There are three closely-related families of dioxins and of these families, there are several hundred individual varieties: the chlorinated dibenzo-p-dioxins (CDDs), chlorinated dibenzofurans (CDFs) and certain polychlorinated biphenyls (PCBs). One chemical in the first group, 2,3,7,8-tetrachlorodibenzo-p-dioxin or 2,3,7,8-TCDD, has been shown to be very toxic in animal studies and is the one most studied.



It causes effects on the skin and may cause cancer in humans.

Usually, dioxins are accidently produced within the manufacturing industry, and the only time they have been used is for the purpose of research. They (mainly 2,3,7,8-TCDD) may be formed during the chlorine bleaching process at pulp and paper mills. Dioxins are also formed during chlorination by waste and drinking water treatment plants. They can occur as contaminants in the manufacture of certain organic chemicals. Dioxins are released into the air in emissions from municipal solid waste and industrial incinerators.

How can dioxins affect my health?

Chloracne is the most notable adverse health effect of dioxin exposure among indiviudals, which exposes them to the largest amounts of 2,3,7,8-TCDD. Chloracne is a severe skin disease with acne-like lesions that occur mainly on the face and upper body. Other skin effects noted in people exposed to high doses of 2,3,7,8-TCDD include skin rashes, discoloration, and excessive body hair. Changes in blood and urine that may indicate liver damage also are seen in people. Exposure to high concentrations of dioxins may induce long-term alterations in glucose metabolism and subtle changes in hormonal levels.

In certain animal species, 2,3,7,8-TCDD is especially harmful and can cause death after a single exposure. Exposure to lower levels can cause a variety of health effects in animals, such as weight loss, liver damage, and disruption of the endocrine system. For many species the exposure to the 2,3,7,8-TCDD causes the immune system to become weakened and eventually halts the ability to combat viruses and bacteria. In other animal studies, exposure to 2,3,7,8-TCDD has caused reproductive damage and birth defects. Some animal species exposed to dioxins during pregnancy had miscarriages. The offspring of animals exposed to 2,3,7,8-TCDD during pregnancy often had severe birth defects including skeletal deformities, kidney defects, and weakened immune responses. How likely are dioxins to cause cancer?

Several studies suggest that exposure to 2,3,7,8-TCDD increases the risk of several types of cancer in people. Animal studies have also shown an increased risk of cancer from exposure to 2,3,7,8-TCDD. The World Health Organization (WHO) has determined that 2,3,7,8-TCDD is a human carcinogen (a substance that causes cancer). The Department of Health and Human Services (DHHS) has determined that 2,3,7,8-TCDD may reasonably be anticipated to cause cancer. How can dioxins affect children?

Very few studies have looked at the effects of dioxins on children. Chloracne has been seen in children exposed to high levels of dioxins. It is unknown whether dioxins affect the ability of people to have children or if it causes birth defects, but given the effects observed in animal studies, this cannot be ruled out. How can families reduce the risk of exposure to dioxins?

Children should avoid playing in soils near uncontrolled hazardous waste sites. Children should be discouraged from eating dirt or putting toys or other objects in their mouths. Everyone should wash hands frequently if playing or working near uncontrolled hazardous waste sites. For new mothers and young children, restrict eating foods from the proximity of uncontrolled sites with known dioxins. How do I determine my dioxin exposure level?

Tests are available to measure CDD levels in body fat, blood, and breast milk, but these tests are not routinely available. Most people have low levels of dioxins in their body fat and blood, and levels considerably above these levels indicate past exposure to above-normal levels of 2,3,7,8-TCDD. Although dioxins stay in body fat for a long time, tests cannot be used to determine when exposure to the dioxin occurred. Has the federal government made recommendations to protect human health from dioxin exposure?

The Environmental Protection Agency (EPA) has set a limit of 0.00003 micrograms of 2,3,7,8-TCDD per liter of drinking water (0.00003 ?g/L). Discharges, spills, or accidental releases of 1 pound or more of 2,3,7,8-TCDD must be reported to EPA. It has been recommended by the U.S. Food and Drug Administration (FDA) that consumption of fish and shellfish with levels of 2,3,7,8-TCDD that are greater than 50 parts per trillion (ppt) is unsafe.