While genetics is known to play a role in neurological problems, only 30 to 40 percent of neurodevelopmental disorders can be definitively tied to family history. "There are a lot of chemicals out there that have been shown to have the capability to injure the developing brain," says study coauthor Philip Landrigan, MD, professor and chair of the department of community and preventive medicine at Mount Sinai School of Medicine in New York City and one of the world's foremost authorities on children's environmental health. "And we're very concerned that a number of chemicals in everyday products have never been properly tested to determine whether they're toxic to the human brain."
In the new report, Dr. Landrigan and his coauthor identified six chemicals that have been discovered, within the past seven years, to trigger brain damage in children. In 2006, he and other researchers ID'd lead, methylmercury, arsenic, polychlorinated biphenyls (PCBs), and toluene as known contributors to rising rates of neurodevelopmental disorders like autism, attention-deficit hyperactivity disorder, and learning disabilities.
Find out more about Dr. Landrigan's 10 Suspect Causes of Autism & Learning Disorders
Now, he's fingering six more. Manganese, generally a problem for people living near mining operations, and the now-banned pesticide dichlorodiphenyltrichloroethane (DDT) are primarily problematic only in developing countries, as is fluoride. "It's not a question that low levels of fluoride are beneficial in terms of preventing cavities and enhancing bone growth," says Dr. Landrigan, referring to the levels found in fluoridated drinking water. "But when a child is exposed to high levels, there's risk of injury to the developing brain." Another industrial solvent, tetrachloroethylene, which is a problem in some U.S. drinking water supplies, is also now known to disrupt neurological function.
PBDEs and Pesticides Putting U.S. Children at Risk
In the U.S., though, he says that the two most important newly added chemicals to watch out for are polybrominated diphenyl ethers (PBDEs), flame retardants added to plastics, cars, and some types of furniture, and pesticides. PBDEs have long been linked to thyroid problems and learning disabilities, and Dr. Landrigan says they're structurally similar to now-banned PCBs.
Thankfully, levels of PBDEs in pregnant women are expected to drop, since California recently overturned its law requiring all furniture to be chemically treated to resist flames. The law was a de facto national standard given the size of California, so most furniture manufacturers have used PBDEs in furniture foam. "When you compare California to the rest of the U.S., the levels of PBDEs in Californians were several times higher and that's all because of this law that had been pushed through requiring very high levels of brominated flame retardants," he says. "Women were exposed day in and day out in their homes."
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Pesticides like DDT have long been banned, and many pesticides in the same class, organochlorines, are heavily restricted. Also, though related pesticides, organophosphates, are eliminated from the body much more quickly, emerging evidence suggests that moms exposed to them have babies with a smaller head circumference, an indicator of slow brain growth, and children with neurological problems at age 7.
Dr. Landrigan says he's concerned about phthalates and bisphenol A, as well, two chemicals that are ubiquitous in both consumer products—plastics and synthetic fragrances, for instance—and people. The body of evidence for these two chemicals isn't as strong as the other six he studied, but Dr. Landrigan says, "Evidence is rapidly accumulating that those chemicals are toxic to the developing brain."
Toxic Chemicals Cause Lifelong Damage
Neurological damage isn't immediately apparent, Dr. Landrigan writes in the study, so chemicals that cause such problems aren't scrutinized nearly as heavily as chemicals that cause visible birth defects. But the costs of the damage are huge. These chemicals can lower IQ by 10 points or less, and one study calculated that each one-point drop in IQ results in a loss of average lifetime earnings of $18,000. The costs associated with lead and mercury poisoning add up to $50 billion and $5 billion, respectively, every year.
The problems don't stop when puberty begins, either. Neurological problems in childhood have been associated with criminal behavior, substance abuse, and antisocial behavior in teenagers and adults. And Dr. Landrigan says that researchers are looking into whether early life exposure to these chemicals may play a role in the development of Alzheimer's disease and Parkinson's later in life.
"Chemicals destined to go into pharmaceuticals—which are often made by the same companies—are exhaustively tested. While there are mistakes, by and large, the ingredients are very carefully tested until their safety has been well established," Dr. Landrigan says. "Then there's post-market surveillance to track adverse effects in everyday life. By contrast, there's nothing comparable in place for consumer chemicals. They're simply put into products with a brief notice to the EPA."
Better testing of chemicals that would avoid the dire neurological damage caused by these compounds could lead to major social benefits, as well. Lead exposure, for instance, is significantly associated with violent crime rates. The authors write that every $1 invested in reducing lead hazards leads to between $17 and $220 savings in healthcare costs and costs associated with criminal behavior and special education services.
What You Can Do
"My best advice to pregnant women is that they exercise prudent avoidance of these compounds during pregnancy," says Dr. Landrigan. That means:
• Test your home for lead paint. "We still have a lead-paint problem here, and there are still tens of thousands of apartments and homes that contain lead paint," he says. Visit epa.gov/lead for tips and advice on how to properly test for, and safely remove, lead paint BEFORE you renovate a new nursery.
• Eat organic. It's the only sure-fire way to keep pesticides out of your diet.
• Eat safe seafood. "Eating fish is important in pregnancy. It really is brain food," he says. The problem is, eating just any fish could expose you to high levels of mercury and PCBs—"the two chemicals tend to go hand in hand," Dr. Landrigan notes—without giving you any beneficial omega-3s. Check out The Worst Seafood Advice You're Getting to find the safest and healthiest fish.
• Be an activist. "The other thing that parents have to do is remember that they're citizens," Dr. Landrigan adds. "They have to start writing to members of Congress and say that it's high time that this country stop letting untested chemicals get into our food supply, into cosmetics, into products." Congress is in the midst of debating a new law that would drastically reform our chemical regulation policies, and you can follow that debate—and write letters in support of it—at Safer Chemicals, Healthy Families.