Something about the alleged air pollution and adult diabetes link stinks

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USA Today reports that a new study “strongly” links adult diabetes to air pollution exposure — even where pollution levels fall below EPA safety limits. Researchers from Children’s Hospital Boston compiled data from the CDC and U.S. Census Bureau using computer algorithms to adjust for diabetes risk factors — such as obesity, exercise, ethnicity and population density — and found that 10 micrograms of particulates per cubic meter air was correlated with a 1 percent increase in the rate of diabetes. Study co-author John Brownstein toldUSA Today that "[they] didn't have data on individual exposure, so [they] can't prove causality, and [they] can't know exactly the mechanism of these peoples' diabetes, but pollution came across as a significant predictor in all [their] models." He subsequently suggests that the data reflect inadequate EPA safety limits for air pollution.

USA Today is a newspaper, so its goal is to gain readership — and people are definitely going to read a headline that says ‘Study strongly links adult diabetes to air pollution — but the story is nonsensical; did they really have to run that story?” asks ACSH's Dr. Elizabeth Whelan.

“These macro-trend studies of zip codes and countywide areas where they monitor some outcome — they’re complete junk,” says ACSH’s Dr. Gilbert Ross. “Even the authors essentially admit that this is not a prospective study. These are all estimates. How do you correct in a countywide area for obesity or population density? A mantra for computer algorithms is ‘GIGO,’ or garbage in, garbage out: if you plug enough estimates into an algorithm, it will give you what amounts to a sort-of educated guess back.”

ACSH’s Dr. Josh Bloom also does not believe that the data adequately adjust for confounding diabetes risk factors. “I believe air pollution is irrelevant. The data reflect the reality that people living in poor neighborhoods get worse air and are more obese and ultimately exhibit higher rates of diabetes. To me, this makes more sense.”