Secondhand Smoke Affects Some Kids More
Reported December 27, 2005
(Ivanhoe Newswire) — Secondhand smoke affects all children, but a new study reveals children who possess a gene called tumor necrosis factor 308A are affected more.
Tumor necrosis factor 308A is a variant genotype that causes genetic susceptibility and increases the risk of respiratory-related illnesses caused by secondhand smoke.
As part of the California-based Child Health Study, Frank D. Gilliland, M.D., Ph.D., and colleagues from the University of Southern California in Los Angeles, analyzed DNA samples of more than 1,300 fourth grade students attending elementary school in southern California.
Genotyping showed 24 percent of the students possessed one or more copies of the variant gene, and questionnaires completed by the children’s parents revealed 20 percent were exposed to secondhand smoke at home. Of those, 6 percent lived with one or more smokers.
The study shows children exposed to secondhand smoke have a 51-percent greater risk of lower respiratory illness compared to those not exposed. Researchers, however, say 15 percent of the children involved in the study had physician-diagnosed asthma, which yields a 50-percent increased risk for illness-related school absences.
In children with at least one copy of the tumor necrosis factor variant, exposure to two or more household smokers was associated with a four-fold risk of school absence due to lower respiratory illness, when compared to children with the same variant but no exposure to secondhand smoke.
Dr. Gilliland says, “Adverse respiratory outcomes caused by secondhand smoke exposure include increased occurrence and severity of respiratory symptoms, respiratory infections, physician visits, emergency room visits, hospital admissions and transient changes in lung function.”
SOURCE: American Journal of Respiratory and Critical Care Medicine, 2005;172:1563-1568