Monday, December 04, 2006

Backyard Burn Barrels Are Largest Source Of Dioxin Emissions

Dec 1: U.S. EPA announced in the Federal Register [71 FR 69564-69565] an Inventory of Sources and Environmental Releases of Dioxin-Like Compounds in the United States for the Years 1987, 1995, and 2000 (EPA/600/P-03/002F, November 2006). The document is a peer-reviewed and final 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. Over 800 references were reviewed and cited in the preparation of the report. The citations generally reflect publications up to and including the year 2003. The final document reflects a consideration of all comments received on an External Review Draft dated March 2005 (EPA600/P-03/002A) provided by an expert panel at a peer-review workshop held September 13–15, 2005, and comments received during a 60-day public review and comment period (May 6–July 5, 2005).

The major identified sources of environmental releases of dioxin-like compounds are grouped into six broad categories: combustion sources, metals smelting, refining and process sources, chemical manufacturing sources, natural sources, and environmental reservoirs. Estimates of annual releases to land, air, and water are presented for each source category and summarized for reference years 1987, 1995, and 2000. The quantitative results are expressed in terms of the toxicity equivalent (TEQ) of the mixture of polychlorinated dibenzo-p-dioxin (CDD) and polychlorinated dibenzofuran (CDF) compounds present in environmental releases using a procedure sanctioned by the World Health Organization (WHO) in 1998. Using this WHO procedure, the annual releases of TEQDF-WHO98 to the U.S. environment over the three reference years are 13,965 g in 1987, 3,444 g in 1995, and 1,422 g in 2000.

The analysis indicates that between reference years 1987 and 2000, there was approximately a 90% reduction in the releases of dioxin-like compounds to the circulating environment of the United States from all known sources combined. In 1987 and 1995, the leading source of dioxin emissions to the U.S. environment was municipal waste combustion; however, because of reductions in dioxin emissions from municipal waste combustors, it dropped to the 4th ranked source in 2000. The inventory also identifies bleached chlorine pulp and paper mills as a significant source of dioxin to the aquatic environment in 1987, but a minor source in 1995 and 2000. Burning of domestic refuse in backyard burn barrels remained fairly constant over the years, but in 2000, it emerged as the largest source of dioxin emissions to the U.S. environment.

Access an overview and links to the complete 677-page report and related information (
click here). Access the FR announcement (click here). [*Toxics]