While oral human papillomavirus (HPV) may not be fatal in its own right, it is often found in oropharyngeal squamous cell carcinoma diagnoses, which led to 2,400 deaths in 2010. A recent study conducted by researchers from Johns Hopkins University and the Ohio State University has revealed that tobacco exposure can increase a person’s risk for being diagnosed with oral HPV type 16.

“HPV is the primary causal agent of HPV-related oral cancer,” Dr. Gypsyamber D’Souza, associate professor at Johns Hopkins Bloomberg School of Public Health, told Time. “But these results suggest that tobacco may make these infections less likely to clear, and therefore smokers may have a higher risk of eventually developing oropharyngeal cancers.”

D’Souza and her colleagues assessed the health profiles of 6,887 individuals participating in the National Health and Nutrition Examination Survey (NHANES). Out of the entire sample, 2,012 reported smoking cigarettes or other tobacco-related products. The research team also tested blood and urine samples from each participant to gauge overall exposure to tobacco, including environmental, smoking, and use of smokeless tobacco products.

After administering a mouth wash to participants that collected mouth and throat cells, researchers found that HPV16 infections were more common among participants who smoked or used tobacco regardless of sexual behavior. Participants with levels of cotinine, a metabolite of nicotine, in their blood that indicated three cigarettes a day increased their risk for HPV16 by 31 percent. Those with detectable levels of NNAL, a chemical found in tobacco, in their urine that indicated four cigarettes a day increased their risk by 68 percent.

“What this adds to the story is an understanding of one reason why people who have not had very heavy sexual history, people who’ve had one lifetime partner . . . develop these cancers,” D’Souza added. “This cross-sectional study suggests that in some people tobacco use might be an explanation.”

According to the Centers for Disease Control and Prevention, the same types of HPV that can infect the genital areas can also infect the mouth and throat. HPV16 can be transmitted from person-to-person via oral sex and is discovered in over 90 percent of oropharyngeal cancer diagnoses. Past research has shown that around seven percent of people have oral HPV, however, only one percent HPV16.

Source: Fakhry C, Gillison M, D’Souza G. Tobacco Use and Oral HPV-16 Infection. JAMA. 2014.