08
May
Developmental Neurological and Brain Damage in Children Intensifies Call for Ban of Organophosphate Pesticides
(Beyond Pesticides, May 8, 2026) A study from Ecuador establishes for the first time the developmental pattern of nervous system toxicants—still widely used in agriculture, mosquito control, and landscaping—on healthy neurological and brain development in children. It is firmly established that widely used organophosphate pesticides are severely toxic to a broad range of organisms. In what’s known as their “classic” mechanism of action, they inhibit acetylcholinesterase (AChE), an enzyme that breaks down the neurotransmitter acetylcholine (ACh), particularly in neuromuscular junctions in the brain. Not enough AChE leads to a buildup of ACh in motor neurons. Organophosphates deplete AChE, and an acute dose can paralyze the heart and lung muscles, causing death. Chronic exposures are implicated in numerous neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis (ALS). Beyond Pesticides’ Gateway on Pesticide Hazards and Safe Pest Management has detailed information on the organophosphates malathion, chlorpyrifos, diazinon, and others.
Acetylcholine and AChE are vital biological chemicals conserved across the animal kingdom, from humans to insects and everything in between. Yet there is no established baseline for normal levels of ACh and AChE in humans. Comparing biomarkers of organochlorine exposure with normal values would be a major step forward in assessing the influence of pesticides on human body burdens and disease, particularly in populations working and living in agricultural areas.
The study, “Acetylcholinesterase activity from childhood to young adulthood,” establishes for the first time the developmental pattern of ACh and AChE levels from early childhood to late adolescence. A collaboration between scientists at the University of California, San Diego, and the Fundación Cimas del Ecuador in Quito, the study is part of the Secondary Exposures to Pesticides among Children, Adolescents and Adults (ESPINA) program, an ongoing prospective project to determine the effects of pesticide exposure on human development in Pedro Moncayo, Ecuador, a center of the flower industry. See Beyond Pesticides’ March 24 Daily News Blog reporting on ESPINA’s research showing other pesticides in the region’s drinking and irrigation water.
The authors note that “Globally, over 100 million children, adolescents, and young adults are involved in agricultural work or live in farming communities.” They followed 746 children from ages five to 25, taking samples from each child eight times over 16 years between 2008 and 2024. They accumulated 3,119 fingerstick samples, measuring AChE as units of enzyme per milliliter (U/mL) in blood. They also measured hemoglobin levels, analyzed urine samples for pesticide metabolites, and gathered data on indirect household-level sources of pesticide exposure, i.e., drift from pesticide-applied fields within 300 meters of the children’s homes and pesticides potentially carried into the homes by adult agricultural workers.
The average participant lived within 300 meters of 13,253 square meters of floricultural crops and 72% lived with an agricultural worker. The children’s AChE levels increased linearly between 5 and 11 years of age, and were very similar between males and females. After 12.5 years, or approximately puberty onset, levels between the sexes diverged. Females’ levels plateaued at 3.80 U/mL at age 15, whereas males’ levels plateaued at approximately 4.40 U/mL at age 21. Across both sexes and at all ages, children who lived nearest to the highest amount of agricultural land had the lowest levels of AChE. However, living with an agricultural worker and levels of urinary pesticide markers did not alter expected AChE levels.
The authors conclude that off-target pesticide drift was most likely the source of the lowered AChE levels among children nearest to agricultural activity. Although this study is the first to try to establish a baseline pattern of ACh and AChE development in children, it does not by itself lead to firm conclusions about the health effects of organophosphate exposure on that baseline. For one thing, the tested population lives in an intensely agricultural area and there was no control group of children living away from agriculture. Further, the amount of greenhouse cultivation in the area doubled between 2008 and 2016, which may have affected the age-related trends in the data.
Nonetheless, the results are important, because although usage of organophosphates is declining, and some are banned, there is no dearth of application, exposures, or damage to the biosphere. The authors cite data indicating 1-2 billion pounds of organophosphate pesticides are used worldwide every year—between a fifth and a third of the total amount of pesticides. In the United States, more than 16 million pounds of 14 different organophosphates are applied every year, according to Earthjustice, with California leading the pack.
