Chlorpyrifos

also see Industry Shenanigans and Legislation/Regulatory, including international Legal/Litigation, Health/Nervous System Effects and /brain damage and  immune/auto- immune and/autism, children, children/organophosphates, organophosphates, Mixture effects, filed under health/nervous system effects/brain damage, children 2 and pesticide fact sheet: chlorpyrifos

SNAP Comment: while Chlorpyrifos is now finally banned in Canada, the PMRA had 297 chlorpyrifos-containng insecticides registered including 172 consumer products for indoor, lawn and garden use.. As of 16 January 2017, there were still 29 chlorpyrifos products registered for use in Canada. 'Though the U.S. Environmental Protection Agency banned chlorpyrifos for household use in 2001, it remains in use in (US) agriculture for non-organic produce and grains. This continued use means farm workers and nearby communities can still be exposed through contaminated air and dust', and it likely comes in on imported produce.

In Canada, chlorpyrifos was first registered 10 years before the IBT scandal, so was one of the pesticides grandfathered at the time. Assuming the products are listed in the order of their registration, the last registration expired on 10 December 2023. So it took 43 years before this pesticide was banned, and at least one formulation was registered 4 years before the ban when there should already have been loads of evidence of harm. 
DURSBAN 2E INSECTICIDE and DURSBAN 6 INSECTICIDE CONCENTRATE (chlorpyrifos) were 1st registered in Canada on 1970-07-01. Chlorpyrifos containing insecticides kept on being registered in Canada at least until 20/02/2019 for MPOWER CHLORPYRIFOS INSECTICIDE.

Chlorpyrifos (PAN fact sheet)  very good. no date of publication but references up to 2017.

300 Studies Link This Neurotoxic Pesticide to Multi-Organ Damage, Chronic Disease (By Pamela Ferdinand, U.S. Right to Know. this post appeared first on Children’s Health Defense  Key findings:    A review of nearly 300 studies summarizes evidence that chlorpyrifos may harm multiple systems throughout the body, including the brain, hormones, liver, gut microbiome, muscles, reproductive organs, and bones.      The review describes DNA damage, chromosome instability, and epigenetic changes that may alter how genes function long after exposure.    Some harmful effects appear at exposure levels below those considered safe under current pesticide exposure testing standards.

Scientists find hidden brain damage from a common pesticide (Columbia University's Mailman School of Public Health, November 7, 2025)    A new investigation has identified a connection between prenatal exposure to the commonly used insecticide chlorpyrifos (CPF) and measurable differences in brain structure, along with reduced motor skills, among children and adolescents in New York City.    For this study group, indoor pesticide use was the main source of exposure.   'Each child had detectable levels of CPF in their umbilical cord blood at birth and underwent brain imaging and behavioral assessments between the ages of 6 and 14.   Results showed a clear pattern: children with higher prenatal exposure to the insecticide displayed more pronounced structural and functional brain differences. They also performed worse on tests measuring motor speed and coordination. The evidence suggests that CPF exposure before birth disrupts brain structure, function, and metabolism in direct proportion to the level of exposure.

United Nations Lists Neurotoxic Insecticide Chlorpyrifos for Elimination, Exempt Uses Criticized   (Beyond Pesticides, May 15, 2025) The United Nations’ Conference of Parties (COP) for the Stockholm Convention on Persistent Organic Pollutants (POPs), originally adopted by 128 countries in 2001, voted to move the highly neurotoxic organophosphate insecticide chlorpyrifos, linked to brain damage in children, to Annex A (Elimination) with exemptions on a range of crops, control for ticks for cattle, and wood preservation, according to the POPs Review Committee. The exemptions drew criticism from groups seeking to eliminate chlorpyrifos without exemptions, as had been originally proposed. In the world of pesticide restrictions, this POPs classification marks a step forward in the international regulation of chlorpyrifos, as the U.S. sits on the sidelines.    SNAP Comment:  There are currently 0 (down from 297) chlorpyrifos products registered for sale in Canada. Stocks purchased before the sales ban may still be used. The last uses of chlorpyrifos was for mosquito control in Winnipeg and Edmonton. 

