In 2014, the Mackenzie Valley Environmental Impact Review Board (Review Board) completed its seven-year environmental assessment of the Giant Mine Remediation Project (GMRP). This was undertaken to address public concerns about the impact of the mine’s clean-up activities, including those it may have on the local population’s exposure to contaminants.

As a result of the environmental legacy that Giant Mine, Con Mine, and other mining projects had on the Yellowknife area, one of the Review Board’s requirements was that the GMRP design and implement a Health Effects Monitoring Program for Ndilo, Dettah and Yellowknife, to look at people’s exposure to arsenic and other contaminants of concern.

This Program needs to start before any remediation work begins at Giant Mine in order to determine baseline levels – that is, what the levels are now.

The Giant Mine Remediation Project has been working with stakeholders over the last two years to prepare and design this program. We are now ready to implement it.


The purpose of the Monitoring Program is to establish a current baseline of levels of arsenic (and other contaminants) in residents. This will allow the Program to compare levels now to levels during and after remediation so they can make sure the remediation activities will not have a negative impact on the health of residents and can take action, if needed, to address any negative changes.

Aside from arsenic, other chemicals of potential concern in the study 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.

Arsenic is found at naturally low levels in the water of many NWT lakes and rivers. However, past gold mining activities have resulted in additional quantities of arsenic being released in the immediate environment surrounding the City of Yellowknife.
In order to understand the presence, the extent, and the mobility of arsenic around our communities, the Government of the Northwest Territories (GNWT), in collaboration with universities, monitors arsenic in water, sediments, soils and fish. Preliminary results of these projects will be shared with the Department of Health and Social Services (HSS) and other interested departments and governments. Final reports will be publicly available. More information is available at here.

In addition, for the past two years the Giant Mine Remediation Project (GMRP) has been undertaking an updated Human Health and Ecological Risk Assessment (HHERA) study which gathered existing data, and in some instances 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 and will be available on INAC’s website in May 2018. This is one of several Human Health Risk Assessments completed since the year 2000 to help GMRP determine the health risks associated with mining operations at Giant Mine. You will find a small piece on it in a Newsletter available here.

If you are concerned about your exposure to arsenic around your communities, the Health Effects Monitoring Program will provide you and other residents an understanding of the current exposure to arsenic and other contaminants of concern. If you participate in the study, you will receive your individual results and what those numbers mean. In addition to that, your involvement will contribute to the overall assessment of our population health, and be able to measure the success of the remediation project with respect to impacts from contaminants.

Arsenic occurs naturally in the earth’s soil, in minerals, and in water. Arsenic is also used to make products such as glass, paper, textiles, and pesticides, and can be released into the environment through mining.

There are two main forms of arsenic: organic and inorganic. Organic arsenic is harmless to us and can be found in some of the food we eat such as rice. Inorganic arsenic is toxic, and can cause harm to parts of our body before it is excreted, mainly through urine. Arsenic cannot be destroyed in the environment. However, arsenic can change its form in the environment or in our body to make it either more, or less toxic.

There are tests available to measure arsenic in your blood, urine, hair, fingernails, and toenails. These tests can determine if you have been exposed to above-average levels of arsenic in recent months. They cannot predict whether the arsenic levels in your body will directly affect your health, and they cannot measure historic exposure to arsenic.

The Health Effects Monitoring Program will specifically measure the different forms of arsenic present in your toenail clippings (representing the past three to six months exposure) and urine (representing past two to three days exposure).

Arsenic trioxide is not naturally found in the environment. At the Giant Mine, the arsenic trioxide was formed as a result of the process used to extract gold from the rock.

The gold was found in arsenopyrite mineral. To get the gold out, the mine had to roast it. During that process, arsenic combined with oxygen and created a more toxic form: arsenic trioxide. Between the years 1948 and 1958, this by-product was released directly into the atmosphere. Once more knowledge about arsenic trioxide and the risks were learned, the mine operations started to store the arsenic trioxide. Currently, 237,000 tonnes of arsenic trioxide is being stored underground in 14 underground stopes and chambers.

The Con Mine also used a roasting process and released contaminants such as arsenic into the environment in and around the Yellowknife-area.

