Giant Mine Human Health and Ecological Risk Assessment

Information about the Giant Mine Human Health and Ecological Risk Assessment (HHERA). 

Why conduct a Human Health and Ecological Risk Assessment?

A Human Health and Ecological Risk Assessment (HHERA) looks at the risks to people and the environment when exposed to contaminants. Since 2000, the Giant Mine site has undergone many assessments of the risks of contamination from historic mining. This includes a Tier 2 Risk Assessment, completed by SENES Consultants in 2006, and updated in 2010.

In 2014, the Mackenzie Valley Review Board concluded the public still ad health concerns about contamination from Giant Mine. The Board decided the team needed an independent HHERA to address these concerns. The new HHERA addresses Measure 10 from the Board's Report of Environmental Assessment.

The new HHERA was developed with stakeholders such as:

The updated HHERA:

In January 2018, the Government of Canada released a final report on the Giant Mine Human Health and Ecological Risk Assessment (HHERA). The report found that there is low risk to very low risk from past activities at the Giant Mine and that the clean-up will further reduce these risks. The report also considered the effect that clean-up activities would have on local wildlife and plants, stating that the clean-up will reduce the risks but that 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 HHERA suggested the need for ongoing management and monitoring of the site.

What did the HHERA include?

The HHERA included:

To establish a useful baseline of exposure, the HHERA considered many sources of contamination. This included:

However, the risk assessment only evaluated the risk due to Giant Mine and the changes to that risk from remediation activities on site.

The HHERA 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.

Was country food included in the HHERA?

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. This includes:

Yellowknives Dene First Nations and North Slave Métis 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 different distances from the mine 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 HHERA report.

Dietary Survey

It is important to have up-to-date information about the types and amounts of food people harvest and eat. Information on the diets of residents of Yellowknife, Dettah and Ndilo was most recently collected in 1998.

In early 2017, Canada North Environmental Services (CanNorth) hosted community meetings to update the 1998 survey. They looked to better understand:

This showed how eating habits have changed since 1998. For example, caribou is not as available so people may eat less. By updating the survey, the team made sure the HHERA uses current information.

The survey asked residents:

The results of the dietary survey and country foods sampling program have been incorporated into the HHERA.

Other health-related studies and links

In addition to health effects monitoring, the Project team will complete two other health-related studies:

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

Health Effects Monitoring Program

The Health Effects Monitoring Program will establish current levels of arsenic in people's bodies. More information on the Program is available here.

Stress Study

The scope of the stress study is still under development. However, it will:

Participants will help develop a survey to measure and analyze stress effects. Wilfred Laurier University's Dr. Ketan Shankardass will lead this study.

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