MINNEAPOLIS, Jan. 2 A carcinogenic chemical in tobacco products was found in toenails of smokers and non-smokers exposed to secondhand smoke, U.S. cancer researchers said.The findings demonstrate clippings subjected to sensitive testing could be used to learn about the role chronic tobacco smoke exposure plays in cancer in humans, said Irina Stepanov, a researcher at the University of Minnesota Cancer Center.NNK is a cancer-causing agent in tobacco products; nicotine is the main known addictive component of tobacco. In humans, NNK is converted to the chemical compound NNAL, while nicotine is converted to the compound cotinine, Stepanov said.Numerous studies have quantified cotinine and NNAL in the urine and blood of smokers, smokeless tobacco users, and non-smokers exposed to secondhand tobacco smoke, Stepanov said. Our study is the first to show these agents also become part of the toenail composition.Stepanov said she thinks studying toenails offers another way of determining negative effects of secondhand smoke in non-smokers. She said toenails grow more slowly so they reflect cumulative exposure over a relatively long period. They also are less likely than fingernails to become environmentally contaminated.Copyright 2007 by UPI
