Syngenta, maker of a controversial pesticide linked to Parkinson’s disease, said on Tuesday that it will stop making its paraquat weed killer by the end of June.

The announcement comes as the company is facing several thousand lawsuits brought by people in the US who allege they developed Parkinson’s disease due to their exposure to Syngenta’s paraquat products.

The company did not mention the litigation in making the announcement, and did not respond to a request for comment.

The company’s announcement cites “significant competition” from generic producers of paraquat and a “less than 1 percent” contribution to the company’s global sales as reasons for exiting the paraquat business.

“This decision is about focusing our resources where they deliver the greatest value for our business and our customers,” Mike Hollands, president of Syngenta UK and head of Syngenta’s global production and supply, said in a statement.

The company said it “affirms that paraquat is safe when used in line with registered label instructions”, and that paraquat remains “highly effective in controlling weeds”.

Michael Okun, chair of neurology at the University of Florida, who has called for a ban on paraquat, called the news a “public health milestone”.

“For decades we have warned that certain pesticides increase the risk of Parkinson’s and other serious diseases. This moment proves that advocacy, data and courage can change the trajectory of disease,” Okun said.

Paraquat has been used in the US since 1964 as a tool to kill broadleaf weeds and grasses. Though banned in several countries, including throughout Europe, Syngenta’s paraquat-based Gramoxone herbicide brand has remained popular with US farmers for use in growing soybeans, cotton and corn as well as in growing grapes, pistachios, peanuts and many other crops.

Syngenta has always maintained that the evidence linking paraquat to Parkinson’s disease is “fragmentary” and “inconclusive”. Numerous scientific studies have found that paraquat damages cells in the brain in ways that can lead to Parkinson’s, and more than 8,000 lawsuits are pending in US courts over the Parkinson’s allegations. The company, which maintains that paraquat does not cause Parkinson’s disease, has settled several cases before they went to trial and has been negotiating to settle a bulk of the ongoing cases.

The New Lede, in conjunction with the Guardian, obtained and revealed many of Syngenta’s internal corporate files, which show that not only was Syngenta aware of research linking paraquat to Parkinson’s decades ago, but it also sought to secretly influence scientific information and public opinion regarding those links.

The US Environmental Protection Agency has previously found “insufficient” evidence linking paraquat to Parkinson’s, but has said it wants to evaluate new data before issuing a final regulatory decision on the pesticide.

Lawmakers in multiple states have introduced legislation to ban paraquat, and several federal lawmakers have also called for bans on the chemical.

“If this is true, then fewer people are going to develop Parkinson’s disease in the future,” said Ray Dorsey, a neurologist and director of the Atria Research Institute’s Center for the Brain and the Environment, a non-profit research initiative investigating the environmental causes of brain diseases.

“It also means that the voices of the Parkinson’s community, the voices of those who’ve been highlighting the toxic effects of this weed killer … are being heard and they’re having an impact,” he said.

Nathan Donley, environmental health science director with the Center for Biological Diversity, noted that while Syngenta has long been known as a key supplier of paraquat in the US, other companies supply generic versions of paraquat.

“It’s great news that Syngenta is exiting the paraquat business, but it’s also a reminder that smaller companies will readily fill the void as long as this poison remains approved in our borders,” Donley said.

This story is co-published with the New Lede, a journalism project of the Environmental Working Group