Air Date: Week of June 4, 1999
The science is in the early stages, but doctors and other health researchers are becoming increasingly concerned that a wide range of synthetic chemicals and pollutants may be linked to brain disorders, ranging from attention deficit disorder to autism. Host Steve Curwood reports from a recent conference of health experts in New York.
CURWOOD: This is Living on Earth. I'm Steve Curwood.
(Milling crowd indoors)
CURWOOD: Hundreds of scientists have gathered here at the New York Academy of Medicine in Manhattan to discuss threats to children's brain development. The conference is one of the first of its kind: a call for more research on the possible links between chemicals in the environment and many common but serious brain disorders. Attention deficit disorder, autism, and Parkinson's disease dominate the agenda, though there are also concerns about delinquency, crime, and cerebral palsy. The common denominator is a deep sense of frustration and the lack of hard data to confirm the suspicions of many participants.
MAN: You really take a hard look at what we know about this issue. And there's not a lot out there. The stakes are huge, and yet there's not a lot out there.
GOLDMAN: In commerce in the United States today, we have between 70,000 and 80,000 chemicals that have been manufactured in this country. And the extent of our ignorance about the toxic effects of these chemicals is truly appalling.
CURWOOD: Neurobehavioral disorders can range in severity from dyslexia to cerebral palsy and affect at least 3% of all Americans. While genetic components have been identified as a factor in some cases, three-quarters of these disorders are still of unknown origin. A slew of suspects were discussed at the conference, among them pesticides, polychlorinated biphenyls or PCBs, and heavy metals, including lead and manganese.
LANDRIGAN: It's hard to mount rational campaigns of prevention if you don't know what you're preventing.
CURWOOD: Dr. Philip Landrigan of the Mount Sinai School of Medicine and a sponsor of the conference, says researchers studying neurobehavioral disorders today are about where cancer researchers were in the early 1960s. At that time, there was a sense that the environment played a role in cancer, but the data weren't there. Since then, researchers have determined nearly 80% of all cancers are caused by preventable factors, such as smoking and other environmental toxins. Dr. Landrigan says the same process could be underway for neurological disorders.
LANDRIGAN: I'd be willing to bet that if we were to reconvene here in 2025, we'd be able to present a chart on the wall that would indicate that specific factors in the environment, again defined broadly, probably are responsible for two thirds or 80% of cases of mental deficit, learning disability, perhaps even autism in children.
CURWOOD: But today there is no chart. And according to Dr. Lynn Goldman, former assistant administrator of the US Environmental Protection Agency, without hard scientific evidence it will be difficult to protect the public from suspected hazards. Dr. Goldman says it reminds her of the debate in the 1970s over the health effects of lead, a debate which eventually led to the removal of lead from gasoline, but only after a fierce fight from the lead industry. She predicts the chemical industry today will be no less combative.
GOLDMAN: You know, there may be assertions by some that there are exposures, but the industry will come back and say, you know, where are the data? And the problem is that we just don't have the kind of information that is needed on the regulatory side.
CURWOOD: Lead is one pollutant that has been researched heavily. A number of studies show that even very low levels of lead are linked unequivocally to increases in developmental disorders, including a 6- to 7-fold increase in learning disabilities and high school dropout rates, as well as a doubling in delinquent behavior. The effects of removing lead from gasoline beginning in 1977 are clear: blood lead levels have decreased 95% since then. The sharp reduction in the nation's crime rate is also attributed by some to taking the lead out of gasoline. Among them, Roger Masters, retired professor at Dartmouth College. He studies statistics that link exposure to lead to violent crime and aggression, and is convinced that the connection between lower lead levels and lower crime rates is indisputable.
MASTERS: When you look at the curves, the decline is just plain extraordinary. It's a 15-year lag. That is, you have to take 15 years after the gas has no longer got lead in it, and look at those kids. Takes 15 years to grow a criminal.
CURWOOD: Dr. Masters says researchers tend to ignore these phenomena because they don't look long enough.
MASTERS: One of the problems with our social science is we have a memory span of about 15 milliseconds, not 15 years. So we don't go back and look at what is the effect 15 years later from taking the lead out of the gasoline? When we've done that, we find a very striking correlation between taking the lead out of gasoline and a reduction in the crime rate.
NEEDLEMAN: I wouldn't go so far as to say that. I don't have the evidence to say yes or no to that.
CURWOOD: Dr. Herbert Needleman of the University of Pittsburgh is one of the nation's preeminent researchers in the field of lead poisoning.
NEEDLEMAN: I think the data is pretty good that lead can cause impulsivity and aggression and attention deficit disorder and delinquency. But I wouldn't take it so far as to say it is the reason that crime is decreasing in this country. We just don't have the data to make that assertion.
CURWOOD: And that raises a critical question: what to do with suspected chemicals before there is clear and convincing evidence that they cause harm. Without definitive evidence, researchers including former EPA Assistant Administrator Dr. Lynn Goldman advocate a more cautious approach in allowing the public to be exposed to chemicals that may harm the developing brain.
GOLDMAN: The presumption is that they are safe until problems are identified, and there is a real issue with this: is that the appropriate assumption to make for chemicals to which children are exposed? I think there are some real concerns that the protections have not been strong enough in the laws for chemicals.
CURWOOD: Others add there is a strong economic argument in favor of taking the cautious approach, even though it could cut into short-term profits for chemical companies. Dr. Bernard Weiss of the University of Rochester School of Medicine coined a term, "econotoxicology," to suggest the economic implications of widespread neurobehavioral deficits as children grow up and enter the workforce.
Researchers and policy makers are beginning to take note. There's evidence that neurotoxins tend to lower intelligence by small amounts. But take a large group, and Dr. Weiss says the numbers add up.
WEISS: If you change the average IQ by 3 points, 3%, a very small amount, according to some calculations you've changed the number of males in jail by about 20%. You've changed the number of children who grow up in a home without a father by about the same amount. Public health really, in the end, is about small changes with big effects.
CURWOOD: Toward the end of the presentations the author of one unpublished study conducted in one southern county suggested that as many as 17% of children, or 1 in 6, have attention deficit hyperactivity disorder. If that is at all reflective of national trends, finding and addressing the causes could reap huge benefits. The solution, say just about all the participants here, is more research done more quickly. Said one speaker, "If these suspected chemicals were physically deforming children like the drug thalidomide did, there would be a national outcry. But because they affect intelligence and behavior and are confounded by many other factors, far too little is being done."
CURWOOD: This report was produced by Jesse Wegman.
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