On August 1, 2021, the Environmental Protection Agency (EPA) published documents in the Federal Register announcing the Agency’s Interim Registration Review Decision for the pesticide paraquat dichloride (paraquat). Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), EPA is tasked with reviewing registered pesticides every 15 years to determine whether those pesticides should remain registered for use. When appropriate, EPA is permitted to issue what is known as an interim registration review decision prior to completing a 15-year registration review. Such decisions allow EPA to impose interim risk mitigation measures as well as identify data or information required to complete the review.

At the same time, Syngenta, the manufacturer of paraquat, is currently facing lawsuits from plaintiffs alleging that exposure to paraquat caused them to develop Parkinson’s disease. These lawsuits are similar to the ones that have been filed by plaintiffs alleging that exposure to glyphosate caused their non-Hodgkin’s lymphoma. It is yet to be determined what impact the paraquat lawsuits will have.

What is Paraquat

EPA originally registered paraquat for use in 1964. It is described as a broad-spectrum, contact herbicide that targets both emerged broadleaf and grass weeds by inhibiting photosynthesis which destroys cell membranes. Paraquat can be applied as a burn-down treatment prior to planting, but can also be applied directly onto the crop, or as a post-harvest desiccant. It is registered for use on a variety of crops, but usage data from 2014-2018 shows paraquat use was highest on soybeans, cotton, corn, grapes, pistachios, and peanuts. While paraquat is also applied to some non-agricultural use sites such as nurseries, landscapes, and rights-of-way, there are no paraquat products registered for homeowner or residential use. Usage of paraquat has increased in recent years as it has proven effective at controlling weeds that have become resistant to glyphosate.

Paraquat is a restricted use pesticide, which means that it can only be purchased and applied by a certified pesticide applicator or someone under the direct supervision of a certified pesticide applicator. Generally, a pesticide will be designated for restricted use if its toxicity exceeds certain hazard criteria, and its labeling does not adequately mitigate those hazards. EPA has recognized paraquat as being “highly acutely toxic when inhaled or ingested.” Due to paraquat’s toxicity, EPA has adopted several mitigation measures to ensure that the pesticide is used safely.

Recent EPA Actions

A pesticide may not be legally used in the United States unless it is registered for use under FIFRA. Once registered, a pesticide will remain register unless either EPA or the registrant moves to cancel the registration. In order to ensure that registered pesticides continue to meet registration criteria, FIFRA requires a periodic review of registered pesticides. Generally, these reviews are mandated every fifteen years after a pesticide is first registered. 7 U.S.C. § 136a(g)(1)(A)(iii)(II). The review process is straightforward – EPA initiates review by establishing a public docket for the registration review case that is open for public comment, and publishes a notice in the Federal Register announcing the availability of docket and providing the public with a 60-day comment period during which anyone may submit information or data. For many pesticides going through registration review, EPA will hold focus meetings involving registrants and other interested parties that are intended to address any areas of uncertainty or concern. Ultimately, EPA will published a proposed decision in the Federal Register presenting proposed findings regarding FIFRA registration criteria, and any changes to the pesticide’s label EPA thinks are necessary. The public have 60 days to comment, after which EPA will review the comments and publish a final registration decision in the Federal Register.

As part of the registration review process, EPA may issue an interim registration review decision if the Agency is not ready to complete the entire review, but has conducted sufficient review to determine that new risk mitigation measures are needed or that additional data or information is needed. 40 C.F.R. § 155.56. Like the final registration review decision, a proposed interim registration review decision is published in the Federal Register, the public are given time to comment, and a final registration review decision is published in the Federal Register after EPA has reviewed the comments.

