ISSUE: Summer 2009, feature stories | May 28, 2009
Three kinds of pesticides have been implicated as possible causes of Parkinson's disease. Scientists believe that the mechanism of damage is different for each category.
Herbicides Chemicals such as Paraquat that destroy broadleaf weeds are thought to stimulate an increase in the protein alpha-synuclein in the brain, which is known to destroy the cells in the substantia nigra that are responsible for producing dopamine.
Insecticides Agents that kill insects, either naturally (such as the botanical Rotenone) or chemically (such as Dieldrin), increase the production of alpha-synuclein in the brain and also damage dopamine-producing brain cells directly. Rotenone, in particular, also seems to lead to dysfunction of the mitochondria, the energy-producing component of a cell, and to oxidative stress in the brain.
Fungicides Antifungal chemicals such as Maneb and Benomyl are thought to affect the mitochondria of certain brain cells and to injure the repair mechanisms of dopamine-producing neurons, making them more vulnerable to stress. This priming function may help explain observations that exposure to Maneb plus Paraquat is much more damaging than exposure to either agent alone.
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