Children who grow up near toxic waste sites are more likely to suffer from cognitive disabilities, repeat grades, score lower on tests, and misbehave in school than siblings born after the pollution has been cleaned up, new research suggests.
It's a striking sign of the long-term toll, often hard to assess, that pollution takes on children and communities, and it suggests that the economic benefits of cleaning up toxic sites may be greater than previously estimated.
Industry has flooded the environment with toxins. About 80 million Americans live within three miles of a Superfund site under the U.S. Environmental Protection Agency program intended to clean up the country’s most polluted places. The Passaic River in New Jersey has been tainted by industrial chemicals for decades. A factory on its banks in Newark made the now-banned pesticide DDT and Agent Orange, the defoliant used in the Vietnam War. The area was designated a Superfund site in 1984. In March, the EPA announced a plan to dredge 3.5 million cubic yards of toxic sediment—enough to fill more than 1,000 Olympic-size swimming pools—along eight miles of the river, at a cost of $1.38 billion.
Scientists are still trying to understand the consequences of these pervasive toxins, including how people exposed at the earliest stages of life will be affected years later. Now researchers from Northwestern University and the University of Florida have analyzed the birth records of children born in Florida from 1994 to 2002 and matched them with school performance records through 2012. They looked at families that lived within two miles of a Florida Superfund site with children conceived both before and after the site was cleaned up. Their findings, published this month as a working paper by the National Bureau of Economic Research, drew on records from almost 4,500 families.
By comparing siblings, the study minimized factors that could distort the results. For example, people who live near industrial pollution are disproportionately poor and minorities, so comparing them with people who live farther away might reflect differences in socioeconomic status rather than the effects of pollution. Siblings, by contrast, share the same household and have similar genetic influences.
“The only thing that changed the neighborhood is that the EPA cleaned up the local toxic waste site,” said co-author Claudia Persico, a doctoral candidate in human development and social policy at Northwestern.
Among families living within two miles of a Superfund site, about 26 percent of children conceived before the site was cleaned up had repeated a grade by fifth grade, compared with about 18.5 percent of their siblings conceived after the cleanup was complete. The older siblings were also more likely to misbehave at school and have lower state test scores. For families within one mile of the sites, children conceived before the cleanup were more likely to be diagnosed with cognitive disabilities than siblings born afterward1. The results suggest that the consequences of pollution for women exposed during pregnancy aren't fully evident until years after their children are born.
While pollution can affect physical health at birth, playing a role in prematurity and low birth weight, for instance, “it actually seems to have a much larger effect on cognitive outcomes,” Persico said. Pollution can hurt children's chances to do well in school even before they are born. "There’s a strong environmental justice issue at work here, in terms of how prenatal exposure to pollution disproportionately affects low-income children," who are likelier to live near toxic sites, she added.
It's difficult to draw firm conclusions from a single study. But if the findings are accurate, cleaning a typical Superfund site could pay for itself in less than 40 years, based solely on lower costs for special education for cognitive disabilities, without counting any other benefits to society, said David Figlio, director of the Institute for Policy Research at Northwestern and a co-author of the paper.
“Clean up one of these sites and you might halve the rate of cognitive disability for kids” born nearby, Figlio said.
Philip Landrigan, a pediatrician and dean for global health at the Icahn School of Medicine at Mount Sinai in New York, called it a credible study that "points in the direction” of establishing that pollution causes the observed cognitive gaps.
"We know that there are numerous industrial chemicals in use today that are toxic to the developing human nervous system,” said Landrigan, who wasn't involved in the research. “We know that vulnerability to those chemicals is greatest during the nine months of pregnancy."
The kind of industrial activity that poisoned the Passaic River and other Superfund sites has largely moved overseas, often to countries with weaker health and environmental rules than the U.S. Landrigan is co-chair of a commission trying to tally the global costs of pollution on human health.
“Even as we’ve been cleaning up industry and cleaning up hazardous waste sites in this country, big heavy polluting industries have been translocating to the Third World,” he said. “Most of the pollution today is in low- and middle-income countries.”
That leaves vulnerable populations to deal with consequences that researchers are just beginning to unravel.