Environmental Causes of PD
The vast majority of cases of PD are thought to be due to the potential interactions of genes and the environment. Environmental causes are presumed to be one or more widely present but weak toxins. The effects of these toxins may build up over time and eventually lead to disease in genetically predisposed individuals. The identity of these toxins is unknown, although several environmental risk factors have been identified through epidemiological studies.
A strong and consistent finding is that the risk of PD is increased by rural living, exposure to well water, and agricultural work, suggesting that pesticides or herbicides may cause or contribute to PD. It should be pointed out, however, that these individual factors do not by any means guarantee the development of PD, nor does their absence protect against it; there are many cases of individuals with none of these risk factors who develop PD, and many with them who do not.
