Report Links Cancers to Herbicide Exposure
August 18, 1993
A report released July 27, 1993 by the Institute of
Medicine (IOM)* has concluded that evidence exists linking three
cancers and two other health problems with chemicals used in
herbicides. The IOM committee's report, "Veterans and Agent
Orange: Health Effects of Herbicides Used in Vietnam," focuses on
Agent Orange (a mixture of 2,4-D and 2,4,5-T) and other
herbicides** used in Vietnam, some of which contained dioxin, an
unintended byproduct of the manufacturing process. The study
results have wide-ranging implications not only for Vietnam
veterans, but also for others exposed to these herbicides (some
of which are still widely used), and people exposed to dioxins
from other sources.
The committee examined more than 230 epidemiological
studies on a range of health problems and their possible
association with herbicides or dioxins. It found sufficient
evidence of a statistical association between exposure to
herbicides or dioxin and three types of cancer: soft tissue
sarcoma, non-Hodgkin's lymphoma, and Hodgkin's disease. The
report also noted sufficient evidence of an association between
herbicides or dioxin and chloracne and PCT. Chloracne is an
acne-like skin disorder; PCT is a liver disorder characterized by
thinning and blistering of the skin. The committee also found
limited or suggestive evidence of an association between
herbicide exposure and three other types of cancer: respiratory
cancers, prostate cancer, and multiple myeloma.
Both toxicological and epidemiological data on herbicides
were studied by the committee. Most of the these studies did not
involve Vietnam veterans, but rather people who were exposed to
herbicides occupationally or environmentally, for example
following industrial accidents. These types of exposures were
often at high levels and for long periods of time. In reviewing
the literature, the committee found that exposure assessment was
the weakest element in most epidemiological studies of veterans.
The link between Agent Orange and other dioxin-
containing herbicides and human health effects has been widely
studied with varying results, and remains a subject of heated
controversy. The difficulty of finding both people with high
exposures and good controls to study is a major reason for
variations in study results.
The committee stated that evidence about exposure during
the war suggests that Vietnam veterans as a group had
substantially lower exposure to herbicides and dioxins than the
subjects in many occupational studies. Veterans who participated
in Operation Ranch Hand (the extensive spraying of approximately
19 million gallons of herbicide over 3.6 million acres of South
Vietnam from airplanes) are an exception to this pattern. There
may also be some former ground troops not directly involved in
the spraying who were exposed to herbicides at levels associated
with adverse health effects. The committee urged that a
non-government organization be commissioned to develop and test
new methods of evaluating herbicide exposure in Vietnam veterans.
The U.S. military sprayed millions of gallons of
herbicides over South Vietnam between 1962 and 1971, before
reports of health effects in laboratory animals resulted in an
end to the spraying. The impacts on the Vietnamese people's
health and environment are poorly documented and often
overlooked. A number of Vietnamese studies contain evidence
suggestive of some cancers and reproductive effects.
* The Institute of Medicine is a private, non-profit
organization that provides health policy advice under a
congressional charter granted to the National Academy of
Sciences.
** "Herbicides" refers to the major herbicides used in
Vietnam: 2,4-D, 2,4,5-T and its contaminant TCDD (2,3,7,8-
tetrachlorodibenzo-p-dioxin), cacodylic acid, and picloram.
Sources/contacts: Susan Turner-Lowe, Institute of Medicine,
Office of News and Public Information, 2101 Constitution Avenue,
NW, Washington, DC 20418, USA; phone (202) 334-2138; fax (202)
334-2158; Dr. Arnold Schecter, Clinical Campus, SUNY Health
Science Center, 88 Aldrich Ave., Binghamton, NY 13903; fax (607)
770-8623.
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