EPA initiated registration review for paraquat in 2011. On October 22, 2020, EPA published a proposed interim registration review decision, followed by a final interim registration review decision on August 1, 2021. The interim decision is meant to mitigate potential human health risks related to occupational handling of paraquat that have been identified by EPA. The mitigation measures identified in the interim decision include:

  • Limiting area applications of paraquat to a maximum of 350 acres per applicator per 24-hour period of all uses except cotton desiccation;
  • Requiring a residential drift buffer for all aerial applications;
  • Prohibiting use of human flaggers;
  • Limiting the single application maximum rate for alfalfa;
  • Requiring PF10 respirators or enclosed cabs for applications to more than 80 acres in a 24-hour period;
  • Prohibiting the use of mechanically pressurized handguns and backpack sprayers;
  • Requiring a 48-hour Restricted Entry Interval for all crop uses except for cotton desiccation;
  • Requiring a 7-day Restricted Entry Interval for cotton desiccation; and
  • Requiring mandatory spray drift management measures.

Most of the proposed mitigation measures are new, however the decision to allow aerial spraying on all registered crops has drawn some criticism. In the proposed interim registration review decision released in October, EPA had proposed prohibiting all aerial applications for all uses except cotton desiccation. Critics argue that the prohibition on aerial applications should have been included in the final interim registration decision.

On-going Lawsuits

The first lawsuit alleging injury as a result of paraquat exposure was filed in 2017. In that lawsuit, the plaintiff alleged that exposure to paraquat caused him to develop Parkinson’s disease. Since 2017, dozens of similar lawsuits have been filed. In June of 2021, those lawsuits were consolidated into a multi-district litigation (“MDL”) located in the Southern District of Illinois.

One of the earliest paraquat lawsuits was filed in 2017 in the 20th Judicial Circuit Court of St. Clair County, Illinois. Like in other paraquat cases, the plaintiffs in Hoffman v. Syngenta, No. 17-L-517 (Ill. Cir. Ct. 2021) allege that they developed Parkinson’s disease as a result of being exposed to paraquat. They raise a variety of state law claims, including: design defect; failure to warn; negligence; public nuisance; breach of implied warranty and merchantability; and violations of the Illinois Consumer Fraud and Deceptive Business Practices Act. In essence, the plaintiffs are claiming that paraquat was manufactured and sold in a defective condition because it is unreasonably dangerous when used in a reasonably foreseeable manner, and that the defendants failed to provide directions for use that would have made paraquat safe, or a warning informing consumers that using paraquat was likely to cause neurodegenerative injuries, including Parkinson’s disease. Additionally, the plaintiffs claim that the defendants should have known that they were putting consumers at risk.

The trial in Hoffman v. Syngenta was scheduled to start June 1, 2021, but has been postponed without a new date being set. It is unclear why the trial was postponed, and neither side has confirmed whether settlement terms have been discussed. Whatever the outcome, this case is being closely watched as a bellwether trial for future paraquat litigation.

In the meantime, dozens of paraquat cases filed in federal district court have been consolidated into an MDL. An MDL is a legal proceeding designed to make litigation more convenient for parties and facilitate overall efficiency in the courts. Lawsuits may be consolidated into an MDL if they share a common issue, or common parties. The plaintiffs in In re: Paraquat Products Liability Litigation, No. 3:21-md-03004 (S.D. Ill. 2021) have raised largely the same claims as the plaintiffs in Hoffman v. Syngenta, including claims of design defect and failure to warn. The judge presiding over the MDL has set a jury trial date for November 15, 2022.


It is currently unclear whether the paraquat lawsuits will have any impact of EPA’s registration review of paraquat. In the final interim registration decision, EPA reasserted that it had not established a link between paraquat and Parkinson’s disease. Until a paraquat case goes to trail, it is also unclear whether plaintiffs in such cases will be able to succeed on their claims.

The National Agricultural Law Center will provide updates as this issue develops.


To read the final interim registration decision for paraquat, click here.

To read the proposed interim registration decision for paraquat, click here.

To read the complaint in Hoffman v. Syngenta, click here.

To read the text of FIFRA, click here.

For more National Agricultural Law Center resources on pesticides, click here.