The Health Effects Monitoring Program (YKHEMP) is a result of a 2013 Report of the Environmental Assessment for Giant Mine, published by the Mackenzie Valley Environmental Impact Review Board, which identified public concern about the potential health impacts of environmental arsenic and Giant Mine clean-up activities.

Consequently, the Giant Mine Remediation Project (GMRP) was required to design and implement a broad health effects monitoring program in the Yellowknife area.

In 2017, YKHEMP was launched to establish a baseline of contaminant exposures and potential health effects for people living in Yellowknife, Ndılǫ, and Dettah to ensure that the GMRP does not negatively impact the health of local residents during its remediation activities.

The purpose of YKHEMP is to establish a baseline of contaminant exposures and potential health effects for people living in Yellowknife, Ndılǫ, and Dettah.  This baseline work was done in 2017 and 2018.

Ongoing YKHEMP work is done to ensure that the GMRP does not negatively impact the health of local residents during its remediation activities.

YKHEMP is designed to be a prospective cohort study. “Prospective” means that the study takes place over a period of time. “Cohort” means that the same individuals participate throughout the length of the study. 

Around 1500 adults and 500 children participated in the YKHEMP baseline study in 2017 and 2018.  The children (aged 3-19 at their first time of participation) are followed-up every 5 years, and the adults every 10 years.   We do this to see if the level of exposure to metals changes overtime, and if the level of exposure is related to health outcomes.

In addition to following up with past-participants, we include a small number of new participants every five years. This is done to account for people moving, us not being able to reach them, or otherwise not being able to participate in the study.

Arsenic is one of the key contaminants being investigated by YKHEMP.  Other contaminants of potential concern include antimony, cadmium, lead, manganese, and vanadium.

These are being measured because other research and studies have shown that they are present at the Giant Mine site.  

Participants are asked to complete an in-person questionnaire about their lifestyle (i.e. outdoor activities) and the types and amounts of foods they eat (e.g. fish, rice, berries, etc.). Participants are also asked to provide samples of toenail clippings and urine. These samples are used to learn about a participant’s exposure to arsenic, cadmium, lead, antimony, manganese, and vanadium. 

Saliva samples are collected to look at specific genes related to arsenic, since our genetics play a part in how well our body processes arsenic. 

Participants may also provide consent to have their medical records reviewed by the research team from the previous 5 years. Researchers only access health conditions that are potentially related to arsenic exposure.

At the request of the Yellowknives Dene First Nation leadership, YKDFN members also completed a medical questionnaire and a brief medical exam that included measurements of height, weight, and blood pressure.

With participant consent, the research team reviews medical records to check for only those medical conditions that are associated with arsenic exposure.

The study will be limited to looking at possible associations at the population level, since it is not possible to link arsenic exposure to diagnosed diseases at the individual level.

The study is designed to look at the long-term relationships, therefore future waves of resampling will help provide more information about the pattern of health conditions and their relationship to measured levels of arsenic.

Yes. Within one year of participating in the study, you will receive a personal letter that includes your individual results and an explanation of what these results mean.

Only population level results (looking at the group as a whole) will be shared publicly.

A local Registered Nurse (RN) will contact individuals whose levels of arsenic, lead and cadmium are above the recommended individual guidance values.

The RN will work with the participant to further investigate possible causes (such as smoking, food consumption, etc.) and to help identify ways to lower their exposure.

If necessary, the participant may be offered additional tests, such as a blood test in the case of higher lead exposure.

The study obtains Ethics and Scientific Research Licences, on a yearly basis, outlining strict privacy and confidentiality protocols.

All the data collected (questionnaires, toenails, urine, and saliva) from individual participants will be managed in a secure manner, and will be housed at the University of Ottawa.

Only the Principal Investigator, along with authorized research students, will have access to the data. The data will only be used for the purpose of this study.

Your name will not be kept with the data. Only the Principal Investigator will be able to link names with individual results.

Eligible individuals who consent to participate in the program receive their results for arsenic and other metals in a personal letter, with an explanation of what they mean. 

Individual involvement contributes to the overall assessment of the population health in Yellowknife, Ndılǫ and Dettah.

As well, it will help us to measure the success of the remediation project with respect to the impacts from contaminants.


YKHEMP is an ongoing monitoring program. This means we will follow-up with children and youth every 5 years, and adults every 10 years. 

Following-up with participants allows the study to see whether arsenic and other metals of concern are increasing, decreasing, or remain the same as a result of the work being done at Giant Mine.

YKHEMP is conducting a 5 year follow-up with children and youth, ages 3 to 19, in Yellowknife in the Spring and Fall 2023, and Winter 2024. 

The team is following up with past participants who participated in the 2017/2018 baseline study, as well as recruiting a new group of children and youth participants from randomly selected households. Randomly selected households will have received a letter in the mail inviting them to participate in the study.

If your household was not randomly selected, but you or your child (aged 3-19) would like to participate,  please contact us at or call 867-445-1574 to be put on our volunteer participant list.

Once you contact us, we will schedule an interview with you and/or your child.  This interview takes between 30-60 minutes and can take place either at your home or at our downtown office, and can be scheduled for any day (including weekends and holidays) and any time of day. 

At the time of your interview, one of our trained Research Assistants will walk you through the consent form and answer any questions you may have before beginning with the interview.  Participants aged 3-12 must have an adult with them, while participants aged 13-19 can participate without an adult. 

Following the interview, your Research Assistant will give you a sample collection kit and explain how to collect the samples.  Since the urine sample needs to be collected first thing in the morning, and toenails might take a while to grow, they will leave the sample kit with you and will pick it up at a later date.


