To evaluate whether paraquat is a major contributor to Parkinson's disease (PD) in California, we can analyze the exposure levels in the state's population, specifically focusing on farmworkers, who would be most directly exposed to this herbicide. Between 2017 and 2021, approximately 5.3 million pounds of paraquat were sprayed across California, and farmworkers, due to their
proximity to pesticide use, would be the population most at risk. Farmworkers in California are predominantly Latino, accounting for 92% of this workforce,
while only 8% are white. Given the high levels of exposure expected among farmworkers, we would expect the incidence of PD to be proportionately higher among this group if paraquat were a significant contributing factor. However, the data from the California Parkinson's Disease
Registry from 2018 to 2022 reveals a different trend. According to the registry:
• 59.3% of PD cases occurred in white individuals.
• Only 14.1% of PD cases occurred in Hispanic individuals.
These figures indicate a striking disparity: despite representing the overwhelming majority of farmworkers directly exposed to paraquat, Latino individuals account for a significantly smaller percentage of Parkinson's cases. In contrast, white individuals, who make up a much smaller
portion of the agricultural workforce and therefore would have considerably less exposure to paraquat, represent the majority of PD cases.
This data suggests that paraquat exposure is unlikely to be the primary driver of Parkinson's disease in California. If paraquat were a major contributor, we would expect the rates of Parkinson's among the highly exposed Latino farmworker population to be much higher. The significant difference in Parkinson's disease incidence between white and Latino populations raises doubts about the role of paraquat as a primary cause of the disease and suggests that other factors—genetic, environmental, or lifestyle-related—may be playing a larger role in its
development. Additionally, over 40% of Californians identify as Latino, compared to 35% who identify as white, further challenging the argument that paraquat exposure is a major factor in the
state’s PD cases. The Environmental Protection Agency (EPA) has not identified a definitive link between paraquat exposure and the development of Parkinson's disease.