June 1, 2022 \u2013 The Emmett Environmental Law & Policy Clinic submitted an amicus brief today on behalf of three leading experts supporting a challenge to an action by the U.S. Environmental Protection Agency (EPA) involving the toxic herbicide paraquat dichloride (often simply called \u201cparaquat\u201d).\u00a0 Specifically, EPA approved paraquat\u2019s use for the next fifteen years under certain conditions, despite the risks paraquat poses to public health.<\/p>\n
The Clinic filed the brief on behalf of J. Timothy Greenamyre, Michael Okun, and Beate Ritz.\u00a0 They are medical doctors and scientists with expertise in neurology or epidemiology, and they have studied and written extensively about the link between toxic substances like paraquat and neurodegenerative disorders\u2014in particular, Parkinson\u2019s disease.\u00a0 The brief argues that EPA failed to adequately recognize the paraquat-Parkinson\u2019s link when approving paraquat\u2019s continued use.<\/p>\n
Paraquat is one of the most widely and increasingly used herbicides in the United States, and it is acutely toxic.\u00a0 A single exposure to paraquat can cause skin and eye irritation and respiratory harm, including lung inflammation, scarring, and compromised lung function.\u00a0 Swallowing even a teaspoonful can be fatal.\u00a0 In addition, as the Clinic\u2019s brief details, a growing body of research has linked paraquat exposure to Parkinson\u2019s for more than twenty years.<\/p>\n
Based on these health effects, at least thirty-three countries have banned the use of paraquat.\u00a0 In fact, it is one of only two pesticides that are approved for use in the United States despite being banned or phased out in the European Union, Brazil, and China.<\/p>\n
Parkinson\u2019s is a progressive, neurodegenerative disorder with no known cure. Approximately one million Americans currently live with Parkinson\u2019s, making it the second-most-common neurological disorder in the country, behind Alzheimer\u2019s. \u00a0Genetic factors can play a role in causing Parkinson\u2019s, particularly for those diagnosed when they are less than 50 years old.\u00a0 But for those diagnosed later in life\u2014who constitute a majority of Parkinson\u2019s patients\u2014the disease is most commonly caused by environmental factors. Those risk factors include exposure to a number of pesticides, including paraquat.<\/p>\n
Despite paraquat\u2019s acute dangers and its association with Parkinson\u2019s, last year EPA issued an \u201cInterim Registration Review Decision\u201d for paraquat under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).\u00a0 Having previously approved paraquat\u2019s use, EPA approved it again, while this time requiring certain exposure mitigation measures, such as the use by pesticide handlers of gloves and other protective equipment.\u00a0 Nonetheless, several groups representing farmworkers, environmentalists, and others concerned about pesticides challenged EPA\u2019s decision, arguing that the mitigation measures would not sufficiently reduce the health risks of paraquat exposure.<\/p>\n
The Clinic\u2019s brief explains the robust lines of evidence developed over many years linking paraquat exposure and Parkinson\u2019s, including in human epidemiology studies, animal model studies, and analyses of paraquat\u2019s effects on the cellular and subcellular level.\u00a0 As just one example, a recent systematic review and meta-analysis synthesizing 13 epidemiology studies found a statistically significant association between paraquat exposure and Parkinson\u2019s, with an overall 64% increase in Parkinson\u2019s risk for those exposed to paraquat.<\/p>\n
The brief then explains several errors EPA made in evaluating these multiple lines of evidence and finding an insufficient showing of causation.\u00a0 Generally for the epidemiology studies, for instance, EPA over-valued the mere potential for certain errors in those studies\u2019 methodologies, without either attempting to assess the actual level of any error or conducting standard analyses that can help correct for them.\u00a0 These and other flaws prevented EPA from appreciating the compelling convergence of the multiple lines of evidence demonstrating that paraquat exposure is causally linked to the onset of Parkinson\u2019s.<\/p>\n
Clinical student Rose Whitlock (JD \u201922) worked on the brief under the supervision of Acting Director Shaun Goho and Clinical Fellow Tommy Landers.<\/p>\n