Dioxins and furans

Source: Health Canada

Dioxins and furans

Dioxins and furans are the common names of toxic chemicals found in very small amounts in the environment, including air, water and soil. Because they are present in the environment, they are also found in some foods.

Exposure to dioxins and furans has been associated with a wide range of adverse health effects in humans and laboratory animals. The type and frequency of adverse reactions generally depend on the duration and level of exposure.

There are 210 different dioxins and furans. All have the same dioxins "structure" chemical base and have all of the chlorine atoms. This is the same for furans, except that their chemical structure is different. The toxicity of these substances varies greatly. This is the most toxic is called 2,3,7,8-TCDD or simply TCDD.

Sources of dioxins and furans

The large-scale incineration of municipal and medical waste is the largest source of dioxins and furans in Canada. Other important sources include:

• The production of iron and steel;
• Burning of household waste, especially plastics;
• Fuel oil, diesel, agricultural fuels and heating oil;
• Heating with wood, especially treated wood;
• Power generation;
• Tobacco smoke.

Dioxins can also result from natural causes such as forest fires and volcanic eruptions. Most dioxins are introduced into the environment through the air. The chemicals in the air can attach to small particles and thus travel considerable distances in the atmosphere, which means that Canadians may be exposed to dioxins and furans produced in other countries.

Dioxins and furans are found in the food chain because they remain stored in fatty tissues of animals. This is the reason why people consume a greater amount of dioxins and furans from the food by air, water or soil. Eighty-five percent of dioxin exposure is through food. Meat, dairy products and fish contain higher concentrations of dioxins and furans as fruits, vegetables and grains.

Effects of dioxins and furans on Health

Scientists have studied the effects of dioxins and furans in laboratory animals. They also studied the effects on the health of people who were exposed to dioxin as a result of an occupational accident or exposure to certain herbicides before the adoption of improved manufacturing processes to reduce these contaminants.

Studies show that dioxins and furans can have many effects on the health of animals and humans. Among the health effects associated with human exposure to dioxins include:

• Skin diseases, such as chloracne;
• Liver problems;Weakened immune system, the endocrine system and reproductive functions;
• Effects on the developing nervous system and other developmental;
• Certain types of cancers.

It is important to remember that with any chemicals, including dioxins, health risk depends on many factors, including:

• The type of exposure (food, air, water, etc.);
• The degree and frequency of exposure (eg, single exposure to a high concentration or daily exposure to low concentrations.); 
• Individual vulnerability, such as overall health status;
• Exposure to other substances that may affect health.

It is a complex problem that scientists do not have all the answers, but they agree that the degree of exposure to dioxins and furans should be as low as possible.