Environmental toxins and autism
Do you ever microwave food while it’s in a plastic container? Do you have the idea that it is safe to do that? Read Nicholas Kristof’s column in the NY Times:
Autism was first identified in 1943 in an obscure medical journal. Since then it has become a frighteningly common affliction, with the Centers for Disease Control reporting recently that autism disorders now affect almost 1 percent of children.
Over recent decades, other development disorders also appear to have proliferated, along with certain cancers in children and adults. Why? No one knows for certain. And despite their financial and human cost, they presumably won’t be discussed much at Thursday’s White House summit on health care.
Yet they constitute a huge national health burden, and suspicions are growing that one culprit may be chemicals in the environment. An article in a forthcoming issue of a peer-reviewed medical journal, Current Opinion in Pediatrics, just posted online, makes this explicit.
The article cites “historically important, proof-of-concept studies that specifically link autism to environmental exposures experienced prenatally.” It adds that the “likelihood is high” that many chemicals “have potential to cause injury to the developing brain and to produce neurodevelopmental disorders.”
The author is not a granola-munching crank but Dr. Philip J. Landrigan, professor of pediatrics at the Mount Sinai School of Medicine in New York and chairman of the school’s department of preventive medicine. While his article is full of cautionary language, Dr. Landrigan told me that he is increasingly confident that autism and other ailments are, in part, the result of the impact of environmental chemicals on the brain as it is being formed.
“The crux of this is brain development,” he said. “If babies are exposed in the womb or shortly after birth to chemicals that interfere with brain development, the consequences last a lifetime.”
Concern about toxins in the environment used to be a fringe view. But alarm has moved into the medical mainstream. Toxicologists, endocrinologists and oncologists seem to be the most concerned.
One uncertainty is to what extent the reported increases in autism simply reflect a more common diagnosis of what might previously have been called mental retardation. There are genetic components to autism (identical twins are more likely to share autism than fraternal twins), but genetics explains only about one-quarter of autism cases.
Suspicions of toxins arise partly because studies have found that disproportionate shares of children develop autism after they are exposed in the womb to medications such as thalidomide (a sedative), misoprostol (ulcer medicine) and valproic acid (anticonvulsant). Of children born to women who took valproic acid early in pregnancy, 11 percent were autistic. In each case, fetuses seem most vulnerable to these drugs in the first trimester of pregnancy, sometimes just a few weeks after conception.
So as we try to improve our health care, it’s also prudent to curb the risks from the chemicals that envelop us…
