Benzene, a potent chemical found in cigarette smoke and automobile emissions, appears responsible for between 8 percent and 48 percent of all smoking-induced leukemia deaths, a new University of North Carolina at Chapel Hill study indicates. The chemical also causes between 12 percent and 58 percent of smoking-related deaths from acute myeloid leukemia.
How likely smokers are to develop the life-threatening illness depends largely on how much they smoke, scientists say.
Dr. Irva Hertz-Picciotto, professor of epidemiology at the UNC-CH School of Public Health, conducted the study with Dr. Jeffrey E. Korte of the International Agency for Research on Cancer in Lyon, France; graduate student Mark R. Schultz and Dr. Louise M. Ball, professor of environmental sciences and engineering, both at UNC-CH; and Dr. Eric J. Duell of Harvard University.
A report on their findings appears in the current (April) issue of the journal Environmental Health Perspectives. They originally intended to help explain why smokers were one-and-a-half to two times more likely to develop the blood-borne cancer than non-smokers and the possible influence of benzene.
"We extrapolated down from different studies that have been done on leukemia and people exposed to benzene in the workplace and established what's called a dose-response curve," Hertz-Picciotto said. "We found that linear mathematical models provided more plausible estimates of benzene's influence than a quadratric model."
Some scientists and industry officials argue that linear models over-estimate the risks at low doses. They say that only at high doses when it overwhelms the body's ability to detoxify the chemical can it cause cancer.
The shape of the dose-response curve is important for the Occupational Safety and Health Administration and Environmental Protection Agency when they attempt to set standards to protect workers and the public. If cancer increases linearly with increases in benzene levels,
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Contact: David Williamson
david_williamson@unc.edu
919-962-8596
University of North Carolina at Chapel Hill
3-May-2000