Limited data suggest possible association between Agent Orang...( WASHINGTON -- A new report from the ...),Health

WASHINGTON -- A new report from the Institute of Medicine finds suggestive but limited evidence that exposure to Agent Orange and other herbicides used during the Vietnam War is associated with an increased chance of developing ischemic heart disease and Parkinson's disease for Vietnam veterans. The report is the latest in a congressionally mandated series by the IOM that every two years reviews the evidence about the health effects of these herbicides and a type of dioxin -- TCDD -- that contaminated some of the defoliants.

A finding of "limited or suggestive evidence of an association" means that the evidence indicates there could be a link between exposure to a chemical and increased risk for a particular health effect, though conflicting results from studies, problems with how the studies were conducted, or other confounding factors limit the certainty of the evidence. Until now, the cumulative evidence had been inadequate to draw conclusions about whether these two conditions may be associated with veterans' exposures to herbicides or TCDD.

Ischemic heart disease -- a condition characterized by reduced blood supply to the heart, which can lead to heart attack and stroke -- is the foremost cause of death among people in industrialized countries. Major risk factors include buildup of cholesterol in the arteries, age, smoking, high blood pressure, and diabetes. The committee that wrote the report reviewed several studies investigating TCDD exposure and heart disease, many of which showed that higher TCDD exposure correlated with greater incidence of disease. The studies had weaknesses; for instance, it is difficult to adjust entirely for the impact of smoking, age, weight, and other common risk factors. But based on the preponderance of the evidence as well as biologic data beginning to show how TCDD can cause this toxic effect, the committee concluded that the evidence suggests that veterans exposed to defoliants contaminated with
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