July 13, 2011 — Secondhand smoke exposure in the home is associated with an increased risk for neurobehavioral disorders among children younger than 12 years of age, according to new research.
Zubair Kabir, MD, PhD, from the Tobacco Free Research Institute, Dublin, Ireland, and colleagues reported their findings online July 11 in Pediatrics.
"The results from this study show yet another reason not to smoke around your children," senior author Hillel Alpert, ScM, from Harvard School of Public Health, Boston, Massachusetts, told Medscape Medical News.
A whole range of childhood diseases have been associated with second-hand smoke exposure and smoking in the home, including those reported in Surgeon General reports, so a smoke-free home has major protective advantages against childhood diseases," Dr. Alpert said.
Respiratory problems, an increased risk for sudden infant death syndrome, acute respiratory infections, and more frequent and more severe asthma attacks have been reported in children exposed to secondhand smoke. Yet, write the researchers, in 2007, about 5.5 million of US children lived in households where someone smoked inside the home.
To examine common pediatric neurobehavioral disorders, including attention-deficit/hyperactivity disorder, learning disabilities, and conduct disorders, in children exposed to secondhand smoke in the home, the investigators accessed the National Survey of Children’s Health conducted between April 2007 and July 2008 and analyzed 55,358 children younger than 12 years of age.
The survey asked parents, in English, Spanish, or an Asian language, about diagnoses their children had received and about smoking practices in the household.
The study found that 6% of the children younger than 12 years were exposed to secondhand smoke in the home. "This 6% corresponds to a weighted total of 4.8 million children across the United States," Dr. Alpert commented.
Of these children, 8.2% had learning disabilities, 5.9% had attention-deficit/hyperactivity disorder, and 3.6% had behavioral and conduct disorders.
The odds of a child having 2 or more of these conditions in a household where people were smoking was 50% greater than in households where there was no smoking.
Boys had a significantly higher risk, and older children aged 9 to 11 years and those living in households with the highest poverty levels were at greater risk.
The researchers estimate that 274,000 cases of neurobehavioral disorders might have been prevented, had those households been smoke-free.
"Secondhand smoke is not the only causative factor of neurobehavioral disease in children," Dr. Alpert said. "However, our analysis was able to control statistically for a wide range of other demographic factors, including poverty, pertaining to the children as well as the parents and the type of household."
He added that it is important to highlight that these neurobehavioral disorders are very preventable. "Many of these conditions might be unnecessary if households were smoke-free."
Invited to comment on this study by Medscape Medical News, Karen Wilson, MD, MPH, from the University of Rochester Medical Center, Rochester, New York, said that it confirms what has already been seen in other studies.
"Secondhand smoke is associated with impaired cognitive abilities and neurobiological problems in children, in addition to the expected increase in respiratory diseases," Dr. Wilson, whose research focuses on secondhand smoke exposure among children, said.
"The study underscores the importance of protecting all children against any secondhand smoke exposure," she said.
Pediatrics. Published online July 11, 2011.