Incense Raises Respiratory Cancer Risk

(August 26, 2008) - That sweet smell from burning incense may be dangerous. Long term use of incense increases the risk of developing cancers of the respiratory tract (Read about "Respiratory System"), according to a new study. The new analysis, which the authors say is the first prospective investigation of incense and cancer risk ((Read about "Cancer: What It Is"), appears in CANCER, a journal of the American Cancer Society.

Incense is an integral part of daily life in large parts of Asia. Researchers have shown that burning incense - which is made of plant materials mixed with oils - produces a mixture of possible carcinogens, including polyaromatic hydrocarbons, carbonyls and benzene. Because incense smoke is inhaled, a number of studies have looked at the possible link between incense burning and lung cancer (Read about "Lung Cancer"), but results have been inconsistent. In addition, the possible association of incense use and other respiratory tract cancers has not been analyzed.

The study involved 61,320 who were free of cancer and aged 45-74 years in the mid 1990's. At that time, they completed a comprehensive interview on living conditions and dietary and lifestyle factors. The investigators followed these individuals through for 10 years or more, noting which participants developed cancer during that time.

The research team documented a total of 325 upper respiratory tract cancers (including nasal/sinus, tongue, mouth, laryngeal and other cancers) and 821 lung cancers during follow-up. (Read about "Head & Neck Cancers" "Oral Cancer") Incense use was associated with a significantly increased risk of upper respiratory tract cancer (other than nasopharyngeal), but there was no overall effect on lung cancer.

The researchers also noted that the duration and intensity of incense use were associated with an increased risk of squamous cell carcinomas in the entire respiratory tract. Squamous cells cover the internal and external surfaces of the body.

According to the study data, incense use seemed to add to the increased risk of upper respiratory tract squamous cell carcinoma in smokers. It also considerably increased the risk in never smokers, which points to an independent effect of incense smoke.