Smokers have yet another reason to ditch the habit as a new study finds a link between tobacco use and HPV-16, a viral infection that causes oral cancers.

Oral human papillomavirus type 16 (HPV-16), which can be transmitted by oral sex, has been associated with an increase of mouth and throat cancers worldwide.

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Some 70 percent of the 30,000 cases of oropharyngeal cancer in the U.S. were tied to HPV, which makes it the most common sexually transmitted infection in the continent. 

Lead author Carole Fakhry, M.D., M.P.H. of Baltimore's Johns Hopkins University of Medicine, and colleagues found the occurrence of oral HPV-16 is more common among people that use cigarettes and other tobacco products, irrespective of their sexual behaviors.

 "It appears that tobacco exposure increases the likelihood of having the oral HPV-16 infection," said Dr. Gypsyamber D'Souza, M.S., M.P.H., an associate epidemiology professor at the John Hopkins Bloomberg School of Public Health.

The study, published Tuesday in the Journal of American Medical Association, involved data from the 2009 to 2012 U.S. National Health and Nutrition Examination Survey (NHANES).

The study also included 6,887 survey participants between the ages 14 to 69. Among the participants, 2,012 were current tobacco users and 63 were infected with HPV-16.

Researchers detected HPV-16 in participants by running an oral rinse and gargle that collected mouth and throat cells. The participants also had their blood and urine tested for chemicals related to tobacco usage.

The results indicated that subjects with higher levels of chemicals related to tobacco in their blood or urine were more likely to have HPV-16, while those who had no detectable levels of compounds indicated lower traces of the virus.

"We found that increasing levels of tobacco exposure were associated with higher odds of oral HPV16 prevalence," concluded Dr. Fakhry.

An increase of cotinine levels in the blood, which is equivalent to three cigarettes per day, raised the odds of HPV-16 occurrence by 31 percent while four cigarettes per day increased the likelihood infection by 68 percent.

Tagssmoking, Tobaco, HPV-16, Oral Cancer