When my husband and I set out to find a nursery school for our daughter, Faith, nearly 10 years ago, we took the decision seriously. I looked at large parent-run cooperatives and small home-based operations. Jeff visited the Montessori school on the hill and the Waldorf school in the valley. In the end, we chose a nursery school close to home with a frog pond out front, a play structure out back, and trees full of chickadees and nuthatches. We had weighed many considerations, and we all, Faith included, were happy.
That is, until I discovered that the school’s beloved play structure—with its wooden gangway, turrets, and tunnels—was made out of pressure-treated lumber, which, at the time, contained arsenic, a carcinogen. A bladder carcinogen, in fact. I am a bladder cancer survivor and am familiar with all the ongoing medical surveillance this disease requires. So, after a lot of research and discussion, we moved our daughter to a different nursery school. The risk of doing nothing just seemed too high.
Seven years later, the Environmental Protection Agency (EPA) released its final risk assessment for wood impregnated with chromated copper arsenate. The conclusion: Children who play frequently on pressure-treated play sets and decks experience elevated cancer risks. And yet, because the EPA stopped short of recalling preexisting structures when it outlawed arsenic-treated lumber for residential use in 2004, the play set at our old nursery school still stands.
Arsenic, as it turns out, is not only a carcinogen but a developmental neurotoxicant as well—one of a family of substances that impair the growth of the brain in ways that interfere with learning. They take many forms, according to a major review published in 2006 in the British medical journal The Lancet. Some of them are heavy metals, such as lead and methylmercury. Some are long-outlawed compounds that still linger among us (PCBs). One common one is used to strip paint, extract natural gas from shale, and suspend pigment in some nail polishes (toluene). Another 200 chemicals are known to act as neurological poisons in human adults and are likely toxic to the developing brains of infants and children, too—but scientific confirmation awaits.
Current laws do not require the systematic screening of chemicals for their ability to cause brain damage or alter brain growth, and only about 20 percent of the 3,000 chemicals produced in high volume in the United States have been tested for developmental toxicity of any kind. The Lancet paper concludes: “The combined evidence suggests that neurodevelopmental disorders caused by industrial chemicals have created a silent pandemic in modern society.”
In the basket of problems labeled neurodevelopmental disorders are a variety of cognitive and psychomotor disabilities. Mental retardation is one. Attention deficit disorder, with or without hyperactivity, is another. A third is learning disabilities, variously characterized by significant difficulties in listening, speaking, writing, memorizing, reading, or calculating. Within the life-altering category of pervasive developmental disorders is autism.
By pandemic, the Lancet study authors mean that developmental disorders are common, cut across all walks of life in all geographic regions, and are ballooning in prevalence. The estimate most often cited by medical literature is that these disabilities—most of the nervous system—now affect about one in every six U.S. children. If this figure is accurate, it means that the number of children with neurodevelopmental disorders now exceeds the number of children with asthma.
By silent, the authors mean that these disorders are subclinical. They don’t announce themselves on an X-ray or in a pathology lab. There is no medical test to herald their increasingly familiar presence among us.
Child neurodevelopmental disorders do, however, leave economic tracks behind. At $77.3 billion per school year, special education and education for disabled students, according to the most recent accounting, consume 19 percent of U.S. school spending.
Four big lessons arise from the frontiers of pediatric neurotoxicology. The first is that the developing brain is more vulnerable than the adult brain, and the timing of exposure can determine whether and how severe the damage might be. PCBs, for example, are linked to memory loss. Specifically, they interfere with recall ability and long-term memory, in part by disrupting the activity of thyroid hormones that, during development, direct neurons to their proper places within the brain. The first cells to arrive help direct the later ones. Thus, for PCBs, the earlier the chemically induced disruption, the more aberrant the final architecture in the memory centers of the brain.
The second lesson is that neurotoxicants can act in concert with each other. Prenatal exposure to lead contributes to the risk of attention deficit hyperactivity disorder (ADHD), as does exposure to tobacco smoke. Both together, however, create a higher risk than either one alone. These findings indicate that neurotoxicants need to be regulated as a group rather than one by one.
The third is that elements of a child’s social and nutritional environment can also be toxic to the development of cognition and can magnify the effects of exposure to chemical toxicants. Poverty and family stress are particularly detrimental. Attention deficit disorder is more prevalent among poor children, as are learning disabilities. Children living within dysfunctional families are also at increased risk for a learning disability.
And fourth is that the chemicals designed to act as neurological poisons—the organophosphate pesticides—truly do so. Frequently used in fruit and vegetable farming, organophosphate insecticides kill by attacking the nervous systems of insect pests. They have the same effect in humans, interfering with the messaging signals that flow between neurons. Mounting evidence collected among various populations of children—from Harlem neighborhoods to the fields of California’s Central Valley—all suggest that organophosphate exposure affects cognition. One large study found that children with above-average levels of pesticides in their urine were twice as likely to have ADHD.
In addition to these chemicals, exposure to air pollution also harms children’s cognitive development. Specifically, it reduces intelligence. Thus, the combustion of fossil fuels not only creates a climate problem, it also renders our children less able to solve it. Polycyclic aromatic hydrocarbons (PAHs)—the sooty chemicals released from tailpipes and power plants—are the leading culprit.
Coal extinguishes intelligence by a second route: through its release of mercury into the atmosphere, which then finds its way into the brain cells of children through the medium of fish. From the earth to the air to the water to the dinner table. And so into blood and neurons.
As parents, we can only do so much to protect our children from the brain-disrupting chemicals that lurk in every part of Earth’s dynamic systems—its water cycles, air currents, and food chains. My children, Faith and Elijah, spend their days in a school full of equipment and furniture that no doubt contain brominated flame retardants. They ride home on a diesel-powered bus. They fly around town on bicycles, passing by pesticide-treated lawns as they go. And when we lie together in the dark at the end of the day, I sometimes wonder how their brain architecture might have been—might still be—irreversibly altered, even if only slightly.
So don’t give me any more shopping tips or lists of products to avoid. Don’t put neurotoxicants in my furniture and my food and then instruct me to keep my children from breathing or eating them. Instead, give me federal regulations that assess chemicals for their ability to alter brain development and function before they are allowed in the marketplace. Give me an agricultural system that doesn’t impair our children’s learning abilities or their futures. Give me an energy policy based on wind and sun.
Because I can do the research associated with making the right school choice for my children. I can help them with multiplication tables and subject-verb agreement. I can pack healthy lunches. But I can’t place myself between their bodies and the 200-plus identified neurotoxicants that circulate freely through the environment we all inhabit.
Adapted from the book Raising Elijah: Protecting Our Children in an Age of Environmental Crisis by Sandra Steingraber. Reprinted by arrangement with Da Capo Press and brought to our attention by Orion (March-April 2011), an award-winning bimonthly magazine connecting people and nature.www.orionmagazine.org