Is Even Low-Level Benzene Exposure Cause for Concern?

A new study that shows that even minimal exposure to benzene at levels below that of the permissible exposure limit (PEL) set by OSHA could have adverse health effects for workers is causing a stir in the occupational safety and health community.

In a study published in the December 3 issue of Science, researchers led by Qing Lan and Nathanial Rothman of the National Cancer Institute and Martyn Smith of University of California-Berkeley discovered significant changes in the blood including a decrease in white blood cells of 240 workers who were exposed to low levels of benzene at a shoe factory in China. The benzene exposure also negatively impacted progenitor cells (platelets), which are crucial to the formation of blood cells.

"We can't say that this is associated with the future risk of disease," admitted Rothman. "But it does raise the question of what else is going on in the bone marrow."

The workers were exposed to levels of benzene at less than 1 part per million (the permissible exposure level set by OSHA in 1987). When contacted by, OSHA released this statement by Bill Perry, director of the agency's Office of Chemical Hazards: "OSHA's current standard for benzene, in effect since 1987, was developed after more than a decade of extensive research and a comprehensive regulatory process. We have not yet reviewed the study in Science Magazine. Evaluation will take some time, however, we look forward to reviewing it."

Benzene is used in many industries as a solvent and is used to make plastics, resins, adhesives and synthetic fibers. Rothman said the new study raises concerns about the risks of low-level exposure to benzene, adding that biological changes are occurring from occupational exposure to the chemical. "The question is," said Rothman, "What are the health consequences to the workers?"

Monday: Industry and worker organization response to the study.

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