Incense burning 'may spark cancer'

Peace of mind might be the last thing incense is giving you.

By CNN's Marianne Bray

HONG KONG, China -- Think twice before lighting that next stick of incense. You might be getting more than a gentle whiff of sandalwood.

According to a group of researchers in Taiwan, burning incense could be a cancer risk.

This news might come as a shock to millions of Buddhists, Hindus and Christians who use incense to purify the air, set their minds at ease and treat diseases, and as part of their ceremonies and devotions.

At the Po Lin Monastery on Lantau Island in Hong Kong, visitors burn about three joss sticks each as they pay their respects to the Buddha and their ancestors, feeding their spirits with incense, according to a spokeswoman.

Others in Japan stand in front of giant vats and breathe in the scent of hundreds of incense sticks to get wise or just for good measure.

And it is not just an Asian or religious act. More and more Westerners are lighting up joss sticks in their search for the path to enlightenment.

"We truly hope that incense burning brings only spiritual comfort, without any physical discomfort," Ta-Chang Lin at the National Cheng Kung University in Tainan told the New Scientist magazine.

But "there is a potential cancer risk. We just cannot say how serious it is."

Get wise

FACTBOX Incense was used in ancient Egypt, Greece, and Rome and is mentioned in the Old and the New Testaments. It is also found in the major religions of Asia. Hindus use it for temple and domestic offerings, Buddhists burn it at festivals, initiations, and daily rites, the Chinese honor ancestors and household or tutelary deities with it, while in Japan it is a mainstay of Shinto ritual. -

Smoke from burning incense is laden with cancer-causing chemicals, Lin told CNN.

Levels of one chemical believed to cause lung cancer were 40 times higher in a badly ventilated temple in Taiwan than in houses where people smoke cigarettes.

Beyond the cancer scare, incense is actually bad for the air. Burning it creates more pollution than road traffic at a local intersection.

In the smoky temple they tested, the incense emissions exceeded the standard "safe" levels for ambient air set in Taiwan.

Burnt offering

Lin's team collected air samples from inside and outside a temple in Tainan City and compared them to samples at a traffic intersection.

Inside the temple, they found very high concentrations of polycyclic aromatic hydrocarbons (PAHs), a large group of highly carcinogenic chemicals that are released when certain substances are burnt.

Incense smoke may be a long way away from purifying the air.

Total levels of PAHs inside the temple were 19 times higher than outside and slightly higher than at the intersection.

"Due to poor ventilation in the temples and accumulation from non-stop incense burning, we were not surprised by these results," says Lin.

A PAH called benzopyrene, which is thought to cause lung cancer in smokers, was found in very high quantities inside the temple.

Levels inside the temple were up to 45 times higher than in smokers' homes, and up to 118 times higher than areas with indoor cooking fires.

"The concentrations of PAHs inside the temple depends on how many visitors come to worship that day. During some major ceremonies, hundreds or even more than a thousand sticks are burnt at the same time," says Lin.

"Sometimes the visibility is so low you can't see clearly across the room. We are concerned for the health of workers or keepers in the temples."

Ventilate

QUOTE "Polycyclic Aromatic Hydrocarbons (PAHs) are a group of toxic chemicals, some of which are known to be either mutagenic or even carcinogenic. During any incomplete combustion of hydrocarbons, PAHs are produced in addition to carbon dioxide, water, nitrogen oxides, and compounds unique to each type of material. Whenever wood, paper, coal, candle, cigarette, incense, gasoline, or diesel is burned, PAHs are produced." - Ta-Chang Lin

The findings will have people reassessing their habits around the world.

Brad Timms, a science information officer at the U.K.-based Cancer Research Campaign has confirmed to CNN there is a link between incense burning and cancer-causing substances.

But more research needs to be done to find out just how much of a risk there is.

Earlier studies looking at air pollution as a whole have shown a link between cancer and the chemicals released by incense, says Timms.

But he reassured that most people should not be overly concerned.

"Those most at risk are those working within temples and exposed to the smoke for long periods of time," he said.

In the meantime if you do light up, ensure you have good ventilation and don't buy cheap sticks, which Lin says usually give out more pollutants.

He hopes to work with public health experts to see how much of the carcinogens reach the lungs of people in the temples.