Ingestion of excessive amounts of contaminants (such as lead, mercury, arsenic, cadmium, PCBs, dioxins) and other chemicals (such as pesticides) through the food supply can have detrimental effects on the health of consumers. Thus, it is essential to analyse the foods we eat for contaminants and other chemicals through regular monitoring and surveillance programs to assure that chemical levels found in foods remain safely within acceptable national and international guidelines.
As part of its mandate to ensure that chemicals are not present in foods at levels that would pose an unacceptable risk to health, the Bureau of Chemical Safety, in Health Canada’s Food Directorate is responsible for carrying out Canada’s Total Diet Study (TDS). The TDS provides estimate levels of exposure to chemicals that Canadians in different age-sex groups accumulate through the food supply. Total Diet Studies are also referred to as a Market Basket Surveys Studies by other countries / jurisdictions. This type of study is recommended by the World Health Organization as an important activity for its member nations to undertake, as it provides reliable estimates of dietary intakes of contaminants.
Since 1969, Health Canada has repeated its Total Diet Study (TDS) over six separate periods. The first Total Diet Study was conducted between 1969 and 1973, the second ran from 1976 to 1978, the third from 1985 to 1988, the fourth from 1992 to 1999, the fifth ran from 2000 to 2004, and the most recent one was started in 2005. These studies are organized by the Food Research Division in the Bureau of Chemical Safety, and are supported by partners both within Health Canada (e.g.: the Nutrition Research and Evaluation Divisions, the Regional Laboratories of the Health Products and Food Branch, the Pest Management Regulatory Agency) and outside of Health Canada (e.g.: the Canadian Food Inspection Agency).
Each TDS study is conducted in several major Canadian cities over the span of the survey period, normally one city each year. For example, the studies from 1992 to present were conducted in the following cities:
For each city, each individual food item tested (there are about 210 individual food items for the current Canadian Total Diet Study) is purchased from three to four different supermarkets. Food samples are sent to Kemptville College where they are prepared and processed as they ‘would be consumed’ in the average household kitchen (i.e., raw meats are cooked; fresh vegetables cooked or properly peeled, trimmed or otherwise cleaned for serving if not cooked). These processed foods are then mixed according to each category to make composites (there are over 140 different food composites in the current study). All food composites are analysed for the presence of toxic and nutritionally important chemicals. These concentrations are then combined with food intake information (estimates of how much Canadians consume of each food group) to provide estimates of the dietary intakes of these chemicals for Canadians in the following 16 different age-sex groups:
Concentrations of contaminants and other chemicals in foods, as well as the corresponding dietary intakes for Canadians in different age-sex groups from Total Diet Studies carried out since 1992 are presented here as public information. Please consult the list of publications for the findings from previous Canadian Total Diet Studies. In an effort to improve public access to this type of information, The Bureau of Chemical Safety will continue to publish its survey results once available for publication.
For more information, please contact:
Bureau of Chemical Safety
Health Products and Food Branch
Postal Locator 2203G2
Telephone: (613) 957-0973
Fax: (613) 954-4674