Colorado Breath: Healthy Links

NNK Carcinogens Found in Blood of Workers
Report Adds to Evidence of Dangers of Second-Hand Smoke
Minneapolis-St. Paul Star Tribune
Gordon Slovut- Star Tribune

A University of Minnesota researcher has found what some scientists describe as the "smoking gun" linking secondhand tobacco smoke with lung cancer in nonsmokers.

Dr. Stephen Hecht, head of cancer prevention at the University of Minnesota Cancer Center, reported in a 2007 report that he has found traces of a powerful tobacco carcinogen in the urine of nine nonsmoking staff members who work in a residential section of a Canadian veterans hospital where smoking is permitted.

He reported his findings at the annual meeting of the American Chemical Society in Las Vegas.

The carcinogen is NNK (for 4-methylnitrosamino)-1-butanone, formed from the nicotine in tobacco. Of 43 known carcinogens in tobacco smoke, it is the only one that originates just from tobacco and thus can be attributed to no other source.

I previous research Hecht proved that subjects exposed to massive amounts of tobacco smoke from a machine while enclosed in a small room had NNK in their urine. But nonsmokers who inhale secondhand smoke in the workplace, at home or in restaurants are exposed to far less smoke than the people in that study, Hecht said.

As a result, no one knew for certain that traces of NNK would be found in nonsmokers exposed to tobacco smoke in nonlaboratory situations.

In addition, his research will make it possible to accurately measure how much exposure people have had to the cancer-causing chemicals in tobacco, said Dr. Curtis Harris, chief of the Laboratory of Human Carcinogenesis at the National Institutes of Health. A key aspect of the work was figuring out how to detect and measure a metabolite, or breakdown product, of NNK. Finding it in the urine "means that NNK got into the lungs, into the bloodstream, was metabolized by enzymes and just a portion of it was excreted in the urine," Harris said.

Dr. John Kersey, head of the University of Minnesota Cancer Center, said that as a result of the research, the tobacco industry should face another "whole group of potential plaintiffs, nonsmokers who have this in their urine and then develop or do not develop cancer, or maybe instead of cancer they develop emphysema or something else."

Public health advocates considered secondhand smoke a contributor to lung cancer and the Environmental Protection Agency has declared environmental tobacco smoke a Class A carcinogen, along with radon and asbestos.

The tobacco industry opposed the classification, arguing that there was insufficient evidence to link tobacco smoking with the nearly 4,000 lung cancer deaths of nonsmokers in the United States each year.

There was no real doubt, however, that secondhand smoke causes lung cancer, said Dr. Richard Hurt, director of the Nicotine Dependence Center at the Mayo Clinic in Rochester, Minn. Spouses of smokers have a higher rate of lung cancer than do the spouses of nonsmokers. Hurt said that secondhand smoke kills more Americans each year than radon or asbestos, yet millions of dollars are spent to protect people from asbestos exposure.

"People put radon detectors in their basement, and then go out to dinner in a restaurant that has just a partition between smokers and nonsmokers," he said.

Hurt said he hopes the findings will strengthen efforts to protect Americans from secondhand smoke. He also described the research as the "smoking gun" in tobacco litigation such as that of flight attendants who claim their health has been damaged by secondhand smoke they inhale on overseas flights.

Hurt said that all workplaces and public areas, such as restaurants, ought to be smoke-free. He said waitresses in restaurants and bars that allow smoking are being exposed to enormous amounts of cancer-causing chemicals. "It is unfair to them," he said.