New study examines archived letters that show how early feds, mine officials knew of Giant's arsenic problem

CBC

28-05-2025

One of the chiefs of the Yellowknives Dene First Nation says decades-old communications that show federal and mining officials knew about arsenic pollution from Giant Mine early on reaffirm what elders in his community have been saying.
"I'm extremely happy and proud that my members [have] remembered the stories and … the sad history of Giant Mine, with losing some of our children, losing some of our dogs, and the devastation that came with it," said Ernest Betsina, chief of Dettah.
A paper published earlier this month in the journal Facets looks at 547 letters and water samples from around Yellowknife between 1949 and 1956 in the early days of gold mining at both Con and Giant mines.
Ernest Betsina, chief of Dettah, pictured here in 2020. Betsina says a study examining early correspondence about arsenic contamination reaffirms what elders have been saying all along. (Alex Brockman/CBC)
Mike Palmer, an aquatic scientist and manager of the North Slave Research Centre, said he was made aware of the documents by the Giant Mine Oversight Board, which had retrieved them through Library and Archives Canada.
"We were really, really impressed with the concerted effort that public health officials put into documenting the distribution of arsenic in and around the environment at that time," he said.
Not only was he impressed by the quality of the more-than-75-year-old data, but Palmer said he was also surprised how early mining and federal officials were aware that arsenic was polluting the environment.
"The narrative I had heard was that, you know, people were doing the best they could at the time and if they knew there was a problem they would have stopped it," said Palmer. "And that clearly wasn't the case."
'It certainly is disturbing'
Giant Mine operated in Yellowknife from 1948 to 2004, and released poisonous dust into the air and water surrounding the mine. In that time, it produced about 198 tonnes of gold and more than 237,000 tonnes of highly toxic arsenic trioxide dust, which is contained underground.
Remediation of the site, one of the most contaminated in Canada, began in 2021.
A two-year-old boy from N'dilo died of arsenic poisoning in 1951. Letters examined in Palmer's study indicate, however, that the first documented case of arsenic poisoning happened in February 1949.
"Roasting commenced on 29th January, 1949, and by mid February the first human case of poisoning reached hospital," reads a letter from Dr. Kingsley Kay, the head of the Industrial Health Laboratory for the Department of National Health and Welfare in a letter to another federal health official on Dec. 6, 1949.
Mike Palmer is an aquatic scientist and manager of the North Slave Research Centre. (Liny Lamberink/CBC)
It goes on to say two men who had been drinking snow water at a camp near Giant were hospitalized and their urine samples led to a diagnosis of arsenic poisoning. The letter also notes six cows that "unquestionably died from arsenic poisoning" and that "fatal poisoning of wildlife was observed widely" as well.
Kay recommended in the same letter that ore roasting stop until environmental mitigation technologies were added to Giant. The report says that the Department of National Health and Welfare also called for ore roasting to stop.
But it says the Northwest Territories Council, which is what governed the territory before the Legislative Assembly was formed, did not approve that recommendation. The report says Con Mine installed an environmental control in the summer of 1949 and was able to bring its arsenic emissions down by 95 per cent.
Giant Mine installed a type of control in 1951 to reduce emissions as well, but production also ramped up which meant that overall emissions didn't go down. It wasn't until a second control was installed in 1955 and a baghouse for arsenic collection was installed in 1959 that emissions were reduced.
"Despite acknowledgement of the public health risks associated with arsenic-bearing emissions in the region, Giant Mine continued to emit more than 2,000 tonnes [of] arsenic trioxide per year to the surrounding landscape," Palmer's study reads.
"It certainly is disturbing," said Betsina.
The Yellowknives Dene First Nation has long been pushing the federal government for an apology and compensation for the harm Giant mine inflicted. Palmer hopes the report — and the documents it sheds light on — can be used as evidence in that process.
"It reassures that we must continue the fight for an apology and compensation because we owe that to my people," said Betsina. "We cannot let this file go on the wayside and [let the] federal government put it on the shelf."