Boston, Mass. -- A national epidemiologic study finds a strong, consistent correlation between adult diabetes and particulate air pollution that persists after adjustment for other risk factors like obesity and ethnicity, report researchers from Children's Hospital Boston. The relationship was seen even at exposure levels below the current EPA safety limit.
The report, published in the October issue of Diabetes Care, is among the first large-scale population-based studies to link diabetes prevalence with air pollution. It is consistent with prior laboratory studies finding an increase in insulin resistance, a precursor to diabetes, in obese mice exposed to particulates, and an increase in markers of inflammation (which may contribute to insulin resistance) in both the mice and obese diabetic patients after particulate exposure.
Like the laboratory studies, the current study focused on fine particulates of 0.1-2.5 nanometers in size (known as PM2.5), a main component of haze, smoke and motor vehicle exhaust. The investigators, led by John Pearson and John Brownstein, PhD, of the Children's Hospital Informatics Program, obtained county-by-county data on PM2.5 pollution from the Environmental Protection Agency (EPA), covering every county in the contiguous United States for 2004 and 2005.
They then combined the EPA data with data from the Centers for Disease Control (CDC) and the U.S. Census to ascertain the prevalence of adult diabetes and to adjust for known diabetes risk factors, including obesity, exercise, geographic latitude, ethnicity and population density (a measure of urbanization).
"We wanted to do everything possible to reduce confounding and ensure the validity of our findings," says Pearson, the study's first author.
In all analyses, there was a strong and consistent association between diabetes prevalence and PM2.5 concentrations. For every 10 μg/m3 increase in PM2.5 exposure, there was a 1
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Children's Hospital Boston