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Children are especially vulnerable to the toxic effects of pesticides. For one, “their detoxification systems are more immature, so they can’t eliminate the pesticide as well,” says pesticide expert Dana Boyd Barr. (Than, 2013) This means a more powerful punch from the same amount of exposure. And because all the systems in their body are still developing, any damage created by pesticides can compound over time.

A child’s brain on pesticides: The neurological effects

Anthropologist Elizabeth Guillette studied the effects of pesticide exposure among children in the Yaqui Indian community in Mexico. She and her colleagues monitored the blood pesticide levels of two different groups of children: One in farm valleys who were exposed to large doses of pesticides, applied around 45 times per crop cycle over two crop cycles per year. Families in this area also used household bug sprays on a daily basis, increasing their exposure even further. The other subset of children came from ranching communities in the foothills, where the only pesticide exposure was from the DDT the government sprayed for malaria control.

Not surprisingly, blood tests revealed that Valley children had much higher levels of pesticide exposure both at birth and at various points throughout their childhood than did their peers from the foothills. She also ran a series of neurobehavioral tests designed to measure things like memory, intelligence, and physical/spatial skills. Children form the Valley farming communities had substantially less stamina, eye-hand coordination, large motor coordination, and less sophistication in their pictures (see the figure below) when compared to their less-exposed peers. All told, it amounted to an overall pattern of potentially permanent developmental delays and neurological impairment. (Guillette et al., 1998)

Pesticide exposure & lower IQ in children

Three separate studies released in the April 21, 2011 issue of Environmental Health Perspectives found a link between in-utero pesticide exposure and lower IQ in children. Women were first screened for exposure to organophosphate compounds such as chlorpyrifos, diazinon and malathion. These bug killers are known to cross the human placenta, and previous studies suggest they inhibit brain signaling compounds. Although such chemicals are no longer available for residential use, they continue to be legally sprayed on farm fields, which is where most of the exposure in these studies came from.

It was found that the IQ of the 20% of children with the highest exposures was an average of 7 points lower compared to the 20% with the lowest exposure. For each additional 4.6 picograms of chlorpyrifos per gram of blood in a woman during pregnancy there was a 1.4% drop in a child’s IQ and a 2.8% drop in working memory. (Raloff, 5-21-2011) Curiously enough, exposure after birth was not as strongly linked to intelligence scores, suggesting a period of special vulnerability during pregnancy. (Szabo, 4-212011) A study of agricultural communities in India turned up similar results: kids conceived during months when pesticides are applied score significantly lower on math and language tests than children conceived at other times of the year. (Winchester, 2007)

Pesticides & behavioral problems in children

Since pesticides are known to damage the brain and alter normal brain development, it’s no surprise that pesticide exposure has been linked to a number of behavioral disorders in children. One of the most consistent links is to symptoms of ADHD. A number of studies, including a recent 2011 study by the Harvard School of Public Health, have found children exposed to higher amounts of pesticides have higher rates of ADHD. (Lloyd, 6-13-2011; Szabo, 4-21-2011 )

A 5-year-study found that a number of pesticides induced more aggressive behavior in mice, even when exposed at low levels. (Porter et al., 1999) There are also links to autism. One 2007 study found that a whopping 28% of children born to women who were living near farm fields sprayed with organochlorine pesticides while pregnant were autistic, and that some children may have had a coinciding genetic vulnerability that made them more susceptible to the chemicals’ effects. (Roberts, 2007)

Health problems in children exposed to pesticides

Children also suffer an assortment of health problems due to pesticide exposures. Studies find that soldiers exposed to pesticides during the gulf war are 3-times more likely to give birth to children with birth defects than soldiers who weren’t exposed, and kids born to farmers are at greater risk for anencephaly, a birth defect in which the baby is missing part of its brain, skull, and scalp. (Shabecoff & Shabecoff, 2010, p. 57)

Another study looked at middle-class families living in California and found that those with the heaviest exposure to pesticides in their first year of life were anywhere from 4- to 10-times more likely (depending on the type of exposure) to develop persistent asthma in childhood than kids who hadn’t been exposed. Herbicides had the most severe effect, leaving kids 10-times more likely to develop asthma. (Salem et al., 2004)

Pesticides can also make kids fat. In one study, scientists measured levels of the pesticide hexachlorobenzene (a known endocrine disruptor that we’re typically exposed to through food), in the umbilical cords of more than 400 newborns. They then followed these kids for 6 more years to track their development. Those with the highest levels of the chemical at birth were twice as likely to be obese by the time they were in elementary school. (Smink et al., 2008)

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