar. We are not in a position to comment as we have not seen, nor have we been briefed on, Dr. Branfireun's report."

Dryden Fibre Canada took over the mill from Domtar in August 2023.

While the wastewater coming from the mill today does not contain mercury, it does contain high levels of sulfate and organic matter, which "feed the bacteria that produce methylmercury from inorganic mercury in the environment," the study says.

These toxins build up in the river's fish, which are then passed on to the people that consume them.

"The accumulation of methylmercury in the human body causes neuromuscular problems and can also lead to death," Branfireun said.

Just under 1,000 people live in Grassy Narrows First Nation, which is about 90 kilometres north of Kenora, Ont. and fish are a staple part of the community's diet.

"Most of the families continue to fish, they continue to eat the fish. It's something they've done for hundreds of years – you can't really stop them," said Grassy Narrows Chief Rudy Turtle in an interview with CBC News.