There are many different types of pesticides, and all of them are bad. One particularly nasty group of pesticides are known as organophosphate compounds. These are sprayed on crops to kill bugs, and include compounds such as chlorpyrifos, diazinon and malathion.· It’s known that these chemicals do cross the placenta and can inhibit brain signaling compounds. Though their use in residential products was phased out in 2000, it remains legal to spray these compounds on farm fields, and they are widely used. The risk is biggest for those women living on or near farms, but because of runoff and tainted produce, they affect us all. For example, in 2009, a New York Times investigation found that 33 million Americans are exposed to atrazine through drinking water, and EPA data from 2010 showed contamination that exceeded the federal limit in 9 out of 10 states monitoring it. In several Midwestern districts, the contamination was anywhere from 9 to 18 times the limit. (Hayes, 2012)
In analyzing CDC data for more than 30 million live births, a paper in Acta Paediatrica in April 2009 found that there was a recurring seasonal increase in birth defects in the United States among babies conceived from April through July. This spike in birth defects seemed to be directly related to pesticide exposure. Surface-water contamination measurements taken by the U.S. Geological Survey during the same years show these are months when concentrations of agricultural chemicals, chiefly nitrate fertilizers and atrazine, peak. This correlated to a 3% higher rate of birth defects such as spina bifida, cleft lip, urogenital defects and Down syndrome among babies conceived from late spring to early summer. (Raloff, 2-27-2010)
Pesticide exposure is also linked to other birth problems. For each 1 ppb (parts per billion) increase in the levels of atrazine in drinking water (as averaged over the length of a woman’s pregnancy) there was a 15% increase in a woman’s chance of giving birth to a baby in the lowest 10% of weight for its gestational age. Such small babies have a poor chance of survival, according to another study by Hugo Ochoa-Acuna of Purdue University. Concentrations above 0.1 ppb was associated with a 17% increased risk. This study also showed the most profound effect occurred during the third trimester, when most of a baby’s growth occurs. So these pesticides seem to affect a fetus in different ways throughout the pregnancy. (ibid) Animal studies have also linked pesticides to genital and sexual abnormalities. (Male frogs exposed essentially undergo a sex change.) While the effects aren’t as profound among humans, scientists suspect it has an impact on the sexual development of human children as well.
The same toxins that disrupt the reproductive systems can also affect the pituitary gland, causing hormonal abnormalities that lead to weight gain. In 2005, a group of scientists in Spain reported that the more pesticides children were exposed to as fetuses, the greater their risk of being overweight as toddlers. Another study by a different group conducted around 3 years later found that children exposed to higher levels of PCBs and DDE (the breakdown product of the pesticide DDT) had more weight problems than their less-exposed peers. (Begley, 9-21-2009)
Organophosphate compounds have been shown to compromise brain development. Three separate studies assessed prenatal exposure (which mostly occurred through farm work) and then tracked children through age 7. It was found that for each 4.6 picograms of chlorpyrifos per gram of blood in a woman during pregnancy, there was an average drop of 1.4% in a child’s IQ and 2.8% decline in working memory. Those 20% of children with the highest prenatal exposure averaged 7 points lower in IQ than the rest of the group. (Raloff, 2011)
Another study used MRI brain imaging scans to assess the effect of chlorpyrifos exposure in the womb (as measured by serum taken from the umbilical cord). It was found that higher levels of the chemical resulted in brain changes that persisted throughout childhood. The 20 kids with the highest prenatal doses were found to have protuberances in some regions of the cerebral cortex and thinning in other regions of their brain. (Biello, 2012)
Though the Environmental Protection Agency argues that the amounts of atrazine or other chemicals found in drinking water are too low to pose any health risk, others would beg to differ. Europe has already taken the step of banning many of the pesticides widely used in the United States due to the fact that they pose a substantial health risk. Moreover, epidemiological studies have found links between prenatal atrazine exposure and things like birth defects, premature birth, and low birth weight at extremely low concentrations…well under the 0.1 ppb that the EPA has listed as “safe.” (The EPA largely used industry-funded research to come up with this number.) As biologist Tyrone B. Hayes explains, “0.1 ppb is not a low dose at all. Estrogen is active at levels that are 100 to 1,000 times lower than that. So in terms of an endocrine disruptor, that’s a high dose.” (Hayes, 2012, p. 67) Any way you put it, pregnant women will want to do their best to avoid these toxic chemicals.