There are a few different ways arsenic can enter the body, including:

Ingestion (eating): If you swallow arsenic in water, soil, or food, most of the arsenic may quickly enter into your body. The amount that enters your body will depend on how much you swallow and the kind of arsenic that you swallowed.

Inhalation (breathing it in): If you breathe air that contains arsenic dust, many of the particles settle onto the lining of the lungs. Most of the arsenic in these particles is then taken up from the lungs into the body. You might be exposed in this way near waste sites where arsenic-contaminated soils are allowed to blow into the air, or if you work with arsenic-containing soil or products.

Dermal (on your skin): If you get arsenic-contaminated soil or water on your skin, only a small amount will go through your skin into your body. This kind of exposure is usually not of concern.
Both inorganic and organic forms of arsenic leave your body in your urine. Most of the inorganic arsenic will be gone within several days, although some will remain in your body for several months or even longer. This is the reason why the Health Effects Monitoring Program can only measure current levels of arsenic in your body.

Although arsenic does not stay in our body very long, the toxic inorganic forms of arsenic affect the whole body as it passes through our system and can cause problems years later. (For example, exposure to arsenic is linked to diabetes and cardiovascular, respiratory, and bladder problems, as well as skin lesions and cancer).

If you are exposed to arsenic, many factors will determine whether you might be harmed. These factors include the dose (how much), the duration (how long), and how you come in contact with it. You must also consider any other chemicals you are exposed to and your age, sex, diet, family traits, lifestyle (for example, smoking) and state of health, which can contribute to how arsenic will affect you personally, in combination with the other factors.

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.

Inhalation (breathing it in): Breathing high levels of inorganic arsenic can give you a sore throat or irritated lungs. Over prolonged time it can cause a darkening of the skin and the appearance of small “corns” or “warts” on the palms, soles, and torso.

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

Effects from short-term overexposure (a brief exposure to an extremely high level) to inorganic arsenic may include vomiting, abdominal pain, and diarrhea. Numbness and tingling of the extremities, muscle cramping and death may also occur in extreme cases.Chronic exposure to elevated levels of toxic forms of arsenic over a long period of time can cause bladder, kidney, liver, lung and skin cancer and other problems with the skin. These may include skin lesions (wounds), changes in the color of the skin, and hard patches on the palms and soles of the feet. Arsenic exposure has also been associated with developmental effects, cardiovascular disease, neurotoxicity, and diabetes.

Several studies have shown that ingestion of inorganic arsenic 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 Environmental Protection Agency, and the International Agency for Research on Cancer have determined that inorganic arsenic is a known human carcinogen. This means that exposure to arsenic can lead to cancer but not everybody who is exposed to arsenic will have cancer.

Total of 1900 Yellowknife households have been randomly selected to participate in the monitoring program using a sampling plan prepared by Statistics Canada. From that number, about 800 randomly selected households and apartments have been contacted and visited this past fall (2017). The remaining 1200 selected households will receive an Invitation Letter in the mail between April 10-12, 2018 informing them that their home was selected to participate in the Health Effects Monitoring Program. Our team of Research Assistants will be following up with those households that do not respond to us after receiving the letter. Data collection will take place between April 16 and June 24, 2018. We will ask up to one adult (18+), and one child (3-17) if present, for their consent to participate.

All Yellowknives Dene members who live in Ndilo, Dettah and the Yellowknife area are encouraged to participate. Sign-up sheets will be posted in the communities and the Community Project Coordinator will follow up with participants to schedule interviews and sample collection.

The study will be advertised by radio, local TV, social media, via news outlets, and in flyers to inform the public about the upcoming sampling in Yellowknife, Ndilo and Dettah.

If your house was not selected and you have concerns about the contaminants in your body, you can email the research team at to volunteer to participate. For the North Slave Métis Alliance members and Yellowknives Dene First Nation, participation in the Monitoring Program is voluntary and encouraged.

Unfortunately, there is currently no technology that will allow us to measure your historical exposure to arsenic. Unlike metals such as mercury, which accumulates in our body over time, arsenic travels through our body creating damage, and then leaves a few days later (3-4), mainly through urine.

