First author Kelly Brunst, a doctoral candidate in the University of Cincinnati's division of epidemiology and biostatistics, said differential gender effects of secondhand smoke exposure was detected using an internal biomarker for secondhand smoke -- hair cotinine, a product of nicotine metabolism.
The study, published online ahead of print edition of the journal Pediatric Allergy and Immunology, found children exposed to high levels of secondhand smoke who also had allergic sensitizations during early childhood (age 2) were at greater risk for decreased lung function at age 7, compared to children who had not developed allergic sensitizations by this age.
Lung function among girls was six times worse than in boys who were exposed to similar levels of both secondhand smoke and allergen sensitization, the study said.
"Our study shows that the timing of allergic sensitization is crucial because children who are sensitized by age 2 are more likely to suffer the greatest lung deficits during childhood as a result of secondhand smoke exposure, Brunst said in a statement. "This association was not observed at age 4 or 7, emphasizing the importance of this critical window for lung development."