{"url":"https://whatshealthyandwhy.com/organophosphate-pesticides/are-organophosphate-pesticides-harmful-to-children","path":"/organophosphate-pesticides/are-organophosphate-pesticides-harmful-to-children","alternates":{"json":"https://whatshealthyandwhy.com/api/articles/organophosphate-pesticides/are-organophosphate-pesticides-harmful-to-children.json","markdown":"https://whatshealthyandwhy.com/organophosphate-pesticides/are-organophosphate-pesticides-harmful-to-children.md"},"topic":{"slug":"organophosphate-pesticides","name":"Organophosphate Pesticides","url":"https://whatshealthyandwhy.com/organophosphate-pesticides"},"slug":"are-organophosphate-pesticides-harmful-to-children","order":1,"title":"Organophosphate Pesticides and Children's Brains","question":"Are organophosphate pesticides like chlorpyrifos harmful to children's brain development?","answer":"Likely: several birth cohorts link prenatal exposure to lower IQ and attention problems, but exposure measures are imperfect and one major cohort found no effect.","description":"Birth cohorts link prenatal organophosphate exposure, including chlorpyrifos, to lower IQ and attention problems. The evidence, its limits and US rules.","confidence":3,"confidenceNote":"Several well-designed birth cohorts agree, but they are observational, measure exposure indirectly, and at least one large cohort found no effect.","evidenceSummary":{"rctCount":0,"observationalCount":7,"metaAnalysisCount":2,"totalParticipants":"About 1,300 children across four birth cohorts","replicated":true,"newestStudyYear":2026},"category":{"categoryTitle":"What's Harming You","categorySlug":"harming-you","subcategoryName":"Environmental Toxins","subcategorySlug":"environment","url":"https://whatshealthyandwhy.com/explore/harming-you/environment"},"actions":["Wash produce and favor organic or low-residue choices in pregnancy and for young children: an organic diet brought children's urinary malathion and chlorpyrifos markers to undetectable levels within days [1].","Use non-chemical pest control at home (seal entry points, use bait stations) rather than organophosphate sprays: most homeowner uses ended around 2000–2001, and exposures were much lower afterwards [2][3].","Near sprayed fields or in agriculture, leave work shoes and clothes at the door and wash separately: urinary organophosphate metabolites fell about 20% per mile from fields [4]."],"cautions":["Pregnancy is the window of greatest concern in the cohort studies, so avoid unnecessary home or garden use of organophosphate insecticides and ask your clinician about any workplace exposure [5][6].","Acute poisoning from a spill or heavy exposure is a medical emergency, since organophosphates can trigger a cholinergic crisis: call poison control (US 1-800-222-1222) or emergency services right away [7]."],"simpleText":"Organophosphates, including chlorpyrifos, are insecticides that disrupt the nervous system. Birth cohorts in New York and California tie higher prenatal exposure to lower IQ, poorer working memory and more attention problems in childhood [5][8][6]. A Cincinnati cohort found no effect [9], and US regulators' position has swung back and forth, so pregnancy is the time for caution.","mediumText":"How it works\n\nWhat they are. Organophosphates block acetylcholinesterase, an enzyme that switches nerve signals off [7]. At high doses they cause acute poisoning. At lower doses over time, studies have linked prenatal exposure to cognitive and behavioral problems in children [7]. Chlorpyrifos, used since 1965, is the best known [2].\n\nHow children are exposed. Homes were once a major source. In 2000 manufacturers agreed to eliminate most homeowner uses of chlorpyrifos [2], and New York newborns born after January 2001 had much lower exposure and no link to birth size [3]. Today the routes are food residues, drinking water and drift near farmland [2][4].\n\nWhat the cohorts found.\n- New York (Columbia): children with the highest cord-blood chlorpyrifos scored 6.5 points lower on a psychomotor index and 3.3 points lower on a mental development index at age 3 [5]. At age 7, each standard-deviation rise went with 1.4% lower full-scale IQ and 2.8% lower working memory [8].\n- California (farmworker families): children of mothers in the highest fifth of urinary organophosphate metabolites averaged 7.0 IQ points lower at age 7 [6].\n- New York (Mount Sinai): prenatal metabolites went with poorer perceptual reasoning, especially in children whose mothers had a slow-clearing enzyme variant [10].\n- Cincinnati: no link to thinking skills at ages 1 to 5 in 327 mother-child pairs [9].