Smoking hookah could lead to exposure to cancer-causing substances.

Young people who smoked hookah were found to have elevated levels of "nicotine, cotinine, tobacco-related cancer-causing agents, and volatile organic compounds (VOC)," an American Association for Cancer Research news release reported.

"This study reports systemic intake of tobacco-specific nitrosamines and VOCs after a typical water pipe-smoking session in a hookah bar setting, thus making the findings generalizable to most water pipe users in the United States," Gideon St.Helen, Ph.D., postdoctoral fellow in the Division of Clinical Pharmacology and the Center for Tobacco Control Research and Education at the University of California, said in the news release.

After a hookah session young men and women were asked to provide urine samples. The participants' urine showed a " 73-fold increase in nicotine; fourfold increase in cotinine; twofold increase in NNAL, a breakdown product of a tobacco-specific nitrosamine, NNK, which can cause lung and pancreatic cancers; and 14 to 91 percent increase in the breakdown products of VOC such as benzene and acrolein that are known to cause cancer and cardiovascular and respiratory diseases," the news release reported.

The presences of the substances also suggest the danger of addicition.

"There was also a substantial increase in nicotine levels, which raises concerns about the potential addictiveness of water pipe smoking and possible effects on the developing brains of children and youths who use water pipes," St.Helen said. "Water pipe smoking is generally perceived to be a safe alternative to cigarette smoking, even for children and youths. Our study shows that water pipe use, particularly chronic use, is not risk-free."

The participants were between the ages of 18 and 48 years old and were asked to refrain from any smoking before the night at the hookah bar. The participants provided "before and after" urine samples as well as information on how much they had smoked and how long they had smoked for.

The subjects smoked for an average time of 74 minutes and smoked an average of 0.6 bowls of water pipe per person.

Levels of NNAL and nicotine were found to persist through the following day.

"I have seen entire families, including young children, smoking water pipes. I have even been offered a smoke by my friend who thought water pipe smoking was 'totally safe,'" St.Helen said. "Our study provides evidence that water pipe smoking leads to significant intake of tobacco-related addictive and harmful substances, and is therefore not without risk, particularly among children and youths."