Even low to moderate levels of exposure to the insecticide chlorpyrifos during pregnancy may lead to long-term, potentially irreversible changes in the brain structure of the child, according to a new brain imaging study by researchers from the Columbia Center for Children's Environmental Health at the Mailman School of Public Health, Duke University Medical Center, Emory University, and the New York State Psychiatric Institute. The changes in brain structure are consistent with cognitive deficits found in children exposed to this chemical.
Results of the study appear online in the April 30 PNAS.
The new study is the first to use MRI to identify the structural evidence for these cognitive deficits in humans, confirming earlier findings in animals. Changes were visible across the surface of the brain, with abnormal enlargement of some areas and thinning in others. The disturbances in brain structure are consistent with the IQ deficits previously reported in the children with high exposure levels of chlorpyrifos, or CPF, suggesting a link between prenatal exposure to CPF and deficits in IQ and working memory at age 7.
The study also reports evidence that CPF may eliminate or reverse the male-female differences that are ordinarily present in the brain. Further study is needed to determine the consequences of these changes before and after puberty, the researchers say.
Notably, the brain abnormalities appeared to occur at exposure levels below the current EPA threshold for toxicity, which is based on exposures high enough to inhibit the action of the key neurological enzyme cholinesterase. The present findings suggest that the mechanism underlying structural changes in the brain may involve other pathways.
According to the lead author, Virginia Rauh, ScD, Professor at the Mailman School of Public Health and Deputy Director of the Columbia Center for Children's Environmental Health, "By measuring a biomarker of CPF exposure during pregnancy, and following the children prospectively from birth into middle childhood, the present study provides evidence that the prenatal period is a vulnerable time for the developing child, and that toxic exposure during this critical period can have far-reaching effects on brain development and behavioral functioning."
"By combining brain imaging and community-based research, we now have much stronger evidence linking exposure to chlorpyrifos with neurodevelopmental problems," adds senior author Bradley S. Peterson, MD, Chief of Child & Adolescent Psychiatry, New York State Psychiatric Institute, and Director of MRI Research in the Department of Psychiatry, Columbia University Medical Center.
In the current study, the researchers used MRI to evaluate the brains of 40 New York City children, ages 5 to 11, whose mothers were enrolled prenatally in a larger cohort study. Researchers compared 20 children with high exposures to CPF with 20 children with lower exposures; all exposures occurred prior to the EPA ban on household use of the chemical in 2001. They found brain anomalies were associated with the higher exposure.
Since the 2001 ban, a drop in residential exposure levels of CPF has been documented by Robin Whyatt, DrPH, a co-author on the present study and Professor of Clinical Environmental Health Sciences and Co-Deputy Director of the Columbia Center for Children's Environmental Health at the Mailman School. However, the chemical continues to be present in the environment through its widespread use in agriculture (food and feed crops), wood treatments, and public spaces such as golf courses, some parks, and highway medians. People near these sources can be exposed by inhaling the chemical, which drifts on the wind. Low-level exposure can also occur by eating fruits and vegetables that have been sprayed. Although the chemical is degraded rapidly by water and sunlight outdoors, it has been detected by the Columbia researchers in many urban residences years after the ban went into effect.
Columbia University's Mailman School of Public Health: http://www.mailman.hs.columbia.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Tooth unearthed by 20-year-old volunteer hailed as major discovery by paleoanthropologist overseeing dig at Arago cave near Tautavel
Autistic children are just as good at reading emotions from the body as those without – they just don't like the closeness that interpreting emotions from faces requires
Individual cells can be made to act like tiny lasers, offering a more accurate way to tag and monitor tumour cells, for example
If you want to know the secret behind the success of Tyrannosaurus rex and its meat-eating dinosaur cousins, look no further than their teeth.
A recent article argued that sexuality is down to choice, not genetics. But the scientific evidence says otherwise, and points to a strong biological origin
When I hear the word “sabertooth”, my mind immediately jumps to the great sabercats who sliced through throats …
The Portland Press Herald reports that "Captain Eli," a rare orange lobster, will be kept at the Fisherman's Catch Café in Raymond, Maine, before Bill Coppersmith releases it back into the ocean.
A very rare genetic mutation causes some people to develop Alzheimer's in their 30s. It also makes these people the ideal candidates for tests of potential Alzheimer's drugs.
Adding pigment may shield eggs from UV radiation
Atlantic bottlenose and spotted dolphins are cooperating in unique mixed-species groups that are mostly platonic, but sometimes cross-species sex is involved