achieved within 30 years. These include a 75% reduction of greenhouse gases, air quality that does not affect human health anymore, a 10-fold reduction of nonrenewable material use, and stabilization of traffic. Other targets can be achieved within 20 years, including the phaseout of the release of hazardous substances into the environment and a ban on all pesticides that are not compatible with organic farming. —MARIA BURKE
Did You Know? Explosives eaten by spinach: Researchers at the Pacific Northwest National Laboratory have found that nitroeductase enzymes in spinach and other natural compounds can eat, digest, and transform explosives such as TNT into low-toxicitv byproducts. Source: Breakthroughs, Spring 1999.
Health Assessment Long-running diesel health assessment needs tweaking, EPA science advisors say For the fourth time, an EPA science advisory panel declined to put its stamp of approval on an agency document analyzing the human health effects from diesel exhaust. But the CASAC did support classifying diesel exhaust as "likely to be carcinogenic to humans". When finalized, the assessment, which has been more than 10 years in the making, is likely to affect several new regulations. At its Dec. 1 meeting last year, everyone on EPA's Clean Air Act Scientific Advisory Committee (CASAC) "agreed by far that this draft was an improvement over the last one," said Joe Mauderly, director of the National Environment Respiratory Center at the Lovelace Respiratory Research Institute in Albuquerque, NM. Frank O'Donnell of the Clean Air Trust, a watchdog group in Washington D.C. which has raised concerns about the potential cancerous effects of diesel exhaust agreed with Mauderly The panel was "the closest it has ever been to signing off on the document" O'Donnell said Nonetheless, enough issues were raised that the panel declined to approve it in full and narrowly agreed that it will review the revised document again, most likely this year. The CASAC disagreed with EPA's description of diesel exhaust as "highly likely to be carcinogenic to humans" and instead supported the phrase "likely to be carcinogenic."
EPA continues to refine its diesel health assessment, which could play an important role in standards development. Some scientists felt, as they have in the past, that there are not enough nonoccupational epidemiological data to allow the agency scientists to calculate the cancer hazard to individuals in an environmental setting. And EPA's new cancer classification does not include "highly likely," Mauderly said. The CASAC also objected to the draft's Reference Concentration (RfC) for diesel exhaust, or the "safe" level of exposure that will cause no toxicity effects over a lifetime. The draft employs two different health effects in its RfC calculation instead of one which is a more traditional way to develop an RfC Mauderly said
The "Draft Diesel Health Assessment Document for Diesel Emissions" sets no regulatory standards, but once finalized, it could carry significant weight. This spring, EPA is expected to propose new rules requiring much lower sulfur levels in diesel fuel and tougher standards for heavy-duty diesel engines. New standards requiring lower diesel emissions from off-road vehicles are also on the drawing board. If EPA is able to finalize a rule reducing the sulfur content in diesel fuel automobile makers are likely to install more fuel-efficient diesel engines in their popular sport utility vehicles to meet forthcoming rules to address global warming said Greg Dana vice president of environmental affairs for the Allianrp of Automobile Manufacturers Washinnlnn D P
The assessment's outcome concerns environmentalists, too. Diesel exhaust is a complex mixture of gases and fine particles, which contains more than 40 substances that EPA considers hazardous. In August 1999, the California Air Resources Board (CARB) listed diesel exhaust particulate matter as a toxic air contaminant And in November, regulators in Southern California approved their report noting that particulates in diesel exhaust make up 70% of the cancer risk from air pollution in the region. EPA's and CARB's assessments review the same diesel studies. —CATHERINE M. COONEY
FEBRUARY 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 7 1 A