Chemicals linked to lung cancer are five to six times higher in the urine of women who live with smokers than in women who live with non-smokers, according to a new study.

The study is the first to demonstrate that tobacco smoke carcinogens - chemicals that cause cancer - are absorbed by people who live in homes with smokers. The study appears Wednesday in the Journal of the National Cancer Institute.

"A number of studies have shown a connection between environmental tobacco smoke and lung cancer," said Stephen S. Hecht, the Wallin Professor of Cancer Prevention at the University of Minnesota, Minneapolis. "Our study provides the first biochemical support for this data."

Hecht, a co-author of the study, said that analyzing the urine of nonsmoking wives of men who smoke at home shows that the women's bodies absorb cancer-causing compounds from the atmosphere through their lungs. The study found elevated levels of compounds called NNAL and NNAL-Gluc, both of which are metabolized products of NNK, a proven, tobacco-specific cancer-causing chemical.

"It is clear that environmental tobacco smoke has all the carcinogens that are contained in tobacco smoke," said Hecht.

In the study, researchers analyzed the urine from 23 women who lived with men who smoked in the home and compared the results with urine from 22 women who lived with non-smokers.

The results showed that women who lived with smokers had levels of NNAL and NNAL-Gluc that was five to six times higher than for women who lived with non-smokers.

Women who lived with smokers had similarly elevated levels of nicotine and cotinine, a metabolic product of nicotine.

Other studies have shown that environmental tobacco smoke increases the risk of lung cancer for non-smokers who work where cigarette and cigar smoking is common, such as bars or taverns. Additionally, studies have shown that children living in the homes of smokers have a higher incidence of asthma and other respiratory problems.

Hecht said that tobacco smoke in homes with central heating and air conditioning systems tends to spread throughout a house.

"If you smoke in one part of a house, the smoke doesn't just stay in that part," said Hecht. "About the only safe thing that a woman who lives with a smoker can do is to tell him to go outside when he smokes."