Thyroid Cancer Risk Linked to Paraquat, Roundup and Other Pesticides: Study

Paraquat was linked to increased thyroid cancer risks under every analysis model researchers tried.

Amid rising concerns about the side effects of Roundup, Paraquat and other controversial pesticides, new research suggests residential use of the weed killers could increase the risk of thyroid cancer.

In a study published in the September 2022 issue of the The Journal of Clinical Endocrinology & Metabolism, researchers with the University of California Los Angeles (UCLA) indicate that a third of pesticides tested were associated with an increased risk of thyroid cancer among residential users, with Paraquat having one of the strongest associations.

There are currently about 1,300 product liability lawsuits filed against Syngenta and Chevron in the federal courts, each raising similar allegations that the companies manufactured and sold Paraquat-based herbicides for decades, without warning about the link between Paraquat and Parkinson’s disease, which research has found may develop years after regularly spraying, mixing, transporting or handling the weed killer.

The study’s findings are also just the latest in a long-series of health concerns regarding Roundup exposure and the active ingredient glyphosate, which has already been linked to an increased risk of non-Hodgkins lymphoma, which has resulted in tens of thousands of Roundup lawsuits in recent years against Monsanto.

Learn More About

Paraquat Lawsuits

Exposure to the toxic herbicide Paraquat has been linked to a risk of Parkinson's disease.

Learn More About this Lawsuit See If You Qualify Now >

In this latest study, UCLA researchers conducted a case-control study looking at thyroid cancer cases from the California Cancer Registry from 1999 to 2012. They examined residential exposure to 29 agricultural use pesticides known to either cause DNA damage in vitro or known to be endocrine disruptors. Of those, 10 were linked to increased thyroid cancer risks.

Researchers looked at 2,067 thyroid cancer cases and 1,003 controls. They found that within a 20-year exposure period, Paraquat users faced a 46% increased risk of thyroid cancer, and glyphosate exposure resulted in a 33% increased risk. They noted that in every model they tried, Paraquat was linked to an increased risk of thyroid cancer.

“Our study provides first evidence in support of the hypothesis that residential pesticide exposure from agricultural applications is associated with an increased risk of thyroid cancer,” the researchers concluded.

Share Your Story

Add comments for the community about your experiences with Paraquat or other weed killers.


October 2022 Paraquat Lawsuit Updates

It is unclear whether this latest study about the potential link between Paraquat and thyroid cancer may result in additional lawsuits against the makers of the controversial herbicide, which is already facing hundreds of Parkinson’s disease lawsuits and calls for the EPA to withdraw authorization for use in the United States.

Given common questions of fact and law raised in the existing Paraquat litigation, all federal cases have been centralized before U.S. District Judge Nancy J. Rosenstengel in the Southern District of Illinois, for coordinated discovery and pretrial proceedings as part of an MDL or multidistrict litigation. To help the parties gauge how juries may respond to certain evidence and testimony that will be presented throughout the litigation, the Court has set an aggressive schedule that anticipated the first Paraquat Parkinson’s trial dates going before a jury on November 15, 2022.

While the outcome of these bellwether trials will not have any binding impact on other plaintiffs, they will be closely watched by all parties involved, and are expected to greatly influence any Paraquat settlement offers the manufacturers may make to avoid hundreds of individual cases later being remanded back for separate trial dates in U.S. District Courts nationwide.


  • PatrickJanuary 4, 2023 at 2:57 pm

    I have under gone a complete thyroidectomy because of Encapsulated papillary thyroid carcinoma, follicular variant with single focus of vascular invasion, 6 cm, involving the left thyroid lobe, organ-confined. This was 09/25/2019.

  • PennyOctober 19, 2022 at 7:36 pm

    I've had my whole thyroid removed I had two different kinds of cancer they were both in stage 2 and that happened in 2008 for about 2 years I tried to tell him something was wrong and I went to like three different doctors and nobody listen to me

"*" indicates required fields

Share Your Comments

I authorize the above comments be posted on this page*

Have Your Comments Reviewed by a Lawyer

Provide additional contact information if you want an attorney to review your comments and contact you about a potential case. This information will not be published.

NOTE: Providing information for review by an attorney does not form an attorney-client relationship.

This field is for validation purposes and should be left unchanged.