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Food and Nutrition

Chemical Contaminants

Health Canada scientists are responsible for the assessment of risks to human health from exposure to food-borne chemical contaminants. They undertake regular surveillance to monitor the levels of contaminants in foods and estimate the exposure of Canadians to these contaminants. Health Canada scientists also conduct research and evaluate scientific data in order to better understand the effects that chemicals can have on the human body. Each of these activities is an essential component of a risk assessment, which provides a basis for developing appropriate strategies to reduce or eliminate the risk of adverse health effects from exposure to chemicals.

Risk management strategies vary depending on the situation. Actions range from providing advice and guidance to Canadians on the risks and benefits of particular food choices, to providing direction on how to reduce contaminant levels, to setting permissible maximum levels in foods:

Canadian Standards ("Maximum Limits") for Various Chemical Contaminants in Foods - the maximum limits that are established by Health Canada are enforced by the Canadian Food Inspection Agency.

In the context of foods, chemical contaminants can be very broadly defined as any chemical not intentionally added to food but present for one of many possible reasons:

Environmental Contamination

  • Certain chemicals are manufactured for industrial use and because they are very stable, they do not break down easily. If released to the environment, they can enter the food chain.
  • Other chemicals are naturally occurring, but industrial activities may increase their mobility, allowing them to enter the food chain at higher levels than would otherwise occur.

Food-Processing-Induced Contamination

  • Undesirable chemicals can be formed in certain foods during processing as a result of reactions between compounds that are natural components of the food.
  • In some cases an undesirable chemical may be formed as a result of a food additive being intentionally added to food and reacting with another compound in the food.

Presence of Natural Toxins

  • Under certain conditions, some plants have the capacity to naturally produce compounds that are toxic to humans when ingested.
  • Certain climatic conditions may favour the growth of toxin-producing fungi on food crops (toxins produced by fungi are called "mycotoxins").
  • Shellfish may contain toxins as a result of filter-feeding on microscopic algae. In such a case, the algal toxin does not harm the shellfish but can be harmful to humans.

Accidental Contamination at a "Point Source"

  • Contamination during the preparation and packaging of processed foods.
  • Contamination of raw food commodities where grown (in the case of plants) or where raised (in the case of animals).
  • Contamination during transport or storage.

There are various programs in place, many of which have been developed by or with the support of the Canadian Food Inspection Agency (CFIA), that serve to guide those involved in food production, processing, and distribution in order to minimise the chances of accidental "point sources" (stages of production when contamination could occur) of contamination. The CFIA's Next link will take you to another Web site Food Safety Enhancement Program is an example of this.

Join Health Canada's Chemical Contaminants e-Notice, a free service to stay on top of issued advice as well as regulatory and scientific developments in the area of food chemical contaminants in Canada.

For More Information

Health Canada:

Food Surveillance

Canadian Food Inspection Agency: