Parkinson's disease is a progressive nervous system disorder that affects movement. Symptoms start gradually, sometimes starting with a barely noticeable tremor in just one hand. Tremors are common, but the disorder also commonly causes stiffness or slowing of movement.

Due to its extreme toxicity, Paraquat is a weed-killing herbicide restricted to commercial use exclusively. Farmers and agricultural laborers are the most vulnerable to paraquat exposure, but residents living near industrial farms may also be at danger.