Prenatal Pesticide Exposure Threatens Children’s Language Development at 18 Months after Birth, Study Finds    (Beyond Pesticides, March 9, 2023) A study published in Environmental Research finds exposure to organophosphate (OP) compounds during pregnancy, or prenatal OP exposure can cause shortfalls in language development abilities at 18 months, stifling preschool-age language expression. Additionally, a timely and co-occurring study published in Environmental International confirms similar results, highlighting that chlorpyrifos (an organophosphate) impedes neurological and psychological development, including language communication and all motor skills of offspring at 12 and 18 months old.   SNAP Comment:  There are still 21 chlorpyrifos pesticides registered in Canada as of 22 March 2023. Chlorpyrifos was commonly used in yards and gardens for decades until banned for this use, and still brodcasted for mosquito control until recently by Winnipeg, and then Edmonton which only recently quit using it. Several other organophosphates are also still registered. 

Insecticide Chlorpyrifos Interacts with Genes to Increase Autism Risk, Research Finds   (Beyond Pesticides, July 20, 2021) Chlorpyrifos exposure results in the expression of genetic mutations associated with autism spectrum disorder in a laboratory model, finds research published in Environmental Health Perspectives by scientists at Johns Hopkins Bloomberg School of Public Health....Organoids were exposed to chlorpyrifos at four and eight weeks of development, representing a short term, high exposure scenario. “High-dose, short-term experimental exposures do not reflect the real-life situation, but they give us a starting point to identify genetic variants that might make individuals more susceptible to toxicants,” says Dr. Smirnova.

Parents Sue Manufacturer of Neurotoxic Insecticide Chlorpyrifos, Corteva (formerly Dow), for Causing Child’s Disabilities   (Beyond Pesticides, October 23, 2020) In central California, what promises to be a landmark series of lawsuits against Corteva (formerly DowAgroSciences), maker of the pesticide chlorpyrifos, is under way,.. This first suit, brought by the parents of Rafael Cerda Calderon, Jr. on his behalf, charges that his lifelong disabilities were caused by chronic exposures to chlorpyrifos. The parents are suing for general damages, compensatory damages (due to Rafael, Jr.’s loss of earning capacity), medical care costs, and “punitive damages for the willful, reckless, and recklessly indifferent conduct of the Defendants” in intentionally hiding the dangers of their chlorpyrifos products from customers and the public. As with so many dangerous pesticides, absent effective federal regulation, states, cities, and other entities are taking action to protect people from this compound, and as in this case, individuals are seeking redress for harms suffered.' 

Major Manufacturer of Chlorpyrifos Drops Out of Market, But EPA Continues to Allow Use   (Beyond Pesticides, February 12, 2020) 'Corteva, a company spun-off from DowDupont, will stop producing chlorpyrifos by the end of this year as a result of declining sales. Despite the move being in the interest of public health, the company is earning little praise from health advocates for what amounts to simply a shrewd financial decision.  At odds is the difference between halting production of chlorpyrifos and cancelling its EPA registration. While Corteva has the ability to voluntarily stop producing its own product, EPA registration permits other generic manufacturers to continue to producing the product. And, over the years, there would be nothing to stop Corteva from reintroducing “new” chlorpyrifos products back onto the market. '    The removal of Corteva (DowDupont) from the chlorpyrifos marketplace is indicative of a pattern within the current administration that puts profit at all cost above the health of the American people, and American children in particular, according to advocates. Decisions regarding public health should not be determined by the dictates of the marketplace, but by the sound science in states like NY, CA, and HI, the EU and other countries are following for the benefit of their residents.

Brain Function Damage from Exposure to Organophosphate Pesticides, including Chlorpyrifos, Documented with Imaging  (Beyond Pesticides, August 30, 2019)  'The subject adolescents — estimated to have relatively high levels of prenatal exposure to organophosphates — showed aberrant brain activity in executive function, attention, social cognition, and language comprehension, compared to their peers.'   'Associate adjunct professor of epidemiology at UC Berkeley and lead author of the new study, Sharon Sagiv, PhD, said, “These results are compelling, because they support what we have seen with our neuropsychological testing, which is that organophosphates impact the brain.”'

European Regulators Issue Warning on Danger of Chlorpyrifos Prior to Release of Full Review   (Beyond Pesticides, August 22, 2019) 'In early August, experts from European Union (EU) member states and staff members of the European Food Safety Authority (EFSA) announced their conclusion that chlorpyrifos fails to meet criteria for renewed approval for use, potentially moving the EU a step closer to an outright ban.'  'The EU and EFSA experts included in their findings:

1. a genotoxic potential for chlorpyrifos cannot be ruled out
2. chlorpyrifos meets the criteria for classification as toxic for reproduction (REPRO 1B, H360D, “May damage the unborn child”), as set out in EU regulation (EC) No 1272/2008)   SNAP Comment: There are still 28 chlorpyrifos products registered in Canada as of 22 August 2019.

