Dioxin

The Issue
The term "dioxin" is commonly used to refer to a family of toxic chemicals that share a similar chemical structure and induce harm through a similar mechanism. Dioxins have been characterized by EPA as likely human carcinogens and are anticipated to increase the risk of cancer at background levels of exposure.

Dioxin levels in the environment have been declining since the early seventies and have been the subject of a number of federal and state regulations and clean-up actions; however, current exposures levels still remain a concern. Examples of dioxins include polychlorinated biphenyls (PCBs), polychlorinated dibenzo dioxins (PCDDs), and polychlorinated dibenzo furans (PCDFs). PCBs were produced commercially in large quantities until production was stopped in 1977. PCDDs and PCDFs are not commercial chemical products, but are unintentional byproducts of most forms of combustion and several industrial chemical processes.

EPA Action
Scientists in EPA's National Center for Environmental Assessment are currently working on a comprehensive reassessment of dioxin exposure and human health effects. The latest draft assessment, Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds, is currently undergoing revisions in light of the review by the National Academy of Sciences(NAS) in November 2004.

Related Links

• Dioxin Reassessment (NAS Review Draft), submitted in Oct 2004, is the most current version of the report.
• Dioxin: Frequently Asked Question (FAQs) Updated Sep 2008. Topics include: general information, overview of the EPA dioxin report, food safety, and risk assessment as prepared by the Dioxin Interagency Working Group.
• Dioxin Exposure Initiative (DEI), started in 1994, the EPA embarked upon a research program to further evaluate the exposure of Americans to this class of compounds. The DEI is a research program jointly funded and managed by EPA's Office of Research and Development (ORD) and EPA's Office of Prevention, Pesticides, and Toxic Substances (OPPTS).
• An Inventory of Sources and Environmental Releases of Dioxin-Like Compounds in the United States for the Years 1987, 1995, and 2000. Final Report (EPA/600/P-03/002F, Nov 2006) is a peer reviewed report representing EPA’s assessment of dioxin sources and their emissions to the environment. To the extent practical, the inventory is a comprehensive analysis of dioxin sources.
• Database of sources of environmental releases of dioxin-like compounds in the U.S. (EPA/600/C-01/012, March, 2001) is a database containing congener-specific emissions and environmental releases of polychlorinated dibenzo-para-dioxins (CDDs) and polychlorinated dibenzofurans (CDFs) from known source activities in the U.S. Included within the database are facility-specific emissions for a variety of CDD/CDF sources, and congener-specific I-TEQ and WHODF-TEQ emission factors. The database contains information that can be used to track CDD/CDF emissions over time; develop and compare congener-specific and homologue profiles for source categories; and to develop congener-specific emission factors that can then be used to undertake an emissions inventory of sources. The database is associated with two reference years: 1995 and 1987.
• EPA Analytical Method 1613 for analysis of dioxin and other related compounds.
• Dioxin: EPA regulations related to dioxin has information on EPA regulations and related activities.
• Dioxin Overview: from EPA's Office of Prevention, Pesticides & Toxic Substances (OPPTS)

History

• Oct 2008 EPA's Science Advisory Board (SAB) Staff Office posted a October 15, 2008 Federal Register Notice soliciting nominations of nationally recognized scientists for consideration of membership on an SAB Panel to provide advice on EPA's reassessment of the health risks from dioxin and related compounds.
• Oct 2004 EPA released the NAS Review Draft of EPA's Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds, in preparation for the first meeting of the NAS panel scheduled for 11/22 -23/2004, in Washington, DC.
• Oct 2003 EPA released a NAS Review Draft with updates on the FAQs and Information Sheets on Dioxin
• Jul 2000 EPA released the Consolidated Comments from the Peer Review of the Draft Dioxin Reassessment. Final Report
• Sep 1994 EPA launched the Dioxin Exposure Initiative
• Aug 1994 EPA released the draft document, Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (TCDD) and Related Compounds Volume (3 of 3)
• Jun 1994 EPA released the draft documents, Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (TCDD) and Related Compounds Volume (1 of 3) and Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (TCDD) and Related Compounds Volume (2 of 3).
• 1984 EPA published the Health Risk Assessment Approach for 2,3,7,8-Tetrachlorodibenzo-P-Dioxin.

Best Resources

U.S. EPA. Dioxin Reassessment. NAS Review Draft 2004. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/P-00/001Cb.

U.S. EPA. The Inventory of Sources of Dioxin in the United States (External Review Draft 2005). U.S. Environmental Protection Agency, Washington, D.C., EPA/600/p-03/002a, 2005.

U.S. EPA. Dioxin Exposure Initiative. 1994.

U.S. EPA. User's Manual for the Database of Sources of Environmental Releases of Dioxin-Like Compounds in the U.S.: Reference Years 1987 and 1995. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-01/012.

U.S. EPA. Relative Congener Scaling of Polychlorinated Dibenzo-P-Dioxins and Dibenzofurans to Estimate Building Fire Contributions in Air, Surface Wipes, and Dust Samples. , Joachim D. Pleil and Matthew N. Lorber (ed.), Submitted to: ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 41(21): 7286 -7293, (2007).

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