Greater total pollution exposure tied to higher cancer risk.
Living in areas with higher total exposures to harmful pollutants in the air, water and land is associated with greater odds of developing cancer, a US study suggests.
Researchers examined the annual incidence rate for cancer diagnoses for each county in the US and found an average of 451 cases for every 100,000 people.
Compared to counties with the highest environmental quality, counties that ranked the lowest had an average of 39 more cancer cases each year for every 100,000 residents.
"We found that counties with poor overall environmental quality experienced higher cancer incidence than those counties with good overall environmental quality."
To assess the connection between environmental quality and cancer risk, the researchers examined county-by-county data on exposure to different pollutants from 2000 to 2005 and on new cancer diagnoses from 2006 to 2010.
Living in the counties with the worst environmental quality was tied to about 10 more cases of these tumours for every 100,000 people.
One limitation of the study is that researchers may not have had enough years of data to fully assess the connection between pollutants and cancer because some slow-growing tumours might appear many years after exposure to pollutants, the authors note.
Researchers also lacked data on individuals’ lifestyle factors that can influence cancer risk, such as alcohol use, exercise habits and nutrition.
"We do have to be careful about drawing conclusions from studies of neighborhood factors that lack detailed information on characteristics of individuals living in those neighborhoods because the observed associations could very well be due to attributes of the individuals rather than the environment itself," said Scarlett Lin Gomez, author of an accompanying editorial and a researcher at the Cancer Prevention Institute of California and the Stanford Cancer Institute.