USEPA Releases Draft Dioxin Report for Peer Review

On May 21, 2010, the USEPA Office of Research and Development released as a draft for public review and response, EPA’s Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments (EPA/600/R-10/038A). The release of the EPA’s Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments (“EPA’s Reanalysis”) report is part of a larger effort by USEPA to complete USEPA’s assessment of dioxin, which was announced in May 2009 by Lisa P. Jackson in the USEPA Science Plan for Activities Related to Dioxins in the Environment. Specifically, EPA’s Reanalysis is intended to respond to comments prepared by the National Academy of Sciences (NAS), based on their review of USEPA’s 2003 report entitled Exposure and Human Health Reassesment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. EPA’s Reanalysis includes analyses of relevant new dioxin studies and addresses issues related to the TCDD dos-response assessment raised by the NAS, as well as three key recommendations made by the NAS to support a “scientifically robust characterization of human response to exposures of TCDD:”

 

1)   Improved transparency and clarity in the selection of key data sets for dose-response analysis.

2)   Further justification of approaches to dose-response modeling for cancer and noncancer endpoints.

3)   Improved transparency, thoroughness, and clarity in quantitative uncertainty analysis.

 

The draft report can be downloaded from the USEPA, National Center for Environmental Assessment (NCEA) home page under “Recent Additions and Publications” menus at http://www.epa.gov/ncea. The 90 day public comment period begins on May 21 and ends on August 19, 2010. Comments must be provided to the USEPA in writing and must be received by USEPA by August 19 for consideration. 

 

As part of the report review process, USEPA is submitting the draft report to its Science Advisory Board (SAB) for an independent external review. The SAB anticipates holding a public teleconference on or about June 24, 2010 and a public panel meeting from July 13 through 15, 2010. The USEPA intends to forward all public comments received in response to the Federal Register Notice by July 7 to the SAB for its consideration. To ensure that technical comments are provided to the SAB, responders can also submit their comments separately via email to Thomas Armitage, the SAB Designated Federal Officer at armitage.thomas.epa.gov. The Federal Register Notice with further details on the public comment process is available at http://www.gpo.gov/fdysys/pkg/FR-2010-05-21/html/2010-12280.htm. Following review by the SAB, the USEPA intends to finalize the document and publish it as a final report.

 

According to the American Chemistry Council (ACS), http://www.DioxinFacts.org, the term “dioxin” refers to a large family of chemical compounds that includes 17 chemical compounds of specific interest, which share a similar chemical structure and are thought to have similar mechanisms of toxicity to human health and the environment. However, the toxicity of the 17 compounds of interest varies by as much as a factor of 10,000. The ACS notes that the term “dioxin” is also used to refer to TCDD (2,3,7,8-Tetrachlorodibenzo-p-Dioxin), which is the most extensively studied and toxic form of dioxin. According to the NCEA, examples of dioxins include the following chemical compounds:

·     Polychlorinated biphenyls (PCBs)

·     Polychlorinated dibenzo dioxins (PCDDs)

·     Polychlorinated dibenzo furans (PCDFs)

 

PCBs were produced commercially in the United States from the 1930s until 1977 and have been regulated since that time under the federal Toxic Substances Control Act (TSCA). PCDDs and PCDFs are not commercially produced products, but are the unintentional byproducts of incineration, uncontrolled burning, and certain industrial chemical processes. The ACS notes on their web site that historically, the largest sources of dioxin were related to incineration, the manufacture of herbicides, and pulp and paper bleaching. However, releases from industry have decreased approximately 90% between 1987 and 2000 and are expected to further decrease during the next several years as new regulations are fully implemented. Therefore, the ACS reports that uncontrolled burning is now the primary source of dioxin release into the environment.

 

This article was authored by Greg Tieman, Acacia Environmental Group LLC. For more information on the author see here.