chemical Class

Tetrachlorinated dioxin

Chemicals in the class:

2,3,7,8-TCDD (tetradioxin), 2,3,7,8-tcdd

Found in these people:

Anonymous Adult 1, Monique Harden, U.S. Representative Louise Slaughter, Andrea Martin, Michael Lerner, Lexi Rome, Charlotte Brody, Davis Baltz, Sharyle Patton

Found in these locations:

New Orleans, LA; Upstate New York, NY; Sausalito, CA; Bolinas, CA; Mill Valley, CA; Round Hill, VA; Berkeley, CA


Laboratory animals. Dioxins cause toxicity to many organ systems in animals. Effects include liver and thyroid tumors; cardiovascular, skeletal, skin, immune, respiratory, neurological and reproductive toxicity; altered lipid and carbohydrate metabolism; reduced fertility and birth defects. Specific birth defects include reproductive tract and skeletal abnormalities, such as cleft palate (ATSDR 1998a). Dioxins are endocrine disruptors because they alter thyroid, reproductive, and adrenal hormone levels and function (ATSDR 1998a). Many of the lowest dose effects are developmental. For example, a one-time exposure to dioxin during fetal life can impair prostate development in male rats (Roman and Peterson 1998, Roman, et al. 1998, Timms, et al. 2002).

Humans. The effects of dioxins have been studied in humans who were exposed through diet, work, military service and industrial accidents. Dioxin (TCDD) is a known human carcinogen. It is associated with increased incidence of cancer in general and with non-Hodgkin's lymphoma and lung and soft-tissue cancer in particular (ATSDR 1998a, NTP 2002). Soft tissue includes muscle, fat, blood vessels or any of the other tissues that support, surround and protect organs of the body. Dioxin is also associated with non-cancer disorders including skin lesions (chloracne), and nervous system toxicity (ATSDR 1998a). Associations with other types of disorders are emerging. For example, recent follow-up of people exposed to an industrial explosion in Seveso, Italy (the highest known population exposure to TCDD) suggest that dioxin may also be associated with breast cancer (Warner, et al. 2002), menstrual irregularities (Eskenazi, et al. 2002), altered thyroid function, and diabetes (Kogevinas 2001). Risk of developing diabetes or glucose intolerance is also increased in military personnel who were exposed to dioxin-contaminated herbicide (Agent Orange) in the Vietnam War (Longnecker, et al. 2001). Although developmental effects of dioxin have not been adequately studied in humans, several studies have linked dioxin to altered sex ratio (in favor of females) (Mocarelli, et al. 2000).

Tetrachlorinated dioxin

Chlorinated dioxins are unwanted byproducts of the manufacture and burning of products that contain chlorine. Dioxins cause cancer in humans, and they are generally considered to be among the most toxic environmental contaminants known to man. As a class, dioxins are extremely toxic, persistent, bioaccumulative, and lipophilic ("fat-loving"). This means that dioxins build up and are stored in fatty tissues and fluids, such as breast milk, and can be passed on to fetuses and infants during pregnancy and lactation. Most people are exposed to dioxin through the food they eat, primarily from meat, dairy, fish and eggs.

In humans, dioxins are associated with cancer, skin lesions, damage to the nervous system and immune system, altered carbohydrate and lipid metabolism, thyroid disruption, altered menstrual cycling, and cardiovascular effects.

In laboratory animals, dioxins are known to cause a variety of effects including cancer and impaired reproductive, endocrine, cardiovascular, immune, respiratory, neurological and metabolic function. In addition, dioxins cause skin disease and birth defects.

Tetrachlorinated dioxin has been found in 11 of the 34 people tested in EWG/Commonweal studies.

Top health concerns for Tetrachlorinated dioxin (References)

health concern or target organ weight of evidence
Immune system (including sensitization and allergies)limited
Birth defects and developmental delaysunknown

Toxicity Classifications (References)

classification governing entity/references
Birth defects - weight of evidence unknown/unassessedATSDR (1998). Toxicological profile for chlorinated dibenzo-o-dioxins (CDDs): Health effects chapter.
Limited evidence in humans - immune system toxicityATSDR (1998). Toxicological profile for chlorinated dibenzo-o-dioxins (CDDs): Health effects chapter.