Wisner Baum Lawsuit Alleges Syngenta Failed to Warn of Atrazine’s Cancer Risks

Apostolos Panayiotou alleges that nearly three decades of mixing and spraying atrazine-based herbicides in Los Angeles County led to his cancer diagnosis. Wisner Baum’s lawsuit also challenges what Syngenta told applicators outside its EPA-approved product labels.

Nationally recognized plaintiffs’ firm Wisner Baum LLP has filed a lawsuit against Syngenta on behalf of California resident Apostolos Panayiotou, alleging that decades of exposure to atrazine-based herbicides caused him to develop non-Hodgkin lymphoma. The case follows a 2025 evaluation by the International Agency for Research on Cancer (IARC) that classified atrazine as “probably carcinogenic to humans.”

According to the complaint, Panayiotou regularly mixed, loaded, sprayed and applied atrazine products in Los Angeles County over a three-decade time span. The lawsuit alleges that Syngenta designed and sold products that exposed users to a risk of cancer and failed to warn them in its advertising, training, sales communications and other channels outside federally approved pesticide labels.

“Mr. Panayiotou handled these products year after year, exactly as they were intended to be used, and he developed cancer. Syngenta knew or should have known about the risks applicators faced, and it failed to warn them,” said Pedram Esfandiary, a partner at Wisner Baum and one of the attorneys representing Panayiotou.

The complaint names Syngenta AG and Syngenta Crop Protection, LLC as defendants. Panayiotou says his lymphoma has caused physical pain, emotional distress, medical expenses and lost income. The lawsuit seeks compensation for his injuries and losses, as well as punitive damages.

Exposure Through Direct Handling

Panayiotou’s lawsuit focuses on exposure through mixing, loading, spraying and applying atrazine-based products, a route distinct from the environmental presence of atrazine in water or soil. The complaint alleges that these products can enter an applicator’s body through skin contact, inhalation and incidental ingestion during ordinary work. It also draws a distinction between atrazine as an individual chemical and the formulated products users handle. Those products contain additional ingredients that the lawsuit alleges can increase absorption and exposure.

The U.S. Environmental Protection Agency (EPA) describes atrazine as a chlorinated triazine systemic herbicide used to selectively control annual grasses and broadleaf weeds before they emerge. Pesticide products containing atrazine are registered for use on several agricultural crops, with the highest use on field corn, sweet corn, sorghum and sugarcane.

Atrazine’s Cancer Risk and Syngenta’s Failure to Warn

In November 2025, IARC classified atrazine as “probably carcinogenic to humans.” The agency found sufficient evidence of cancer in experimental animals, strong mechanistic evidence and evidence of a positive association with non-Hodgkin lymphoma in humans. Atrazine has been banned throughout the European Union since 2004 and is not permitted for general agricultural use in Switzerland, where Syngenta AG is headquartered.

The complaint alleges that Syngenta knew or should have known that published research linked atrazine exposure to non-Hodgkin lymphoma and showed that atrazine suppresses the immune system. It further alleges that the company failed to adequately investigate the risks or warn users and continued to market its products without disclosing the cancer risk.

Panayiotou says he would not have purchased or used the products had he received an adequate warning. His failure-to-warn claim concerns communications outside EPA-approved labels, including promotional materials, sales and technical communications, product stewardship programs and applicator training.

“People deserve to know whether the products they use to do their jobs could put their health at risk,” said Timothy A. Loranger, a senior partner at Wisner Baum who is also representing Panayiotou. “Syngenta had information these workers needed to protect themselves, and it failed to share it. Mr. Panayiotou and others deserved better.”

Lawsuit Challenges Syngenta’s Product Design and Conduct

Panayiotou brings three claims under California law: strict liability for design defect, strict liability for failure to warn outside the label, and negligence. The complaint alleges that Syngenta could have reduced or eliminated the cancer risk through alternative ingredients, formulations, packaging and application systems.

It also alleges that Syngenta waged a campaign to shape, suppress and undermine the science on atrazine, including a plan to discredit a scientist whose research raised concerns, as well as the use of paid advocates whose financial ties to the company were not disclosed.

Wisner Baum previously announced an investigation into claims involving atrazine exposure and non-Hodgkin lymphoma. The firm continues to speak with people who regularly mixed, loaded or sprayed atrazine-based herbicides and were later diagnosed with the disease.

“For someone who handled these products for decades, the decisions behind their design and safety communications had real consequences,” Esfandiary said. “Mr. Panayiotou is asking the court to examine those decisions and hold Syngenta accountable for the harm they caused.”

About Wisner Baum

Wisner Baum is a nationally recognized plaintiffs’ law firm with offices across the United States. For decades, the firm has represented individuals harmed by corporate misconduct, dangerous products, environmental exposure and systemic failures. For more information, visit www.wisnerbaum.com.

References

• U.S. Environmental Protection Agency. (2025, October 7). Atrazine.
• International Agency for Research on Cancer. (2025, November 21). IARC Monographs evaluation of the carcinogenicity of atrazine, alachlor, and vinclozolin. iarc.who.int/news-events/iarc-monographs-evaluation-of-the-carcinogenicity-of-atrazine-alachlor-and-vinclozolin/
• Panayiotou v. Syngenta AG, No. 2:26-cv-11652 (C.D. Cal. Oct. 6, 2026) (complaint for damages and demand for jury trial)
• Wisner Baum. (2026, May 12). Wisner Baum investigates Syngenta amid renewed questions over atrazine safety. wisnerbaum.com/in-the-news/wisner-baum-investigates-syngenta-amid-renewed-questions-over-atrazine-safety/