PCBs in Food and Environment

by Health Canada

Low levels of PCBs are found in the environment, and as result, in foods. The presence of these contaminants in foods and the environment means that everyone can be exposed to very low levels of PCBs.

Exposure to these low levels does not appear to affect human health. However, PCBs can accumulate in the human body and remain there for years. This edition of It's Your Health addresses concerns about health effects that may develop over time.

PCBs stands for Polychlorinated Biphenyls. The name refers to any one, or any combination of 209 specific chemicals that are similar in structure. PCBs are extremely persistent. They last for many years because they do not break down easily on their own and they are difficult to destroy.

PCBs were first manufactured in 1929. For several decades, they were used widely as ingredients in many industrial materials, such as sealing and caulking compounds, cutting oils, inks and paint additives. PCBs were also used to make coolants and lubricants for certain kinds of electrical equipment, such as transformers and capacitors.

Attention began to focus on potential hazards linked to the use and disposal of PCBs, when the presence of PCBs was detected in the Great Lakes for the first time in 1966. By 1977, concern over the impact of PCBs on the environment led to a North American ban on manufacturing and importing PCBs. The ban did not cover PCBs that were already in use in electrical applications. These are being phased out now, and the federal government has set strict regulations for the handling, storage and disposal of PCBs.

Where PCBs are Found Today

Trace levels of PCBs in the environment (air and water) are found all over the world, including remote areas of Canada. Some of this was caused by accidental releases and improper disposal practices in the past, but today, contamination is due primarily to the long-range transport of PCBs by global air currents. Once PCBs get into the environment, they accumulate in the cells of animals. The highest concentrations are found in animals at the top of the food chain, including humans.

PCBs are still present in certain types of electrical equipment. Also, public concern over disposal practices has led to the storage of PCBs in many facilities around the country. In some instances, PCBs have been put into specially engineered landfills. Despite strict controls on the handling and storage of PCBs, there remains the potential for accidental releases into the environment.

How Canadians are Exposed to PCBs

Everyone is exposed to very small amounts of PCBs through food, and to a lesser extent, through air, soil and water. As a result, all Canadians have PCBs in their bodies. These low levels are unlikely to cause adverse health effects. Based on recent results from Total Diet Studies (a series of studies organized by Health Canada), the average daily dietary intake of PCBs is thought to be less than half of one microgram (one microgram = one-millionth of a gram). People who eat large amounts of sports fish, wildlife or marine mammals may be exposed to higher dietary levels of PCBs.

There is a risk of workplace exposure for people who replace or service old electrical equipment, and for those who transport PCBs to storage and destruction facilities or handle PCBs at these sites. Workers involved in these activities should wear protective clothing and follow prescribed decontamination procedures when they complete their work.

Canadians could also be exposed to PCBs through accidental releases, including uncontrolled fires involving PCBs. In these situations, several different things could happen:

PCBs could be released in liquid form. They could then contaminate soil or water nearby.

High temperatures in a fire could turn liquid PCBs into an aerosol form. If this happens, the PCBs could be inhaled. They could also be transported somewhere else by air currents.

When PCBs are burned at high temperatures, the process can turn them into different substances called dioxins and furans, which are far more toxic than PCBs.

About the Author

www.hc-sc.gc.ca
Health Canada is the Federal department responsible for helping Canadians maintain and improve their health, while respecting individual choices and circumstances.