Giant Mine Human Health and Ecological Risk Assessment

On this page

• Human Health and Ecological Risk Assessment
• The Human Health and Ecological Risk Assessment process
• Country food and the Human Health and Ecological Risk Assessment
• Other health-related studies and links

Human Health and Ecological Risk Assessment

A Human Health and Ecological Risk Assessment examines the risks to people and the environment when exposed to contaminants.

Since 2000, the Giant Mine site has undergone many assessments examining the risks of contamination from historic mining. This includes a Tier 2 Risk Assessment, completed by SENES Consultants in 2006, and updated in 2010. A Tier 2 Risk Assessment is a Quantitative Risk Assessment that builds on and fills gaps identified at the initial Tier 1 screening level assessment done on contaminated sites.

In 2014, the Mackenzie Valley Review Board concluded that the public still had health concerns about contamination from Giant Mine. The board decided it was important to get an independent Human Health and Ecological Risk Assessment to address these concerns. The new risk assessment addresses Measure 10 (PDF Version, 233 pages) from the Board's Report of Environmental Assessment.

The new risk assessment was developed with:

• the Giant Mine Working Group
• the Giant Mine Advisory Committee

The updated risk assessment:

• looks at where and how much people, animals or plants face exposure to chemicals from Giant Mine
• finds out if the level of exposure is of concern, that is if it could cause health effects
• predicts if this is likely to change during and after remediation

In January 2018, the Government of Canada released a final report on the Giant Mine Human Health and Ecological Risk Assessment. The report found:

• low to very low risk from past activities at the Giant Mine
• clean-up will reduce more of these risks

The report also considered the effect that clean-up activities would have on local wildlife and plants, stating that:

• clean-up will reduce the risks
• the potential for risks to small animals still exists

In Yellowknife Bay, low risks to small insects in the sediments were found, but these conditions will slowly improve.

The Human Health and Ecological Risk Assessment suggested the need for ongoing management and monitoring of the site.

A plain language summary of the risk assessment is available on the website. For the report in full, please contact the Project team.

The Human Health and Ecological Risk Assessment process

The Human Health and Ecological Risk Assessment:

• analyzed contaminant levels in the environment (such as in country foods, soil, and water) to understand the sources of exposure
• evaluated how people face exposure to contaminants in ways such as:
  • eating fish
  • eating locally-grown food
  • making contact with contaminated soil, sediment or water
• evaluated current risks due to exposure to arsenic and other contaminants from Giant Mine and future risks after the remediation of the mine
• identified possible health effects related to the levels of exposure

To establish a useful baseline of exposure, the assessment considered many sources of contamination, including:

• sources outside the Giant Mine site such as off-site contaminated soil and water
• grocery store food consumption

The risk assessment only evaluated the risk from the Giant Mine site in its current state and the changes to that risk when remediation activities take place on site.

The risk assessment resulted in benchmarks against which to measure the project, to protect both people and the environment during and after remediation. The Project team anticipates remediation will lower contaminant levels and risks over time. Knowing what the levels are now will help confirm reduced levels later.

Country food and the Human Health and Ecological Risk Assessment

To more accurately reflect local exposure and conduct a more precise risk assessment, the Project team conducted a local country food sampling program. This took place in 2016 and 2017. The program measured potential contaminant exposure levels through eating country foods, including:

• fish
• game
• berries
• medicinal plants

Yellowknives Dene First Nation and North Slave Métis Alliance members and Yellowknife residents submitted samples of country food and medicinal plants to the Project team. These samples were harvested from the land near Yellowknife. The food samples were analyzed by a laboratory for arsenic and other contaminants of concern. The location where a sample was taken was also recorded, so samples of different distances from the site could be compared.

The results allow the team to better understand the amount of contaminants in the foods people eat. The results are included in the final risk assessment report.

Other health-related studies and links

In addition to the Human Health and Ecological Risk Assessment, the Project team will complete 2 other health-related studies:

• a Health Effects Monitoring Program
• a wellness study, called Hoèla Weteèst’eèdeè: Understanding Community Wellbeing Around Giant Mine

While there are links between the 3 health-related studies, they have different objectives and will take place separately. The Project team will identify links between the studies and share the information as these develop.