Burning incense linked to respiratory cancers

The researchers found that incense use was associated with a statistically significant higher risk of cancers of the upper respiratory tract, with the exception of nasopharyngeal cancer. However, they observed no overall effect on lung cancer risk.

Those who used incense heavily also had higher rates of a type of cancer called squamous cell carcinoma, which refers to tumors that arise in the cells lining the internal and external surfaces of the body. The risk was seen in smokers and nonsmokers.

Study participants who used incense in their homes all day or throughout the day and night were 80 percent more likely than non-users to develop squamous cell carcinoma of the entire respiratory tract.

The link between incense use and increased cancer risk held when the researchers weighed other factors, including cigarette smoking, diet and drinking habits.

"This association is consistent with a large number of studies identifying carcinogens in incense smoke," Friborg's team writes, "and given the widespread and sometimes involuntary exposure to smoke from burning incense, these findings carry significant public health implications."

They say further studies are needed to see whether different types of incense are associated with different degrees of cancer risk. In Singapore, the researchers note, most people burn long sticks or coils of incense that burn slowly over an extended period.

SOURCE: Cancer, October 1, 2008.