17
Mar
Can FDA Step In When EPA Fails to Ensure Safety from Pesticide Mixtures in Food?
(Beyond Pesticides, March 17, 2025) When Secretary of Health and Human Services Robert F. Kennedy, Jr. announced last week that he is directing the U.S. Food and Drug Administration (FDA) to explore rulemaking to review substances in food affirmed by the food companies to be Generally Recognized as Safe (GRAS), he said he is “committed to promoting radical transparency to make sure all Americans know what is in their food.†The issue of independent review of the food industry’s GRAS declarations has long been the subject of critiques raising public health concerns. As this issue emerged, on another food safety issue, Beyond Pesticides is asking FDA to use its broad authority under the Federal Food, Drug, and Cosmetic Act to “ensur(e) that human foods and animal feeds are safe†from residues of pesticide mixtures, in light of new troubling scientific data.
Under various memoranda of understanding between FDA, the U.S. Environmental Protection Agency (EPA), and the U.S. Department of Agriculture (USDA) going back decades, FDA could consult with EPA on food safety issues ignored by the agency, including  recent data published in Pesticide Biochemistry and Physiology, which “suggest that combined [pesticide] exposure may further amplify the toxicity and compromise the intestinal barrier.†Where EPA fails to consider exposure to mixtures of pesticides in people’s diet, Beyond Pesticides sees a role for FDA to recommend regulatory action.
>> Tell Secretary of Health and Human Services Robert F. Kennedy, Jr. to instruct FDA to recommend tolerances for mixtures of pesticides.Â
On the GRAS concern, Beyond Pesticides raised the issue when telling the National Organic Standards Board (NOSB) that it could not, by law, allow GRAS substances without a thorough independent review. Beyond Pesticides, whose executive director served on the NOSB, cited a comprehensive review (2011) of the U.S. food additive regulatory program, which found that 60% of food safety decisions allowing substances in food are made by manufacturers and a trade association: “Overall, federal agencies made approximately 40% of the 6000 safety decisions allowing substances in human00pm food. These decisions allowed an estimated 66% of the substances currently believed to be used in food. Manufacturers and a trade association made the remaining decisions without FDA review by concluding that the substances were generally recognized as safe (GRAS).â€
The U.S. General Accountability Office (GAO) reported on FDA’s regulation of food additives, particularly GRAS items in its report, Food Safety: FDA Should Strengthen Its Oversight of Food Ingredients Determined to Be Generally Recognized as Safety (2010). The GAO found:
- “FDA’s oversight process does not help ensure the safety of all new GRAS determinations. FDA only reviews those GRAS determinations that companies submit to the agency’s voluntary notification program—the agency generally does not have information about other GRAS determinations companies have made because companies are not required to inform FDA of them.â€
- “FDA has yet to issue a final regulation for its 1997 proposed rule that sets forth the framework and criteria for the voluntary notification program, potentially detracting from the program’s credibility.â€
- “FDA is not systematically ensuring the continued safety of current GRAS substances. While, according to FDA regulations, the GRAS status of a substance must be reconsidered as new scientific information emerges, the agency has not systematically reconsidered GRAS substances since the 1980s.â€
- FDA has also not generally responded to concerns raised by individuals and public interest groups. “In fact, FDA has decided on the validity of these concerns in only 1 of 11 cases. In addition, FDA does not know to what extent, or even whether, companies track evolving scientific information about their GRAS substances.â€
- “FDA’s approach to regulating nanotechnology allows engineered nanomaterials to enter the food supply as GRAS substances without FDA’s knowledge.â€â€¦FDA encourages, but does not require, companies considering using engineered nanomaterials in food to consult with the agency regarding whether such substances might be GRAS. Because GRAS notification is voluntary and companies are not required to identify nanomaterials in their GRAS substances, FDA has no way of knowing the full extent to which engineered nanomaterials have entered the U.S. food supply as part of GRAS substances.