Large numbers of people, including pregnant women, fetuses, and children, are exposed, and research has shown associations with numerous neurological problems, including abnormal reflexes in newborns and verbal comprehension, attention deficits and autism spectrum disorder in school-age children. Beyond Pesticides reported on a 2025 California study finding that, “Despite a 54 percent decrease in overall use of the neurotoxic insecticide chlorpyrifos in the state between 2016 and 2021, after a statewide ban on the organophosphate insecticide in 2016, researchers found that in one California county, ‘more than 50 [percent] of pregnant people lived within 1 km of [organophosphate] pesticide use.’” Only two states – California and Washington – currently require biomonitoring of pesticide applicators, including requiring workers to stop working with pesticides if their AChE and red blood counts fall below specific minimums.
A further reason for concern is that AChE is not just a controller of a neurotransmitter in specific brain regions involved in motor activity. AChE is expressed in cells and tissues far beyond the nervous system; recent research on African clawed frogs and octopuses shows that AChE plays major roles in embryonic development, especially in the intestines, in cell differentiation, and in configuring cell structural elements. It is also involved in healing and regeneration of damaged tissue. These are “non-classical” aspects of AChE, again conserved across varied biological families, that are very likely adversely affected by the presence of organophosphate pesticides. The frog researchers cite previous experiments in the same frog species in which gut malformation was produced by organophosphate insecticides malathion and chlorpyrifos, writing that “our results suggest that chemicals used to inhibit AChE esterase function (e.g., organophosphates) also perturb its in vivo morphogenetic [developmental biology] activity; therefore, environmental exposure to such compounds may be an unrecognized risk factor for intestinal malformations.”
The Ecuador study, the work on non-classical AChE processes, and the human developmental evidence, all indicate that the trend away from organophosphate use is not moving fast enough. It is worth remembering that the toxicity of organophosphates was known almost as soon as they were developed. Chemist Gerhard Schrader, PhD, is known as the “father of modern organophosphate insecticide toxicology,” having discovered from personal experience the neurological effects of an early organophosphate while working for the German chemical giant I.G. Farben in the 1930s. He went on to synthesize thousands of the compounds. During World War II, Dr. Schrader and other German scientists developed the branch of organophosphate synthesis leading to chemical weapons, including sarin gas.
By comparison, the insecticidal uses they also worked on have been considered more benign despite the clear evidence that emerged right after World War II of severe organophosphate toxicity to not only insects but mammals as well—as Dr. Schrader could easily have concluded when inhaling and tasting the first organophosphate, tetraetylpyrophosphate, which caused “a marked pressure…in the larynx combined with breathlessness…mild disturbances of consciousness, and painful hypersensitivity of the eyes to light.” That it was AChE causing these disruptions has been known for more than 75 years, having been reported in work on parathion in 1949.
In fact, organophosphates are simply so deeply and widely toxic to the biosphere that health and environmental advocates have called for their removal from the global market without delay. The move toward organic, regenerative agriculture is the most direct way to reduce everyone’s exposure to these terrible chemicals.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
Acetylcholinesterase activity from childhood to young adulthood
Suarez et al
Journal of Exposure Science & Env Epidemiology 2026
https://www.nature.com/articles/s41370-026-00866-7
Advances in acetylcholinesterase-based biosensing technologies for organophosphorus pesticide detection: A comprehensive review (2020–2024)
Zhang et al
Food Chemistry 2025
https://www.sciencedirect.com/science/article/abs/pii/S030881462504021X?via%3Dihub
Organophosphate Pesticide Drift from Agricultural Fields Elevates Risk for Pregnant Farmworkers
Beyond Pesticides, October 28, 2025
https://beyondpesticides.org/dailynewsblog/2025/10/organophosphate-pesticide-drift-from-agricultural-fields-elevates-risk-for-pregnant-farmworkers/
Organophosphate (OP) Pesticides in Agricultural Area Residents’ Urine Year Round
Beyond Pesticides, April 28, 2023
https://beyondpesticides.org/dailynewsblog/2023/04/organophosphate-op-pesticides-in-agricultural-area-residents-urine-year-round/
Pesticide Exposure Again Linked to Neurotoxic Effects in Humans and Wildlife in Comprehensive Review
Beyond Pesticides, March 12, 2026
https://beyondpesticides.org/dailynewsblog/2026/03/pesticide-exposure-again-linked-to-neurotoxic-effects-in-humans-and-wildlife-in-comprehensive-review/
Beyond Pesticides
Organophosphate Archives
https://beyondpesticides.org/dailynewsblog/category/chemicals/organophosphate/
