Passive smoking may harm infants from birth

Significant levels of nicotine and carcinogenic compounds have been found in babies as young as three months, raising fears that some children are being harmed by passive cigarette smoking from birth.

The team that conducted the study of the youngest infants ever to be tested for signs of inhaling smoke said such exposure to nicotine could increase the chances of a child becoming addicted later in life. Other compounds raised the risk of the child developing smoking-related cancers, including lung, bladder, mouth, liver, kidney and pancreas.

"The take-home message is that parents should not smoke around their children, because they will suffer from the exposure," said Stephen Hecht of the University of Minnesota cancer centre.

The team measured exposure by testing urine samples from 144 children aged three months to a year in smoking families. Their mothers were aged 18 to 48 and 82% were daily smokers.

Tests showed that 98% of the babies had nicotine in their urine, with 93% testing positive for cotinine, a breakdown product produced when nicotine enters the body. The tests also revealed that 47% had significant levels of a chemical called NNAL, a cancer-causing compound produced when the body processes NNK, a chemical specific to cigarette smoke.

Babies tested positive for NNAL when family members smoked an average of 76 cigarettes a week when the child was present. The levels were typically between 1% and 5% of those found in smokers, although one child in the study had NNAL levels comparable to a smoker's.

"Persistent exposure to environmental tobacco smoke in childhood could be related to cancer later in life," said Dr Hecht, whose study appears in the journal Cancer Epidemiology Biomarkers and Prevention today. Aggressive advertising campaigns and tougher taxation were needed to encourage smokers to quit.

According to a study in the British Medical Journal last year, passive smoking may kill 30 people every day in the UK. The report added that passive smoking at home might account for 2,700 deaths among 20 to 64-year-olds each year and 8,000 among the over-65s. A child born into a home shared with smokers has a 25% greater risk of developing lung cancer.

John Britton, chairman of the tobacco advisory group at the Royal College of Physicians, said that even though the levels of carcinogens detected in the infants were low, they were still a concern.

"There are no safe levels for carcinogens - the greater your exposure, the higher your risk of developing cancer. So someone born into a home where people smoke is going to have a higher risk of developing all the cancers smokers are at risk from," he said. "Most passive smoking happens in the home and we need ways of addressing that, and the best way is to strongly encourage people to quit."