Secondhand smoke may be hurting kids' grades

http://www.msnbc.msn.com/id/38471348/ns/health-kids_and_parenting/

updated 7/29/2010 2:15:56 PM ET

NEW YORK — Children and teenagers exposed to secondhand smoke at home may get poorer grades than their peers from smoke-free homes, a study of Hong Kong students suggests.

Secondhand smoke is a well-known health threat to children, being linked to increased risks of asthma, as well as bronchitis, pneumonia and other respiratory infections. Studies have also found a connection between smoking during pregnancy and higher risks of childhood behavior problems and attention-deficit/hyperactivity disorder.

Some research has also found that children exposed to cigarette smoke in the womb or at home may trail their peers when it comes to cognitive abilities like reasoning and remembering. But whether secondhand smoke itself is to blame remains unclear.

In the new study, researchers found that among 23,000 11- to 20-year-old non-smoking students, the one-third who lived with at least one smoker were more likely to describe their own school performance as "poor."

Of students who said they were exposed to smoking at home at least five days a week, 23 percent said their school performance was poor compared with their classmates'. That rate was 20 percent among kids who had less frequent secondhand-smoke exposure at home, and 17 percent among those from smoke-free homes.

The researchers were able to account for certain other factors, like parents' education levels and the type of housing -- both markers of socioeconomic status. They found that students' exposure to secondhand smoke, itself, was linked to a 14 percent to 28 percent greater risk of poor school performance, depending on how frequent the exposure was.

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Still, Ho's team notes, it is biologically plausible that the many toxic compounds in tobacco smoke -- including lead, arsenic, ammonia and hydrogen cyanide -- could affect children's cognitive abilities.

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