Current Case

Paraquat Herbicide and Parkinson’s Disease

Since at least the mid‐1960s, experts have known that the herbicide paraquat — manufactured, marketed, and distributed by Chevron and Syngenta — is highly toxic to both plant and animal cells. Paraquat has been used since that time to kill broadleaf weeds and grasses before the planting or emergence of more than 100 field, fruit, vegetable, and plantation crops. It’s also used to control weeds in orchards and to dry plants before harvest.

Paraquat is sold as a liquid concentrate that is diluted with water and applied by spraying onto target vegetation. The herbicide is typically formulated with crop oil so it will stay in contact with and penetrate the leaves of target plants and enter plant cells. Typically, paraquat is applied using knapsack sprayers, hand‐held sprayers, aircraft (i.e., crop dusters), trucks with attached pressurized tanks, and tractor‐drawn pressurized tanks. It is commonly used multiple times per year on the same ground, particularly when used to control weeds in orchards and in farm fields where multiple crops are planted in the same growing season or year.

People who used paraquat were commonly exposed to paraquat while it was being mixed and loaded into the tanks of sprayers, including through spills, splashes, and leaks while equipment used to spray it was being emptied or cleaned or while clogged spray nozzles, lines, or valves were being cleared.

Paraquat is highly toxic to nerve cells, including dopaminergic neurons, and creates a substantial risk of neurotoxic harm to persons exposed to it. Paraquat enters the human body via absorption through the skin, mucous membranes, and other epithelial tissues, including tissues of the mouth, nose and nasal passages, trachea, lungs, and conducting airways, particularly where cuts, abrasions, rashes, sores, or other tissue damage is present, as well as through the digestive tract. When paraquat enters the body, it enters the bloodstream and ultimately the brain.

Once in the brain, paraquat causes the degeneration and death of dopaminergic neurons consistent with that seen in human Parkinson’s disease, and motor deficits and behavioral changes consistent with those commonly seen in human Parkinson’s disease. Hundreds of in vitro studies (experiments in a test tube, culture dish, or other controlled experimental environment) have found that paraquat causes the degeneration and death of dopaminergic neurons. Finally, epidemiological studies (studies of the patterns and causes of disease in defined populations) suggest an association between paraquat exposure and Parkinson’s disease, including multiple studies finding a two‐ to five‐fold or greater increase in the risk of Parkinson’s disease in populations with occupational exposure to paraquat compared to populations without such exposure.

DiCello Levitt’s team of skilled attorneys led by Diandra “Fu” Debrosse Zimmermann, who was appointed to the plaintiffs’ executive committee by the federal court overseeing this litigation, represent thousands of victims exposed to paraquat and who have developed Parkinson’s as a result of that exposure. Our team seeks hundreds of millions of dollars to compensate these clients for their suffering caused by Chevron and Syngenta’s misconduct surrounding paraquat.