Writing in the Dec. 15 issue of the American Journal of Respiratory Critical Care Medicine, the scientists report that children who have a variation in a key gene and who live in a home with smokers are four times more likely to miss school days because of lower-respiratory illness than children who are free from the variation and live in smoke-free homes.
The study points to a clear public health message, says Frank D. Gilliland, M.D., Ph.D., professor of preventive medicine at the Keck School of Medicine and senior author of the study. "Parents or others who choose to smoke around children are causing illness and school absences, potentially affecting how well the children do in school."
In the study, researchers examined the gene called tumor necrosis factor (TNF) alpha. This gene is linked to the body's inflammatory response to chemicals such as those found in second-hand smoke. About 24 percent of the children had a variation in at least one of their two copies of the TNF-alpha gene.
The team based the paper on data from the Children's Health Study, a long-term project monitoring air pollution and children's lung health in a dozen Southern California communities. For this segment of the study, researchers focused on school absences among 1,351 fourth-graders at 27 elementary schools in 1996.
They collected a variety of information about the children, from their history of asthma, if any, to their exposure to smoking and allergens. They also collected school absence reports and took DNA samples from the children.
The group found that 20 percent of children lived with second-hand smoke, and nearly 6 percent of children lived with two or more
Contact: Kathleen O'Neil
University of Southern California