North American companies have been banned from making PCBs since the 1970's. But they are still found in soil, plants, animals, and humans. The main reason for this is that many people were not careful when they disposed of electrical equipment or oils that contained PCBs. Today, most of us are exposed to PCBs mainly through the food we eat. Metals Metals occur naturally, and can also result from activities related to our lifestyles.
Heavy metals cause the most problems, since even low doses are toxic.
Municipal and industrial wastes are the main sources. In most cases, we are exposed to these metals from the air and the food we eat. DDT Humans created DDT to be used in farming and controlling insects. It has been banned in Canada since 1989. This question was prepared for the Canadian Health Network by Ontario Healthy Communities Coalition .