Children exposed to passive smoking may incur irreversible damage to their arteries, it adds three years to the blood vessels' age.
Passive smoking thickens the child's arteries increasing the risk of heart attacks and stroke later in life. Researchers also found that if children are exposed to passive smoking from both parents in the household, an average of 3.3 years is added to the age of the child's blood vessels.
"Our study shows that exposure to passive smoke in childhood causes a direct and irreversible damage to the structure of the arteries," the lead researcher, Dr Seana Gall, a Research Fellow in cardiovascular epidemiology at Menzies Research Institute, Tasmania, said in a press statement.
This is one of the first studies that followed a child through adulthood to measures the link between exposure to passive smoking and increased carotid intima-media thickness (IMT). For the study, researchers examined 2401 participants in the Cardiovascular Risk in Young Finns Study and 1375 participants in the Childhood Determinants of Adult Health study. All participants were aged between three and 18 at the start of the study. Information on the children's parents' smoking habits was gathered. Researchers also measured the thickness of the participants' arteries once they reached adulthood.
Researchers found that children who were exposed to both parents smoking had 0.015 mm thicker carotid IMT in adulthood than children who had parents that didn't smoke. The increase in carotid IMT ranged between 0.637 mm and 0.652 mm. Other influencing factors like education, physical activities, the children's smoking habits, BMI, alcohol consumption and biological cardiovascular risk factors such as blood pressure and cholesterol levels in adulthood were also considered during the study.
"Parents, or even those thinking about becoming parents, should quit smoking. This will not only restore their own health but also protect the health of their children into the future," authors of the study said.
"While the differences in artery thickness are modest, it is important to consider that they represent the independent effect of a single measure of exposure - that is, whether or not the parents smoked at the start of the studies - some 20 years earlier in a group already at greater risk of heart disease. For example, those with both parents smoking were more likely, as adults, to be smokers or overweight than those whose parents didn't smoke."
The study didn't find any effects on children's IMT when only one parent in the house smoked. Dr Gall explained this by saying that the consequences of increased IMT thickness only in children with both parents smoking was probably because of the high dose of passive smoking the child is exposed to during childhood.
A previous study conducted found that exposure to passive smoking in childhood reduced the ability of the main artery in the arm to dilate in response to blood flow in adulthood.
"The negative health effects of passive smoking are well known, but this study goes a step further and shows it can cause potentially irreversible damage to children's arteries increasing their risk of heart problems in later life," Doireann Maddock, senior cardiac nurse at the British Heart Foundation told BBC News.
More than 5 million deaths per year in the United States are caused due to tobacco. According to the World Health Organization (WHO), one in every 10 tobacco-related deaths is due to passive smoking.
Passive smoking, also known as second-hand smoking, is a mixture of gases and fine particles including smoke from a burning cigarette, smoke that has been exhaled or breathed out by the person smoking and more than 7,000 chemicals. Of these, at least 250 are known to be harmful and more than 50 are known to cause cancer.
According to the Centers for Disease Control and Prevention (CDC), second-hand smoking is responsible for an estimated 150,000 to 300,000 new cases of bronchitis and pneumonia annually. Approximately 7,500 to 15,000 hospitalizations annually in the United States are also a consequence of passive smoking.
Health experts suggest that having a 100 percent smoke-free environment is the only way to tackle this problem. Legislation can reduce passive smoke exposure, with restriction on smoking in public places reducing hospitalizations for cardiovascular and respiratory disease. Banning smoking in cars with children should be another law, health officials should implement.
The United States, Australia and Canada have already such a law and Britain said last month that it too would be introducing a ban soon, according to a previous Reuters report.
Findings of the new study were published online in the European Heart Journal.
