Six U.S. senators have written a letter to the Environmental Protection Agency asking it adopt a health protective interim standard for exposure to trichloroethylene vapors.

The senators noted that TCE, a solvent used for cleaning metal parts, is a widespread contaminant found in at least 325 of the nation´s more than 1,200 Superfund sites, and that the chemical has been linked to cancer and damage to the nervous and immune systems.

The EPA published a health risk assessment report in August 2001 that called for increasing protections from TCE, but the EPA is asking the National Academies of Science to re-evaluate TCE´s toxicity. The process "may take years," the senators complained in their Oct. 5 letter to EPA Administrator Stephen Johnson.

In the absence of a national standard, standards set by states and the federal government vary at sites across the country. "Today, thousands of Americans may be exposed to unhealthy levels of TCE," the senators wrote.

TCE vapors from hazardous waste sites can seep into nearby basements and homes.

The senators signing the letter were Hillary Rodham Clinton, D-N.Y.; Barbara Boxer, D-Calif.; Christopher Dodd, D-Conn.; Frank Lautenberg, D-N.J.; Joseph Lieberman, D-Conn.; Gordon Smith, R-Ore.; and Ron Wyden, D-Ore.