, published January 2013 in Proceedings of the National Academy of Sciences, the UCLA team discovered a link between Parkinson's and the pesticide benomyl, a fungicide that has been banned by the U.S. Environmental Protection Agency. That study found that benomyl prevents the enzyme aldehyde dehydrogenase (ALDH) from converting aldehydes — organic compounds that are highly toxic to dopamine cells in the brain — into less toxic agents, thereby contributing to the risk of Parkinson's.

In an earlier study