Thursday, March 24, 2011

Pesticides harm kids’ ability to learn

Pesticide Action Network

Kids and pesticides just don't mix, according to scientists. The body of evidence showing children's health harms from pesticide exposure continues to grow. Case in point: current research by Dr. Warren Porter, covered by the Bay View Compass reveals how pesticide exposure in the womb harms the ability to learn. According to the Compass article, girls may be especially vulnerable.

Porter found that:

... female mice whose mothers were exposed to the pesticide chlorpyrifos during pregnancy were slow learners. Male mice from the same mothers were unaffected, possibly because they have different levels of liver-detoxifying enzymes.

The article notes that 94% of the U.S. population has measurable pesticide break–down products in our urine from the family of pesticides to which chlorpyrifos belongs. Additional data is forthcoming, though the Compass reports that Porter is hesitant to offer public preview before publishing due to his experience with attacks from the pesticide industry.

Porter's work builds on other research that links pesticides with learning and developmental disorders, such as ADHD. “I really got into the issue of children’s pesticide exposure after reading an article in 1997 that looked at student disabilities in the Madison Metropolitan School District,” Porter explained in his 2004 article, "Do Pesticides Affect Learning and Behavior?" “The data showed that the number of children in Madison [who] were emotionally disturbed increased 87 percent, children with learning disabilities increased 70 percent, and children with birth defects increased 83 percent” from 1990 to 1995.

Porter's scientific assessment is blunt:

We’re dosing our kids with neurotoxins like chlorpyrifos, and then we wonder why they’re having trouble learning and concentrating. We wonder why we have to medicate them all the time.

The Compass article also highlighted research showing the power of personal food choices as a solution. A recent study of 23 elementary-school-age children in Seattle showed:

When parents in the study fed their children an organic diet...for as little as one week, the levels of chlorpyrifos metabolites in their urine dropped more than four-fold to undetectable levels. This study demonstrated that an organic diet provides a dramatic and immediate protection against exposures to organophosphate pesticides commonly used in agricultural production.

Article source:


Children | Pesticide Action Network
Article source:

Baby reaching for bottle

When it comes to pesticides, children are among the most vulnerable. Pound for pound, they drink 2.5 times more water, eat 3-4 times more food, and breathe 2 times more air. They therefore absorb a higher concentration of pesticides than do adults.

Infants and children also face unique exposure because of how they interact with the world: they crawl on the ground, and put things in their mouths - including their hands. They also face exposure during critical windows in the womb and via breast milk.

Developing Brains & Bodies

Children drawingsSince they grow so fast, infants and young children are more susceptible to the effects of pesticide exposure than adults. Their developing brains and bodies are in the midst of complex and fragile developmental processes that regulate tissue growth and organ development - these developmental processes can be irreversibly derailed by pesticide exposure.

Drawings by preschoolers exposed to pesticides (Valley) compared to those by preschoolers not exposed (Foothills). See "Developmental Delay" below.

Research indicates that children exposed to pesticides either in utero, or during other critical periods face significant health risks including higher incidence of:

  • Birth defects
  • Childhood brain cancers
  • Autism Spectrum Disorders (ASD)
  • Attention-Deficit/Hyperactivity Disorder (AD/HD)
  • Neurodevelopmental delays
  • Endocrine dysruption

Many of the worst pesticides, known as “persistent organic pollutants,” or POPs, contaminate our water and soil for years. They move on the wind and in streams, rivers and oceans and concentrate as they move up the food chain. So, while farmer and farmworker's children bear some of the highest risks, pesticides contaminate the environment and permeate the food chain such that even kids in city cafeterias face daily exposure.

Health Effects: the State of the Science

Attention-Deficit/Hyperactivity Disorder & dietary pesticide exposure :: A May 2010 study out of Harvard shows that even tiny, allowable amounts of a common pesticide class can have dramatic effects on brain chemistry. Organophosphate pesticides (OP’s) are among the most widely used pesticides in the U.S., they work by interfering with brain signaling in insects. OPs have long been understood to be particularly toxic for children, but this is the first study to examine their effects across a representative population with average levels of exposure.

Childhood Brain Cancer :: Brain cancer is the second most common type of cancer in children, and it has been on the rise, but why it develops remains unclear. This February 2009 study finds that children who live in homes where their parents use pesticides are twice as likely to develop brain cancer versus those that live in residences in which no pesticides are used.

Developmental Delay :: A study of Yaqui Indian children in Mexico sharing similar genetic and cultural backgrounds with one significant difference - those living in one area were regularly exposed to pesticides in an agricultural community. Researchers found that an array of impaired brain and nervous system functions, including social behaviors and the ability to draw, are correlated to pesticide exposure during development.

atrazine birth defects chart
Acta Pediatrica, Vol. 98, Issue 4, 2009

Birth Defects :: This April 2009 study reports that birth defect rates in the United States are highest among women conceiving in the spring and summer, a time period correlated with increased levels of pesticides in surface water.

Autism Spectrum Disorder :: Researchers found a sixfold increase in risk factor for autism spectrum disorders (ASD) for children of women who were exposed to organocholorine pesticides, this study was one of the first to link in utero pesticide exposure to ASD.

Brain Development :: Many developmental effects are not measurable at birth, or even later in life, because brain and nervous system disturbances are expressed in terms of how an individual behaves and functions. Reviewing the literature on pesticide exposure at various points in neurological development, this article finds that current pesticide risk assessment strategies are ill-equipped to measure or protect against the many kinds of exposure faced by developing fetuses, infants and children.

Developmental Neuroxicity :: Results indicate that chlorpyrifos (CPF) affects serotonin—a neurotransmitter involved in brain development—in several ways during discrete critical gestational periods. These effects are likely to contribute to the noncholinergic component of CPF's developmental neurotoxicity.

Developmental Neurotoxicity :: Fetal and childhood exposures to widely used organophosphate pesticides, especially chlorpyrifos (CPF), have raised concerns about developmental neurotoxicity. This study finds a wide window of vulnerability of cholinergic systems to CPF, extending from prenatal through postnatal periods, occurring independently of adverse effects on general cellular neurotoxicity.

Developmental Effects Beyond Neurotoxicity: Immediate & Delayed-Onset Effects on Heart & Liver Function :: The fetal and neonatal neurotoxicity of chlorpyrifos (CPF) and related insecticides is a major concern. Developmental effects of CPF involve mechanisms over and above cholinesterase inhibition, notably events in cell signaling that are shared by nonneural targets. This study finds that the developmental toxicity of CPF extends beyond the nervous system, to include cell signaling cascades that are vital to heart and liver functioning.

Low Birth Weight :: Pregnant women in upper Manhattan who were heavily exposed to two common insecticides had smaller babies than their neighbors. Recent restrictions on the two substances quickly lowered exposure and increased babies' size.

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