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Certain Pesticides Linked to Altered Brain Activity In Teenagers

Pesticides are harmful to developing brains, especially during pregnancy. A number of studies have already found that higher exposure to organophosphate pesticides during pregnancy is linked to poorer cognitive functioning and behavior problems in children. A recent University of California study actually looked at the brain activity in 95 teenagers while they were doing a number of mental tasks. Using advanced brain imaging, they found altered brain activity in those teens who had the highest organophosphate pesticide exposure prenatally. These teenagers live in Salinas Valley, California - an agricultural area with many farms.

The researchers point out that "Over 800 million pounds of pesticide active ingredients are applied in the United States each year, with organophosphates (OPs) the most commonly applied class of insecticides. Exposure to OP pesticides, which are endocrine-disrupting compounds, is widespread in the US population, including among pregnant women and children." [PLEASE NOTE: Conventional farming uses organophosphates. Organic farming does not allow the use of organophosphates.]

The main way people get exposed to organophosphate pesticides is diet - especially pesticide residues on fruits and vegetables. Also, if people live near farms where such pesticides are used, or live with a person who works on a farm. They bring home the pesticides on their clothes. People also breathe breathe in pesticides when they are applied on nearby farms or properties due to pesticide drift.

Chlorpyrifos is one example of an organophosphate pesticide. It is considered so dangerous to the developing fetus and children (lower IQs, neurological effects, behavioral effects) that the EPA was going to ban it in the United States. However, the Trump administration overruled the ban (chemical/pesticide lobbyists at work!). Since then, several states (NY, Hawaii, California) have enacted legislation to ban all use of chlorpyrifos in those states, but it will take several years for the bans to become fully in effect.

From Science Daily: Prenatal pesticide exposure linked to changes in teen's brain activity  

Summary: Prenatal exposure to the organophosphate pesticides has been linked to poorer cognition and behavior problems in children. A new study is one of the first to use advanced brain imaging to reveal how exposure can actually change brain activity. Teenagers estimated to have higher levels of prenatal exposure to organophosphates showed altered brain activity compared to their peers while performing tasks that require executive control, the study found.

Organophosphates are among the most commonly used classes of pesticides in the United States, despite mounting evidence linking prenatal exposure to the chemicals to poorer cognition and behavior problems in children.

A new study led by University of California, Berkeley, researchers is one of the first to use advanced brain imaging to reveal how exposure to these chemicals in the womb changes brain activity.

The study, which appeared this week in the journal Proceedings of the National Academy of Sciences, used functional near-infrared imaging (fNIRS) to monitor blood flow in the brains of 95 teenagers born and raised in California's Salinas Valley, where agricultural spraying of pesticides is common.

Compared to their peers, teenagers estimated to have higher levels of prenatal exposure to organophosphates showed altered brain activity while performing tasks that require executive control, the study found.

"These results are compelling, because they support what we have seen with our neuropsychological testing, which is that organophosphates impact the brain," said Sharon Sagiv, associate adjunct professor of epidemiology at UC Berkeley and lead author on the study.

The teenagers were part of the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a longitudinal study examining the effects of pesticides and other environmental toxins on childhood development. The study was initiated by UC Berkeley investigators more than 20 years ago. Previous CHAMACOS work has linked prenatal organophosphate exposure with attention problems and lower IQ in children.

In the current study, the researchers used fNIRS to measure brain activation while teens ages 15 to 17 engaged in a variety of tasks requiring executive function, attention, social cognition and language comprehension.

The fNIRS technique uses infrared light to monitor blood flow in the outer regions, or cortex, of the brain. It provides similar information as functional magnetic resonance imaging (fMRI), but only requires a small cap of infrared light sources, rather than massive MRI tube, making it a more affordable and portable choice for research studies.

The researchers also used data from the California Pesticide Use Reporting program, which documents when and where agricultural pesticides are sprayed, to estimate their residential proximity to organophosphate application during pregnancy.

They found that teens with higher prenatal organophosphate exposure had less blood flow to the frontal cortex when engaged in tasks that test cognitive flexibility and visual working memory, and that they had more blood flow to the parietal and temporal lobes during tests of linguistic working memory.

Little is known about the relationship between pesticide exposure and the brain, so it's not clear why organophosphate exposure is associated with lower brain activity for some tasks and higher brain activity for others.

However, similar patterns have been observed in other conditions affecting the brain, including Type 1 diabetes, Parkinson's and Alzheimer's, said Allan L. Reiss, the Howard C. Robbins Professor of Psychiatry and Behavioral Sciences and a professor of radiology at Stanford University and co-author of the paper.

"The brain has a remarkable ability to utilize compensatory mechanisms to counteract long-term insults," Reiss said. "Higher activation may represent the recruitment and utilization of extra neural resources to address functional inefficiency related to a long-term insult, and lower activation, then, could be related to the eventual failure to recruit these resources after continued exposure or disease exhausts the brain's ability to bring compensatory responses online."

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