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News from the National Academies
Date: Oct. 13, 1999
Contacts: William Kearney, Media Relations Associate
Megan O'Neill, Media Relations Assistant
(202) 334-2138; e-mail <news@nas.edu>

[ EMBARGOED: NOT FOR PUBLIC RELEASE BEFORE 5 P.M. EDT WEDNESDAY, OCT. 13 ]

Publication Announcement

New Waste Incinerators Safer, But Some Emissions
and Health Concerns Need Further Study

Incineration is widely used in the United States to reduce the volume of waste. Hundreds of incinerators -- including industrial kilns, boilers, and furnaces -- combust municipal and hazardous waste, while many more are used to burn medical waste. Whether waste incineration poses a health risk to incinerator employees or to people living and working nearby has been the subject of much debate.

When operated properly by well-trained employees, modern waste incinerators pose little risk to public health. But older designs, human error, and equipment failure can result in higher-than-normal, short-term emissions that need to be studied further, says a new report by the National Research Council of the National Academies. Three federal agencies asked the Research Council to assess the relationship between waste incineration and human health.

Few studies have tried to establish a link between an incinerator and illness in the surrounding area, and most studies have been unable to detect any adverse health effects, said the committee that wrote the report. The studies that did identify effects on health had shortcomings and failed to provide convincing evidence. The fact that ailments may occur infrequently or take years to appear, and the presence of pollution from other sources, make it difficult to determine if waste incineration can be blamed for local health problems.

Some studies have shown, however, that workers at municipal-waste incinerators have been exposed to high concentrations of dioxins and toxic metals, particularly lead, cadmium, and mercury, the report says. But follow-up studies were not performed to determine if this exposure caused disease. Workers can be exposed to emissions directly, or -- when doing maintenance inside the combustion chamber -- to the toxic residue resulting from incomplete combustion and chemicals trapped by pollution-control devices.

Better epidemiological research is needed to assess the health risks of exposure to pollutants from incinerators, including studies that evaluate combined data from all incinerators in a particular area and that compare findings from similar facilities located in different regions, the report says. Biological tests should be used to monitor the exposure of workers. And researchers need to examine health risks that may be attributable to emissions resulting from incinerators which do not run properly, paying particular attention to particulate matter, lead, mercury, and dioxins.

The report also calls for better data on the level of emissions that occur during start-up and shutdown, when they are likely to be greater. Sudden increases in emissions also can result from maintenance problems, accidents, a change in the composition of the waste being burned, and poor management of the incineration process. Furnaces designed for municipal-waste incineration prior to the mid-1980s are less efficient at combustion than newer designs. Modern plants often use auxiliary burners to maintain an optimal temperature during start-up and shutdown, though increased emissions can still occur. But with current technology, incinerators can achieve nearly complete combustion of the burnable portion of waste under normal operating conditions, emitting low amounts of unhealthy pollutants. In addition, using highly trained employees can help ensure maximum combustion efficiency and proper operation of emission-control devices.

Policy-makers should base future regulatory decisions on the actual performance of incinerators, from start-up through shutdown, taking into consideration accidents and other mishaps, the committee said. Since the highest emissions may occur at these times, failure to include them in monitoring records may misrepresent the total emission output of a facility. To better measure actual emissions, government agencies should encourage research into improved continuous-emission monitors, and make real-time data available to regulators and the public, perhaps on the Internet.

Environmental monitoring studies indicate that specific waste incinerators are not likely to add much to local concentrations of airborne pollutants, but flaws in the methodology of these studies prevented the committee from drawing any general conclusions about the contribution of waste incineration to pollution levels overall. However, the committee noted that although one incinerator might emit only a small fraction of total concentrations, the sum of emissions from all incinerators in a region can be considerable.

The U.S. Environmental Protection Agency (EPA) has issued standards that would decrease emissions of key pollutants from waste incinerators. The EPA rules require incinerators to reduce emissions to a standard known as "maximum achievable control technology," or MACT. The Research Council report says compliance with MACT regulations will diminish the exposure of local populations to emissions, but it is unclear what effect compliance will have on a metropolitan or regional scale, since little is known about the risks posed by collective emissions from several incinerators. The committee noted that cumulative emissions of dioxins and metals are of substantial concern since those pollutants are capable of traveling long distances and persisting in the environment. It also recommended that all medical- and municipal-waste incinerators have uniform limits for each pollutant irrespective of plant size, age, or design, as is currently the case for hazardous-waste incinerators.

MACT standards were not designed to address the exposure of incinerator workers to emissions and other toxic byproducts, the report notes. It calls on EPA and the U.S. Occupational Safety and Health Administration to continue striving to improve coordination of their enforcement activities to protect the health of incineration workers.

The study was funded by EPA, the U.S. Agency for Toxic Substances and Disease Registry, and the U.S. Department of Energy. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provides independent advice on science and technology issues under a congressional charter. A committee roster follows.

Read the full text of Waste Incineration and Public Health for free on the Web, as well as more than 1,800 other publications from the National Academies. Printed copies are available for purchase from the National Academy Press Web site or at the mailing address in the letterhead; tel. (202) 334-3313 or 1-800-624-6242. Reporters may obtain a pre-publication copy from the Office of News and Public Information at the letterhead address (contacts listed above).


NATIONAL RESEARCH COUNCIL
Commission on Life Sciences
Board on Environmental Studies and Toxicology

Committee on Health Effects of Waste Incineration

Donald R. Mattison, M.D. (chair)
Medical Director
March of Dimes Defects Foundation
White Plains, N.Y.

Regina Austin, J.D.
Professor of Law
University of Pennsylvania Law School
Philadelphia

Paul C. Chrostowski, Ph.D.
Principal
CPF Associates Inc.
Takoma Park, Md.

Marjorie J. Clarke, Ph.D.
Instructor
Department of Geography
Rutgers University, and
Environmental Consultant
New York City

Edmund A. Crouch, Ph.D.
Senior Scientist
Cambridge Environmental Services Inc.
Cambridge, Mass.

Mary R. English, Ph.D.
Associate Director
Energy, Environment, and Resources Center
University of Tennessee
Knoxville

Dominic Golding, Ph.D.
Research Assistant Professor
Center for Technology, Environment, and Development
The George Perkins Marsh Institute
Clark University
Worcester, Mass.

Ian A. Greaves, M.D.
Associate Professor
Department of Environmental and Occupational Health
University of Minnesota
Minneapolis

S. Katharine Hammond, Ph.D.
Associate Professor of Public Health
Environmental Health Sciences Division
School of Public Health
University of California
Berkeley

Allen Hershkowitz, Ph.D.
Senior Scientist
Natural Resources Defense Council
New York City

Robert J. McCormick, B.S.
President
Franklin Engineering Group
Franklin, Tenn.

Thomas E. McKone, Ph.D.
Adjunct Professor
School of Public Health
University of California
Berkeley

Adel F. Sarofim, S.M., Sc.D.
Professor of Chemical Engineering
Department of Chemical Engineering
University of Utah
Salt Lake City

Carl M. Shy, M.D., Ph.D.
Professor
Department of Epidemiology
University of North Carolina
Chapel Hill

George D. Thurston, Ph.D.
Associate Professor
Department of Environmental Medicine
New York University School of Medicine
Tuxedo

RESEARCH COUNCIL STAFF

Raymond Wassel, M.S.
Study Director