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Birnbaum testifies on heart disease and Agent Orange

By Eddy Ball
October 2010

Linda Birnbaum, Ph.D., NIEHS/NTP Director
Birnbaum has appeared before several Congressional committees and subcommittees as an expert in environmental health and disease caused by environmental exposures. (Photo courtesy of Steve McCaw)

NIEHS/NTP Director Linda Birnbaum, Ph.D., entered the national conversation on Vietnam-era exposure to dioxin in Agent Orange and its link to ischemic heart disease (IHD). She joined two other scientists, Secretary of Veterans Affairs (VA) Eric Shinseki, and former Secretary Anthony Principi as witnesses at a hearing on "VA Disability Compensation: Presumptive Disability Decision-Making" Sept. 23 conducted by the United States Senate Committee on Veterans' Affairs.

While she maintained scientific objectivity about the level of evidence in studies of dioxin and IHD, Birnbaum testified that exposure to the chemical is associated with alterations in the vascular structure, gene expression, and several other diseases and conditions related to ischemic heart disease.

"There are a number of other risk factors that can influence the development of this disease," said Birnbaum. "It is also unclear from studies available to us how much risk remains many years after exposure."

Chaired by Senator Daniel Akaka (D-Hawaii), the committee heard first from Shinseki's one-person panel on the role of presumptions of service connection in claims for Veterans' benefits and, in particular, to discuss presumptions established pursuant to the Agent Orange Act of 1991. In his testimony and in response to questions from committee members, Shinseki underscored the government's commitment to provide Vietnam veterans with treatment and compensation for the health effects of herbicide exposure, including IHD.

Birnbaum was part of panel two and joined Principi, National Heart, Lung, and Blood Institute scientist Diane Bild, M.D., and University of Southern California researcher Jonathan Samet, M.D., who headed the Institute of Medicine (IOM) Committee on Evaluation of the Presumptive Disability Decision-Making Process for Veterans. They spoke on details of IHD and the several factors, including dioxin exposure during service in Vietnam, that increase risk for developing the disease.

"Understanding the role that environmental and occupational exposures play in the development of chronic diseases can be challenging," Birnbaum explained, "particularly for diseases that have significant risk factors in addition to the chemical exposure." She reviewed a meta-analysis that she and her colleagues published in 2008, the IOM conclusion that "there is limited or suggestive evidence of an association between Agent Orange or dioxin exposure and ischemic heart disease," and the ongoing reassessment of dioxin by the U.S. Environmental Protection Agency (EPA).

Following her testimony (, Birnbaum was asked by Akaka about the latest EPA evaluation of dioxin's impact on health. Although she observed that very few studies specifically addressed IHD,  she said, "It is clear that ... dioxin can cause heart disease as a consequence."

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