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Food and Nutrition

Chemical Contaminants

Food contaminants and other adulterating substances are chemicals that may be present in foods at levels that could impact the overall safety and/or quality of foods. These substances can either be inadvertently present in foods or in some cases, have been intentionally added for fraudulent purposes.

Health Canada scientists are responsible for the assessment of risks to human health from exposure to food-borne chemical contaminants and other adulterating substances. Health Canada and the Canadian Food Inspection Agency (CFIA) conduct regular surveillance of the levels of chemical contaminants in the Canadian food supply. Health Canada uses this information to estimate dietary exposure of Canadians to these substances. 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 is used to determine if dietary exposure to specific substances would result in a potential safety concern. Risk assessments also provide a basis for developing appropriate strategies to mitigate the risk of adverse health effects from exposure to contaminants in foods.

Risk management strategies vary depending on the situation. These types of actions can include providing advice and guidance to Canadians on the risks and benefits of particular food choices, providing direction on how to reduce contaminant levels, or setting maximum levels for contaminants in foods. For certain adulterating substances, a "zero tolerance" approach may be taken, which means that no amount of the substance in question would be considered acceptable in foods.

Health Canada's Maximum Levels for Chemical Contaminants in Foods are the maximum levels that are established by Health Canada and enforced by the Canadian Food Inspection Agency

Most chemical contaminants are inadvertently present in foods for one of many possible reasons, as summarised below:

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.

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.

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 Point Source Contamination

  • 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 minimize the chances of accidental point sources of contamination. The CFIA's Food Safety Enhancement Program is an example of this.

Adulteration

  • Intentional addition of a chemical to a food for fraudulent purposes (e.g. intentionally substituting one ingredient for another and misrepresenting the final product)

Join Health Canada's Chemical Contaminants e-Notice, a free notification service for 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: