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Young minds at risk from secondhand smoke

Keeping homes smokefree can greatly limit cases of neurobehavioral disorders in young children, a massive study finds.

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Children exposed to secondhand smoke at home are at least twice as likely to develop a neurobehavioral disorder as are kids in smokefree homes, a new study finds. And roughly 6 percent of U.S. children — some 4.8 million — encounter smoke at home.

Researchers at the Tobacco Free Research Institute in Dublin, Ireland, and at the Harvard School of Public Health’s Center for Global Tobacco Control in Boston mined information collected as part of the National Survey of Children’s Health. This health report card — conducted by the CDC’s National Center for Health Statistics — was compiled from telephone surveys in 2007 and 2008. Parents or guardians were asked about the health, household income, race and other family demographics of more than 55,000 U.S. children under age 12. Households were selected to yield findings that would be nationally representative.

Overall, 8.2 percent of surveyed children had learning disabilities, 5.9 percent had attention-deficit/hyperactivity disorder and 3.6 percent had been diagnosed as having other behavioral disorders (such as oppositional defiant or conduct disorders).

Although children often have more than one of these conditions, encountering secondhand smoke at home increased by 50 percent the likelihood that a child would have multiple neurobehavioral disorders, the researchers reported early online July 11 in Pediatrics. (The authors claim that theirs is the first study to link an exaggeration of this multiplicative effect with cigarette smoke.)

The new analysis attributes between 2.6 and 4.5 percent of the neurobehavioral cases reported among these children (based on the particular disorder) to secondhand-smoke exposure. If these associations indeed prove causal, the authors conclude, it will mean that “274,100 excess cases in total of these three disorders could have been prevented.”

Of course, these are not the only health risks that cigarette smoke poses to children. Other studies have linked passive smoking with respiratory problems (including asthma), sudden infant death syndrome, ear problems and low birth weight.

Some parents work hard to limit their children’s exposure to tobacco smoke. I was particularly impressed with neighbors who went cold-turkey within a month of learning they were pregnant with their first child. Even 25 years later, both remain tobacco abstainers. But these academics always had the advantage of being economically comfortable enough to afford a detached home.

Most families aren’t. And that's unfortunate because a study published last year demonstrated that even when no one in a household lights up, children living in apartments are substantially more likely to encounter secondhand tobacco smoke than are kids in detached homes. The reason: pollution from neighboring units that passes through walls and ventilation ducts. That study proved apartment-dwelling kids were exposed (because even those from nonsmoking households were excreting tobacco-breakdown products in their urine).

Pediatrician Jonathan Winickoff of the Massachusetts General Hospital for Children in Boston told me that those data constitute “really the last link in the chain of evidence demonstrating the need for smoke-free buildings — because it proves that children are absorbing that smoke.”


Z. Kabir, G.N. Connolly and H.R. Alpert. Secondhand smoke exposure and neurobehavioral disorders among children in the United States. Pediatrics, Vol. 128, August 2011 (published early online July 11). doi: 10.1542/peds.2011-0023. Abstract: [Go to]
Further Reading

J. Raloff. Apartments share tobacco smoke. Science News Online, Dec. 14, 2010. Available to subscribers: [Go to]

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