A look at some chemicals awaiting risk assessments

Some of the products for which the Environmental Protection Agency process for determining cancer and other health risks has been delayed:

- Naphthalene, a chemical used in rocket fuel and manufacturing a wide range of commercial products, including mothballs, dyes and insecticides. It is a major source of contamination at many military bases. The EPA wants to determine if it should be reclassified from a "possible" to "likely" human carcinogen. A long-standing dispute with the Pentagon over the chemical prompted the White House in 2004 to initiate a new EPA policy requiring more interagency involvement in assessing the health risks of a chemical. "Six years after the naphthalene assessment began, it is now back at the drafting stage," said the Government Accountability Office.

- Trichloroethylene, or TCE, a widely used industrial degreasing agent and a common contaminant in air, soil and both surface and ground water. The EPA in 2001 issued a draft assessment that TCE is "highly likely to produce cancer in humans." Interagency reviews have concluded more outside studies are needed. "Ten years after EPA started ... the TCE assessment is back at the draft development stage," the GAO said.

- Perchloroethylene, or "perc," a chemical widely used in dry cleaning fabrics, degreasing metal and making chemical products. The EPA began its risk review of perc a decade ago and an interagency review was completed two years ago. Since then the assessment has been in limbo because of a dispute among senior EPA officials over what the cancer risk assessment should be. The dispute has prevented the proposed assessment from being forwarded to the National Academy of Science for peer review.

- Formaldehyde, a colorless, flammable gas used to make plywood and other building materials, which the EPA has been reviewing since 1997 to determine if should be upgraded from a "probable" to a "known" carcinogen. The EPA does not expect to complete that review for another two years.

- Royal Demolition Explosive, or RDX, a chemical explosive used in munitions and classified as a possible human carcinogen. The chemical is known to leach from soil to groundwater. The EPA began a risk assessment of the chemical in 2000 but has made minimal progress, the GAO said.

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