It's also possible germs could cause chronic inflammation that could boost the likelihood of cancer, he said.
The source of the germs is unclear, but Pauly said they could appear during the preparation of tobacco. Sapkota agreed, adding that the cigarettes "could have been contaminated anywhere from seed to pack."
David Sutton, a spokesman for Altria Group, Inc., formerly known as Philip Morris USA, said it hasn't reviewed the new study. But "after an initial look at it, I would point out the authors' conclusion section: 'The overall public health implications of these findings are unclear at this time.'"
The study findings appear in an upcoming issue of the journal Environmental Health Perspectives.
Learn more about the dangers of smoking at the American Cancer Society.
SOURCES: Amy R. Sapkota, Ph.D., assistant professor, University of Maryland School of Public Health, College Park; John L. Pauly, Ph.D., cancer research scientist, department of immunology, Roswell Park Cancer Institute, Buffalo, N.Y.; David Sutton, spokesman, Altria Group, Inc., Richmond, Va.; upcoming, Environmental Health Perspectives
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