Kids exposed to their parents' smoking may have a higher risk of developing heart disease in adulthood than those whose parents didn't smoke, according to research in the American Heart Association journal Circulation.

We have known that second hand smoke is a risk particularly for children whose lungs are young and growing. Now a new study further reinforces that those effects can have a lasting effect on children well into adulthood, and that lasting effect is on the cardiovascular system.

In the Cardiovascular Risk in Young Finns Study, childhood exposure to parental smoking in 1980 and 1983 were tracked over years. They collected carotid ultrasound data (the main artery on either side of your neck) when they were adults in 2001 and 2007. In 2014, researchers went back to blood samples that were collected and frozen in 1980 and measured the childhood blood cotinine levels. Cotinine is a biomarker that is present in blood when you have had passive smoke exposure. The percentage of children with non-detectable cotinine levels were highest among households where neither parent smoked, decreased in households where one parent smoked and were lowest among households where both parents smoked. Then regardless of other factors, the risk of developing carotid plaque in adulthood (a marker of heart disease) was almost two times higher in children exposed to one or two parental smokers compared to children of parents who did not smoke.

Further, risk was elevated whether parents seemed to limit their children's exposure:

  • Almost two times (1.6) higher in children whose parents smoked, but seemed to limit their children's exposure.
  • Four times higher in children whose parents smoked but did not seem to limit their children's exposure.

Although it is impossible to be sure that children with a detectable blood cotinine in this study was a result of passive smoke exposure directly from their parents, it is known that a child's primary source of passive smoke exposure occurs at home rather than elsewhere.

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 second-hand smoke by not smoking inside the home, car, or smoke well away from their children.