NEW YORK (Reuters) -- Researchers have established a solid biochemical link between occasional exposure to environmental tobacco smoke and decreased lung function in children.
In their report in the September issue of the American Journal of Respiratory and Critical Care Medicine, the researchers tied higher urine levels of cotinine -- a chemical formed by the body's metabolism of nicotine -- to reduced lung function in a group of healthy nonsmoking 12 to 15 year olds whose parents were also nonsmokers.
The report from Italy says exposure to "background" tobacco smoke in public places -- cafes, shops, restaurants, public transportion -- and from friends who smoke probably accounted for the adverse affects on the children's lungs.
"Our findings, although perhaps surprising, must be interpreted in the light of the very high prevalence of smoking in Italy," says study respiratory physiologist Giuseppe M. Corbo and his colleagues from Catholic University in Rome, Italy's National Institute of Health, and the University of Massachusetts in Lowell.
Corbo notes that in his entire sample of school children from which his subjects were drawn, 50% of fathers and 32% of mothers smoked tobacco.
"Furthermore, at the time of the study, smoking was permitted in most public buildings," he adds.
The population studied included children in the Lazio district of central Italy, which includes Rome. Corbo and his colleagues collected their data during a survey in 1990 and 1991.
The children studied were given standard "spirometry" tests in which they exhale forcibly into a tube. The spirometer device records the total volume of air breathed out, known as the forced vital capacity (FVC). It also records the volume of air breathed out in one second, known as the forced expiratory volume (FEV-1). Other measures include peak expiratory flow (PEF) and forced expiratory flow (FEF). These measures when figured as ratios to each other provide a picture of lung function, which is a key factor in overall respiratory health.
The ratio of FEV-1 to FVC and the ratio of PEF to FEF were lower in children with higher levels of urinary cotinine, the researchers discovered, thus indicating a "dose-response" effect -- which they say suggests cause and effect.
In their report, the authors state that the issue of environmental background exposure to tobacco smoke "has considerable public health importance, especially in countries like Italy, where cigarette smoking is still widespread and allowed in most public places."
SOURCE: American Journal of Respiratory and Critical Care Medicine (1996;154:695-700)
