Date: Feb. 27, 2002
Contacts: Barbara Rice, Deputy Director
Chris Dobbins, Media Relations Assistant
(202) 334-2138; e-mail <>

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 Veterans 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 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).

[This news release and the report are available at]

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)
Department of Epidemiology and Preventive Medicine
School of Medicine
University of California

Margit L. Bleecker, M.D., Ph.D.
Center for Occupational and Environmental Neurology

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
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

David G. Hoel, Ph.D.*
Distinguished University Professor, and
Associate Director
Hollings Oncology Center
Medical University of South Carolina

Loren D. Koller, D.V.M., Ph.D.
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


David A. Butler, Ph.D.
Study Director

* Member, Institute of Medicine