Numerous research studies in the late 1990s established a connection between a higher rate of Parkinson’s disease and long-term exposure to common poisons used to kill pests (pesticides) and weeds (herbicides). Key support for this connection includes an unusually high rate of Parkinson’s disease among people who live in farm communities where pesticide and herbicide use is frequent. People who often use home pesticides and herbicides, such as for gardening and lawn care, also have higher rates of Parkinson’s disease. As well, autopsy evidence consistently demonstrates that people who have Parkinson’s when they die have higher levels of chemicals found in pesticides and herbicides in their brain than people who do not have Parkinson’s.
What this connection means as far as proving that they might cause Parkinson’s remains uncertain. Researchers know that there are close chemical similarities between many pesticides and herbicides and the illicit narcotic contaminant (from amateurish attempts to synthesize the synthetic narcotic pethidine) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that is used in the laboratory to create a Parkinson’s model in research animals. Yet far more people who live in farming communities with ostensibly the same exposure to pesticides and herbicides do not have Parkinson’s than do. Limiting exposure to these substances is prudent, regardless of the connection to Parkinson’s disease, as they are known neuro-toxins that can produce a wide range of damage to the brain and nervous system.