Paraquat Exposure Damages Neurons in Way That May Lead to Parkinson’s Disease: Study

Tests on human cell lines revealed exposure to Paraquat caused build-up in proteins linked to the development of several neurodegenerative diseases.

The findings of a new study provide more proof that Paraquat exposure can lead to Parkinson’s disease, and possibly explain how the controversial weed killer causes the devastating neurological condition.

Paraquat has been widely used as a weed and grass killer on farms throughout the United States for decades, even though it has been banned in several countries due to serious health risks. However, warnings and safety instructions provided for users largely focus on the risk of Paraquat poisoning, as ingesting even small amounts can result in fatal injuries.

In recent years, a number of studies have identified a link between Paraquat and Parkinson’s disease, which is a serious and progressive neurological condition that causes shaking, stiffness and difficulty walking, balancing and coordinating body movements.

Syngenta, the manufacturer, currently faces thousands of Paraquat lawsuits filed by agricultural workers, farmers, landscapers and others nationwide, who were frequently exposed to the herbicide and subsequently diagnosed with Parkinson’s disease, indicating they were never warned about the neurological side effects of Paraquat exposure.

In findings of a new published in the journal Ecotoxicology and Environmental Safety on August 10, a team of researchers led by Ai Qi and Kaidong Wang of the Ningxia Medical University School of Public Health, report that exposure to Paraquat results in the buildup of a protein in the brain that is linked to neurodegenerative diseases, such as Lewy body disease and Parkinson’s disease.

The Paraquat exposure tests on the human neuroblastoma cell lines revealed a buildup of α-synuclein (α-syn), which the brain could then not get rid of efficiently. This is what also appears to happen in the brains of those suffering from neurodegenerative diseases, the researchers noted.

“The lack of amyloid clearance is now widely recognized as one of the important etiologies of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases,” the researchers indicated. “Epidemiological studies and rodent experiments have shown that [Paraquat] is associated with Parkinson’s disease and causes typical pathological changes such as misfolding of soluble α-syn monomers into insoluble aggregates that are difficult to degrade.”

The study noted that this effect has previously been seen on mouse models, but the researchers’ use of actual verified human cell lines is likely to be seen as a stronger argument that Paraquat can cause Parkinson’s disease and other neurodegenerative problems in humans, and may provide compelling evidence in litigation currently moving forward in several U.S. courts.

September 2024 Paraquat Lawsuit Update

There are currently more than 8,000 Paraquat lawsuits pending in federal and state courts nationwide, each raising similar allegations that former workers exposed to the toxic herbicide may have avoided a Parkinson’s disease diagnosis if better warnings had been provided about the Paraquat exposure risks.

Given common questions of fact and law raised in complaints brought throughout the federal court system, the Paraquat litigation has been centralized before U.S. District Judge Nancy J. Rosenstengel in the Southern District of Illinois since June 2021, as part of a federal MDL, or multidistrict litigation.

To help the parties evaluate how juries may respond to certain evidence and testimony that will be repeated throughout various claims, the Court previously established a “bellwether” process where a small group of Paraquat lawsuits are being prepared for trial, which are expected to be representative of the bulk of claims in the litigation.

If the parties have not reached a Paraquat settlement agreement or other resolution after the bellwether trials are concluded, it is likely that Judge Rosenstengel will begin remanding the cases back to their originating District Courts for individual trial dates.