The YKHEMP study can only measure up to about one year of arsenic exposure, this is measured by looking at arsenic in toenail clippings. There is currently no existing technology which would allow us to measure historical exposure to arsenic beyond one year. 

Unlike metals such as mercury, which accumulate in our body over time, arsenic travels through our body creating some damage, and then leaves 2-5 days later, mainly through urine.

We need written permission from the participants of past arsenic studies in order to try to access their results.  If you participated in historical arsenic testing, please let us know. 

If you have your results from historical arsenic testing, please share this information with us.  If you do not have your results, you can choose to give us permission to try to access them. 

If we have success in finding your results, we will share them with you and we will incorporate these historical results into our study analysis.

We are not specifically focusing on mine workers, but any individual who would like to participate in the study is welcome to reach out to us about opportunities to participate on a voluntary basis.


Arsenic occurs naturally in the earth’s soil, in minerals, and in water.  It is a metalloid element on the periodic table, with atomic number 33. Arsenic cannot be destroyed in the environment. It can only change its form.  

There are two main forms of arsenic: organic and inorganic. 

Inorganic arsenic compounds are formed when arsenic combines with elements such as oxygen, chlorine, and sulphur.  These compounds are toxic, and can be very harmful to human health if ingested in high amounts over a long period of time. Arsenic in minerals, rocks, plants, mushrooms, and water are mostly in inorganic form. 

Organic arsenic compounds are formed with arsenic combined with hydrogen and carbon.  These compounds are less toxic and are considered not harmful to people or wildlife. Foods such as seaweed, fish and shellfish have higher proportions of arsenic in organic forms.  

Inorganic arsenic compounds are mainly used in industrial processes such as to  preserve wood. They are also used to make products such as glass, paper, and textiles.  Organic arsenic compounds are used as pesticides, mainly on cotton fields and orchards.

Arsenic trioxide is not naturally found in the environment. In the Yellowknife area, gold mining has released arsenic into the environment that was previously trapped in the rocks. Giant Mine and Con Mine in particular operated in the area for many decades.  The mines had to use extremely high temperatures to extract gold from the ore. These high temperatures released arsenic from the bedrock in a different, more toxic form called arsenic trioxide which was then spread as dust into the environment. 

Arsenic trioxide is an example of a toxic inorganic arsenic compound, formed when arsenic is combined with oxygen.  Between the years 1948-1951, about 7,500 kg of arsenic trioxide was released into the environment per day. In 1951, the mine started to capture some of the arsenic and store it underground. Currently, there is approximately 237,000 tonnes of arsenic trioxide stored in 14 underground stopes and chambers at the Giant Mine site.

People get exposed to some levels of arsenic from the food and water they eat and drink. You can also be exposed to arsenic if you smoke. Natural inorganic arsenic is present in tobacco because tobacco plants take up arsenic naturally present in the soil.

Additionally, people can be exposed to arsenic from inhaling dust and ingesting contaminated soil. Arsenic is found at very low levels in many foods, including animal products, baked goods and cereals, vegetables, and fruits and fruit juices. Higher levels of arsenic are found in rice, seafood, and some mushrooms.

Many factors will determine whether you might be harmed from exposure to arsenic. These factors include the dose (how much), the duration (how long), and how you come in contact with it. Other factors include your age, sex, diet, genetics, lifestyle, and overall health. 

How you come into contact with arsenic will impact how it affects you.  Common ways that people are exposed to arsenic include:

  • Ingestion (eating): Exposure to low levels of arsenic can cause nausea and vomiting, decreased production of red and white blood cells, abnormal heart rhythm, damage to blood vessels, and a sensation of “pins and needles” in hands and feet. Ingesting high levels of arsenic can result in death. 
  • Inhalation (breathing it in): Breathing low levels of inorganic arsenic for a long time can cause a darkening of the skin and the appearance of small “corns” or “warts” on the palms, soles, and torso. Breathing high levels of inorganic arsenic can give you a sore throat or irritated lungs.

Dermal (skin): Only a small amount of inorganic (toxic) arsenic enters through skin, therefore this is usually not a type of exposure of concern. Skin contact with inorganic arsenic may cause redness and swelling.

Several studies have shown that ingestion of inorganic arsenic over the long-term can increase the risk of skin cancer and cancer in the liver, bladder, and lungs. Inhalation of inorganic arsenic can cause increased risk of lung cancer. The International Agency for Research on Cancer (IARC) has determined that inorganic arsenic is carcinogenic to humans.

Our study is focusing on human health only and is not testing pets or other animals.  If you are concerned about your dog’s arsenic exposure, we suggest reaching out to your veterinarian.

The results of our 2017-18 baseline study found that most people living in Yellowknife, Ndılǫ, and Dettah had arsenic levels comparable to the average Canadian.

If you are worried about arsenic exposure, check-out our booklet: Tips to Keep Your Arsenic Levels Low, and the GNWT’s pamphlet on arsenic in Yellowknife, Ndılǫ, and Dettah.

In order to understand the presence, the extent, and the mobility of arsenic around our communities, the Government of the Northwest Territories (GNWT) monitors arsenic in water, sediments, soils and fish. 

Final reports are publicly available and can be found at

In addition, the Human Health and Ecological Risk Assessment (HHERA) study gathered existing data and collected samples of water, soil, sediment, plants, and animals to test for arsenic and other contaminants of concern. 

The results from this study were shared in public meetings in October 2017 can be found here.

This is one of several Human Health Risk Assessments completed since the year 2000 to help the Giant Mine Remediation Project team determine the health risks associated with mining operations at Giant Mine.