Children of smokers may be up to four times more likely to develop heart disease later in life . And the dangers still exist even if smokers try and limit their child 's exposure to secondhand smoke , researchers warn . Therefore , the only way to protect children is to not smoke at all , they say . The findings confirm previous research that linked tobacco smoke and toxins with a lasting effect on children 's cardiovascular health . The new research confirms tobacco smoke and toxins have a lasting effect on children 's heart health . Finnish children were measured for their exposure to passive smoking and whether their carotid arteries - the blood vessels that carry oxygen-rich blood to the head , brain and face - had become narrowed or blocked due to plaque build-up in adulthood . Plaque buildup is made up of fatty deposits and other cells that can build up in the walls of the arteries over time , making them thicker ( and therefore harder for blood to flow ) As plaque continues to build , it can actually narrow or begin to clog arteries . This slow plaque buildup in arteries over time is a progressive disease called atherosclerosis . The study involved children whose blood samples were taken in in 1980 and 1983 as part in the Cardiovascular Risk in Young Finns Study . In 2001 and 2007 , ultrasound readings of their carotid arteries were taken . Then in 2014 , Finnish researchers measured the participant 's childhood blood cotinine levels from samples collected and frozen in 1980 . Cotinine is a biomarker of passive smoke exposure . The researchers found that 84 per cent of children from households where neither parent smoked had non-detectable cotinine levels in their samples . However , only 62 per cent of children from households where one parent smoked and 43 per cent of children from households where both parents smoked had blood samples with non-detectable cotinine levels . The dangers still exist even if smokers try and limit their child 's exposure to secondhand smoke , the researchers warn . Therefore , the only way to protect children is to not smoke at all . The risk of developing carotid plaque in adulthood was almost two times ( 1.7 ) higher in children who had one or both parents who smoked , compared to children of non-smoking parents . And the risk was elevated even if parents tried to limit their children 's exposure , warned the study , published in the journal Circulation . Children whose parents smoked but did n't limit exposure had almost twice the risk - and those fiull exposed had four times the risk , the study found . Study author Dr Costan Magnussen , of the University of Turku , said : 'Although we can not confirm that children with a detectable blood cotinine in our study was a result of passive smoke exposure directly from their parents , we know that a child 's primary source of passive smoke exposure occurs at home . 'For parents who are trying to quit smoking , they may be able to reduce some of the potential long-term risk for their children by actively reducing their children 's exposure to secondhand smoke , by not smoking inside the home , car , or smoke well away from their children . 'However not smoking at all is by far the safest option ' . Repeated exposure of children to secondhand smoke is child abuse , a leading doctor has warned . Adam Goldstein , a professor in family medicine , says exposure is as abusive as leaving children unattended in hot car , or drink driving . He claims he was forced to speak out after caring for 'too many children hospitalised with asthma and pneumonia , caused in large part to their repeated exposure to secondhand smoke ' . Dr Goldsteimn argues that purposefully and repeatedly exposing children to a something known to cause cancer in humans would strike many people as child abuse . His controversial opinion piece has been published in the latest issue of the Annals of Family Medicine . In it , he argues that purposefully and repeatedly exposing children to a something known to cause cancer in humans would strike many people as child abuse . 'But what if the substance is secondhand smoke ? , ' he asks . Dr Goldstein , who is director of the tobacco intervention programs in the University of North Carolina School of Medicine , says the damage from smoke is 'as abusive as many other commonly accepted physical and emotional traumas of children ' . His comments come after years of caring for children who have suffered severe respiratory illness due to secondhand smoke exposure . In the opinion piece , he writes : 'Scientific research over the last decade has increasingly demonstrated that exposure to secondhand smoke is not simply a nuisance ; it is deadly . 'Secondhand smoke exposure causes multiple diseases in children , including asthma and pneumonia , and results in thousands of avoidable hospitalisations . 'It is a major cause of sudden infant death syndrome and may cause lung cancer and heart attacks with repeated exposure . He argues that purposefully and repeatedly exposing children to a something known to cause cancer in humans would strike many people as child abuse . 'No safe level of exposure exists . ' [ Therefore ] , purposefully and recurrently exposing children to secondhand smoke - a known human carcinogen - despite repeated warnings , is child abuse . '
The dangers still exist even if smokers try and limit their child 's exposure . The only way to protect children is not to smoke at all , say Finnish experts . Study confirms tobacco toxins can permanently damage child health . Comes as doctor said passive smoking should be classed as 'child abuse '