An Institute of Medicine report released Friday said that exposure to Agent Orange and other herbicides that were used by the U.S. military during the Vietnam War might put veterans at increased risk for ischemic heart disease and Parkinson's.

The report written by a 14-member committee charged by the Institute of Medicine with determining whether certain medical conditions were caused by exposure to herbicides used to clear stretches of jungle found "suggestive but limited" evidence of an elevated risk for these two conditions among soldiers who served in that conflict.

The IOM's report is the seventh update in a series requested by the U.S. Department of Veterans Affairs and mandated by Congress.

Agent Orange, named for the color of the barrel it was stored in, was one of the "broad-leaf defoliants" used in Vietnam to destroy vegetation and make enemy activity easier to spot. More than 20 million gallons of herbicides were sprayed in the jungles of Vietnam between 1962 and 1970 and Agent Orange was the herbicide used most often.  

Made up of tetrachlorodibenzo-para-dioxin (TCDD, compounds known to be contaminated with a type of dioxin during manufacture, Agent Orange was reclassified as a group 1 carcinogen in 1997 by the International Agency for Research on Cancer.

Richard A. Fenske, chair of the committee that compiled the report and a professor in the School of Public Health at the University of Washington in Seattle said Parkinson's and heart disease were in the category of "inadequate or insufficient evidence until this report. Those two have been moved to the limited or suggestive evidence of an association, and those are the only two that have been changed."                                                                                                                                                            

Veterans groups have been working to get the government to pay for treatment of illnesses they believe originated on the battlefield and the study results, though not conclusive, are an important beginning. Some other conditions linked to Agent Orange already qualify.

Since 1994 the Institute of Medicine committee has found 17 conditions associated with exposure to the chemical, 13 of which qualify veterans for service-connected disability benefits provided by the Department of Veterans Affairs.

Recent studies have also suggested links between Agent Orange and aggressive forms of prostate cancer and high blood pressure.

Bernard Edelman, deputy director for policy and government affairs of Vietnam Veterans of America plans to write a letter to the secretary of veteran’s affairs, Eric K. Shinseki, asking for extended benefits.

The report said that its conclusions about ischemic heart disease are tentative due to the difficulty in separating risk factors like age, weight and the effects of smoking.

The link between Parkinson’s disease and Agent Orange is also uncertain because, while new studies have strengthened the connection between the condition and certain chemicals, there is still no data on veterans and the condition.

Keith A. Young, vice chair for research at the Texas A&M Health Science Center College of Medicine, in the department of psychiatry and behavioral science and genetics core leader at the VA Center of Excellence for Research on Returning War Veterans at the Central Texas Veterans Health Care System said, "As we grow older, we become more fragile, and problems may not show up until we get more fragile.

"Differences tend to accumulate, and diagnoses get more sure and valid," he said. "As time goes on, the underlying pathology starts to break through, and we're able to see it more clearly. The chemical exposure did some damage that starts to be expressed as our bodies become more fragile."

The evidence "certainly point to the value of collecting lots of data on lots of different conditions to understand the effects of the environment on our bodies," Young said.