# Undisclosed safety data surfaces in US paraquat lawsuits linked to Parkinson's Syngenta faces legal challenges as evidence mounts against its weedkiller's health risks. - **Source:** [Environment | The Guardian](https://www.theguardian.com/us/environment) - **Published:** 2026-09-25 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/ab7fa3c7-88c8-40ad-9c7d-3822ef35e0c0 ## Global ban momentum Sweden first called for a paraquat ban in 2004, followed by dozens of countries including China, which halted domestic use after its own safety studies. The chemical remains in US markets despite mounting evidence linking it to Parkinson's disease, with only Vermont and California implementing state-level bans so far. ## Regulatory divergence While California regulators announced paraquat makers' voluntary sales halt in August 2023 following new health research, the EPA maintains its registration. This regulatory gap persists even as federal lawmakers push for nationwide prohibition, highlighting tensions between state and federal chemical oversight. ## Corporate accountability questions Syngenta, owned by Chinese state since 2017, faces lawsuits alleging it withheld relevant safety data from EPA. The company denies these claims while operating in a shrinking global market - its chemical banned in China since 2012 but still sold in US agricultural sectors. ## Scientific consensus Years of peer-reviewed research established paraquat's association with Parkinson's, prompting California's action. The state identified specific health concerns in new studies, though EPA's risk assessment process hasn't yet reflected these findings, creating a scientific-regulatory disconnect. ## Legal landscape Plaintiffs in multiple lawsuits allege Syngenta knew about paraquat's neurological risks but failed to warn users. These cases join broader product liability trends targeting agrochemical manufacturers, testing corporate responsibility frameworks for legacy products with emerging health data. ## Market implications Paraquat's US market persistence contrasts sharply with global retreat, creating competitive disadvantages for Syngenta in regions with stricter regulations. The litigation wave may accelerate industry shifts toward alternative herbicides as liability concerns grow. ## Regulatory scrutiny EPA's continued paraquat registration faces mounting challenges from state actions and congressional pressure. The agency's delayed response to emerging science raises questions about chemical reevaluation timelines and industry influence in standard-setting processes. ## Public health crossroads The paraquat controversy underscores systemic gaps in chemical regulation where new health risks emerge post-approval. With Parkinson's links now actionable in courts but not yet in federal policy, the outcome could reshape accountability for legacy agrochemicals industry-wide. ## Sources covering this story - https://www.theguardian.com/environment/ng-interactive/2026/sep/25/syngenta-paraquat-parkinsons-lawsuits-epa — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._