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Common Pesticide “Disturbs” the Brains of Children

The views expressed are those of the author and are not necessarily those of Scientific American.

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chemical-spraying-agricultureBanned for indoor use since 2001, the effects of the common insecticide known as chlorpyrifos can still be found in the brains of young children now approaching puberty. A new study used magnetic imaging to reveal that those children exposed to chlorpyrifos in the womb had persistent changes in their brains throughout childhood.

The brains of 20 children exposed to higher levels of chlorpyrifos in their mother’s blood (as measured by serum from the umbilical cord) “looked different” compared to those exposed to lower levels of the chemical, says epidemiologist Virginia Rauh of the Mailman School of Public Health at Columbia University, who led the research published online by Proceedings of the National Academy of Sciences on April 30. “During brain development some type of disturbance took place.”

The 6 young boys and 14 little girls, whose mothers were exposed to chlorpyrifos when it was commonly used indoors in bug sprays prior to the ban, ranged in age from seven to nearly 10. All came from Dominican or African American families in the New York City region. Compared to 20 children from the same kinds of New York families who had relatively low levels of chlorpyrifos in umbilical cord blood, the 20 higher dose kids had protuberances in some regions of the cerebral cortex and thinning in other regions. “There were measurable volumetric changes in the cerebral cortex,” Rauh notes.

Though the study did not map specific disorders associated with any of these brain changes, the regions affected are associated with functions like attention, decision-making, language, impulse control and working memory. The “structural anomalies in the brain could be a mechanism, or explain why we found cognitive deficits in children” in previous studies, Rauh notes.

The findings echo similar results with animal studies of the insecticide, which remains widely used in agriculture to kill crop-spoiling insects. Rats exposed to the chemical also experience changes to the brain as well as altered behavior—all at doses below those considered safe by current federal guidelines from the U.S. Environmental Protection Agency (EPA). The change, at least for rats, is irreversible.

Previous studies have linked chlorpyrifos in children to everything from low birth weight to attention problems in both urban and agricultural exposures. And a low, but measurable, dose reaches yet other populations via food—a study that fed children a diet of organic food showed drops in the levels of chlorpyrifos and other organophosphate pesticides that then rebounded when they returned to their regular diet. The insecticide is used on everything from peaches to cilantro. “It’s the fruits and vegetables,” that can carry chlorpyrifos, Rauh notes.

Of course, it remains unclear what, if any, danger such doses pose but it is now apparent that chlorpyrifos exposure in the womb has impacts on brain structure that persist through childhood, at least. And the children in this study were exposed to lower levels of chlorpyrifos than found in a random sampling from a Cincinnati blood bank (which showed levels twice as high as those in the affected children). It also remains unclear whether the brain changes—some of which skew masculine or feminine brain characteristics—will have an impact in puberty. “Whether or not there would be any measurable effects is not clear,” Rauh says. “Hopefully, going forward, we’ll be able to answer some of those questions and determine whether the process of puberty or other aspects of sexual differentiation could be assessed.”

The good news is that washing fruits and vegetables can rinse away lingering chlorpyrifos and, presumably, mitigate any risk. In addition, although chlorpyrifos can persist in indoor environments, it breaks down relatively quickly when exposed to sunlight and other natural elements. And the EPA is now following up its prior ban on indoor use by re-evaluating its policy more broadly. “We have a lot of risky chemicals in our environment,” Rauh says. “We need to determine if the risk persists, if it is reversible and look at the larger regulatory picture for chemicals.”

As of now, however, the use of chlorpyrifos remains widespread in conventional agriculture. “Eating organic is a great idea, however, it is very expensive and out of reach for many average families,” such as the ones in this study, Rauh notes. It’s a “better idea to wash your apples. That would eliminate a whole variety of problems.”

Image: © / Federico Rostagno

David Biello About the Author: David Biello is the associate editor for environment and energy at Scientific American. Follow on Twitter @dbiello.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Happy Phil 3:03 am 05/2/2012

    I choose to buy organic labeled food, (though the USDA rules on what constitutes organic are questionable), whenever possible. I have yet to find it prohibitively expensive and I live within the limits of a small fixed income.

    Seeing the ‘organic is more expensive’ slogan in this and other articles is puzzling, but the ‘just wash the poison off with water and it will be safe to eat’ advice is downright insulting. It is rarely authenticated by any independent scientific studies.

    What a shame. Even in the face of brain altering side effects, the profit motive allows the use of this poison on our food.

    Link to this
  2. 2. singing flea 11:18 am 05/2/2012

    “It’s a “better idea to wash your apples.”

    Yea right. That sounds to me like trying to wash the hormones and pesticides out of the hamburgers we eat too.

    Once these chemicals get absorbed into the soil, it is far to late to worry about washing if off. You can be certain that Monsanto and Exxon spent millions on the advertising campaigns that swear on a stack of bibles that our food is perfectly safe using their products.

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  3. 3. jerryd 9:06 pm 05/2/2012

    Too many fields are having effects from vaious herbicides build up over yrs, is killing the soil.

    One called Milstone which is suppose to be short acting is showing up in manure from cows, horses fed crop fodder with it, killing gardens, crops it was put on. So make sure you know where your manure comes from too if used to garden.

    I’m going to start a hanging garden made from 2L coke bottles cut and the top upside down on a rope filled with soil, chain, etc with 3-6 in a row and raised beds.

