Air pollution increases bone loss from osteoporosis

In the United States, about 2.1 million osteoporosis-related bone fractures occur each year, resulting in $20.3 billion in annual direct health costs. Osteoporosis disproportionally impacts women compared to men, with 80 percent of the ten million Americans suffering from this disease being females. Moreover, postmenopausal women appear to be at higher risk, with one in two women older than 50 experiencing bone fractures due to osteoporosis.

Now, a team of researchers led by Columbia University has found that high levels of air pollution are associated with bone damage among postmenopausal women. These negative effects were most evident on the lumbar spine, with nitrous oxides – a type of pollutants found in car and truck exhaust and emissions from electrical power generation plants – twice as damaging to this area than seen during normal aging.

While previous studies on individual pollutants have examined their adverse effects on bone mineral density, osteoporosis risk, and fractures in older individuals, this is the first study to comprehensively assess the connection between air pollution and bone mineral density in postmenopausal women, as well as the first to explore the impact of air pollution mixtures on bone outcomes.

The experts examined data on an ethnically diverse cohort of 161,808 postmenopausal women and estimated their exposure to several pollutants (PM10, NO, NO2, and SO2) based on their home addresses. In order to clarify the impact of these pollutants, they measured bone mineral density (BMD) in the whole body, total hip, femoral neck, and lumbar spine at enrollment, as well as after one, three, and six years.

The analysis revealed that the effect of nitrous oxides on lumbar spine BMD would amount to 1.22 percent annual reductions, which is nearly double the effect of age on any of the anatomical sites evaluated. According to the researchers, these effects happen most likely through bone cell death caused by oxidative stress and other mechanisms.

“Our findings confirm that poor air quality may be a risk factor for bone loss, independent of socioeconomic or demographic factors. For the first time, we have evidence that nitrogen oxides, in particular, are a major contributor to bone damage and that the lumbar spine is one of the most susceptible sites of this damage,” reported study lead author Diddier Prada, an expert in Environmental Health Science at Columbia.

“Improvements in air pollution exposure, particularly nitrogen oxides, will reduce bone damage in postmenopausal women, prevent bone fractures, and reduce the health cost burden associated with osteoporosis among postmenopausal women. Further efforts should focus on detecting those at higher risk of air pollution-related bone damage,” concluded senior author Andrea Baccarelli, the Chair of the Department of Environmental Health Sciences at the same university.

The study is published in the journal EClinicalMedicine.

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By Andrei Ionescu, Earth.com Staff Writer

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