The etiology of Parkinson disease (PD) is multifactorial and involves both genetic and nongenetic factors. Only approximately 10%–20% of the incidence of PD can be attributed to genetics, implying a larger role for nongenetic factors, including—but not limited to—environmental toxins. There is currently broad interest in the identification of environmental toxins that may increase the risk of PD because such factors are potentially modifiable and could therefore be targeted as part of a public health campaign aimed to prevent PD.