Long-term exposure to burning incense raises the risk for developing upper respiratory tract cancers, a study finds.

Researchers from Statens Serum Institute in Copenhagen, Denmark conducted interviews with more than 61,000 Singapore Chinese ages 45-74 who were cancer-free at the beginning of the study, HealthDay News reported.

They found that being regularly exposed to burning incense almost doubled the risk of developing squamous cell upper respiratory tract carcinomas including nasal/sinus, tongue, mouth and laryngeal.

The study, to be published in the Oct. 1 issue of the journal Cancer, found no increased risk of lung cancer, but that incense did increase the risk of squamous cell carcinoma of the lung. A carcinoma is any malignant cancer that arises from the epithelial cells, which line the structures of the body.

"Given that our results are backed by numerous experimental studies showing that incense is a powerful producer of particulate matter and that incense smoke contains carcinogenic substances, I believe incense should be used with caution," study author Dr. Jeppe Friborg, of the department of epidemiology research at Statens Serum Institute, told HealthDay.

Click here to read more on this story from HealthDay News.

Click here for more on squamous cell carcinoma from the Mayo Clinic.