Wednesday, January 14, 2004

Flash! Carcinogens Actually Cause Cancer

The first lesson I'd try to communicate when teaching a health and safety class about workplace chemical exposures was that "legal doesn't mean safe. OSHA's Permissible Exposure Limits (PELs) were mostly based on voluntary standards set in the 1960's, mainly to prevent "acute" effects -- like poisoning or immediate death -- from high, short term exposures. The standards don't address the long term effects of low exposure that can result in cancer years or decades later.

Furthermore, the PELs are based on "8-hour time weighted averages," which means your exposure could be above the PEL for a period of time, as long as the 8-hour average was below the PEL. Finally, even the poor testing that had been done on the chemicals was based on exposure to one chemical at a time, not the "synergistic" effects of exposure to a combination of many chemicals together.

I've written before (here and here) about the trial being held in California over accusations by two workers, Alida Hernandez and James Moore, that their cancers are the result of chemicals exposures while working at IBM. The company denies the allegations, and while much is known about some chemicals that cause cancer, it is often difficult to prove that any specific cancer was caused by specific chemical exposures.

But now California's top occupational physician, Robert Harrison, chief of the California Department of Health's occupational health surveillance and evaluation program, has, for the first time linked the workers' exposure to their cancers.
IBM argues that its clean rooms were safe and that the chemicals used there were not believed to be carcinogenic during the time of Moore's and Hernandez's employment.

But Harrison testified that virtually all the chemicals cited in the case, including trichloroethylene, benzene and epichlorohydrin, are recognized as carcinogens either by California's Proposition 65 or scientific studies.

Proposition 65, also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, requires the state to publish an annual list of chemicals known to cause cancer. Moore worked for IBM from 1966 to 1993 and Hernandez was employed from 1977 to 1991.


He estimated that exposure to chemical solvents played a 70 percent to 80 percent role in causing Hernandez's breast cancer, in relationship to other factors like her age and the early onset of puberty. He discounted factors that IBM has cited, such as weight and hormone replacement therapy, saying they were nullified by other medical conditions.

In Moore's case, Harrison said solvents played an 80 percent to 90 percent role in his non-Hodgkin's lymphoma.