LOS ANGELES — A large prospective cohort study has found an association between long-term exposure to burning incense and cancers of the respiratory tract, according to a poster presentation by Dr. Jeppe T. Friborg at the annual meeting of the American Association for Cancer Research.
Among 61,320 Singapore Chinese, long-term incense users had more than twice the relative risk of non-nasopharyngeal carcinomas of the upper respiratory tract, compared with people who did not use incense.
The risk of squamous cell carcinomas of the lung rose 1.7-fold and the risk of squamous cell carcinomas of the entire respiratory tract rose 1.8-fold among long-term incense users, wrote Dr. Friborg of the University of Minnesota, Minneapolis, and colleagues.
The use of incense did not increase the risk of non-squamous cell carcinomas. Participants in the study were 45–74 years old and were cancer free when they enrolled between 1993 and 1998. They underwent a comprehensive interview on living conditions, dietary factors, and lifestyle factors. Investigators followed the cohort through 2005.
In the multivariate analysis, results were adjusted for age, gender, dialect group, education level, number of cigarettes smoked per day, years of smoking, frequency of alcohol intake, intake of isothiocyanates, intake of Chinese-style preserved foods, body mass index, and parity in women.
The investigators noted that the burning of incense is an integral part of daily life in large parts of Asia and is not restricted to places of worship: About half the population in Southeast Asia burns incense at home every day. Incense burning produces a great deal of particulate matter and releases many possible carcinogens including polyaromatic hydrocarbons, carbonyls, and benzene.
Risk of squamous cell carcinomasrose 1.8-fold in long-term users.