FRIDAY, May 12, 2006 (HealthDay News) -- New parents who smoke are putting their infants in danger because secondhand smoke contains cancer-causing chemicals, a new study found.
These carcinogens were found in urine samples from nearly half of the infants of parents who smoked, the researchers said.
"There were detectable levels of a lung carcinogen that comes from cigarette smoke in the urine of these infants," said lead author Stephen S. Hecht, a professor at the University of Minnesota, and Wallin Chair of Cancer Prevention at The Cancer Center at the school.
"This indicates that parents should not smoke around their infants," Hecht said.
The findings appear in the May issue of the journal Cancer Epidemiology, Biomarkers & Prevention.
In their study, Hecht and his colleagues examined 144 infants and found detectable levels of a chemical called (methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in the urine of 47 percent of the babies exposed to secondhand smoke. NNAL is a cancer-causing compound produced in the body as it processes NNK, a carcinogenic chemical specific to tobacco.
The level of NNAL detected in the urine was higher than in most other studies of secondhand -- or "environmental" -- tobacco smoke found in children and adults, Hecht said. "You don't find NNAL in urine, except in people who are exposed to tobacco smoke, whether they are adults, children, or infants."
Hecht is concerned that these findings might indicate a real susceptibility to lung cancer among the babies once they reach adulthood.
"This begins what could turn into a lifelong pattern of exposure to secondhand smoke and to these cancer-causing agents," he said. "We don't know for sure if that is going to result in cancer in any given individual; overall, we do know that secondhand smoke is a cause of lung cancer."
Based on these findings, Hecht suspects that exposure to secondhand smoke in infancy can lead to lung cancer later in life. His advice: "Don't smoke around kids."
Dr. Michael Thun, vice president of epidemiology and surveillance research at the American Cancer Society, agreed that parents shouldn't smoke around their children, and being pregnant may be a good motivator to stop.
"This is a very solid study," he said. "It's well known that being exposed to smoke increases respiratory problems in infants and it increases middle-ear infections. And there is a suggestion of an increased risk of cancer."
Cigarette smoke contains 50 different carcinogens and more than 2,000 chemicals," Thun said. "It's not good for babies and small children."
"Pregnancy is an opportunity for both mothers and fathers to stop smoking," Thun said. "But many women relapse. Just the knowledge that you are exposing your baby to carcinogens may provide additional motivation to prevent relapse."
Thun thinks the key message for women is that, while quitting smoking is hard, "it's the best thing you can do for yourself and your baby."
For more on secondhand smoke, visit the National Cancer Institute.