03
Apr
Research Spotlights New Hazard Severity of Chlorpyrifos, Ag Insecticide Widely Found in Food Supply
(Beyond Pesticides, April 3, 2025) As highlighted by Beyond Pesticides in recent comments to the U.S. Environmental Protection Agency (EPA), chlorpyrifos (CPF) has been under scrutiny for decades due to associated adverse health effects, noted particularly in the extensive and consistent scientific evidence of neurotoxic dangers to children’s health. The latest research on CPF, published in Environmental Toxicology and Genes & Diseases, reveals additional threats to the immune system and male reproduction that are not captured in current EPA risk assessments of chlorpyrifos and raises serious health questions, given that residues are found throughout the food supply.
CPF, a widely used organophosphate insecticide in agriculture, is a cholinesterase inhibitor that binds irreversibly to the active site of an essential enzyme for normal nerve impulse transmission, acetylcholine esterase (AChE), inactivating the enzyme. Many insecticides, including organophosphates and carbamates, target AChE, causing them to be highly toxic to both insects and mammals that have this enzyme as a crucial part of their nervous systems. The history of chlorpyrifos exemplifies the failure of pesticide law and policy, as this chemical, among many others, not only has direct adverse health effects but is contributing to the climate crisis, biodiversity collapse, and disproportionate levels of illness in people of color communities.
The study in Environmental Toxicology, performed by researchers in Taiwan, notes: “Although chlorpyrifos poses considerable risks to the environment and human health, it is still used in many countries. This pesticide has various toxic effects on humans, including neurotoxicity, reproductive toxicity, genotoxicity, and organ damage caused by oxidative stress and DNA damage.†Their results add immunotoxicity to this list, as they find that chlorpyrifos induces apoptosis (cell death) in macrophages (a type of white blood cell vital in immune system functions).
As the authors state, “[F]ew studies have comprehensively analyzed the direct effects of chlorpyrifos on macrophages and the immune response. Thus, this study aims to investigate the cytotoxic effects of chlorpyrifos on macrophages, with a focus on elucidating the molecular mechanisms underlying chlorpyrifos-induced apoptosis through intrinsic and extrinsic apoptotic pathways.†Evaluating immunotoxic impacts of CPF is important, as the immune system is responsible for protecting the body against infections and diseases caused by pathogens.
“Macrophages, key players in the immune system, are responsible for engulfing pathogens, presenting antigens, and releasing cytokines to regulate immune responses,†the researchers share. They continue: “Chlorpyrifos exposure affects macrophages first because they play the role of sentinels. Chlorpyrifos-induced macrophage apoptosis can impair immune function, weakening the body’s ability to fight infections and maintain tissue homeostasis.â€
In using a murine (rodent) macrophage cell line exposed to concentrations of CPF, the authors report reduced cell viability, an increase in the proportion of apoptotic (controlled cell death) and necrotic (uncontrolled cell death) cells, an upregulation of the expression of death receptors, disrupted mitochondrial function, and the imbalance of proteins. “Chlorpyrifos induced cytotoxicity and apoptosis in a concentration-dependent manner,†the researchers state. They continue: “The simultaneous activation of both apoptotic pathways represents a novel finding, highlighting the strong proapoptotic effect of chlorpyrifos on macrophages through multiple mechanisms. Our findings offer compelling evidence of chlorpyrifos’ multifaceted toxic effects.â€
These results add to the wide body of science on public health implications from CPF exposure. In referencing the scientific literature, the authors include:
- “[S]tudies have reported that chlorpyrifos caused neurotoxicity and hepatotoxicity in SH-SY5Y, HepG2, and PC12 cells by inducing DNA damage, oxidative stress, and apoptosis.†(See studies here, here, and here.)
- Organophosphates “not only cause immediate harm but also persist in the environment, entering the food chain and exposing humans to long-term health risks, such as chronic toxicity.â€
- “Studies on developmental toxicity have revealed that exposure to these pesticides during pregnancy may disrupt fetal neurodevelopment, leading to cognitive impairments, such as reduced intelligence, attention deficits, and hyperactivity.†(See here and here.)
- “[P]rolonged or substantial exposure to these pesticides can reduce lymphocyte levels and weaken the immune system, thereby increasing the risks of infections and blood cancers such as leukemia and lymphoma in humans, particularly agricultural and industrial workers.†(See studies here, here, and here.)
- “Chlorpyrifos has been demonstrated to inhibit AChE activity in the nervous systems of Wistar and Sprague–Dawley rats; this pesticide led to behavioral abnormalities in the rats and reduced the reproductive potential in the male animals.†(See here and here.)