\n\nReviews disagree. A systematic review found that most prenatal studies showed lower mental development and more attention problems [11]. A review funded by the pesticide industry's trade association said the human studies did not strongly implicate any one pesticide as a cause [12]. Exposure is hard to measure: urine metabolites are not specific and can come from residues already on food [9].\n\nUS rules. In 2017 the EPA said the science on neurodevelopment was unresolved. A court ordered action, and in 2021 the agency revoked all chlorpyrifos food tolerances. An appeals court vacated that rule in 2023 and the tolerances returned. Food uses have since been canceled except for 11 crops, and in December 2024 EPA proposed revoking all other tolerances; its page, last updated 24 August 2026, reported no final rule [2].\n\nWhat to do. Wash produce and choose organic when you can (see pesticide residues on produce). For other farm chemicals, see glyphosate and atrazine.","deepText":"The evidence in detail\n\nNew York cohort\n\nThe Columbia cohort measured chlorpyrifos in umbilical cord plasma. Among 254 children, those above 6.17 pg/g scored 6.5 points lower on the Bayley Psychomotor Development Index and 3.3 points lower on the Mental Development Index at 3 years; delayed psychomotor development was 5 times and delayed mental development 2.4 times more common, and attention, ADHD and pervasive developmental problems were more likely [5]. At 7 years in 265 children, each standard-deviation rise (4.61 pg/g) went with a 1.4% fall in full-scale IQ and a 2.8% fall in working memory, adjusted for maternal education, maternal IQ and home environment [8].\n\nCalifornia and Mount Sinai cohorts\n\nIn the CHAMACOS birth cohort of farmworker families, 329 children had IQ tested at 7 years. Maternal dialkylphosphate metabolites averaged over pregnancy went with poorer working memory, processing speed, verbal comprehension, perceptual reasoning and IQ; the highest quintile had a 7.0-point deficit. Children's own urinary metabolites were not consistently linked, and maternal levels were higher than typical but within the general US range [6]. In Mount Sinai's cohort, prenatal metabolites went with a decrement in mental development at 12 months among Black and Hispanic children, with enhanced effects in mothers carrying the PON1 Q192R QR/RR genotype, and with lower perceptual reasoning at ages 6 to 9 in mothers with the QQ genotype [10].\n\nThe null result\n\nThe Cincinnati cohort measured six dialkylphosphates twice in pregnancy in 327 mother-infant pairs and tested children from age 1 to 5. It found no associations. Mothers with higher metabolite levels had higher socioeconomic status and ate more fresh fruit and vegetables, and the authors suggested a healthier diet may protect the fetus, or that dietary metabolites are harmless and a poor measure of exposure to the parent compound [9].\n\nSystematic reviews\n\nA review of 20 studies (7 prenatal, 8 postnatal, 5 both) found that most prenatal studies observed worse mental development and more attention problems, postnatal evidence was less consistent, and designs varied so much that standardized methods are needed before firm conclusions [11]. The industry-funded review concluded that, as a whole, the epidemiology did not strongly implicate any particular pesticide as causally related to adverse outcomes and that animal effects generally appeared at doses at or above those in regulatory studies [12]. Its funder was the European Crop Protection Association.\n\nExposure and regulation\n\nAmong 314 mother-newborn pairs, each log-unit rise in cord chlorpyrifos went with 42.6 g lower birth weight, and the association was strong before the 2000 to 2001 residential phase-out but absent in newborns born after January 2001, when exposure was substantially lower [3]. In Washington State, a urinary dimethyl organophosphate metabolite (DMTP) was higher in farmworkers (71 versus 6 µg/L) and their children (17 versus 8 µg/L) than in non-farmworker households, and fell 20% for each mile from farmland [4]. The EPA's 2020 assessment judged chlorpyrifos residues in food not of concern but found drinking water added significantly to risk. Courts then reshaped the legal outcome: the Ninth Circuit forced the 2021 revocation, and the Eighth Circuit vacated it in November 2023, noting EPA should have considered modifying tolerances, with 11 crops as candidates [2].