New York, NY Contrary to the claims of the activist group Natural Resources Defense Council (NRDC), there is no scientific validity to fears that diesel exhaust emissions from school buses pose a cancer risk to schoolchildren.
This was the conclusion reached by scientists affiliated with the American Council on Science and Health (ACSH), which today released a peer-reviewed analysis entitled School Buses and Diesel Fuel. The ACSH report criticized a recently promoted report on diesel exhaust, authored by the NRDC.
The NRDC report, No Breathing in the Aisles, is replete with invalid and unsupported assertions, according to the ACSH document. NRDC's allegations, the ACSH report states, are based on uncontrolled observations and unjustified extrapolations. The ACSH report was authored by renowned toxicologist Daland R. Juberg, Ph.D., DABT, and reviewed by 12 independent colleagues in academia and consultative toxicology, in addition to the ACSH professional staff.
The ACSH review of the NRDC report includes these conclusions:
- The NRDC monitoring study, which forms the basis of the report and from which the NRDC derived its risk estimates for children, is not described in sufficient detail to allow for an informed critique of its validity. Thus, the conclusions regarding cancer risk to children from diesel exhaust (DE) exposure cannot be confirmed.
- The estimated DE exposures for children riding a diesel-fueled school bus have not been confirmed through other independent studies. Quantitative human exposure data are scanty for DE, particularly for non-occupational settings; thus comparisons to the NRDC findings are not possible.
- DE has been associated with a small increase in lung cancer risk in some epidemiological studies involving occupational exposures. Typically, occupational DE exposures are far greater than ambient exposures to which children would likely be exposed. We know of no published studies that link non-occupational exposure to DE with increased cancer risk.
- The estimated cancer risk for children calculated by the NRDC uses a unit risk factor that has not received general acceptance by the scientific community and is not recognized by the U.S. EPA.
- There are no published studies that link childhood exposure to DE, either from buses or any other exposure, with an increased risk of developing cancer.
Gilbert Ross M.D., ACSH's medical director and project coordinator for School Buses and Diesel Fuel
, commented, "This peer-reviewed critique of the NRDC's attack on diesel fuel shows the difference between hype and sound science. Their report is riddled with fallacy and half-truths, which have no place in scientific discourse."
He continued: "The NRDC is an activist group, not a scientific organization, and its 'science' is never subject to criticism by independent review. They were the main proponents of the infamous 1989 Alar hoax, and their report on the health risks of diesel exhaust falls into the same category."