Questions and Answers

What is dioxin?

Dioxin is the name of a family of chemical compounds that are unintentional byproducts of certain industrial, non-industrial and natural processes, usually involving combustion.

Different dioxin compounds have different toxicities.  Sometimes the term dioxin is also used to refer to TCDD, the most well studied and most toxic form of dioxin.  The many different types of dioxin actually vary greatly in toxicity -- some of them 10,000 times less toxic than TCDD.

Where does dioxin come from?

No one makes dioxin on purpose. Historically, incinerators, the manufacture of certain herbicides, and pulp and paper bleaching were among the largest industrial sources of dioxin.  However, according to the Environmental Protection Agency (EPA) data, regulations and voluntary changes by industry have dramatically reduced dioxin releases from these industrial sources by 90 80% between 1987 and 2000 1995, with releases expected to drop by more than 90% within the next few years as new regulations are fully implemented.

How much dioxin am I exposed to?

Levels of dioxin in food -- which account for 95 percent of our exposure to dioxin -- have been cut in half over the past seven years. ^[1]  EPA has clearly emphasized that the U.S. food supply is among the safest and most nutritious in the world. ^[2]

The World Health Organization sets its Tolerable Daily Intake (TDI) at a range of 1 to 4 pg/kg/bw/day (picograms per kilogram of body weight per day) for adults. A picogram is one-trillionth of a gram. EPA estimates that the average U.S. adult intake is 0.5 to 1 pg/kg/bw/day, clearly within, or below, that range.

People today are exposed to less dioxin than at any time in the recent past. According to EPA, the amount of dioxin in the average person's body has declined by more than 50% since the late 1980s. ^[3]  Studies of levels of dioxin in human breast milk, blood and fat tissue all show significant declines -- with decreases ranging from 50 to 70 percent between 1980 and 1996. ^[4]

Over the past 30 years, researchers have conducted many studies to investigate the potential for adverse health effects from accumulated levels of dioxin in people's bodies. According to EPA, "currently there is no clear indication of increased disease in the general population attributable to dioxin-like compounds." ^[6]

Adverse health effects related to dioxin -- such as chloracne, a severe skin condition -- have only been seen in people exposed to extremely large quantities of dioxin. Extensive studies of people exposed to relatively high levels of dioxin through occupational exposures, accidents or military service do not suggest that adverse effects to human health will occur at the low levels in today's environment.

A large historical study of workers showed increased rates of cancer, possibly from dioxin. However, those rates were only seen in workers exposed for many years at amounts 100 to 10,000 times more than the general population. ^[7]  Exposure to other chemicals and cigarette smoking may also have affected the results of the study, published in the May 1999 Journal of the National Cancer Institute.

What are companies and the government doing about dioxin?

Government and industry have worked together to reduce dioxin emissions dramatically since the 1970s. According to EPA data, as a result of these efforts, known industrial emissions in the United States have been ill be reduced by more than 90% since 1987. ^[8] 

Environmental Levels of Dioxins and Furans Have Dropped Dramatically Over the Past 25 Years [9]

Since 95% of human exposure to dioxin is through the diet, exposure levels are generally more a function of what we eat rather than where we live. Our food comes from a wide range of sources throughout the world. Recent studies suggest that the source of food items has little impact on dioxin levels in human blood serum. ^[10] Therefore, living near an industrial facility does not necessarily mean that you are exposed to higher levels of dioxin than the overall population.

Is there anything I can do to reduce my exposure to dioxin?

The EPA, FDA and other agencies note that since dioxin accumulates in animal fats, following normal dietary recommendations for a healthy, low-fat diet is the best way to reduce the potential for dioxin exposure. 

"The best strategy for lowering the risk of dioxins while maintaining the benefits of a good diet, according to the agencies," is to follow the recommendations in the Dietary Guidelines to choose fish, lean meat, poultry, and low or fat-free (skim) dairy products and to increase consumption of fruits, vegetables and grain products..^[11] 

Yet while recognizing people’s concern over dioxin exposure, the Environmental Protection Agency, Food and Drug Administration, and other federal agencies stress that the U.S. food supply is among the safest and most nutritious in the world.  Neither agency recommends avoiding specific foods or taking any special precautions to avoid dioxin exposure.