\n\nWhere the evidence conflicts\n\nMost data are urinary metabolites that are not specific to one pesticide, and mothers with higher levels may differ in income and diet. The cohorts differ in design and results, one is null, and a randomized trial of this exposure would be unethical. In the New York cohort, exposure fell sharply after the residential bans, so today's exposures are probably lower than in the earliest cohorts [3].\n\nBottom line\n\nConfidence is 3 of 5. Several independent birth cohorts and systematic reviews point to harm from prenatal exposure at levels people actually had. The exposure measures are imperfect, and current exposures are probably lower, so sensible precautions in pregnancy are justified while the science and rules keep moving.","deepTruncated":false,"references":[{"id":"1","title":"Organic diets significantly lower children's dietary exposure to organophosphorus pesticides","authors":"Lu C, Toepel K, Irish R, et al.","year":2006,"journal":"Environ Health Perspect","pmid":"16451864","url":"https://pubmed.ncbi.nlm.nih.gov/16451864/"},{"id":"2","title":"Chlorpyrifos: regulatory history and current status","authors":"U.S. Environmental Protection Agency","year":2026,"journal":"EPA, Ingredients Used in Pesticide Products","url":"https://www.epa.gov/ingredients-used-pesticide-products/chlorpyrifos"},{"id":"3","title":"Prenatal insecticide exposures and birth weight and length among an urban minority cohort","authors":"Whyatt RM, Rauh V, Barr DB, et al.","year":2004,"journal":"Environ Health Perspect","pmid":"15238288","url":"https://pubmed.ncbi.nlm.nih.gov/15238288/"},{"id":"4","title":"Organophosphate pesticide exposure and residential proximity to nearby fields: evidence for the drift pathway","authors":"Coronado GD, Holte S, Vigoren E, et al.","year":2011,"journal":"J Occup Environ Med","pmid":"21775902","url":"https://pubmed.ncbi.nlm.nih.gov/21775902/"},{"id":"5","title":"Impact of prenatal chlorpyrifos exposure on neurodevelopment in the first 3 years of life among inner-city children","authors":"Rauh VA, Garfinkel R, Perera FP, et al.","year":2006,"journal":"Pediatrics","pmid":"17116700","url":"https://pubmed.ncbi.nlm.nih.gov/17116700/"},{"id":"6","title":"Prenatal exposure to organophosphate pesticides and IQ in 7-year-old children","authors":"Bouchard MF, Chevrier J, Harley KG, et al.","year":2011,"journal":"Environ Health Perspect","pmid":"21507776","url":"https://pubmed.ncbi.nlm.nih.gov/21507776/"},{"id":"7","title":"Developmental neurotoxicity of the organophosphorus insecticide chlorpyrifos: from clinical findings to preclinical models and potential mechanisms","authors":"Burke RD, Todd SW, Lumsden E, et al.","year":2017,"journal":"J Neurochem","pmid":"28791702","url":"https://pubmed.ncbi.nlm.nih.gov/28791702/"},{"id":"8","title":"Seven-year neurodevelopmental scores and prenatal exposure to chlorpyrifos, a common agricultural pesticide","authors":"Rauh V, Arunajadai S, Horton M, et al.","year":2011,"journal":"Environ Health Perspect","pmid":"21507777","url":"https://pubmed.ncbi.nlm.nih.gov/21507777/"},{"id":"9","title":"An Observational Study to Evaluate Associations Between Low-Level Gestational Exposure to Organophosphate Pesticides and Cognition During Early Childhood","authors":"Donauer S, Altaye M, Xu Y, et al.","year":2016,"journal":"Am J Epidemiol","pmid":"27539379","url":"https://pubmed.ncbi.nlm.nih.gov/27539379/"},{"id":"10","title":"Prenatal exposure to organophosphates, paraoxonase 1, and cognitive development in childhood","authors":"Engel SM, Wetmur J, Chen J, et al.","year":2011,"journal":"Environ Health Perspect","pmid":"21507778","url":"https://pubmed.ncbi.nlm.nih.gov/21507778/"},{"id":"11","title":"A systematic review of neurodevelopmental effects of prenatal and postnatal organophosphate pesticide exposure","authors":"González-Alzaga B, Lacasaña M, Aguilar-Garduño C, et al.","year":2014,"journal":"Toxicol Lett","pmid":"24291036","url":"https://pubmed.ncbi.nlm.nih.gov/24291036/"},{"id":"12","title":"Pesticide exposure and neurodevelopmental outcomes: review of the epidemiologic and animal studies","authors":"Burns CJ, McIntosh LJ, Mink PJ, et al.","year":2013,"journal":"J Toxicol Environ Health B Crit Rev","pmid":"23777200","url":"https://pubmed.ncbi.nlm.nih.gov/23777200/"}],"wordCount":1079,"source":{"path":"src/content/topics/organophosphate-pesticides/are-organophosphate-pesticides-harmful-to-children.md"},"citeAs":"“Are organophosphate pesticides like chlorpyrifos harmful to children's brain development?.” What's Healthy and Why. https://whatshealthyandwhy.com/organophosphate-pesticides/are-organophosphate-pesticides-harmful-to-children","notice":"General information backed by peer-reviewed research, not medical advice."}