Undisclosed safety data at issue as weedkiller maker Syngenta faces US Parkinson's lawsuits

The maker of the weedkiller paraquat, Syngenta, is facing lawsuits in the United States linked to Parkinson's disease, amid claims that undisclosed safety data was kept from regulators even as the chemical has been banned in dozens of countries around the world.

Syngenta has denied withholding relevant data from the US Environmental Protection Agency. Paraquat remains available on the US market, even as evidence connecting the chemical to Parkinson's disease has led a growing number of countries to ban its use.

Sweden was among the first to raise concerns, calling for a ban on paraquat in 2004, more than two decades ago. Since then, dozens of other countries have followed with bans of their own, citing mounting evidence of links between the weedkiller and the neurodegenerative disease.

Despite this global trend, paraquat has continued to be sold and used in the United States, where it remains registered for agricultural use. The lawsuits against Syngenta centre on claims that the company held back safety information relevant to the EPA's assessment of the chemical's risks.

The case adds to a broader pattern of scrutiny facing agrochemical companies over their handling of safety data and the transparency of information shared with regulators. Syngenta has maintained that it has acted appropriately in its dealings with the EPA, and the litigation remains ongoing.