Living in a Fog: Secondhand Smoke May Dull Kids' Wits

Article excerpt

Millions of U.S. children and adolescents could have deficits in reading and other skills caused by breathing secondhand smoke, researchers estimate. A new study links poor performance on several cognitive tests to tobacco-smoke exposure, even at low levels.

Past studies identified "intellectual and behavioral problems in children of parents who smoked but didn't determine the pervasiveness of exposure or the consequences of different degrees of exposure. Also, most previous research didn't separate the effects of exposure in the womb from those of breathing tobacco smoke during childhood.

To fill these gaps, Kimberly Yolton of Cincinnati Children's Hospital Medical Center and her colleagues sifted data from a large study of the U.S. kids' health.

For 4,399 nonsmoking children and adolescents between 6 and 16, the researchers compared smoke exposure and performance on four cognitive tests. The team estimated exposure from measurements of blood concentrations of cotinine, a by-product of nicotine. The cognitive tests examined math skills, visual perception of spatial relationships, recognition of printed words, and short-term memory.

In 84 percent of the subjects, at least 0.05 nanogram of cotinine was detectable per milliliter of blood. Smokers' blood generally contains more than 100 ng/ml cotinine, and 1 ng/ml is typical in children living with an adult smoker who consumes less than a pack of cigarettes per day, Yolton says. …