The U.S. environment has come a long way since the 1970s, when smog indexes were a regular feature on the weather forecasts and weeping Indians were a fixture of TV’s public service announcements. Happily, we managed to survive the decade that gave birth to both Earth Day and the EPA, learn some lessons, and clean up our act. But a new study out of the University of Illinois at Chicago School of Public Health, showing just how tightly-linked environmental factors are to breast and prostate cancer risk, is an indication that some areas in the country may still have a ways to go.

The highest incidences of any kind of cancer have been tracked back to the counties hosting the poorest environments. The biggest impact was exerted by air quality and factors of the “built” environment, e.g., the presence of major highways and the availability of public transit and housing. Water quality and land pollution had no measurable effect on cancer rates.

“Most research has focused on single environmental factors like air pollution or toxins in water,” said Jyotsna Jagai, lead author of the study. “But these single factors don’t paint a comprehensive picture of what a person is exposed to in their environment – and may not be as helpful in predicting cancer risk, which is impacted by multiple factors including the air you breathe, the water you drink, the neighborhood you live in, and your exposure to myriad toxins, chemicals and pollutants.”

The researchers cross-referenced more than 200 environmental variables – including radon levels, pesticide use, air and water pollution, the presence of heavily-trafficked highways and roads – as tabulated in the EPA’s Environmental Quality Index against cancer incidence rates from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program State Cancer Profiles. The EPA’s database tracks the environment down to the county level, and the NCI had data available for 85 percent of the 3,142 of those U.S. counties.

The study showed that counties with poor environmental quality had higher incidence of cancer than counties with high environmental quality. The numbers indicated that prostate and breast cancer held the strongest association with poor environmental quality.

“Some of the counties we looked at were very large, with both urban and rural areas in a single county, so to tease apart the interplay between the measures of quality in our five domains and how they impact urban and rural areas,” Jagai said, “we will need to look at geographic areas smaller than counties.”

The research has been published in Cancer.