Secondhand Smoke Poses Risk to Children's Health

By Stephen Hecht, Ph.D.
(January 5, 2007)

Close contact with a loving parent helps an infant thrive, but when this contact exposes the baby to secondhand smoke, it’s a mixed blessing.

Children exposed to secondhand tobacco smoke experience health problems that occur less frequently in children not exposed to secondhand smoke.  When exposed to secondhand smoke:

• Children with asthma have more frequent and more serious attacks.
• Children get more respiratory infections, such as bronchitis and pneumonia.
• School-age children cough more, wheeze more, and feel breathless more often.
• Children are more likely to get ear infections and to need an operation to insert ear tubes.
• Babies are more likely to die from sudden infant death syndrome (SIDS).

Tobacco smoke can begin harming children even before they are born. Mothers who smoke or who are exposed to secondhand smoke while pregnant are more likely to have low birthweight babies.  (Low birthweight babies weigh less than 5 pounds, 8 ounces and are at increased risk for many health problems.) Also, babies with mothers who smoked during the pregnancy are at increased risk for dying of SIDS.

Both the smoke from a cigarette and the smoke exhaled by the smoker are considered secondhand smoke. This smoke contains over 250 chemicals that are toxic or known to cause cancer, including hydrogen cyanide, carbon monoxide, arsenic, and lead.

The best thing parents can do to protect their children from secondhand smoke is to not smoke. Parents who smoke should do it away from their children, not in shared spaces such as the home or car. It is not sufficient to open a window, sit in a separate room, or use ventilation, air conditioning or air purifiers; family members are still being exposed.  

At the University of Minnesota Cancer Center, we tested the children of parents who smoke in their homes or cars and found detectable levels of the cancer-causing chemical known as NNAL in the urine of 47 percent of the infants exposed to cigarette smoking.  In this study, infants with detectable levels of NNAL in their urine lived with family members that reported smoking an average of 76 cigarettes per week in their home or car while the infants were present.  NNAL is a chemical produced in the human body as it metabolizes NNK, a cancer-causing chemical specific to tobacco.  NNAL is found only in the urine of people exposed to tobacco smoke.

The babies in the study, all under a year old, showed higher concentrations of NNAL in their urine than older children or adults exposed to secondhand smoke in earlier studies. Why was it higher in the babies?  They spend more time close to their parents than older children. If the parent is smoking, the infant is inhaling the smoke.

The good news is that when children stop breathing secondhand smoke, the short-term health problems it causes begin to lessen. Parents can protect their children by not smoking themselves and by:

• Asking people not to smoke around their children.
• Choosing daycare centers, schools, restaurants, and businesses that are smoke-free.
• Teaching children to stay away from secondhand smoke.
• Avoiding secondhand smoke, especially during pregnancy.

For those who want to quit smoking, assistance and support is available by calling the Minnesota Quit Plan at 1-888-354-PLAN.

Stephen Hecht, Ph.D., holds the Wallin Chair in Cancer Prevention at the University of Minnesota Cancer Center and is a professor in the Department of Laboratory Medicine and Pathology.

Health Talk & You is an educational service of the University of Minnesota. Advice presented should not take the place of an examination by a health-care professional. For more health-related information, go to http://www.healthtalk.umn.edu/.  For comments or questions about Health Talk & You e-mail lafor016@umn.edu.