The federal judge presiding over 3,200 Paraquat lawsuits, consolidated in multidistrict litigation (MDL), will hold hearings in August that will determine which expert witnesses will be allowed to testify. Plaintiffs in the MDL, mostly farmers and agricultural workers, are suing Syngenta and Chevron, manufacturers of the herbicide, accusing the corporations of failing to warn about the risk that Paraquat exposure may lead to Parkinson’s disease. 

Agricultural workers are particularly vulnerable to Paraquat poisoning when mixing or spraying the weedkiller. 

A 2020 review published in Scientific Reports concluded that Paraquat (PQ) is “exceedingly toxic to humans” and that there is no “specific antidote to PQ poisoning.” The study also stated, “Toxicity caused by PQ results in lipid peroxidation and an increase in reactive oxygen species (ROS) … damage to the biliary system, gastrointestinal system and nervous system, in addition to lungs, kidneys, and the liver.” 

The biliary system is a group of organs including the gallbladder that drain waste from the liver and assist in the digestion of foods, particularly fats.

The Paraquat MDL was approved in June 2021, and the cases were consolidated in the Southern District of Illinois before U.S. District Judge Nancy J. Rosenstengel. An MDL is created to prevent U.S. District Courts from becoming clogged with cases that share similar facts and plaintiff claims.  

If no settlement is reached between the defendants and the plaintiffs, prediscovery for the first test cases or bellwether trials is set to begin in October of this year. In April, Judge Rosenstengel scheduled “Daubert” hearings for August 21. 

Daubert hearings serve two primary functions: to rule on the admissibility of scientific evidence that will be presented by expert witnesses and, if necessary, to rule on a summary judgment. If granted, a summary judgment motion could dismiss all 3,200 lawsuits outright without a full trial. This will only occur if Judge Rosenstengel rules that there is no conclusive evidence based on good science that links Paraquat usage with Parkinson’s disease. 

In addition to the Paraquat MDL, Paraquat lawsuits have been filed in state courts. According to a 2022 investigative report, Syngenta’s internal records reveal that the company has known about the association between Paraquat and Parkinson’s since 2001, and since the mid-20th century, the company was aware of other risks linked with the herbicide. The investigative report is known as the “Paraquat Papers.”