Citation: Jagai, J. S., Messer, L. C., Rappazzo, K. M., Gray, C. L., Grabich, S. C. and Lobdell, D. T. (2017), County-level cumulative environmental quality associated with cancer incidence. Cancer, 123: 2901–2908. doi:10.1002/cncr.30709
Known to Cause Cancer
Anyone who has ever visited California or watched local evening news reports knows that many things can cause cancer. We already know that your chances of getting cancer are impacted by your genes and your environment, but those factors can also work together. Much of the research done in the past focuses on specific causes, but this may leave out parts of the story because there are many things humans are exposed to in our environment that can have an impact on health. It turns out that overall environmental quality may increase your risk for cancer. This means that where you live can be an important risk factor.
While you visit a doctor to learn more about your personal health, public health looks at causes and effects for a larger population. This helps us find out what we should be concerned about on broader scales. A lot of public health research is focused on how to make sure we live in safe environments.
This study uses something called the Environmental Quality Index (EQI), which accounts for all exposures that might be relevant. Exposures include quality and contamination in the air, water, land, and built environment. Contamination can come from emissions from cars and factories, runoff from fertilizer used to grow food, or residue from facilities that used to manufacture harmful materials. Socioeconomic and demographic factors, which describe the human element, are included in this index as well. The authors looked at the EQI value and the number of cancer cases in each county. Because cancer does not develop immediately and there is a lag time, the authors assessed environmental exposures from 2000-2005 and cancer rates for 2006-2010. Cancer occurring anywhere on the body was considered and the most common cancers, including lung, breast, colorectal, and prostate, were looked at separately as well. By separating out men and women as well as people living in rural and urban environments the authors were able to differentiate findings for location and gender in their research outcomes. Finally, the number of cancer cases in each group and location were compared to the exposures for each group and location.
Only about half the risk for cancer is determined by genetics, which means that environmental exposures can have a significant impact. Breast, prostate, and lung cancers are all associated with poor environmental quality. Breast and prostate cancers are most strongly related to air quality compared to other parts of the environment.
The researchers found that locations with poor environmental quality had more cancer cases. The worse the environmental quality was, the more cancer that county had. This is particularly true in metropolitan areas. They looked at the quality of different parts of the environment in additionto the overall environmental quality. Overall, bad air quality is associated with an increase in cancer, but worse water quality either was unrelated to cancer rates or associated with a decrease in cancer. The quality of the land had different relationships with cancer based on how densely populated the area is. In more urban areas poor land quality is associated with higher cancer rates, but the opposite is true in rural areas. Poor quality in the built environment was associated with higher rates of cancer in all groups. Unsurprisingly, poor air quality was associated with increased rates of lung cancer.
What’s the big deal?
We already know that living in different places and being around different things can cause us to get sick, including getting cancer. This study has expanded that knowledge because it looks at many different parts of our environment at once. The researchers found that air, the built environment, and socio-demographics (or information about people including crime rates and population density) are the parts of our environment most related to getting cancer. This shows why we need to take action to protect our air and make sure we live and work in healthy buildings. We, as a society, need to work to keep our environment clean to keep ourselves and our neighbors healthy.