Dioxins build up in living tissue (bioaccumulate) over time, so even small exposures may accumulate to dangerous levels.

Excessive exposure to dioxin may cause a severe form of persistent acne, known as chloracne. This is the only known direct result of dioxin exposure at levels below the lethal dose. Other possible effects may be

• Developmental abnormalities in the enamel of children's teeth.[2]
• Damage to the Immune systems.[3]
• Endometriosis
• Birth defects
• Diabetes
• And at least in laboratory animals, increased rates of liver and lung cancer are observed

Yes. The EPA report confirmed that dioxin is a cancer hazard to people. In 1997, the International Agency for Research on Cancer (IARC) -- part of the World Health Organization -- published their research into dioxins and furans and announced on February 14, 1997, that the most potent dioxin, 2,3,7,8-TCDD, is a now considered a Class 1 carcinogen, meaning a "known human carcinogen" (source: IARC Monographs, Volume 69).

Also, in January 2001, the U.S. National Toxicology Program upgraded 2,3,7,8-TCDD from "Reasonably Anticipated to be a Human Carcinogen" to "Known to be a Human Carcinogen." See their reports on dioxins and furans from their most recent 10th Report on Carcinogens. Finally, a 2003 re-analysis of the cancer risk from dioxin reaffirmed that there is no known "safe dose" or "threshold" below which dioxin will not cause cancer.

A July 2002 study shows dioxin to be related to increased incidence of breast cancer

In addition to cancer, exposure to dioxin can also cause severe reproductive and developmental problems (at levels 100 times lower than those associated with its cancer causing effects). Dioxin is well-known for its ability to damage the immune system and interfere with hormonal systems.

Dioxin exposure has been linked to birth defects, inability to maintain pregnancy, decreased fertility, reduced sperm counts, endometriosis, diabetes, learning disabilities, immune system suppression, lung problems, skin disorders, lowered testosterone levels and much more. For an detailed list of health problems related to dioxin, read the People's Report on Dioxin.