Agent Orange Component Linked to Parkinson’s Disease


SUNNYVALE, CA – September 14, 2008 – Workplace use of  the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), a key constituent of  the defoliant Agent Orange, is associated with an increased risk of  developing Parkinson’s disease, according to a report published in the Archives of Neurology by Caroline M. Tanner, M.D., Ph.D., Director of Clinical Research at the Parkinson’s Institute, and her colleagues at eight Parkinson’s disease research centers in the U.S. and Canada. Two other pesticides – paraquat and permethrin – were also associated with higher risk of Parkinson’s disease.

Pesticide exposure has been suspected to increase risk of PD since 1983, when study co-author  J. William Langston, M.D., Scientific Director of the Parkinson’s Institute, described parkinsonism caused by intravenous injection of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), a chemical used in the manufacture of herbicides. Pesticide use for farming has been associated with Parkinson’s disease risk in prior studies, but few have been able to identify specific pesticides. 

In the current study, lifelong occupational histories were collected for 519 persons with Parkinson’s disease and 511 persons who were the same age, sex, and who lived in the same location, but did not have Parkinson’s disease. Participants provided detailed information about their jobs, including specific tasks and chemicals used, including solvents and pesticides. Parkinson’s disease risk was doubled in those using pesticides at work. For those using 2,4-D, the risk was  more than two and a half times greater.

An Institute of Medicine panel, reviewing evidence collected in other studies, recently determined that there is “Limited or Suggestive Evidence of an Association” between exposure to Agent Orange and Parkinson’s disease (see the report Veterans and Agent Orange: Update 2008, http://www.iom.edu/CMS/3793/4689/71705.aspx ). Legislation currently under consideration by the 111th Congress (HR 1428, sponsored by Rep. Bob Filner, D-CA) asks the Secretary of Veterans Affairs to provide wartime disability compensation to veterans with Parkinson's disease who had herbicide exposure in Vietnam.  The current study suggests that civilians may also be at increased risk for Parkinson’s disease after exposure to 2,4-D.

Leaders in Parkinson’s disease research partnering with the Parkinson’s Institute and who co-authored the study include G. Webster Ross, M.D., at the Veterans Affairs Pacific Islands Health Care System,  Honolulu, HI; Robert A. Hauser, M.D., at the  University of South Florida, Tampa, FL ; Joseph Jankovic, M.D., at Baylor College of Medicine Houston, TX ; Stewart A. Factor, D.O., at Emory University School of Medicine, Atlanta, GA; Susan Bressman, M.D., at Beth Israel Medical Center, New York, NY, Connie Marras, M.D., Ph.D., at Toronto Western Hospital, Toronto, Ontario, Canada; Kelly Lyons, Ph.D. at University of Kansas Medical Center, Kansas City, KS and Robert Abbott, Ph.D. at the University of Virginia School of Medicine, Charlottesville, VA.

Approximately 1 million Americans are affected with Parkinson’s disease, a common neurodegenerative disease that causes a high degree of disability and adds financial burden for our health care system. It is estimated that the number of Parkinson’s disease cases will double by the year 2030. Identification of the causes of Parkinson’s disease, more effective treatments, and, ultimately, ways to prevent or cure the disease are the focus of the Parkinson’s Institute.

About the Parkinson’s Institute and Clinical Center

Founded in 1988, The Parkinson’s Institute and Clinical Center (PI) is America’s only independent non-profit organization that provides both basic and clinical research, clinical trials and a comprehensive movement disorder patient clinic for Parkinson’s disease (PD) and related neurological movement disorders, all under one roof. Its mission is to find the causes, provide first class patient care and discover a cure.  Its unique freestanding organization supports a strong collaboration of translational medicine designed to more directly connect research to patient care – from the "bench to bedside".

For more information, please visit www.thepi.org or call 408.734.2800

Contact:
Mary Tunison
Development Director
The Parkinson's Institute and Clinical Center
mtunison@thepi.org


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