Insights on secondhand smoke
In the past few years, several counties and cities in Minnesota have enacted smoking ordinances that prohibit smoking in public venues, including restaurants and some bars. Despite the fervor surrounding these new ordinances, some people are still unaware — or unconvinced — that exposure to environmental tobacco smoke can cause cancer in nonsmokers.
Each year, about 3,000 lung cancer deaths in nonsmokers are attributable to environmental tobacco smoke. In one study, lung cancer rates were 20 percent higher in women who work or live in smoky environments compared with those not exposed to tobacco smoke. These figures can be tough to ignore.
But if there remains any doubt about the connection between secondhand smoke and cancer, public health researchers Kristin Anderson, Ph.D., and Ozlem Tulunay, M.D., hope they can dispel it for good. The two, along with fellow investigators, have completed studies examining the connection between exposure and increases in tobacco-specific cancer-causing chemicals in the body. Anderson examined the effects in nonsmokers exposed to secondhand smoke in casinos, while Tulunay analyzed how environmental tobacco smoke affects employees who work in bars and restaurants that permit smoking. In both studies, the nonsmokers were exposed to passive cigarette smoke for several hours.
Public health researcher Kristin Anderson, Ph.D., has authored groundbreaking studies on passive smoke in public places. The results show that nonsmokers exposed to smoky casinos, bars, and restaurants have significantly higher levels of cancer-causing substances in their bloodstreams.
The results showed significant increases in nonsmokers' NNAL levels in both situations. In the casino study, NNAL levels increased more than twofold. In the bars and restaurants study, nonsmoking employees had up to 4.5 times more total NNAL in their blood after working their shift.
"I think the public health message is that it's not a benign exposure," says Anderson, an associate professor in the School of Public Health. "It is a potentially harmful exposure because we have carcinogens in our blood and body that would not be there if we did not have that exposure. And lung cancer is just one of many health effects possible through passive smoke exposure."
The road ahead
The work on cancer-related tobacco research moves forward at a frenzied pace. But for the investigators involved, it seems to be the pace that's most comfortable. While they are publishing their work with one brand of reduced-exposure tobacco product, they are working on another. As they use NNAL and other tobacco-related biomarkers to examine the toxicity of smoking, they continue to evaluate precisely how effective these markers are in predicting cancer in humans. While they work to identify those who are most susceptible to developing cancer, they are also identifying the mechanisms of addiction — what makes people so hooked on nicotine — and what can be done to combat that addiction.
Most recently, Hatsukami has been working with Paul Pentel, M.D., and other colleagues to develop and test a so-called "nicotine vaccine." The goal is to stimulate the immune system to deliver less nicotine to the brain and, therefore, fewer pleasurable effects from smoking. The vaccine has shown promising results, according to Hatsukami, and the team plans to do clinical trials with it in the near future.
"The fact that our work involves so many different research angles demonstrates how all-encompassing it can be to combat tobacco-related cancer," she says. "You have to focus on the biomolecular level of exposure, examine the toxicity of the tobacco products themselves, find ways to prevent initiation and addiction in the first place, identify and support those policies that reduce the incidence of smoking, and help people who want to quit. It's really an inter-disciplinary effort."
It may seem to be a long and winding road, but to Hecht, the public health impact of his team's work is already upon them.
"All of our work ties together," says Hecht, and it all contributes to the general effort to protect consumers via taxation (also known as "user's fees"), legislation (such as smoking ordinances), public education, anti-tobacco advertising, and smoking cessation.
"We're making a difference now, certainly," he says, "but we also know we can't stop. We've only scratched the surface."