Study: CT confirms early emphysema connected to childhood smoke exposure

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Using CT scans on a non-smoking adult population, researchers have concluded that regular exposure to cigarette smoke during childhood is associated with the development of early emphysema among adults.

The study was published in the December issue of the American Journal of Epidemiology. Gina S. Lovasi, PhD, assistant professor of epidemiology at Columbia University’s Mailman School of Public Health in New York City, and colleagues studied CT scans of 1,781 non-smokers who came from Forsyth County, N.C.; northern Manhattan and the Bronx, New York City; Baltimore and Baltimore County, Maryland; St. Paul, Minnesota; Chicago, Illinois; and Los Angeles.

These participants did not have any clinical cardiovascular disease and were between the ages of 45 and 84 when recruited for the study in 2000-2002. They reported they had smoked fewer than 100 cigarettes, 20 cigars and 20 pipefulls of tobacco in their lifetimes. In addition, their urinary cotinine levels were less than 100 ng/mL at the time of the CT scan.

About half of the participants in the study had at least one smoker in their childhood home. The authors found that those with more early-life exposure to tobacco smoke (ETS) had more emphysema-like lung pixels. Those adults who lived with two or more smokers as a child had an average of 20 percent of CT scan pixels that were emphysema-like, while those who live with one smoker had 18 percent of scan pixels that were emphysema-like. This compared to just 17 percent for those who reported they did not live with a regular inside smoker as a child.

“We were able to detect a difference on CT scans between the lungs of participants who lived with a smoker as a child and those who did not,” said Lovasi.  “Some known harmful effects of tobacco smoke are short term, and this new research suggests that effects of tobacco smoke on the lungs may also persist for decades.”

Childhood ETS exposure was based on participants’ retrospective reports in response to the question: ‘‘In your childhood, did you live with a regular cigarette smoker who smoked in your home?’’ Participants also reported the number of smokers (‘‘In your childhood, how many smokers lived in your home?’’), and childhood ETS was categorized as none, one regular smoker in the home, or two or more regular smokers in the home.

The authors classified parental smoking as neither mother nor father, father only, mother only or both mother and father based on a separate item that asked whether each parent smoked.

According to Lovasi and colleagues, the exposure information in the study doesn’t provide information on the timing of ETS exposure during childhood, making it difficult to distinguish it from in utero exposure. But, said Lovasi, the “association between childhood ETS and early emphysema among participants whose mothers did not smoke, suggests that the effect we are detecting is for smoke exposure in the home during childhood rather than in utero exposure alone.”