29
Jul
EPA’s Office of Inspector General Must Investigate EPA’s Failure to Fully Assess Pesticide Hazards
(Beyond Pesticides, July 29, 2019) A research study, published in March in Scientific Reports, uncovers a pesticide effect on a sugar-metabolizing enzyme common to all cells that has broad health ramifications ignored by the U.S. Environmental Protection Agency’s (EPA) safety testing protocol. This finding raises a larger question regarding the need for EPA to test for the synergistic effects of pesticides, whereby pesticides and chemicals in combination have an even greater effect than they do by themselves.
The research, by T. Tristan Brandhorst, PhD, Iain Kean, PhD, and others in the lab of Bruce Klein, PhD, of the University of Wisconsin–Madison and UW School ofMedicine and Public Health, specifically sheds light on the mode of action of the fungicide fludioxonil. Fludioxonil, a phenylpyrrole fungicide, was developed to treat seeds during storage, and has come to be used commonly on grains, vegetables, fruits, and ornamental plants during cultivation, and produce after harvest to extend “shelf life.” As reported by the American Association for the Advancement of Science publication, EurekAlert, “The ability of [the fungicide] fludioxonil to act on a sugar-metabolizing enzyme common to all cells, and to produce the damaging compound methylglyoxal, may mean that the pesticide has more potential to harm non-fungal cells than previously thought. Although fludioxonil has been deemed safe for use, the authors . . . suggest that the effects of this widely used pesticide has upon animals be re-examined.”
EPA, under the current administration, has not shown a willingness to restrict pesticide use to protect humans and the environment. However, EPA has an investigative office—the Office of Inspector General (OIG)—whose job is to “perform audits and investigations of the EPA to promote economy and efficiency, and to prevent and detect fraud, waste and abuse.” In order to ensure its independence of EPA, OIG receives funding directly from Congress. Congress may request audits and investigations by OIG.
In a previous investigation, Drs. Brandhorst and Klein pointed to the uncertainty about the mechanism by which fludioxonil actually causes fungi cell death, asserting that this uncertainty merits a reevaluation by EPA of its potential impacts on human health—noting reports of the fungicide’s ability to disrupt hepatic, endocrine, and neurological systems. The scientists in Dr. Klein’s lab found that a common effect of pesticides on their targets, oxidative stress, is crucial. In this case, the oxidative stress that triggers the toxicity of fludioxonil comes from the natural breakdown of sugars, which is enhanced by the fungicide. Dr. Brandhorst notes, “The take-home lesson is that fludioxonil is multifactorial. It’s not compromising cells by one solitary mechanism. It has potential to damage cells in a variety of ways.” The enzyme-suppressing action of fludioxonil on an enzyme common to all cells is at the heart of the alarm this research raises, but it is not the only reason the fungicide needs to be reevaluated.
The fungicide’s extensive post-harvest use on food crops is of particular concern because it eliminates the chance for environmental degradation of the compound, and once applied, the waxy fungicide is not easily removed by rinsing. Further, UV treatment of produce (sometimes used to reduce pathogens on fresh fruits and vegetables) actually significantly increases the toxicity of fludioxonil. In addition, the lead author indicates that “there is also reason to believe that breakdown products of this pesticide may be 100 times more toxic than fludioxonil itself.”
There are several lessons from this research. First, life is complex, and synergism is the rule, not the exception. Note that in this case, synergism occurs between the pesticide and naturally-occurring processes in humans and other organisms.
Second, EPA should not regulate pesticides with the assumption that the absence of an enzyme in one group of organisms protects the overall health of all other organisms. EPA made a similar mistaken assumption in assessing glyphosate/Roundup, which caused it to ignore the impacts of that herbicide on the human gut microbiota.
Third, EPA must have a complete understanding of the mode of action of any pesticide it registers and act on new information that arises in the peer-reviewed scientific literature. It is a major shortcoming of EPA’s risk assessment process that it does not respond to current science.
Letter to Congress
I am writing to ask you to request an investigation by the Environmental Protection Agency’s Office of Inspector General of a failing in EPA’s risk assessment of pesticides.
A research study, published in March in Scientific Reports, uncovers a pesticide effect on a sugar-metabolizing enzyme common to all cells that has broad health ramifications ignored by the U.S. Environmental Protection Agency’s (EPA) safety testing protocol. This finding raises a larger question regarding the need for EPA to test for the synergistic effects of pesticides, whereby pesticides and chemicals in combination have an even greater effect than they do by themselves. (Brandhorst, T.T., Kean, I.R., Lawry, S.M., Wiesner, D.L. and Klein, B.S., 2019. Phenylpyrrole fungicides act on triosephosphate isomerase to induce methylglyoxal stress and alter hybrid histidine kinase activity. (Scientific Reports, 9(1), p.5047)
The study specifically sheds light on the mode of action of the fungicide fludioxonil, which was developed to treat seeds during storage, and is now used on grains, vegetables, fruits, and ornamental plants during cultivation, and produce after harvest. As reported in EurekAlert, “The ability of [the fungicide] fludioxonil to act on a sugar-metabolizing enzyme common to all cells, and to produce the damaging compound methylglyoxal, may mean that the pesticide has more potential to harm non-fungal cells than previously thought. Although fludioxonil has been deemed safe for use, the authors . . . suggest that the effects of this widely used pesticide has upon animals be re-examined.”
EPA, under this administration, has not shown a willingness to restrict pesticide use to protect humans and the environment. This makes a request on this matter to the OIG especially important now.
Previous work by Drs. Brandhorst and Klein pointed to the uncertainty about the mechanism by which fludioxonil actually causes fungi cell death, asserting that this uncertainty merits a reevaluation by EPA of its potential impacts on human health—noting reports of the fungicide’s ability to disrupt hepatic, endocrine, and neurological systems. They found that a common effect of pesticides on their targets, oxidative stress, is crucial. In this case, the oxidative stress that triggers the toxicity of fludioxonil comes from the natural breakdown of sugars, which is enhanced by the fungicide. The enzyme-suppressing action of fludioxonil on an enzyme common to all cells is at the heart of the alarm raised by this research.
The fungicide’s extensive post-harvest use on food crops is of particular concern because it eliminates the chance for environmental degradation of the compound, and once applied, the waxy fungicide is not easily removed by rinsing. Further, UV treatment of produce (sometimes used to reduce pathogens on fresh fruits and vegetables) significantly increases the toxicity of fludioxonil. In addition, “there is also reason to believe that breakdown products of this pesticide may be 100 times more toxic than fludioxonil itself.”
There are several lessons from this research. First, life is complex, and synergism is the rule, not the exception. In this case, synergism occurs between the pesticide and natural processes in humans and other organisms.
Second, EPA should not regulate pesticides with the assumption that the absence of an enzyme in one group of organisms protects the overall health of all other organisms. EPA made a similar mistaken assumption in assessing glyphosate/Roundup, which caused it to ignore the impacts of that herbicide on the human gut microbiota.
Third, EPA must have a complete understanding of the mode of action of any pesticide it registers and act on new information that arises in the peer-reviewed scientific literature. The failure to respond to current science is a major shortcoming of EPA’s risk assessment process.
Please ask the OIG to investigate EPA’s risk assessment practices highlighted by this research.
Thank you.
Pls. investigate the EPA. They’re allowing chemical companies to spray our food w/poison! Thx.
July 29th, 2019 at 11:10 am