The Center for Public integrity's Jim Morris was the first to report that two long awaited cancer mortality studies of US workers exposed to diesel exhaust finds significantly elevated levels of lung cancer. Researchers with the National Cancer Institute (NCI) and CDC's National Institute for Occupational Safety and Health (NIOSH) proposed the studies two decades ago, going great lengths to address methodological limitations identified in previous epidemiological studies of diesel exhaust-exposed workers. The bottom line, and with now stronger evidence than ever, there should be no question that diesel exhaust is carcinogenic to humans.
Underground miners in the U.S. are some of the workers most heavily exposed to diesel exhaust. By 1998, there were already dozens of studies showing elevated risk of lung cancer in groups of exposed workers (e.g., here, here, here, here) and the Mine Act directs the agency to issue health standards based on the "best available evidence." For those reasons and because feasible controls were available to reduce miners' exposure to diesel exhaust, the Labor Department's Mine Safety and Health Administration (MSHA) proposed a rule to address this serious hazard. After public hearings and a comment period, MSHA staff worked to prepare the final rule to be published before the end of the Clinton Administration. The complication?
Members of Congress, including Senator Harry Reid, sent letters in June 2000 to Labor Secretary Alexis Herman urging her to delay issuing a final rule to protect miners from diesel particulate matter until the NIOSH/NCI epidemiological study was complete.
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