Asbestos at Thetford Mines, Quebec Canada

Author: Wyatt Anthony

This case study is part of a collection of pages developed by students in the 2012 introductory-level Geology and Human Health course in the Department of Earth Sciences, Montana State University. Learn more about this project.

After being the focal point for the economies of nations such as Canada for a century, the asbestos industry looks to be all but dead. The health hazards that this silky-white product presents are now seen to outweigh the benefits of its fire, rust, and rot resistance, tensile strength, and sound absorption.


In 1876 large deposits of asbestos were discovered near what is now Thetford Mines in Quebec Canada. It quickly became one of the largest asbestos producing regions in the world as Canada began to supply more asbestos than any other country in the world. The fiber was valued for its unique fire, rust, and rot resistance, as well as its tensile strength and sound absorption. It was even referred to as the miracle fiber for these rare, valuable properties. Before the true nature of the health hazards that asbestos presented were discovered it was used extensively in the construction of buildings and Navy vessels. Many buildings built around the 1960s during the heyday of asbestos were constructed with many products that contain asbestos fibers. The governments of most developed countries have place restrictions on the use of asbestos. In many cases the use of asbestos is no longer permitted and strict regulations have been placed on the silky white fiber. It is now clear that extensive exposure to asbestos can greatly increase the risk of lung cancer and other health problems related to the respertory system. This web page will cover the history of asbestos mining in Canada, the health hazards related to asbestos, and steps that can be taken to avoid repertory damage from asbestos fibers.

Good resource for Asbestos

Sources of Asbestos

The most common mineral type of asbestos is chrysotile and this is the type present at the location of Thetford Mines. This particular type is white in color and shares the same characteristics of the other variations of asbestos. It occurs naturally as long, thin fibers that are similar to fiberglass. Although the different types of asbestos largely share the same characteristics they do vary in color ranging from white (chrystotile), gray (anthophyllite), brown (amosite), and blue (crocidolite). Chrysotile is part of a group of sheet silicates which is called serpentine. These are formed when hot water reacts with a type of igneous rock called peridotite. This reaction creates silicates throughout the rock, but the chrysotile is only found in the veins in the rock. These veins are what is then mined and made into a variety of products.

Transport of Asbestos

Asbestos is concentrated in veins or bundles in the rock and is formed through volcanic activity. When this activity subsides and cools asbestos is formed in fissures in the rock. It is mined in much the same way iron, lead, and copper are; however, when these are crushed they turn to dust. When asbestos is crushed it turns up into small fibers that are too small to be seen by the human eye. In this form asbestos presents the largest health risk for humans. The tiny particles can easily become airborne and inhaled, leading to a large variety of repertory illnesses.


Asbestos poses the greatest health risk when it becomes crushed into microscopic fibers. In this state it enters the air and can be inhaled by anyone ranging from miners, to members of a nearby community. It also poses a threat even when it has been made into a finished product. If a product such as a ceiling tile constructed with asbestos is broken, the tiny asbestos fibers are released into the air and become a threat to anyone in the area. Today the majority of airborne asbestos comes from places where asbestos is naturally exposed at the earths surface, or from the breakdown of man-made products such as asbestos shingles or tiles.

asbestos affects on humans

Impacts on Human Health

The specific type of asbestos that is found at Thetford Mines is chrysotile. While this strand is less harmful compared to other strands such as amphibole, it still poses major health risks to the miners and the community that is now built up around the mine. The fibers enter the body through respiration and are caught in your air passages and in your lungs. Many of these fibers do not say lodged in your repertory system and are instead trapped in mucus and swallowed into the stomach. The majority of the asbestos fibers that are swallowed pass through the body; however some can remain stuck to the cells that line your stomach and even a smaller amount are absorbed through the lining of the stomach and the intestines. Some fibers that are carried deeper into the lungs take longer to remove or they may never be removed. The U.S. Department of Health and Human Services has determined that asbestos in a carcinogen as it causes cancer in humans. The two main types of cancer associated with asbestos are cancer of the lung tissue itself and mesothelioma. Mesothelioma is a cancer in the thin membrane that surrounds the lung along with other internal organs. Both of these cancers are fatal in most cases.

Prevention or Mitigation

The biggest threat posed by asbestos today comes from old buildings that were constructed before the true dangers of asbestos were known. Many buildings still contain asbestos tiles and insulations and billions of dollars have been spent over the last 30 years to limit people's exposure to asbestos. A step that individuals can take to reduce their exposure to asbestos is to make sure that their homes do not contain products made with asbestos. If it does, report this to a company that is certified in dealing with asbestos products. If this process is not handled properly large amounts of asbestos fibers can be released into the air.

Recommended Readings

Asbestos Strategies: Lessons Learned About Management and Use of Asbestos. Global Environment & Technology Foundation. May 16th 2003

This article contains a vast amount of information on the topic of how to reduce the risk of asbestos exposure.

Related Links

  • United States Department of Labor

Outiles the hazards of asbestos mining and asbestos products in the work place.

  • National Cancer Institute. Asbestos Exposure and Cancer Risk

This website gives a good overview of the topic and covers the related health risks.

  • EPA Asbestos

This cite shows how to be aware of the threat of asbestos and the steps that can be taken to reduce the risk.

  • "Town built on Asbestos Downplays Health Risks" Mines and Communities. Michelle Lalonde, Montreal Gazette

This article is based on interviews and research done in Thetford Mines. The opinions of the locals living around the mine are very different than what one might expect.

  • "Where Does Crysotile Form?"

This site gives an easily understood explanation of how crysotile asbestos is formed.