24
Jun
U.S. Policy Allows Cancer-Causing Pesticide Use Even Though It Is Not Needed to Grow Food and Manage Land
(Beyond Pesticides, June 24, 2025) As changes in the executive branch of the federal government upend expectations among environmental stakeholders, the regulation of food safety in the United States is being revealed as a rickety structure built over a century with unpredictable and sometimes contradictory additions, extensions, remodels, and tear-downs. In the short term, clarity is unavailable, but there have been calls for revision and strengthening of regulatory processes—requiring lawmaker and regulator willingness to incorporate the vast body of evidence that pesticides do far more harm than good, and that organic regenerative agriculture is the surest path to human and ecological health. News reports out of Costa Rica in May brought public attention to drafted legislation to ban pesticides in the country that the World Health Organization (WHO) has defined as “extremely or highly hazardous, or those with evidence of causing cancer, genetic mutations, or affecting reproduction, according to the Globally Harmonized System (GHS).” The headline sparked a relook in this Daily News at the current and historical failure of U.S. policy, which allows cancer-causing pesticides in food production and land management, despite the booming success of a cost effective and productive, certified organic sector for which petrochemical pesticides are not needed.
Over the last century, pesticide regulation has been based on two different assumptions about how people might be protected from chemicals that cause cancer and other diseases. Food safety regulation began with the Federal Food, Drug and Cosmetic Act of 1938 (FFDCA). FFDCA was modified by the Food Additives Amendment of 1958 (which included the notorious Delaney Clause to prohibit cancer-causing pesticides in processed foods). EPA regulates pesticides under the 1947 Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), to which Congress mandated a major revision with the Food Quality Protection Act (FQPA) in 1996—which repealed the Delaney Clause with the codification of risk assessment protocol that allows for uncertainty, ignores preexisting health conditions and vulnerabilities, fails to evaluate chemical mixtures and synergistic effects, and establishes levels of acceptable harm.
Historically, concern about cancer topped the list for both the public and lawmakers enacting regulations; the Delaney Clause was added during a period when people were becoming aware of the risks of food dyes and the estrogen compound diethylstilbesterol. Worries about pesticides were not far behind, as Rachel Carson’s book Silent Spring made clear in 1962. These worries have been borne out. A 2024 study in Frontiers in Cancer Control and Society found that agricultural pesticide use “has a significant impact on…all cancers, bladder cancer, colon cancer, leukemia, lung cancer, non-Hodgkin’s lymphoma, and pancreatic cancer…and these associations are more evident in regions with heavy agricultural productivity….” The effects of pesticides on non-Hodgkin’s lymphoma, bladder cancer and leukemia are “more significant than the effects of smoking.” For all cancers, the highest number of cases per year correlates strongly with the highest pesticide usage, with the Midwest—Iowa, Illinois, Indiana, Ohio, and Nebraska—seeing more than 150,000 additional cases annually. The study includes the 69 pesticides the U.S. Department of Agriculture monitors by county, although it does not connect any specific pesticides to cancer incidence.
Beyond Pesticides provides numerous resources about carcinogenic pesticides registered for use in agriculture, lawns and gardens, and nonagricultural land management. See, for example, “40 Common Lawn and Landscape Chemicals,” which counts 26 carcinogens among them. The Pesticide-Induced Diseases database provides scientific evidence for 29 kinds of cancer.
The Delaney Clause required the banning of chemical additives in food that cause cancer in humans or animals: If a substance was carcinogenic, no level of it would be tolerated in processed food. There was no acceptable threshold below which safety could be assumed. While this affected many chemicals intentionally added to food, such as dyes, it also applied to pesticides, which are only incidentally present, but which are intentionally toxic to a wide variety of organisms. However, Delaney was never fully enforced until successful litigation brought by the state of California and the Natural Resources Defense Council resulted in a 1992 court decision forcing EPA to start removing carcinogens from the food supply. It was at this point that Congress intervened to replace the Delaney Clause with a risk assessment provision in FQPA that allows cancer-causing chemical use, including pesticides, in food production. While the risk assessment provision in FQPA is often characterized as a “health-based standard,” critics point to the continued allowance and registration of cancer-causing pesticides and synthetics under fundamentally flawed risk assessment reviews. (For an historical read on this critical point in the legalization of cancer-causing pesticides and other synthetics in the food supply, see Unreasonable Risk—The Politics of Pesticides (1998).) At the point of FQPA passage, synthetic chemicals were ubiquitous in the food supply, the environment, and human bodies.
