Children who are exposed to secondhand smoke are more likely to develop behavior and learning problems, a new study shows. Researchers at the Harvard School of Public Health and the Tobacco Free Research Institute in Dublin have found that exposure to secondhand smoke places children at an increased risk of developing certain mental and behavioral disorders such as learning disabilities and attention deficit hyperactivity disorder (ADHD), as well as behavior problems. Previous studies have provided enough evidence suggesting that exposure to the toxins found in cigarette smoke such as nicotine increases the children's risk of experiencing health conditions such as ear infection, high blood pressure, asthma, and other lung disease and infections. However, the analysis of more than 55,000 US children aged less than 12 showed that passive smoker kids are 50 percent more prone to one or more multiple neurobehavioral problems. According to the results, one in every five kids living with smoking parents or 20.4 percent of them are diagnosed with at least one neurobehavioral condition while the rate is as low as one in every 12 or 8.6 percent in children who were not exposed to smoke, said a report published in the journal Pediatrics. "[The findings] underscore the health burden of childhood neurobehavioral disorders that may be attributable to secondhand smoke exposure in homes in the States,” researchers wrote."This is particularly significant with regard to the potential burden of pediatric mental health care on an overextended health care system, a problem that could be dramatically reduced if voluntary smoke-free home policies were widely adopted," they added."We estimate that 274,000 cases of the most common neurobehavioral disorders could have been prevented with smoke-free homes," said lead author Hillel Alpert. Figures show that only in the US about 4.8 million of the children younger than 12 live with a smoker.