By Mark Wheeler - January 03, 2013
For several years, neurologists at UCLA have been building a case that a link exists between pesticides and Parkinson's disease. To date, paraquat, menab, and ziram - common chemicals sprayed in California's Central Valley and elsewhere - have been tied to increases in the disease, not only among farmworkers, but in individuals who simply lived or worked near fields and likely inhaled drifting particles.
Now UCLA researchers have discovered a link between Parkinson's and another chemical, benomyl, whose toxicological effects still linger some 10 years after the chemical was banned by the U.S. Environmental Protection Agency.
Even more significantly, the research suggests that the damaging series of events set in motion by benomyl may also occur in people with Parkinson's disease who were never exposed to the pesticide, according to Jeff Bronstein, senior author of the study and a professor of neurology at UCLA, and his colleagues.
Benomyl exposure, they say, starts a cascade of cellular events that may lead to Parkinson's. The pesticide prevents and enzyme called ALDH (aldehyde dehydrogenase) from keeping a lid on DOPAL, a toxin that naturally occurs in the brain. When left unchecked by ALDH, DOPAL accumulates, damages neurons and increases and individual's risk of developing Parkinson's.
The research is published in the current online edition of Proceedings of the National Academy of Sciences.
Parkinson's disease is a debilitating neurodegenerative disorder that effects millions worldwide. It's symptoms - including tremor, rigidity, and slowed movements and speech - increase with the progressive degeneration of neurons, primarily in a part of the mid-brain called the substantia nigra. This area normally produces Dopamine, a neurotransmitter that allows cells to communicate, and damage to the mid-brain has been linked to the disease. Usually, by the time Parkinson's symptoms manifest themselves, more than half of these neurons, known as dopaminergic neurons, have already been lost. - While researchers have identified certain genetic variations that cause an inherited form of Parkinson's, only a small fraction of the disease can be blamed on genes, said the study's first author, Arthur G. Fitzmaurice, a postdoctoral scholar in Bronstein's laboratory.
"As a result, environmental factors almost certainly play an important role in this disorder," Fitzmaurice said. "Understanding the relevant mechanisms - particularly what causes the selective loses of dopaminergic neurons - may provide important cluse to explain how the disease develops."
Past Research on this subject:
High Risk of Parkinson's disease for people exposed to pesticides near workplace.
Study first to implicate pesticide ziram as possible cause for disease By Mark Wheeler May 26, 2011
Pesticide Exposure Found to Increase the Risk of Parkinson's Disease
Study finds exposure may have occurred years before symptoms appear By Mark Wheeler April 20, 2009