EPA sees “greater uncertainty” with paraquat risk factor, seeks more data
New data is adding to regulatory concerns about potential human health risks from the weed killer paraquat, leading the US Environmental Protection Agency (EPA) to seek more information from manufacturers of the pesticide.
The EPA last week publicly released an updated review of paraquat that incorporates a new study pertaining to potential “post-application inhalation exposures” to people that could result from the volatilization of paraquat from treated farm fields.
The EPA’s Health Effects Division (HED) said in the new report that after reviewing the fresh data, HED determined that “there is greater uncertainty regarding the potential for paraquat to volatilize than previously considered.”
Paraquat is a highly toxic weed killer commonly used by farmers to wipe out weeds in fields before crops are planted, for drying out crops before harvest, and for killing weeds in pastures and non-agricultural areas. Even a tiny amount, if ingested, can quickly kill a person, so the pesticide is restricted to licensed applicators.
There are mounting concerns, however, about the chronic effects of exposure to paraquat, and many scientific studies have linked long-term exposure – through inhalation or other routes of exposure – to Parkinson’s disease. Many countries have banned paraquat, and there have been calls for bans from many US groups, including from several members of Congress.
The concerns noted about volatilization could be significant, as volatilization occurs when a pesticide converts into a vapor and then releases into, and moves through, the atmosphere beyond where it was applied.
People who lived beyond the area where the pesticide was sprayed could thus be impacted, inhaling the pesticide vapor.
The agency said while the new data showed a vapor pressure much higher than previously thought, there are some “contrasting indicators” that may mitigate cause for concern.
To help clarify the issue, the EPA is asking paraquat manufacturers to provide additional volatilization data. Once that new data is received and reviewed by the agency, the EPA plans to issue an updated analysis, the EPA said.
The EPA raised the issue of volatilization earlier this year when it said it was moving to withdraw its interim regulatory decision on paraquat and extending a delay in making a final decision on reregistration of the pesticide. The move came after several health advocacy organizations challenged the EPA’s 2021 interim registration review decision in which the agency concluded that there was “insufficient” evidence linking paraquat exposure to Parkinson’s.
The new data that gave the EPA cause for concern was turned over to the EPA by longtime paraquat maker Syngenta, a Chinese-owned company that has been engaged in the manufacture and sale of paraquat globally for decades.
Thousands of people around the US are now suing Syngenta claiming the company has long known paraquat could cause Parkinson’s disease, but has worked to hide the evidence of risk rather than warning users.
Syngenta has always maintained that the evidence linking paraquat to Parkinson’s disease is “fragmentary” and “inconclusive.” But numerous scientific studies have found that paraquat damages cells in the brain in ways that can lead to Parkinson’s.
And many of the company’s internal documents show it was aware of research connecting paraquat to Parkinson’s disease decades ago.
The New Lede, in conjunction with The Guardian, obtained and revealed many of those internal files, and maintains a library of some of the documents. Not only was Syngenta aware of research linking paraquat to Parkinson’s but it also sought to secretly influence scientific information and public opinion regarding those links, the internal corporate records show.
Featured image: Syngenta handout