The review of all the participant’s medical records, taken together with their current results, may help our research team make associations of possible health effects that could have been caused by past exposure, but will not be able to assess levels or duration of any past exposure.

If you’ve been part of a historical study (we know there have been several), we would like to know. If you received your results at that time, we’d be happy to have you share that information with us.

If you did not receive your results at that time, we have found data for some of the studies, though not all of them. If we do have access to your results, we will share those with you. That will be included with your results and interpretation from this current study.

For most Yellowknife residents, the interview will take place at your home, at your convenience, and last approximately 30 minutes. Interviews with the Yellowknives Dene First Nation (YKDFN) members will take approximately 45 minutes because the interview will also include a brief medical exam (as requested by YKDFN leadership), and a medical questionnaire conducted by a research nurse working for the Program.

The Program will also carry out follow-up sampling five years later for participants younger than 18 years of age, and within 10 years for both adult and children participants.

You will be asked to answer some questions about your lifestyle, and the types and amounts of country food (for example, fish, berries, etc.) you eat.

You will be asked to provide biological samples, which include toenail clippings and urine. Collected samples of urine and toenails will be used to find out whether your body has been exposed to arsenic, cadmium, lead, antimony, manganese, and vanadium.

In addition, our genetics play a part in how well our body gets rid of arsenic. The study will also request a sample of your saliva in order to conduct a DNA test to check whether you have particular genes that help a person get rid of arsenic more efficiently from their body.

The research team will review all of the participants’ medical records to see if there are any 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.

Yes. Each participant will receive their individual results, with interpretation, in a personal letter in the Fall 2018, for the first round of participants, and in the Spring 2019 for the second round of participants. Your personal results will not be shared with anyone. Only population level results (that is, looking at the group as a whole) will be shared publicly. The Program will also hire a local nurse to follow-up with individualsfound with high levels of arsenic, explain their results, and help lower their exposure. The nurse will also be available to answer any questions or concerns from any of the participants.

A local nurse will be hired specifically to answer questions and work closely with those individuals whose levels of arsenic are above the recommended individual guidance value, to further investigate possible causes (such as smoking, food consumption, etc.) and to help identify ways to lower their exposure. As well, additional tests may be performed (such as a blood test) to confirm exposure, if necessary.

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 three 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.

The study is also obligated to obtain Ethics and Scientific Research Licenses, on a yearly basis outlining strict privacy protocols.

Currently, the Health Effects Monitoring Program is focusing on the entire population of Yellowknife, Ndilo and Dettah. However, even if your household was not randomly selected, any individual who is interested to find out their current exposure to arsenic and other contaminants can ask to participate on a voluntary basis.

The Research Team is also planning to conduct a separate study specifically looking at exposure of individuals who worked or are currently working on mine sites.

Unfortunately, our study is focusing on human health only. We will not be able to interpret results of exposure among domestic animals.

In the Fall 2017, we interviewed children 6 and above to make sure we could compare our data with the available data from the Canadian general population. Recently, the Canadian Health Measures Survey lowered their age to 3 therefore starting in April 2018 the Health Effects Monitoring Program will do the same.

REFERENCE: Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Toxicological Profile for Arsenic (Update). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.

Find more information online at Toxic Substances Portal – Arsenic


Arsenic is naturally higher in some of the NWT rivers, lakes and soils because of local geology…

However, through decades of gold mining operations at Giant, Con and Negus mines in Yellowknife, a toxic form of arsenic, called arsenic trioxide in the form of dust, was released into the environment.

In the environment, arsenic is found in two forms:

  • Organic (less harmful); and Inorganic (toxic).
  • Organic arsenic is commonly found in fish and shellfish.

YKHEMP results found that local fish are safe to eat.

Inorganic arsenic is commonly found in some rice and rice products, seaweed, berries, and some mushrooms.

Some arsenic is found in cigarettes.

SHORT-TERM EXPOSURE – Accidental occupational exposure to an extremely high level of inorganic (toxic) arsenic:

  • Vomiting, abdominal pain and diarrhea.
  • Numbness and tingling of hands and feet.
  • Muscle cramping and death may also occur in extreme cases.


