Human health risks from arsenic exposure low or very low around Yellowknife, study says

'We have even compared it to getting hit by lightning. It is a low risk, but there is still some risk,' says Natalie Plato of the Giant Mine Remediation Project.

Like 'getting hit by lightning. It is a low risk, but there is still some risk,' says Natalie Plato

A sign on a trail near Yellowknife warns people that arsenic, stemming from nearby Giant Mine, lingers in the area. (Richard Gleeson/CBC)

People who live in Yellowknife and the neighbouring Dene communities of Dettah and N'dilo have a low — or very low risk — of getting cancer from arsenic exposure through country food, dust and water.

That's according to an updated human health risk assessment of Giant Mine.

The study paints a clear picture of arsenic concentrations — natural and from mining — found in water, soil and country food, and the potential current and future impacts on human health.

"When you try and describe what risk is, we put it on a scale of the risk of developing cancer over your lifetime," says Natalie Plato, deputy director of the Giant Mine Remediation Project.

"Low risk is comparable to having a CT scan," said Plato. "We have even compared it to getting hit by lightning. It is a low risk, but there is still some risk."

'Negligible risk, very low risk and low risk'

During its 56-year life span, smelters at Giant Mine belched thousands of tonnes of arsenic trioxide dust into the air. People have long worried about the impact that dust has today on humans and wildlife.

The report, produced by the Canada North Environmental Services, focused on Yellowknife, Dettah, N'Dilo, the Giant mine site and Ingraham Trail. It looked at different scenarios varying on where people live and how much country food they eat.

"In all our scenarios [the risk] fell somewhere along the spectrum of negligible risk, very low risk and low risk," said Plato.

Of the three communities studied people in N'dilo who eat country food regularly have the highest cancer risk — about one in 10,000 — largely because of higher concentrations of arsenic in the soil, both natural and left over from mining.

For people in Dettah who regularly eat country food, the risk is slightly higher than one in 100,000.

The risk for people who live in Yellowknife and eat supermarket food is negligible — one in 100,000 people.

The study also measured arsenic concentrations in Back Bay and Yellowknife Bay. All were considered safe to drink, said Plato.

The study also found Yellowknifer's who swam frequently in Long Lake over the summer — two hours, three times a week — also had a very low risk of getting cancer.

1 in 2 Canadians will get cancer

The research also factored in arsenic concentrations in soil and household dust.

While the overall risk is low, the researchers noted berries and animals like hare, grouse and ptarmigan found within 10 kilometers of the mine have arsenic concentrations four times higher than those found 50 kilometers away. Arsenic concentrations in moose were only slightly higher. Levels in fish in Yellowknife Bay were considered safe.

The final report is expected in December.

Plato says the information will help improve the current remediation plan and future use of the site once it's cleaned up.

Arsenic levels are naturally higher in the soil around Yellowknife.

One in two Canadians will get cancer over their lifetime, according to the Canadian Cancer Society.