Perchlorate (ClO4-) is an inorganic compound that occurs naturally in nitrate deposits and potash ore. It may also be present in air, soil, and water as a result of the industrial uses of perchlorate salts (perchlorate combined with another element or compound such as sodium or ammonium) and nitrate fertilizers. Perchlorate salts are primarily used in solid fuels, explosives, fireworks, road flares, air bag inflators, rubber manufacturing, paint and enamel manufacturing and pulp and paper processing. As a result of its ubiquitous presence in the environment, trace amounts of perchlorate may also enter the food chain.

In humans, high doses of perchlorate have been used to treat hyperthyroidism since it has the ability to disrupt the function of the thyroid gland by preventing the uptake of iodine. However, the potential exposure to perchlorate from the diet is expected to be orders of magnitude less than a therapeutic dose.

Health authorities became concerned with perchlorate when it was detected in a number of well water and drinking water supplies across the United States in the 1990s. However, it was mostly detected in water sources in proximity to military areas or perchlorate salt production facilities. Perchlorate has been detected in samples of ground and surface water in Canada, but levels are so low that there would be no human health concern associated with consuming this water. It has also been detected at low levels in certain foods.

What is Health Canada Doing?

Scientists at the Food Directorate of Health Canada have measured the levels of perchlorate in various foods available in Canada such as cow's milk, infant formula, fruits and vegetables. Preliminary estimates indicate that exposure to perchlorate in Canada is below levels that are expected to cause adverse health effects. This is similar to the conclusions derived by, for example, the United States (U.S.) Environmental Protection Agency, the U.S. Food and Drug Administration and the Joint Food and Agriculture/World Health Organization Expert Committee on Food Additives. Health Canada continues to review the data on occurrence of perchlorate in food as well as toxicological studies on perchlorate as they become available.

What Can You Do?

Health Canada is not recommending that Canadians change their dietary habits due to the presence of perchlorate in some foods at this time. Health Canada continues to recommend that Canadians consume a variety of foods from each food group according to Eating Well with Canada's Food Guide.

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