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  4. 4. denke42 3:15 am 05/3/2012

    Before scorning the washing of apples, check the work of Bruce Ames, Professor of Biochemistry and Molecular Biology, University of California, Berkeley, Senior Scientist at Children’s Hospital Oakland Research Institute, and inventor of the Ames test ( Many, if not most, artificial pesticides are analogs of natural natural pesticides that plants produce to defend themselves. Organically grown plants have far higher concentrations of these natural pesticides, presumably because they’re not protected by artificial pesticides. Two points: (1) Little animal research is done on the safety of the natural pesticides, because it’s expensive and there is no mandate to test (because they’re natural and no one is responsible for them), yet more than half of those tested in rats caused cancer; (2) whereas artificial pesticides are found ON the plant (where they can be mostly washed off), the natural pesticides are typically found IN the plant (where they cannot be washed off). “Americans eat about 1,500 mg of natural pesticides per person per day, which is about 10,000 times more than they consume of synthetic pesticide residues [Ames et al., Nature’s chemicals and synthetic chemicals: Comparative toxicology. Proc. Natl. Acad. Sci. USA 87, 7782-7786.]”

    Ames and his group note that ‘Half of all chemicals tested, whether occurring naturally or produced synthetically, are “carcinogens”; there are high-dose effects in rodent cancer tests that are not relevant to low-dose human exposures and which may contribute to the high proportion of chemicals that test positive.’ (They conclude that the rodent-cancer tests may be misleading.) More at and lots more at

    Eating more fruits and vegetables, organically grown or not, may reduce your chances of cancer. Washing them before eating may not protect you from cancer, but it could protect you from Salmonella, Toxoplasma, Listeria, and norovirus – which could kill you (

    Of course you could skip washing your organic produce, because Salmonella, Toxoplasma, Listeria, and norovirus are natural.

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  5. 5. anon321 2:20 pm 05/3/2012


    “The good news is that washing fruits and vegetables can rinse away lingering chlorpyrifos and, presumably, mitigate any risk.”

    pre·sum·a·ble (pr -z m -b l). adj. That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster.

    It is a known FACT; that…
    “Pesticides can be absorbed by plants through the leaves and roots. Pesticides that are taken up by plants can move (translocate) to other parts of the plant.” (from National Pesticide Information Center Website)

    Of course, we presume the author is just some idiot who has a degree in English and likes science but has no idea of how water is absorbed into plants roots and moved into the actual tissue we feed our children, our parents, and ourselves. This is because this is the purpose of these types of pseudo science magazines and the reason the government makes costs so high for publicly funded research articles that common, ordinary people cannot afford to know anything; and this can has statements like;

    “The good news is that washing fruits and vegetables can rinse away lingering chlorpyrifos and, presumably, mitigate any risk.”



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  6. 6. bucketofsquid 5:54 pm 05/3/2012

    I wonder how much this correlates with the drop in fertility in America.

    If you want to gather a lot of support for getting rid of this chemical entirely just convince the religious right that it causes homosexuality to increase. It does after all, change brain gender characteristics. Call Westboro Church!

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  7. 7. ErnestPayne 4:59 pm 05/8/2012

    A cautionary tale well worth further and deeper exposure to the national media. Particularly to those that wish to, like Reagan, “free enterprise” and deregulate. I have taken to going to the local farmers markets for my food. A shorter food chain and a, hopefully, less chemical diet.

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  8. 8. GarryHamlin 5:15 pm 05/11/2012

    The following is offered in response to a statement in the blog post above (Common Pesticide “Disturbs” the Brains of Children) to the effect that “rats exposed to [chlorpyrifos] experience changes to the brain as well as altered behavior – all at doses below those considered safe by current federal guidelines from the U.S. Environmental Protection Agency.” This statement is based on the recent Columbia Center for Children’s Environmental Health paper, “Brain anomalies in children exposed prenatally to a common organophosphate pesticide” (Rauh et al 2012) (

    Specifically, Rauh et al state, in discussion of certain animal work with chlorpyrifos addressing reported changes in brain morphology, that “The exposures at which these mechanisms become manifest in animal models are comparable to exposure levels in our own population.” However, if the authors are relying on citations 18, 19, and 30 (from Rauh et al 2012) as support for this claim, their statement is incorrect; current estimates of human exposure to chlorpyrifos are, in fact, thousands of times less than the doses used in those studies.

    Specifically, in citations 18 and 19 (Roy et al., 2004; and Roy et al., 2005 – presumably the studies upon which this statement is based since citation 30 is a review article – the experimental dose to newborn rats was 5 mg per kg body weight (5000 ug/kg/day).

    By contrast, Eaton et al (2008) estimated the dose of chlorpyrifos in the Columbia cohort study to be 0.027 ug/kg/day and daily exposure rates in the general U.S. population to be less than 0.01 ug/kg/day. This makes relevant human exposures to chlorpyrifos at least 185,000 times less than the doses used in these animal studies. It also makes the doses used in these animal studies more than 16,000 times greater than EPA’s 2011 health-based standard for repeat chlorpyrifos exposure in the U.S. population.

    We appreciate the opportunity to offer this clarification.

    Daland R. Juberg, PhD
    Dow AgroSciences LLC

    Eaton et al 2008. Crit. Review Toxicol. S2:1-125.
    Rauh et al 2012. PNAS. Early edition. 1203396109.
    Roy et al 2004. Dev. Brain Res. 148:197-206.
    Roy et al 2005. Dev. Brain Res. 155:71-80.

    Link to this

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