US consults on dioxin contamination

The US Environmental Protection Agency is looking for public input on its plans to set targets for the clean up dioxin-contaminated soils.

The publication of these draft interim preliminary remediation goals (PRGs) for dioxins in soils by the end of 2009 was one of the commitments announced by EPA chief Lisa P Jackson.

Dioxins are contaminants that are very widespread in the environment that have been of concern to EPA and the public health community for decades.

The proposed PRGs only slightly reduce the current recommended 'safe' levels of dioxin contamination at commercial and industrial sites, but make huge cuts to the allowed level for housing developments.

The EPA believes the new plans would strengthen its powers to tackle dioxin contaminated sites while it draws up a more complete long-term strategy on dioxins.

"While EPA works to complete the dioxin reassessment, this interim guidance will help us make better informed decisions on cleanup alternatives at contaminated sites," said Mathy Stanislaus, assistant administrator for EPA's Office of Solid Waste and Emergency Response.

"We are following through on our commitment to use the best available science to help protect human health and the environment."

Dioxins may cause a wide number of serious health problems, from cancers to damage of the reproductive system and child development.

Dioxins are of concern because they are the result of combustion, and are absorbed from the air into the food chain where they can stay for many years.

Currently, EPA's recommended dioxin PRGs are 1,000 part per trillion (ppt) for dioxin in residential soil and a level within the range of 5,000-20,000 ppt in commercial/industrial soil.

The draft interim PRGs proposed today are 72 ppt for residential land uses and 950 ppt for commercial/industrial land uses, thus lowering the amount of dioxins levels for residential land uses and commercial/industrial land uses.

In addition, the draft interim PRGs differ from the current dioxin PRGs in that they include consideration of the potential absorption of dioxin through skin exposure. This will provide a tool for site evaluation that was not available when EPA last recommended PRGs for dioxins in soil in 1998.

In 1991, in light of significant new data on the potential human health effects of dioxins, EPA began the development of a comprehensive evaluation of exposure and human health effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic of the group of chemicals known as dioxins, and other dioxin-like compounds.

This draft dioxins assessment has been through several independent external peer reviews, the latest a 2004 review by a scientific panel convened by the National Academy of Sciences.

When the EPA dioxin risk assessment is complete, it will be the agency's scientific foundation for future decision-making about dioxins in the environment.

More information on the draft recommended interim PRGs and how to comment can be found here.

Sam Bond



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