Trade Secrets
Example: 2,3,7,8-TCDD (tetradioxin), 2,3,4,7,8-PeCDF (pentafuran)

Potential Health Effects in Humans and Animals:

Dioxin is classified by the National Toxicology Program and the World Health Organization as a known human carcinogen. Dioxin causes increases in cancers throughout the body and is believed to intensify the effects of other toxic chemicals. Some workers with high level exposures developed rare cancers of connective and soft tissues called soft tissue sarcomas. Dioxin is a known endocrine disrupter. It causes chloracne skin lesions in humans and is toxic to the nervous system and liver. Based on animal tests and some evidence in humans, dioxin is also suspected to cause immune system and thyroid damage, diabetes, endometriosis, testicular atrophy, lowered testosterone levels and developmental and reproductive problems.

There is broad scientific agreement that dioxins and furans are among the most toxic chemical compounds known. Furans are chemically similar to dioxins and generally exert the same types of toxic effects.

Bill Moyers had the highest overall levels of dioxin-like compounds in his test group. Other much larger studies have found levels similar to Moyers' in all who have been tested. According to the Environmental Protection Agency, these exposures are “uncomfortably close” to levels that cause health problems in laboratory animals and are “likely to result in an increased risk of cancer” in humans - possibly as many as 1 extra cancer for every 100 people. In January 2001, the National Toxicology Program at the National Institutes of Health added dioxin to the list of known human carcinogens.

Dioxin is an unwanted byproduct of the manufacture and burning of products that contain chlorine. The incineration of plastics made of polyvinyl chloride (PVC) is a major source. So are paper mills that bleach wood pulp with chlorine. Incinerators across the country discharge dioxins every day. Even backyard burning of plastic trash can produce dioxins.

Once dioxin enters the environment, it attaches to dust particles and can be carried long distances by the wind. From there, dioxin molecules are absorbed by plants and small organisms, moving up the food chain to fish, animals and humans.

Most people in the general population are exposed to dioxin through the food they eat – primarily meat, dairy, fish and eggs. People who consume large amounts of fatty meat and fish probably get the most, but dioxin is also found at lower levels in grains, fruits and vegetables. Infants get dioxin in breast milk.

A recent EPA study found dioxin contamination in limestone dust from cement kilns that burn toxic waste as fuel. According to EPA, the tainted lime dust is sometimes recycled as fertilizer. Most states have no restrictions on the use of such fertilizers on food crops.

No data are available on current dioxin releases from specific industries. In 1999, EPA added dioxin to the list of chemicals that must be reported on the Toxic Releases Inventory, but no information on dioxin will be available under TRI until July 2001.

In 1991, EPA began a major reassessment of dioxin’s health effects – but ten years later - as of March 2001, the EPA’s final report had not been approved. The agency attributes the long process to the complexities of new scientific findings– but also acknowledges that controversy over dioxin’s toxicity contributed to the delay. Industries linked to dioxin contamination have challenged nearly every aspect of the reassessment. Many people fear that the long delay will interfere with efforts to impose stricter regulations on industries and incinerators, although EPA has taken some steps in the interim to tighten restrictions on dioxin emissions from paper mills and cement kilns.

For more information on the health effects of dioxin, visit EPA’s dioxin reassessment pages:



Highlights of the reassessment:

pdf - http://www.epa.gov/ncea/pdfs/

Dioxin health effects chapters:


For information on dioxin and cancer, go to the National Toxicology Program page:

pdf - http://ehis.niehs.nih.gov/roc/ninth/known/tcdd.pdf

Persistent, Bioaccumulative and Toxic Chemicals – dioxin fact sheet:


Full list of sources available via e-mail

Dioxin is an unwanted byproduct of the manufacture and burning of products that contain chlorine. The incineration of plastics made of polyvinyl chloride (PVC) is a major source.

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Photo Credits: Elaine Ross