Back to pesticide mixtures. The researchers in the study cited above found that the toxic effects of the insecticides abamectin and spirodiclofen, as well as the fungicide fluazinam, individually and in combination caused serious adverse effects to the intestines, raising an alarm not considered by EPA. In exposing mice and in vitro colorectal cells to these pesticides, both singularly and in mixtures, the results show the disruption of intestinal functions caused by the interaction of pesticides in mixtures. These findings highlight the need to assess potential synergistic effects of pesticide mixtures as a part of the regulatory review process. FDA may recommend regulatory action in this regard.Â
>> Tell Secretary of Health and Human Services Robert F. Kennedy, Jr. to instruct FDA to recommend tolerances for mixtures of pesticides.Â
“Currently, most studies investigating the effects of pesticide residues on the barrier function of Caco-2 cells [human colorectal adenocarcinoma cells used as a model of the intestinal epithelial barrier] concentrate on the exposure to a single residue, while the potential toxic effects arising from the concurrent presence of multiple pesticide residues remain largely overlooked,†the authors say. As previously reported, scientists and health advocates have urged prioritizing further studies on the effect of mixtures on organisms for many decades, given that exposure in the environment is not limited to a single pesticide at a time. Â
“[R]ecent studies have increasingly highlighted the toxic effects of abamectin on non-target organisms and human cells,†the researchers state. The combination of pesticides is widely used due to widespread resistance among red spider mites to individual pesticides. The interaction effects of commonly used pesticides remain largely unexplored. This study exposes a mechanism for the synergistic effects of concurrent exposure to a combination of pesticides and highlights the importance of considering synergy in risk assessments. “These findings enhance our understanding of the interactions among multiple pesticide residues and further clarify the complexity of these interactions and their impact on human exposure,†the authors conclude. (See additional coverage on health effects from pesticide mixtures here and here.) Â
Additional research referenced in the study supports the findings of intestinal damage from pesticide exposure. This includes:Â
- The insecticide imidacloprid, which “induces disruption of the intestinal epithelial barrier, specifically through the down-regulation of tight junction protein complexes†and has enhanced toxicity against the gut microbiota in mice with co-exposure to zinc oxide. (See studies here and here.)Â
- The insecticide chlorpyrifos, which is “observed to disrupt the integrity of the gut barrier in mice, resulting in increased entry of lipopolysaccharides into the body.†(See study here.)Â
- The fungicide carbendazim, which when combined with epoxiconazole or fluazinam has synergistic effects in Caco-2 cells, according to a study in Food Chemistry.Â
The findings are very concerning, given that pesticide residues in food are introduced directly to the intestines. As the researchers note, “The intestinal tract functions as a congenital barrier for homeostasis, preventing pathogenic bacteria, toxins, and other harmful substances from entering the body.†They continue: “Pesticides ingested through the diet are absorbed and transported into the human body, directly interacting with intestinal epithelial cells. This exposure results in alterations to cell permeability and integrity, ultimately compromising the barrier function of these cells.â€Â
The complex interactions among pesticide mixtures are not fully understood but represent a significant threat to human health The U.S. Environmental Protection Agency (EPA) fails to adequately regulate mixtures of chemicals to which organisms are exposed in the real world. Risk assessments have been highly criticized as inadequately addressing the full range of adverse effects that put human health and the health of all organisms at risk. (See more on regulatory deficiencies here and here.)Â
Scientists and advocates have long asked EPA to evaluate and regulate full formulations of pesticides, and their mixtures, instead of assessing active ingredients singularly. As the body of knowledge base evolves, so should the systems for assessments that are meant to inform decisions that have a wide impact on human and ecosystem health.Â
Given both the known and still unevaluated effects of pesticides, including the impact of mixtures and synergistic effects, Beyond Pesticides urges the elimination of petrochemical pesticides and synthetic fertilizers by 2032. As a holistic solution, organic land management practices offer both health and environmental benefits, with proven commercial viability and effectiveness in both agricultural and nonagricultural uses.Â
Letter to Secretary of the Department of Health and Human Services, Robert F. Kennedy, Jr.
Under your authority to protect the safety of the food supply from pesticide residues, it is critical that you recommend the setting of tolerances for pesticide mixtures, an area of health concern not currently considered by the U.S. Environmental Protection Agency (EPA). Study results published in Pesticide Biochemistry and Physiology “suggest that combined [pesticide] exposure may further amplify the toxicity and compromise the intestinal barrier.†The researchers found that the insecticides abamectin and spirodiclofen, and the fungicide fluazinam, individually and in combination cause serious disruption of intestinal functions caused by the interaction of pesticides in mixtures. These findings highlight the need to assess potential synergistic effects of pesticide mixtures as a part of the regulatory review process. Under memoranda of understanding with EPA, please instruct the U.S. Food and Drug Administration to recommend tolerances based on combined exposure when pesticides are used together.
“Currently, most studies investigating the effects of pesticide residues on the barrier function of Caco-2 cells [human colorectal adenocarcinoma cells used as a model of the intestinal epithelial barrier] concentrate on the exposure to a single residue, while the potential toxic effects arising from the concurrent presence of multiple pesticide residues remain largely overlooked,†the authors say. This study exposes a mechanism for the synergistic effects of concurrent exposure to a combination of pesticides and highlights the importance of considering synergy in risk assessments and the setting of pesticide tolerance to protect health.Â
Additional research referenced in the study supports the findings of intestinal damage from pesticide exposure, including disruption of the intestinal epithelial barrier by imidacloprid, enhancing toxicity of zinc oxide to gut microbiota; disrupt the integrity of the gut barrier in mice by chlorpyrifos, resulting in increased entry of lipopolysaccharides into the body, and synergistic effects of carbendazim combined with epoxiconazole or fluazinam in Caco-2 cells.Â
The findings are very troubling, since pesticide residues in food are introduced directly to the intestines. As the researchers note, “The intestinal tract functions as a congenital barrier for homeostasis, preventing pathogenic bacteria, toxins, and other harmful substances from entering the body.†They continue: “Pesticides ingested through the diet are absorbed and transported into the human body, directly interacting with intestinal epithelial cells. This exposure results in alterations to cell permeability and integrity, ultimately compromising the barrier function of these cells.â€
The complex interactions among pesticide mixtures are not fully understood but represent a significant threat to human health. EPA fails to adequately regulate mixtures of chemicals to which organisms are exposed in the real world. Risk assessments have been highly criticized as inadequately addressing the full range of adverse effects that put human health and the health of all organisms at risk. Since establishing tolerances for pesticide residues is the responsibility of FDA, I ask you to require FDA to set tolerances based on combined exposure when pesticides are used together.
Given both the known and still unevaluated effects of pesticides, including the impact of mixtures and synergistic effects, petrochemical pesticides can be better regulated through the setting of tolerances and replaced by organic land management practices, which have proven commercial viability and effectiveness in both agricultural and nonagricultural uses.
Thank you.