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Tuesday, August 14, 2012

In-Utero Pesticide Exposures Linked to Brain Abnormalities

From www.BeyondPesticides.org Daily News Blog

Source: San Francisco Chronicle
May 2, 2012

New research published online in the Proceedings of the National Academy of Sciences reports that babies exposed in the womb to a commonly used insecticide have brain abnormalities after birth. The insecticide, chlorpyrifos (used in agriculture, mosquito control, and golf course management) , is well documented as inducing neurodevelopmental abnormalities in infants exposed in their mother’s womb, including ADHD, cognitive deficits, and serious learning, behavioral or emotional disorders.

Entitled, “Brain anomalies in children exposed prenatally to a common organophosphate pesticide,” the study investigated associations between chlorpyrifos exposure and brain morphology using magnetic resonance imaging in 40 New York City children. It found significant associations of prenatal exposure, at standard use levels, with structural changes in the developing human brain, including enlargement of superior temporal, posterior middle temporal, and enlarged superior frontal gyrus, gyrus rectus, cuneus, and precuneus along the mesial wall of the right hemisphere. These areas of the brain impacted are related to attention, language, reward systems, emotions and control may be affected by the chemical.

Twenty high-exposure children (upper third of chlorpyrifos concentrations in umbilical cord blood) were compared with 20 low-exposure children. The children, ages 6-11 years, considered to have a high exposure to the chemical, have levels that are much lower than doses shown to cause no effect in laboratory animals. The study also shows that high-exposure children did not have expected sex differences in their brains, which may reflect future impacts on their hormones and behavior.

The study is the first to use imaging scans to show that prenatal exposure to the chemical is linked to structural changes in the brain five to 10 years after exposure, said Virginia Rauh, Ph.D., the lead author. While the chemical’s use was banned in residential areas 12 years ago, many women are exposed to moderate levels in agricultural settings and through food residue. Dr. Rauh believes studies are needed to look at what effect the chemical has on the children as they grow.

“Prenatal exposure to chlorpyrifos is risky for pregnant women and should be avoided,” said Dr. Rauh, a professor of clinical population and family health at Columbia University in New York. “Mother breathes or ingests the chlorpyrifos, which then enters her blood stream. The chemical crosses the placenta and enters the infants’ blood stream.”

Chlorpyrifos is an organophosphate insecticide that has been linked to a host of neurodevelopmental problems, especially in children. This is important to study since roughly one in six children in the U.S. has one or more developmental disabilities, ranging from a learning disability to a serious behavioral or emotional disorder. Emerging science demonstrate that the amount of toxic chemicals in the environment that causes developmental and neurological damage and contributes to the rise of physical and mental effects being found in children.

Organophosphates, like chlorpyrifos, are extremely toxic to the nervous system. They are cholinesterase inhibitors and bind irreversibly to the active site of an enzyme essential for normal nerve impulse transmission –acetylcholine esterase (AchE)– inactivating the enzyme. High concentrations of organophosphates have been found in the bodies of pregnant women and children.

Previous studies have shown that exposure to some organophosphate compounds cause hyperactivity and cognitive deficits in animals. A study published in Pediatrics found that exposure to organophosphates in developing children might have effects on neural systems and could contribute to ADHD behaviors, such as inattention, hyperactivity, and impulsivity. Researchers discovered that for children with a 10-fold increase in the concentration of the most common phosphate metabolites measured in their urine, the odds of ADHD increases by more than half compared to those without detectable levels. A recent study found that exposure of pregnant women to organophosphate pesticides may affect both length of pregnancy and birth weight. Women with higher levels of organophosphates were found to have pregnancies that were 3 to 4 days shorter and babies that were about ⅓ pound lighter on average than women with lower levels of pesticides.

Chlorpyrifos, like many organophosphates, have had their household uses cancelled because of the extreme health risks to children. However, agricultural uses remain on the market. In 2010 Beyond Pesticides and over 13,000 other organizations sent a letter to the EPA, calling for a ban on chlorpyrifos and a phase out of other organophosphate (OP) pesticides. Chlorpyrifos was phased out for residential use under a 2000 agreement between EPA and Dow Agrosciences but continues to expose farmworkers and consumers through its use in agriculture.

EPA’s decision in 2000 and subsequent action removed chlorpyrifos’ residential uses but retains all agricultural uses except tomatoes (allowable residues on apples and grapes were adjusted), golf course and public health mosquito spraying. The agency argued at the time of its decision that it had adequately mitigated risks through the removal of high exposure uses to children in the residential setting, but ignored the special risks to farmworkers’ children, as well as the availability of alternative agricultural practices and products that made chlorpyrifos unnecessary and therefore its risks unreasonable.

In order to reduce exposure to these chemicals, Beyond Pesticides recommends that expectant mothers choose organic foods. Families should also stop using pesticides in and around the home and to be vigilant about the cosmetic ingredients they use. For more information on what you can do, see Beyond Pesticides’ materials for new parents with tips on food choices and safer pest management, specifically designed for new moms and dads.


To see more scientific research on the effects of pesticides on human health, including neurodevelopmental abnormalities, see our Pesticide-Induced Diseases Database.

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