The California EPA, the nation's largest and best-funded state environment agency, assessed TCE in 1999 and also found reason for concern. Its risk assessment fell in the middle of the EPA risk range, according to the study's author, Joseph Brown.
Rodents fed TCE develop liver and kidney cancer, and humans exposed to TCE show elevated rates of many types of cancer and birth defects. But industry experts fire back that evidence on TCE is still weak. Just because rats and mice get cancer from high levels of TCE doesn't prove that humans will get cancer from low levels of TCE, they say. And the epidemiological research is less convincing than animal studies, they say.
For The Record
Los Angeles Times Friday March 31, 2006 Home Edition Main News Part A Page 2 National Desk 2 inches; 71 words Type of Material: Correction
Risks of solvent: Due to an editing error, an article in Wednesday's Section A about the regulation and dangers of the industrial solvent trichloroethylene, or TCE, quoted Alex A. Beehler, the Pentagon's top environmental official, as saying: "We are all forgetting the facts on the table. Meanwhile, we have done everything we can to curtail use of TCE." Beehler actually said, "We are all for getting the facts on the table."
The U.S. still uses about 100 tons of TCE annually, a fraction of the consumption before the mid-1980s, when it was first classified as a probable carcinogen. It was once widely used in consumer products, such as correction fluid for typewriters and spot cleaners.
"If TCE is a human carcinogen, it isn't much of one," said Paul Dugard, a toxicologist at the Halogenated Solvents Industry Alliance Inc., which represents TCE manufacturers. "People exposed at low levels shouldn't be concerned.
"EPA's philosophy is still one of being super conservative and that is being pushed back against."
EPA officials were braced for such a controversy when the TCE assessment was issued and quickly convened a scientific advisory board to review the work. The board included public health officials at state agencies, academics and chemical industry scientists.
About one year later, the board issued its findings, praising the risk assessment and urging the EPA to implement it as quickly as possible. But the board also suggested some changes, including stronger support for its calculations of TCE's health risks and a clearer disclosure of its underlying assumptions.
The report, particularly the request for additional work, was interpreted as a serious problem by Gilman, the EPA research director.
He said the board's findings represented a "red flag" and "raised very troubling issues," all of which were key arguments by Gilman and others for stopping the assessment.
But members of the scientific advisory team dispute Gilman's interpretation, saying they felt the 2001 risk assessment was good science and their recommended changes amounted to normal commentary for such a complex matter.
