Aug. 19 (HealthDay News) -- Paraffin wax candles, used mainly for romantic ambiance, fragrance and light, may also contribute to air pollution inside your home.

The candles, which are made from petroleum, are a source of known human carcinogens and indoor pollution, researchers said in a study to be presented Wednesday at the American Chemical Society's national meeting in Washington, D.C.

In the study, R. Massoudi and Amid Hamidi found that candles made from beeswax or soy, although more expensive, apparently are safer because they do not release potentially harmful pollutants.

"An occasional paraffin candle and its emissions will not likely affect you," Hamidi said in a news release. "But lighting many paraffin candles every day for years or lighting them frequently in an unventilated bathroom around a tub, for example, may cause problems."

Ventilation can help reduce the level of pollutants in closed rooms, the researchers said.

Besides the more serious risks, Hamidi also said that some people who believe they have an indoor allergy or respiratory irritation may actually be reacting to pollutants from burning candles.

SOURCE: American Chemical Society, news release, Aug. 19, 2009