20 July 2012
Diesel fumes causing waistlines to bulge?
by Will Parker
Pregnant mice exposed to diesel exhaust pollution gave birth to offspring with a significantly higher rate of obesity and insulin resistance in adulthood. The effect, say the researchers, was especially prevalent in male mice, which were heavier regardless of diet. The findings were published in the Federation of American Societies for Experimental Biology's FASEB Journal. The new study builds on decade-old work that showed a strong correlation between air pollution and diabetes prevalence.
To make the new discovery, Duke University's Jessica L. Bolton used two groups of pregnant female mice, one of which was exposed to diesel exhaust during the latter half of pregnancy. The second group was exposed to filtered air for the same time period. The mice lived in specialized chambers for four hours each day breathing polluted air and then were returned to normal housing after these exposures.
Prior to birth, some of the fetal brains of the mice from both groups were analyzed to measure immune proteins and to get a snapshot of the fetal brain immune response to the in utero conditioning. Once the offspring were adults, they were placed on either a low-fat diet (10% saturated fat) or a high-fat diet (45% saturated fat). All other nutritional aspects of the diets were identical.
The researchers measured food intake, body weight and activity levels before putting the mice on their diets, and then weekly throughout the experiment. At the end of six weeks, metabolic hormones were assessed. They found that males from diesel-exposed moms were heavier than the males from clean air-exposed moms regardless of their diet as adults.
In contrast, females from diesel-exposed moms were heavier than control females only if they were fed a high-fat diet as adults, and they never developed signs of insulin resistance.
"It is becoming clearer that our environment profoundly affects our health in ways that are little understood," said Bolton. "We believe these data have important implications for health disparities as a consequence of socioeconomic conditions, in which low income neighborhoods tend to be disproportionately exposed to high levels of pollution, which we hope will inform policy and regulation decisions."
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