TCDD Hazard Summary
Hazard Summary 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is formed as an unintentional by-product of incomplete combustion. It may be released to the environment during the combustion of fossil fuels and wood, and during the incineration of municipal and industrial wastes. It causes chloracne in humans, a severe acne-like condition. It is known to be a developmental toxicant in animals, causing skeletal deformities, kidney defects, and weakened immune responses in the offspring of animals exposed to 2,3,7,8-TCDD during pregnancy. Human studies have shown an association between 2,3,7,8-TCDD and soft-tissue sarcomas, lymphomas, and stomach carcinomas. EPA has classified 2,3,7,8- TCDD as a probable human carcinogen (Group B2).
Assessing Personal Exposure
Body fat, blood, and breast milk may be analyzed for 2,3,7,8-TCDD.
Health Hazard Information
The major acute (short-term) effect from exposure of humans to high levels of 2,3,7,8-TCDD in air is chloracne, a severe acne-like condition that can develop within months of first exposure. Acute animal tests in dogs, monkeys, and guinea pigs have shown 2,3,7,8-TCDD to have extreme toxicity from oral exposure.
Chronic Effects (Noncancer):
Chronic Effects (Noncancer): Chloracne is also the major effect seen from chronic (long-term) exposure to 2,3,7,8-TCDD in humans. (1) Animal studies have reported hair loss, loss of body weight, and a weakened immune system from oral exposure to 2,3,7,8-TCDD. (1) EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for 2,3,7,8-TCDD. ATSDR has calculated a chronic oral minimal risk level (MRL) of 1 x 10-9 milligrams per kilogram body weight per day (mg/kg/d) based on neurological effects in monkeys. The MRL is an estimate of daily exposure to a dose of a chemical that is likely to be without appreciable risk of adverse noncancerous effects over a specified duration of exposure. Exposure to a level above the MRL does not mean that adverse effects will occur. The MRL is used by public health professionals as a screening tool.
The results of available reproductive and developmental studies in humans are inconclusive. (1) Animal studies have reported developmental effects, such as skeletal deformities, kidney defects, and weakened immune responses in the offspring of animals exposed to 2,3,7,8-TCDD during pregnancy. (1) Reproductive effects, including altered levels of sex hormones, reduced production of sperm, and increased rates of miscarriages, have been seen in animals exposed to 2,3,7,8-TCDD.
Human studies, primarily of workers occupationally exposed to 2,3,7,8-TCDD by inhalation, have found an association between 2,3,7,8-TCDD and lung cancer, soft-tissue sarcomas, lymphomas, and stomach carcinomas, although for malignant lymphomas, the increase in risk is not consistent. (1) No information is available on the carcinogenic effects of 2,3,7,8-TCDD in animals following inhalation exposure. (1) Animal studies have reported tumors of the liver, lung, tongue, thyroid, and nasal turbinates from oral exposure to 2,3,7,8-TCDD. (1) EPA has classified 2,3,7,8-TCDD as a Group B2; probable human carcinogen. (2,3) EPA has calculated an inhalation cancer slope factor of 1.5x10 5 (mg/kg/d) -1 and an inhalation unit risk estimate of 3.3 x 10 -5 (pg/m 3 ) -1 for 2,3,7,8-TCDD. (2,3) EPA has calculated an oral cancer slope factor of 1.5 x 10 5 (mg/kg/d) -1 and an oral unit risk factor of 4.5 (µg/L) -1 for 2,3,7,8-TCDD. (2,3)
My uncle Joseph Stetler served in Vietnam and died of lymphoma. I've witnessed how much he suffered and I wish I could offer help, any help, to whom needs it. God bless you.