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A study by U of O researchers found high levels of arsenic in water in the Northwest Territories. Photo: CC Viv Lynch

‘So high we couldn’t believe it at first’: Professor Jules Blais

The long-term repercussions of gold mining in the Northwest Territories are still being studied more than a decade
after the closure of The Giant Mine located just outside of Yellowknife.

A study published in the scientific journal, PLOS ONE, this past week by a team of researchers from the University of Ottawa has found high levels of arsenic and methyl mercury, a toxic type of mercury that can accumulate in food chains, in lakes near the mine. The original study began in 2010 when researchers were looking at climate change and its thawing effect on permafrost, and how these issues were affecting the surrounding lakes.

Lead author and PhD candidate in the Department of Biology, Adam Houben, said the group began comparing water chemistry in proximity to The Giant Mine out of curiosity, and were surprised at how strong the correlation was between the distance of the mine and the concentration of arsenic.

“When we saw the results for the arsenic, it really became clear that the arsenic was going to be the big story,” said Jules Blais, director of the study and professor of biology
and environmental toxicology at the U of O.

Houben said some of the samples tested well over the guidelines for both aquatic life protection and acceptable drinking water. Water quality guidelines for drinking water are 10 micrograms per litre (μg/L) and 5 μg/L for the protection of aquatic life.

“We were up over, well over, 100 micrograms per litre, even some places that were over 200. So yeah, there was some very, very high arsenic, so high we couldn’t believe it at first,” said Blais.

The study also showed that larger lakes had lower levels of arsenic than smaller ones,most likely because they have
a larger surface area, therefore receiving more rain and snowfall, which is uncontaminated,” said Blais.
While most drinking water is derived from the Yellowknife River, a larger one presenting less of a risk, it’s communities that fish or use wells, which may get water from smaller lakes, that are at risk of contamination. Professor Laurie Chan, a specialist in toxicology and environmental health at U of O, is heading to Yellowknife

soon to meet with officials from the department of health and the chief medical officer, and begin a follow-up study on the effects of human exposure from arsenic.

“Any advisory to the people to do something or not to do something has to come from the chief medical officer, so I will be discussing with them the interpretation of the results,” he said.

Chan said although there have been cases of high arsenic contamination in other countries linked to bladder and skin cancers, they aren’t expecting to see such high levels around Yellowknife.

Because arsenic doesn’t stay in the body long, often only days or hours, it’s unknown
whether residents of the surrounding communities have already been affected by the contamination, as they previously weren’t being monitored, said Chan.

“We’re not expecting people currently exposed to the high level though. But historically, whether they’ve been exposed to such high levels or not, we don’t know.”