Evaluation Used to Support Registration of Neurotoxic Chlorpyrifos Found To Be Fundamentally Flawed (Beyond Pesticides, November 20, 2018)  Scientific conclusions used to support the registration of the insecticide chlorpyrifos were flawed and omitted key health impacts, according to a fresh analysis of the original data by a team of independent scientists from northern Europe and the U.S. This re-review not only casts further doubt on the safety of the neurotoxic chlorpyrifos, it highlights a major flaw within federal pesticide regulation that allows pesticide producers to submit their own safety evaluations to the U.S. Environmental Protection Agency without public oversight. “One conclusion we draw is that there is a risk that the results of industry-funded toxicity tests are not reported correctly,” says co-author Axel Mie, PhD. “This makes it difficult for the authorities to evaluate the pesticides in a safe and valid way... While these studies are generally considered ‘confidential business information’ and not available to the public, using Swedish freedom of information laws, researchers were able to obtain two key studies relating to the developmental neurotoxicity of chlorpyrifos”

Brain and Behavioral Effects of Early Exposures to Neurotoxicants  (University of California Television (UCTV), Aug 11, 2015)  There is also a significant link to meaningful tremors and learning deficits. This presentation addresses the impact of prenatal exposure to a common neurotoxicant on brain structure and neuropsychological function in an inner-city cohort of minority children. The toxic chemical, an organophosphate insecticide (chlorpyrifos), has been banned for indoor residential use in the U.S. since 2001, but continues to have widespread application for agricultural purposes. Possible moncholinergic mechanisms involve disruption of neural cell development and neurotransmitter systems, including the formation and activity of synapses in different brain regions. This presentation examines the evidence for long-term effects of prenatal chlorpyrifos exposure on neuropsychological profiles and brain morphology as measured by MRI. Series: "MIND Institute Lecture Series on Neurodevelopmental Disorders" Health and Medicine Professional Medical Education Show ID: 29838

California to List Chlorpyrifos as a Toxic Air Contaminant (Beyond Pesticides, August 8, 2018) "based on evidence of its neurological effects and exposure risks of concern...According to the assessment, “chlorpyrifos meets the criteria of TAC designation based on either the developmental neurotoxicity endpoint or the AChE inhibition endpoint, even without the additional 10x uncertainty factor necessary to account for the fact that the developmental neurotoxicity effects occur at a lower level than AChE inhibition.” As defined in California, a TAC is “an air pollutant which may cause or contribute to an increase in mortality or an increase in serious illness, or which may pose a present or potential hazard to human health.”"

Poison Fruit    Dow Chemical Wants Farmers to Keep Using a Pesticide Linked to Autism and ADHD (The Intercept, 14 January 2017) A fascinating article reviewing the history of the organophosphate chlorpyrifos regulation in the United States. Reviews the research directly linking it to autism and several other disorders, the need for suing the US EPA to get action and Dow's constant efforts to keep chlorpyrifos on the market including bad studies, threats to sue the EPA, and success in changing the law. Long and lots of links." While the US nationwide autism rate is now one in 68, for women who lived near fields where chlorpyrifos was sprayed during their second trimester, the chance of having a child with autism was closer to one in 21." Effects on children's brains occur at levels 20 times below the EPA’s safety level. In spite of the evidence linking autism to environmental causes, the National Institute of Health (NIH) is only funding studies on environmental causes at 1/20th of the genetic ones. Dow's latest efforts: "Instead, the chemical industry has renewed its efforts to derail the proposed regulation. On November 29, (2016)  CropLife America launched a Hail Mary effort to stop the ban. The business group petitioned the head of the office of pesticide programs to “cease regulatory decision making” on chlorpyrifos until it has developed standards “for acceptance of epidemiologic studies in human health risk assessment,”" a process that could easily take several years.". However, there are still several potential ways it (Dow) could circumvent the regulation without technically defying the law.

SNAP comment: Here we have it from the mouth of industry: there is currently no process “for acceptance of epidemiologic studies in human health risk assessment.” That is why it is so easy for regulatory agencies to ignore or set aside epidemiological studies in their pesticide re-evaluations, especially when the committees consist of several 'regulatory' scientists or others deriving their income from the pesticide industry. I don' t believe there is much of a mechanism or standard for regulatory agencies to evaluate anything but the studies mandated for registration. As of 16 January 2017, there are still 29 chlorpyrifos products registered for use in Canada.