Forty years after the passage of the Delaney Clause, FQPA traded a “zero risk” standard for a system based on acceptable pesticide tolerances, or thresholds, in food, while imposing new protections for infants and children. The threshold model assumes the truth of the ancient toxicological maxim “the dose makes the poison.” Crucially, FQPA also required EPA to screen pesticides for endocrine disruption. By then it was clear that endocrine disrupting chemicals—DDT, for example—were associated with disease induction. However, EPA has not produced an effective screening system as of this writing.
As Beyond Pesticides noted in 2021, “In 1996, the promise of screening pesticides for endocrine disruption generated support from environmentalists and public health advocates for the FQPA, which traded the absolute prohibition of carcinogens in food of the Delaney Clause for a risk assessment standard that is subject to manipulation and an underestimation of real-life hazards. And now, 25 years later, we have yet to see EPA use endocrine disruption findings in pesticide registration decisions.”
EPA has also struggled to adapt its registration requirements to new science and new technologies revealing pesticides’ effects that reach far beyond the strictures of traditional regulatory toxicology. Standard toxicological screens have not incorporated the last several decades’ staggering advances in molecular biology, epidemiology, genetics and exposure science. These advances are illuminating the many connections between pesticide exposures and diseases of all kinds. At the molecular and cellular level, pesticides cause inflammation and oxidative stress, alter lipid metabolism, change gut microbiota composition and behavior, affect gene expression, and many other cellular processes increasingly linked to both cancer and diseases like Alzheimer’s, diabetes, and inflammatory bowel disease.
In fact, pesticides have been implicated in harm to nearly every aspect of human physiology, from microbial gut health to neurodevelopmental disorders and reproductive issues. At the same time, however, these scientific advances have also connected many of these other disease processes to the longstanding concern about cancer.
Nowhere is this connection more salient than in endocrine disruption, particularly the derangement of reproductive hormones such as estrogen and testosterone. Beyond Pesticides has documented hundreds of studies showing that hundreds of pesticides affect hormonal balance and that exposure to these pesticides raises the risk of cancer. See Beyond Pesticides’ breast cancer prevention resource regarding exposures to DDT, organophosphates, glyphosate, neonicotinoids, and dioxins.
The associations are undeniable. One recent example is a 2024 case-control epidemiological study that also incorporates urinalysis to determine pesticide exposures in women from a Brazilian agricultural region who were screened for breast cancer. The study grouped the women according to whether they did or did not have breast cancer and were exposed or not exposed to pesticides. The researchers found that women exposed to the agricultural pesticides glyphosate, atrazine, and 2,4-D have significantly higher risk of breast cancer than unexposed women. The risk of metastasis, a major predictor of mortality, was 54% higher among women with breast cancer who were exposed to pesticides than among women with breast cancer who were not exposed to pesticides. The authors cite plausible cellular mechanisms for cancer induction including glyphosate’s effects on DNA methylation, oxidative stress, and alteration of estrogenic pathways, along with atrazine’s known disruption of estrogen in both normal and cancerous breast cells. While not mechanistic, this study confirms a strong association between pesticide exposure and aggressive forms of breast cancer.
Such evidence highlights the urgency of reforming the regulation of pesticides. There is strong evidence that pesticides lead to cancer via upstream mechanisms such as immune inhibition, hormonal derangement, and inflammation that are also common to other health disorders. Health advocates argue that a new approach must address the reality that these mechanisms predispose physiological systems to become disordered, and that averting these dangers would provide a multitude of positive outcomes across the disease spectrum.
In addition to failing in its duty to evaluate pesticides for endocrine disruption, EPA has also failed to demonstrate the efficacy of replacing the Delaney clause with the threshold model. It has not been established that there are distinct levels of exposure below which there is no harm. Research since the FQPA was passed has shown that even very low pesticide residues and exposure levels can trigger health consequences. This is especially true for hormone-disrupting pesticides, because hormones normally act at extremely low concentrations. For many chemicals, low exposures and high exposures can have very different effects. Some effects, in addition, can be epigenetic across generations, affecting cancer risk and fertility in unexposed descendants. And unstudied and unregulated are the cumulative effects of mixed exposures or the lifelong consequences of exposures at crucial developmental stages early in life.
