SINGAPORE: Long-term daily use of incense, an important feature of Asian religious practices, increases the risk of some cancers, an international study has found.

The research found that people who burned incense at home daily for more than 40 years had a risk of getting a certain type of cancer more than 70 per cent higher than people who did not.

"This is chronic, long-term exposure," Koh Woon-Puay, a co-author of the study, told AFP in an interview late Wednesday.

"We're not saying, therefore, that people must stop burning it. Try to reduce exposure to it."

The study involved about 61,000 middle-aged and elderly ethnic Chinese people in Singapore who were cancer-free between 1993 and 1998.

Researchers looked at how frequently they used incense at home and tracked them until the end of 2005 to see whether they developed cancer.

Singapore is a majority ethnic Chinese city-state where most people live in apartments. Incense burning is practised by followers of Taoism or ancestor worship.

The research found the incense smoke was associated with only one type of cancer, upper airway cancer, which includes cancer of the tongue, oral cavity and sinuses.

Koh, of the National University of Singapore, urged users to improve ventilation in their homes if they are burning incense, and said follow-up studies could examine which types might be less harmful.

The study, believed to be the first of its kind, was done in collaboration with the University of Minnesota's Cancer Center and Statens Serum Institute in Denmark. It will be published next month.

- AFP/ir