Date: Feb. 27, 2002 Contacts: Barbara Rice, Deputy Director Chris Dobbins, Media Relations Assistant (202) 334-2138; e-mail <email@example.com>
FOR IMMEDIATE RELEASE
Revised Analysis Leads to Different Conclusion About Agent Orange Exposure and Childhood Leukemia
WASHINGTON -- Evidence is too weak to establish whether an association exists between exposure to the herbicides used during the Vietnam War and the development of a form of leukemia in veterans' children, says a new report from the Institute of Medicine of the National Academies. Based on a review of all available research, as well as corrected data from an Australian study, the committee that wrote the report revised its earlier finding of a possible association.
The prior IOM review founded its conclusion in part on a report from the Australian Institute of Health and Welfare that looked at the incidence of acute myelogenous leukemia (AML) in the children of Australian veterans of the Vietnam War. The Australian study was later found to have contained a miscalculation that led its authors to incorrectly conclude that these children faced a significantly greater risk of AML than children in the general population did. The revised analysis found that the incidence of the illness was within the range that might be expected in the general population. The committee also considered new evidence from German and Norwegian studies of AML in the offspring of parents who had occupational exposure to pesticides. Neither study found a significant difference in incidence from unexposed populations.
"On the whole, there is insufficient evidence at this time to determine whether a connection exists between AML in children and their parents' military service in Vietnam or Cambodia," said committee chair Irva Hertz-Picciotto, professor of epidemiology, University of California, Davis. "Our review of available studies, combined with the revised analysis from Australia, indicates that the evidence is too weak to draw any conclusions or even make tentative ones."
Leukemia is the most common type of childhood cancer. Acute myelogenous leukemia is a rapidly spreading form that originates in certain bone marrow cells. The disease accounts for about 8 percent of all childhood cancers. Little is known about what causes such diseases in children, the potential environmental risk factors for them, or how parental chemical exposures affect offspring.
The ability of researchers to pinpoint the health risks faced by veterans or their children is hampered by inadequate information about herbicide exposure levels of troops in Vietnam. Most information comes from studies of civilians who were exposed to herbicides on the job or in industrial accidents. It also is difficult to say precisely which troops may have been exposed.
U.S. forces sprayed Agent Orange and other defoliants over parts of south Vietnam and Cambodia beginning in 1962. Most large-scale sprayings were conducted from airplanes and helicopters, but considerable quantities were dispersed from boats and ground vehicles or by soldiers wearing back-mounted equipment. A 1969 scientific report concluded that one of the primary chemicals used in Agent Orange could cause birth defects in laboratory animals. The U.S. military therefore suspended the use of Agent Orange in 1970 and halted all herbicide spraying in Vietnam the following year.
The committee's work was sponsored by the U.S. Department of Veterans Affairs. The Institute of Medicine is a private, nonprofit institution that provides health policy advice under a congressional charter granted to the National Academy of Sciences. A committee roster follows. Read the full text of Veterans and Agent Orange: Herbicides/Dioxin Exposure and Acute Myelogenous Leukemia in the Children of Vietnam Veteransfor 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 by calling (202) 334-3313 or 1-800-624-6242. Reporters only may obtain a print copy from the Office of News and Public Information (contacts listed above).
INSTITUTE OF MEDICINE Board on Health Promotion and Disease Prevention
Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides
Irva Hertz-Picciotto, Ph.D. (chair) Professor Department of Epidemiology and Preventive Medicine School of Medicine University of California Davis
Margit L. Bleecker, M.D., Ph.D. Director Center for Occupational and Environmental Neurology Baltimore
Thomas A. Gasiewicz, Ph.D. Professor of Environmental Medicine and Deputy Director Environmental Health Sciences Center Department of Environmental Medicine School of Medicine and Dentistry University of Rochester Rochester, N.Y.
Tee L. Guidotti, M.D., M.P.H. Professor and Chair Department of Environmental and Occupational Health School of Public Health and Health Services, and Director Division of Occupational Medicine Department of Medicine School of Medicine George Washington University Washington, D.C.
Robert F. Herrick, Sc.D., C.I.H. Senior Lecturer on Industrial Hygiene Department of Environmental Health Harvard School of Public Health Boston
David G. Hoel, Ph.D.* Distinguished University Professor, and Associate Director Hollings Oncology Center Medical University of South Carolina Charleston
Loren D. Koller, D.V.M., Ph.D. Consultant Environmental Health and Toxicology Corvallis, Ore.
Howard Ozer, M.D., Ph.D. Chief of Hematology/Oncology, Director of the Cancer Center, and Professor of Medicine University of Oklahoma Oklahoma City
John J. Stegeman, Ph.D. Senior Scientist Department of Biology Redfield Laboratory Woods Hole Oceanographic Institution Woods Hole, Mass.
David S. Strogatz, Ph.D., M.S.P.H. Associate Professor and Chair Department of Epidemiology School of Public Health State University of New York Albany