Why am I hearing about dioxins now?

EPA’s Toxics Release Inventory was established in 1986 to track information on 650 chemical substances manufactured, processed or used by U.S. production facilities each year.  EPA may add or remove chemicals to the TRI list based on their toxicity.  Dioxin was added to the TRI for reporting purposes beginning in the year 2000.

^[1] Assessment of the Health Risk of Dioxins: Re-Evaluation of the Tolerable Daily Intake (TDI), Executive Summary, World Health Organization, 1998.

^[2] Questions and Answers About Dioxins, Interagency Working Group on Dioxin (representatives from the U.S.  Environmental Protection Agency, Department of Health and Human Services, Department of Agriculture, Department of Veterans Affairs, Department of Commerce, Department of State, and the White House Office of Science and Technology Policy), October 2004.

^[3] Draft Dioxin Reassessment, Environmental Protection Agency, September 2000.

^[4] Päpke, O., "PCDD/PCDF: Human Background Data for Germany, a 10-Year Experience," Environmental Health Perspectives 106: 723-731, 1998.  Stanley, J.S., Ayling, R.E., Cramer, P.H., Thornburg, K.R., Remmers, J.C., Breen, J.J., Schwemburger, J., Kang, H.K., and  Watanabe, K.,  "Polychlorinated Dibenzo-p-Dioxin And Dibenzofuran Concentration Levels in Human Adipose Tissue Samples From The Continental United States Collected From 1971 Through 1987," Chemosphere 20: 895-901, 1998.

^[5] Pinsky, P. & Lorber, M.N., "A model to evaluate past exposure to 2,3,7,8-TCDD," Journal of Exposure Analysis and Environmental Epidemiology, 8, (2), 187-206, 1998.

^[6] Dioxin: Summary of the Dioxin Reassessment, Information Sheet 1, U.S. Environmental Protection Agency, Office of Research and Development, June 12, 2000.

^[7] Steenland, K., Piacitelli, L., Deddens, J., Fingerhut, M. and Chang, L.I., "Cancer, Heart Disease and Diabetes in Workers Exposed to 2,3,7,8-Tetrachlorodibenzo-p- dioxin," Journal of the National Cancer Institute 91:779-86, 1999.

^[8] U.S. EPA (Environmental Protection Agency). 2006. An inventory of sources and environmental releases of dioxin-like compounds in the United States for the years 1987, 1995, and 2000. National Center for Environmental Assessment, Washington, DC; EPA/600/P-03/002F. (http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=159286)

^[9] Hagenmeier, H. and Walczok, M., "Time Trends in Levels, Patterns and Profiles for PCDD/PCDF in Sediment Cores of Lake Constance," Organohalogen Compounds 28: 101-104, 1996 (sediment).  Ferrario, J., Byrne, C., Dupuy, A.E., Winters, D.L., Lorber, M., and Anderson, S., "Analytical Method and Results from the Analyses of USEPA Historical Food Samples for Dibenzo-p-Dioxins/-Furans/Coplanar PCBs," Organohalogen Compounds 35: 29-32, 1998 [food].  Winters, D.L., Anderson, S., Lorber, M., Ferrario, J., and Byrne, C., "Trends in Dioxin and PCB Concentrations in Meat Samples from Several Decades of the 20th Century," Organohalogen Compounds 38:  75-78, 1998 [food].

^[10] University of Michigan Dioxin Exposure Study (UMDES). 2006. Measuring people's exposure to dioxin contamination along the Tittabawassee River and surrounding areas: Findings from the University of Michigan dioxin exposure study. University of Michigan, School of Public Health, Ann Arbor, MI. August.

^[11] Questions and Answers About Dioxins (see citation #2)