The emerging picture is one of such complexity that a return to the simple assumption of Delaney—that exposure to a carcinogen at any level is unacceptable—has become increasingly reasonable in light of the availability of productive and cost-effective organic food production that does not allow the vast majority of petrochemical pesticides and synthetic substances. There are those who argue that the assumption of harm is manifestly incorrect, because the dose makes the poison – many substances humans are exposed to are technically carcinogenic yet do not produce obvious cases. Yet even the American Chemistry Council-funded consultancy ToxStrategies has admitted the inadequacy of the threshold model as well: “[T]he shape of the dose-response curve for chemical carcinogenesis may be more complex than the default assumption of linear, no threshold behavior—a fact that would dramatically affect estimated points of departure for risk assessments as well as the fundamental understanding of cancer risk (no added risk below the threshold vs. added risk at any dose).”
It is the position of Beyond Pesticides that the post-Delaney threshold standard is unworkable because science cannot determine a threshold dose for cancer induction. Further, the evidence that the conditions for cancer induction have much in common with those for many other diseases means a much larger view must be taken—without, of course, downplaying the devastation caused by cancer itself. Thresholds remain a crude tool on which to base risk assessments purporting to define “acceptable” exposures. The solution to the overarching problem that pesticides produce large-scale physiological harms, both singly and in combination, is to transition to organic regenerative agriculture without further delay. Nothing can eliminate human disease or ecological change altogether, but eliminating pesticides would go a long way toward reducing these heavy burdens. The next step in pesticide regulation must recognize this and act on it, according to Beyond Pesticides.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
EPA’s Proposed Endocrine Disrupting Pesticide Review Called Deficient
Beyond Pesticides, February 5, 2024
https://beyondpesticides.org/dailynewsblog/2024/02/epas-proposed-endocrine-disrupting-pesticide-review-called-deficient/
Tell EPA: It Must Ban Pesticides Unless Shown Not To Be Endocrine Disruptors
Beyond Pesticides, August 16, 2021
https://beyondpesticides.org/dailynewsblog/2021/08/tell-epa-it-must-ban-pesticides-unless-shown-not-to-be-endocrine-disruptors/
Exposure to Pesticides and Breast Cancer in an Agricultural Region in Brazil
Carolina Panis et al
Environ Sci Technol. 2024
https://pmc.ncbi.nlm.nih.gov/articles/PMC11191594/
Endocrine-disrupting chemicals and endocrine neoplasia: A forty-year systematic review
Sofia Macedo et al
Environmental Research 2023
https://www.sciencedirect.com/science/article/pii/S001393512202196X?via%3Dihub
Comprehensive assessment of pesticide use patterns and increased cancer risk
Gerken et al
Front. Cancer Control Soc. 2024
https://www.frontiersin.org/journals/cancer-control-and-society/articles/10.3389/fcacs.2024.1368086/full
Resolving the “Delaney Paradox” Congress Resets the Table for Pesticides on Food
James D. Wilson
Resources for the Future 1996
https://www.resources.org/archives/resolving-the-delaney-paradox-congress-resets-the-table-for-pesticides-on-food/
Potential Role of Glyphosate, Glyphosate-Based Herbicides, and AMPA in Breast Cancer Development: A
Review of Human and Human Cell-Based Studies
Hannah M Schluter et al
Int J Environ Res Public Health. 2024
https://pmc.ncbi.nlm.nih.gov/articles/PMC11354939/
Pesticides Tied to Widespread Health Threats
Beyond Pesticides Retrospective 2021
https://www.beyondpesticides.org/assets/media/documents/journal/bp-retrospective21-final6.pdf
Children’s Health Threatened as Rates of Pediatric Cancers are Linked to Agricultural Pesticide Mixtures
https://beyondpesticides.org/dailynewsblog/2025/03/childrens-health-threatened-as-rates-of-pediatric-cancers-are-linked-to-agricultural-pesticide-mixtures/
Beyond Pesticides, March 4, 2025
Continued Reduction in Sperm Count Raises Call for Action
Beyond Pesticides, November 29, 2022
https://beyondpesticides.org/dailynewsblog/page/28/?feed