LONG-TERM EXPOSURE – Exposure to arsenic over months, years:

  • Can cause bladder, kidney, liver, lung and skin cancer.
  • Other skin problems include skin lesions (wounds), changes in the color of the skin, and hard patches on the palms and soles of feet. This is currently seen in people who have long term higher exposures to arsenic in drinking water (i.e., in Bangladesh)*.
  • May harm the nervous system and may affect learning in children.
  • May contribute to cardiovascular disease and may affect lung function.

*Current YKHEMP arsenic results show that this is not the case in present day Yellowknife.

  • NWT’s Chief Public Health Officer has recommended to avoid harvesting berries, mushrooms or other plants in areas impacted by industrial activities, and to avoid fishing and recreational water activities in lakes with documented high arsenic levels as part of a precautionary public health advisory. 
  • If you have an infant, breastfeed if you can. Feed a variety of cereals to your infant, not only rice-based.
  • Have children wash their hands after they play outside.
  • Reduce dust and soil going inside the house (i.e., vacuum front entrance often).
  • Do not burn older pressure-treated wood (manufactured before 2004) and avoid using it for home projects.

Click here for the GNWT Arsenic Fact Sheet

*YKHEMP 2017-2018 baseline study found that in general, the arsenic levels of participants in Yellowknife, Ndilo and Dettah were lower compared with the rest of Canada. For more information refer to our 2020 Progress Report.


Naturally found in the environment, in air, soil, water, food, and drinking water.

  • Man-made activities like burning fossil fuels, mining, and manufacturing.
  • Batteries, radiation shielding, circuit boards. 
  • Ammunition. Canada has banned the use of lead shot for hunting but lead ammunition is still readily available.
  • Some consumer products like paints, ceramics, caulking, solder and pipes, although these are now very rare.

Lead poisoning is extremely rare in Canada. Children are more susceptible than adults to toxic effects of lead.

Short term (a brief exposure to an extremely high level):

  • Vomiting; Diarrhea; Convulsions; Coma, and death


Long term (exposure over months/years):

  • Development in children
  • Growth and hearing impairment
  • Brain development (intellectual and behaviour)
  • Damage to the nervous system
  • Impaired mental function o Weakness in fingers, wrists, and ankles
  • Small increases in blood pressure and increased risk of anemia
  • Kidney damage
  • Damage to reproductive system
  • Prenatal exposure is linked to premature birth, impaired growth, decreased mental abilities in infants.
  • Use steel, bismuth or iron shot to hunt.
  • Properly dispose of old lead-based paint, leaded gasoline, some ceramics or other lead containing products.
  • Prevent children from chewing or having mouth contact with surfaces that have been painted with lead-based paints.
  • Some make-up or hair dyes could contain lead, keep those products away from young children.
  • Thoroughly wash hands and faces, particularly of children, to avoid contact with potential lead dust or soil on food, dirty fingers, toys, or other objects.
  • Check water pipes in older (pre-1980’s) houses to check if pipes contain lead solder.


The main source of cadmium exposure is food, unless you are a smoker.

  • All soils and rocks, including coal and mineral fertilizers, contain some cadmium.
  • Cigarettes and other tobacco smoke.
  • In the workplace (battery manufacturing, metal soldering or welding).
  • Living near burning of fossil fuels or municipal waste.
  • There are low levels in all foods, but highest in shellfish, and liver and/or kidney of some animals such as moose.
  • Drinking contaminated water from untreated lakes, and rivers.
  • Cheap metal jewelry, including some charm bracelets.
  • Rechargeable batteries labeled NiCd or NiCad.

When cadmium enters the body, it is stored in the body for many years. Most of it will be stored in the kidneys. It could:

  • Affect brain development in young children.
  • Damage the lungs and kidneys.
  • Increase risk of lung cancer.
  • Weaken bones.
  • Do not smoke or let children breathe cigarette or other tobacco smoke.
  • Dispose of batteries correctly and keep them out of reach of children.
  • Eat a variety of foods to reduce your exposure to cadmium.
  • Do not let children wear or play with cheap metal jewelry or charm bracelets.
  • If you do any welding or metalworking, ensure your work area is well ventilated and use proper protective equipment.
  • Keep children away from welding fumes and other metal vapours and dusts.