Urine samples of children who lived with smokers showed high levels of tobacco-related carcinogens, according to a recent study.
The analysis also found that the average level of tobacco metabolites in the children was about 8 percent of the level found in smokers.
"This finding is striking, because while all of the researchers involved in the study expected some level of exposure to carcinogens, the average levels were higher than what we anticipated," said lead researcher Janet L. Thomas, an assistant professor of behavioural medicine at the University of Minnesota.
She said that levels of carcinogens found in the urine of adult non-smokers exposed to second-hand smoke are about 1 to 5 percent that of smokers.
"No one knows the long-term impact of cumulative exposure to these chemicals. It could prime the body in some way that leads to DNA changes in cells that might contribute to lung damage, and potentially lung cancer," said Thomas.
The researchers also found a direct correlation between the numbers of cigarettes smoked by one or more adults in a house each day and tobacco metabolites in the children who lived there.
There was also an association between childhood exposure to second-hand smoke and lower socio-economic status, employment and parental education.
She said they conducted the study with the hope that the parents might be open to banning smoking inside the home.
The researchers took urine samples from 79 children aged one month to 10 years who lived in a home where at least one parent smoked.
"We need to act now to ensure that all parents have the facts they need to make informed decisions to protect their families from this completely preventable health hazard," Thomas said.
The team presented the results at the Ninth AACR Frontiers in Cancer Prevention Research Conference.