In a similar study, the latest research in Genes & Diseases also finds reproductive impacts with CPF exposure. After subjecting male Sprague-Dawley rats to different concentrations of chlorpyrifos for 30 days, as well as cell cultures, assays, RNA sequencing, and additional analyses, the researchers report disruption in the blood-testis barrier (BTB) and abnormal spermatogenesis (the process of producing sperm cells).
As the authors mention, “CPF can enter animals and humans through dermal contact, ingestion, and the food chain, leading to its accumulation, metabolism, and subsequent toxic effects.†In studying the effects of chlorpyrifos—and its main metabolite, 3,5,6-trichloro-2-pyridinol (TCP)—in mammals, this research provides insight into the mechanisms in which organophosphates can alter important functions such as reproduction.
The study results show impaired spermatogenesis through sperm deformation and a lower number of sperm in the exposed rats, as well as a decreased expression in the testes of PLZF and Stra8, important markers involved in sperm production. The researchers highlight that, “[P]repubertal exposure to CPF resulted in abnormal testicular morphology, decreased sperm count and quality, and BTB integrity impairment, suggesting that CPF resulted in abnormal spermatogenesis by disrupting BTB integrity.â€
Additional analyses, such as with RNA sequencing, confirm that CPF exposure triggered ferroptosis in testes and Sertoli cells based on gene expression. Ferroptosis is a specialized cell death triggered by an imbalance between iron and lipid metabolism. Sertoli cells form the blood-testis barrier, which supports spermatogenesis. Alterations in gene expression that promote ferroptosis and impact Sertoli cells play a vital role in the impairment of male reproduction, as the researchers also report in previous literature. (See studies here and here.)
“In this study, we confirmed that CPF and TCP promoted ferroptosis in vivo [in rats] and in vitro [in cell cultures],†the authors conclude. The results demonstrate how chlorpyrifos exposure compromises BTB integrity through ferroptosis and leads to abnormal spermatogenesis. “Our findings provide novel insights into understanding the mechanisms of CPF-induced male infertility,†the researchers postulate.
The study also highlights previous relevant research, sharing:
- “[R]ecent studies have revealed that CPF can adversely affect male reproduction, as indicated by decreased levels of serum testosterone, follicle-stimulating hormone, and luteinizing hormone, as well as reduced sperm count and quality.â€
- “CPF has been found to induce structural abnormalities in the seminiferous tubules. An investigation of the mechanisms underlying the CPF-induced impairment of male reproductive function revealed that CPF caused oxidative damage to the testes. The reduced levels of superoxide dismutase, catalase, glutathione peroxidase, and glutathione (GSH) contribute to the observed damage.†(See studies here, here, and here.)
- Studies show that “exposure to toxicants during the prepubertal stage has detrimental effects on the development and maturation of the male reproductive system. These effects can persist into adulthood and lead to abnormal spermatogenesis.†(See studies here, here, and here.)
As Beyond Pesticides shared in a recent Daily News article, pesticides can cause spermiotoxicity, which is defined as toxic effects of a substance on sperm cells, leading to reduced sperm quality or function. The referenced research, published in Toxics, was the first study to evaluate the cytotoxic effect of the triazole ipconazole on mammalian spermatozoa, ending in the conclusion that exposure causes spermiotoxicity through significantly reduced sperm viability, as well as alterations in enzyme and gene expression related to fertility.
The scientific evidence presented in all of these studies, as well as previous coverage from Beyond Pesticides on the impacts of pesticides on sperm, infertility, and other sexual and reproductive dysfunction, showcases the myriads of health effects that EPA does not consider in their chemical registration processes. (See more on EPA failures and regulatory deficiencies here.)
The threats to public health, as well as to the environment and all organisms it supports, from harmful chemicals require mitigation in the form of a systemic, holistic solution. An alternative land management option, through the organic production system, exists that can replace petrochemical pesticides and synthetic fertilizers, which endanger all life. Learn more about the health and environmental benefits of organic here and here.
Beyond Pesticides’ mission of fully transitioning to organic land management is rooted in protecting healthy air, water, land, and food for ourselves and future generations. To help support this work, join as a member today or give now to help support our work in 2025.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
Chiang, C.-Y. et al. (2025) Chlorpyrifos Induces Apoptosis in Macrophages by Activating Both Intrinsic and Extrinsic Apoptotic Pathways, Environmental Toxicology. Available at: https://onlinelibrary.wiley.com/doi/10.1002/tox.24515.
Fu, Y. et al. (2025) Chlorpyrifos induces spermatogenic dysfunction via ferroptosis in Sertoli cells, Genes & Diseases. Available at: https://www.sciencedirect.com/science/article/pii/S235230422500090X.
