MSU Chemical Exposure Lawsuit Over Pesticide-Linked Cancer

A former Michigan State University graduate student, LingLong Wei, has filed a $100 million lawsuit against MSU alleging that years of unprotected pesticide exposure during her horticulture research caused her thyroid cancer. The MSU pesticide exposure lawsuit was filed in Ingham County Circuit Court in August 2025 and brings claims of gross negligence and negligent infliction of emotional distress against the university, several of its units, and three individual defendants.¹

What Wei Says Happened at MSU

Wei enrolled at MSU in 2008 as an international graduate student in the College of Agriculture and Natural Resources, pursuing a master’s in horticulture. Her program required her to work as a student research assistant, and that role, according to her complaint, meant spraying pesticides and herbicides in field research settings.¹

Supervisors directed her to apply three specific chemicals: paraquat dichloride, glyphosate, and oxyfluorfen. The complaint says she worked with these substances for up to eight hours in a single day and estimates her total exposure between 2008 and 2011 exceeded 7,000 hours.²

Wei alleges she was never given masks, gloves, or coveralls, and received no training on how to handle the chemicals safely. She has said wind would blow the substances into her face while she sprayed, and that university staff told her the exposure was “harmless.”³ When she sought care at MSU’s Olin Health Center in 2010 for shortness of breath, the complaint says, her symptoms were attributed to anxiety rather than chemical exposure.⁴ When Wei raised concerns about safety, the complaint alleges, supervisors dismissed or intimidated her.

The Cancer Diagnosis

More than a decade after leaving MSU, Wei had a thyroid biopsy on June 26, 2024, that identified cancerous cells. She received a formal diagnosis of papillary thyroid carcinoma on July 11, 2024.² Her thyroid was surgically removed, leaving a permanent scar near her throat. She has reported hormone imbalances that require daily medication, persistent fatigue, and difficulty having children.⁵

The Science the Complaint Relies On

Wei’s complaint ties her diagnosis to a 2022 study in the Journal of Clinical Endocrinology and Metabolism that examined pesticide exposure and thyroid cancer in an agricultural region of central California. The study analyzed more than 2,000 thyroid cancer cases and found statistically significant associations between thyroid cancer risk and each of the three chemicals Wei sprayed. Paraquat showed the strongest and most consistent association across all of the study’s models.⁶

The three chemicals sit in very different regulatory positions. Paraquat dichloride is a restricted-use pesticide in the United States, meaning only commercially licensed applicators are supposed to handle it, and it has been banned outright in at least 32 countries.⁷ Glyphosate, the active ingredient in Roundup, is the subject of a long-running scientific dispute: the U.S. Environmental Protection Agency maintains it “is not likely to be carcinogenic to humans,” while the International Agency for Research on Cancer classified it in 2015 as “probably carcinogenic.” The EPA is currently updating its evaluation after a federal appeals court vacated its earlier assessment in 2022.⁸ Oxyfluorfen showed a modest but statistically significant association with thyroid cancer in the 2022 study’s single-pollutant models.⁶

The Claims and the Defendants

The lawsuit brings two counts: gross negligence and negligent infliction of emotional distress. It alleges that MSU and the individually named defendants had “actual knowledge” that students were applying hazardous pesticides without protective equipment and knowingly allowed Wei to continue working under those conditions. The complaint accuses defendants of ignoring “countless safety protocols and governmental regulations,” failing to maintain spraying equipment, and requiring students to handle chemicals “against the directions and warnings of the product labels.”²

Beyond the university itself, the suit names the MSU Board of Trustees, the College of Agriculture and Natural Resources, the Department of Horticulture, and the Office of International Students and Scholars. Three individuals are also named: Bernard Zandstra, a professor emeritus in the Department of Horticulture who is accused of directing Wei’s pesticide work without providing safety training or equipment; Peter Briggs, the former Director of the Office for International Students and Scholars; and Rodney V. Tocco Jr., identified as a research manager and professor who allegedly instructed Wei to spray the chemicals.²

Under Michigan’s Governmental Tort Liability Act, state employees can generally claim immunity from personal liability, but gross negligence can strip that protection. The complaint argues the individual defendants’ conduct was “so reckless” that they should not be entitled to that immunity.²

How MSU Has Responded

University spokesperson Amber McCann said MSU “cannot comment on pending litigation” but said the university “prioritizes the health and safety of our entire campus community.” McCann added that “appropriate and required training and necessary personal protective equipment is provided in compliance with applicable university policies and state and federal laws.”⁹ The statement disputes Wei’s central allegation in general terms without addressing the specifics of her experience.

Where the Case Stands

Wei first signaled her intent to sue by filing a notice of intent with the Michigan Court of Claims around November 2024.¹⁰ The full complaint and jury demand were filed in Ingham County Circuit Court in August 2025. As of mid-2026 the case remains in its early stages, with no reported rulings on motions to dismiss or other substantive matters.¹

Wei is represented by Maya Green of the GreenLight Law Firm and Tilmandra Wilkerson.⁵ Green has said she believes other research assistants and students may have been harmed by similar conditions, raising the prospect of additional litigation against the university.⁴

1
Michigan Advance. Former Michigan State Horticulture Student Files $100 Million Lawsuit Over Pesticide Exposure
2
Michigan Advance. Wei v. Michigan State University Complaint
3
NBC News. Former Michigan State Student Says She Got Cancer Using Chemicals at School
4
Detroit Free Press. Michigan State University Lawsuit Research Assistant
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Spectrum News. Former Student Sues MSU
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PubMed. Thyroid Cancer and Pesticide Use in a Central California Agricultural Area: A Case Control Study
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National Library of Medicine. Thyroid Cancer and Pesticide Use in a Central California Agricultural Area
8
U.S. Environmental Protection Agency. Glyphosate
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CBS News Detroit. Former Student Sues Michigan State University Over Exposure to Chemicals
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The State News. Former Grad Student Says Pesticides in MSU Research Gave Her Cancer