PITTSBURGH—Even if everyone in Allegheny County had quit smoking 20 years ago, lung cancer rates in the region would only have dropped by 11 percent, according to a new analysis, which suggests that air pollution plays a significant role in western Pennsylvania cancer rates.
The analysis, published as a letter to the editor in the journal Environmental Health, used existing data on smoking and cancer rates in 612 counties across the U.S. to estimate what would have happened if everyone in those counties had quit smoking 20 years ago.
The researchers used census data and county-specific data on cancer rates and smoking to estimate how many cancer cases were caused by smoking, then used statistical modeling to estimate how cancer rates would have changed over time if smoking was eliminated.
They found that in some counties lung cancer rates would have declined by more than 80 percent, while other counties would have seen a decline of less than 15 percent, with an average reduction of 62 percent. Allegheny County, which encompasses Pittsburgh, would have seen a decline of just 11 percent, putting it in the bottom 2 percent of counties when it comes to the potential for quitting smoking to lower lung cancer rates.
“Very few rural counties had a high residual cancer risk after removing smoking risk, which indicates that air pollution is likely an important piece of this puzzle,” David Kriebel, a professor and director of the Lowell Center for Sustainable Production at the University of Massachusetts and one of the study’s authors, told EHN.
Allegheny County in the top 2 percent of counties nationwide
Previous research has already put Allegheny County in the top 2 percent of counties nationwide for cancer risk specifically caused by air pollution. Radon exposure is the second leading cause of lung cancer nationally and is a known factor in western Pennsylvania, as are traffic emissions and unusually high levels of industrial pollution—particularly from coke ovens used by the steel industry, which generate highly carcinogenic emissions. Cancer-causing chemicals in the region’s drinking water could be another contributing factor.
The new analysis follows a 2020 paper published in the journal Environmental Health that looked at the impacts of smoking cessation on the rates of lung cancer and 11 other smoking-associated cancers (including esophageal cancer, cancer of the larynx, and stomach and bladder cancer) nationwide. That study, which was conducted by the same group of researchers at Boise State University and the University of Massachusetts, found that about 60 percent of smoking-associated cancers would not have gone away even if no one in the U.S. had smoked cigarettes for the last 20 years, suggesting that environmental factors play a larger role than previously thought.
When the researchers presented their early findings for that study at a symposium on cancer and the environment in Pittsburgh in 2019, local health advocates asked them to look at the same data specifically for lung cancer in Allegheny County. The researchers did, and also created a tool that any U.S. county can use to do the same type of analysis.
They said they hope the tool will help public health departments in places like Allegheny County assess how much of their efforts aimed at reducing local lung cancer rates should be directed toward smoking-related initiatives versus cleaning up the air and reducing other environmental exposures to carcinogens.
“Smoking is obviously a hugely important risk factor when it comes to lung cancer,” said Polly Hoppin, one of the study’s authors, former Senior Advisor at the U.S. Department of Health and Human Services and Environmental Protection Agency, and program director at the Lowell Center for Sustainable Production at the University of Massachusetts.
“Lowering smoking rates goes a long way toward reducing cancer rates, and we don’t want to detract from the importance of those efforts in any way,” Hoppin told EHN. “But our analysis does suggest that it’s not the only important factor, and that in some places putting resources toward reducing air pollution and other environmental exposures could go even further toward reducing the region’s lung cancer rates.”
Thinking beyond smoking to tackle cancer
The researchers’ previous analysis found that even if Allegheny county eliminated smoking entirely, it would still be in the highest 10 percent of all U.S. counties for these cancers. But most current cancer prevention strategies in the county (and in the U.S. as a whole) are focused on individual behaviors: diet, exercise, and smoking.
“There’s no question that these are important causes of cancer,” Kriebel said, “but we’re concerned over the degree to which we focus on smoking, obesity and exercise may lead people to conclude that the solution to the cancer epidemic lies solely in individual actions and lose sight of how socioeconomic and political decisions could be made that would also help prevent cancer.”
Doug Myers, a professor at Boise State University and another of the study’s authors, pointed out that other types of cancer that aren’t associated with smoking could also be reduced by lowering environmental exposures to cancer-causing chemicals.
“There are lots of other cancer types that aren’t related to smoking, and our analysis doesn’t address those at all,” he said. “So the impacts of lowering environmental exposures on reducing overall cancer rates would likely be even greater.”
EHN asked the Allegheny County Health Department whether they had reviewed the study, what portion of their cancer prevention resources are allocated toward smoking cessation vs. environmental factors, and how they’re working to protect the residents of Allegheny County from carcinogens in the local environment. A spokesperson wrote they “have no comment to offer.”
“If you remove the progress we’ve seen as a result of people quitting smoking, we’ve made no headway whatsoever in the so-called war on cancer [at the national level]”, Kriebel said. “That doesn’t mean we shouldn’t focus on tobacco control. But it does mean it’s a big mistake to stop there.”
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