Smoking in the teenage years causes dramatic and lifelong DNA damage in the lungs, according to a study published in the Journal of the National Cancer Institute. In fact, young smokers could be at a permanently higher risk of developing lung cancer, even if they quit later.

Damage to the body from smoking begins right away. In this study, researchers tested for DNA alterations in the non-cancerous lung tissue of patients being treated for lung tumors. The healthy tissue was tested for the number of DNA alterations per 10 billion cells. Researchers found that former smokers who started between age 7 and 15 had an average of 164 genetic alterations. Ex-smokers who started between ages 15 and 17 had on average 115 alterations. And among former smokers who did not start smoking until after age 20, the number of DNA alterations averaged 81.

Experts say that DNA alterations in the lung tissue occur when chemicals in tobacco smoke fuse with genes in the DNA and cause mutations that can significantly increase the likelihood of cancer.

Also, the American Cancer Society reports that students who smoke are also more likely to use other drugs, get in fights, carry weapons, attempt suicide, and engage in high-risk sexual behaviors.

The better news is that fewer teens have tried cigarettes or are smoking today than a decade ago, according to the University of Michigan's annual "Monitoring the Future" study. In 2006, 25 percent of 8th graders had tried a cigarette compared to 49 percent in 1996. By 12th grade, 12.2 percent of students reported that they smoked daily - half that of a decade ago.

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External Sources National Cancer Institute University of Michigan Centers for Disease Control and Prevention

This article was reviewed and updated June 2007.