Home gardeners in the Yellowknife area, rest easy: your veggies might contain a bit more arsenic than those in the supermarket, but not enough to cause concern.
That is the main takeaway from research jointly undertaken by the Aurora Research Institute, Queen’s University, Royal Military College of Canada, and Yellowknives Dene First Nation.
The four groups teamed up for a two-year project titled the Yellowknife Garden Metals Study, which sought to determine whether produce grown in Yellowknife, Dettah, and Ndilǫ contains higher-than-average levels of arsenic and other mining metals.
Michael Palmer, manager of Aurora College’s North Slave Research Centre, said the project follows a separate study published earlier this year that declared previous estimates of the naturally occurring arsenic level in Yellowknife soil were wrong. That study found the natural level to be comparable with the rest of Canada, placing the blame squarely on mines for elevated arsenic levels around Yellowknife.
“That project took us about five years to complete,” Palmer explained, “and through public presentations and just meeting with folks and discussing those results, people consistently kept asking about what levels were like in garden soils and then in their produce.
“It highlighted to us that it’s still a persistent question in Yellowknife.”
Soil samples and produce such as carrots, potatoes, and leafy greens were collected from 47 gardens in the three communities last fall. The samples were sent to labs in Kingston, Ontario. Another 40 samples were collected this summer.
‘Very low risk’
A couple of key findings emerged from the first set of results.
First, arsenic levels in Yellowknife soil were consistently higher than Canadian residential guidelines, but consistently lower than levels found in undisturbed soil in the surrounding area.
The team is still looking into the reasoning behind this.
Palmer speculated residents in the city often add bagged soils to garden beds, which would reduce the levels of arsenic present. Moreover, soil that has been undisturbed would accumulate arsenic over time, whereas mixing the soil – as home and commercial gardeners often must do – would dilute it.
The study also found arsenic levels in produce grown in the city was higher than the average for supermarket produce – but not high enough to pose any significant health risk to consumers.
Iris Koch, an adjunct professor at the Royal Military College of Canada, is one of the project’s researchers. She was part of a similar study in 2001 that showed comparable results, though arsenic concentrations measured in 2020 were lower than in 2001.
“If you were eating carrots from a supermarket compared to a blend of supermarket carrots and Yellowknife carrots, the risk is not higher to the extent that we are concerned with it,” Koch explained.
“There’s risk from eating any food because all food has arsenic in it. It’s a little bit higher when you’re eating the Yellowknife vegetables, but it’s still in this very low-risk category.”
Recently, a test of Yellowknifers’ toenails, saliva, and urine found arsenic levels akin to others across Canada, Palmer pointed out.
“We need to recognize that there is a mining impact in the community,” Palmer said. “This study provides information on what it’s like for our day-to-day activities, living in a community that has been impacted by past mining emissions.
“We do see higher levels of arsenic in our properties, but those levels shouldn’t really discourage us from eating our garden products.”
Palmer, Koch, and the rest of the team have been sharing their findings widely. They held an online public forum a couple of weeks ago and have been keeping the GNWT’s environmental health division up to date.
Samples collected from gardens this year are now being studied, with results expected next year.