Importance

Air pollution is a major threat to global health. Osteoporosis is responsible for a substantial burden of disease globally and is expected to increase in prevalence because of population aging. Few studies have investigated the association between air pollution and bone health, and their findings were inconclusive.

Objective

To quantify the association between ambient and household air pollution and bone mass in a sample of the general population in peri-urban India.

Design, Setting, and Participants

This was a population-based cross-sectional analysis of the Andhra Pradesh Children and Parents Study cohort, which recruited participants from 28 villages near Hyderabad, South India, during 2009 to 2012. Separate linear mixed models were fitted with nested random intercepts (household within villages) for each exposure-outcome pair and were sequentially adjusted for potential confounders. Data analysis was conducted between April 2019 and July 2019.

Exposures

Annual mean ambient particulate matter air pollution less than 2.5 µm in aerodynamic diameter (PM_2.5) and black carbon (BC) levels at the residence estimated by land-use regression and self-reported use of biomass cooking fuel.

Main Outcomes and Measures

The primary outcome was bone mineral content (BMC) measured in grams, corrected by bone area at the lumbar spine and left hip, as measured by dual-energy x-ray absorptiometry. The secondary outcome was bone mineral density measured in grams per centimeters squared.

Results

A total of 3717 participants were analyzed (mean [SD] age, 35.7 [14.0] years; 1711 [46.0%] women). The annual mean (SD) PM_2.5exposure was 32.8 (2.5) μg/m³, and the annual mean (SD) BC exposure was 2.5 (0.2) μg/m³; 57.8% of participants used biomass cooking fuels. In fully adjusted models, PM_2.5was associated with lower BMC in the spine (mean difference, −0.57 g per 3 μg/m³increase in PM_2.5; 95% CI, −1.06 to −0.07 g per 3 μg/m³increase in PM_2.5) and hip (mean difference, −0.13 g per 3 μg/m³increase in PM_2.5; 95% CI, −0.3 to 0.03 g per 3 μg/m³increase in PM_2.5). After confounder adjustment, exposure to PM_2.5was also associated with lower bone mineral density in the spine (mean difference, −0.011 g/cm²per 3 μg/m³increase in PM_2.5; 95% CI, −0.021 to 0 g/cm²per 3 μg/m³increase in PM_2.5) and hip (mean difference, −0.004 g/cm²per 3 μg/m³increase in PM_2.5; 95% CI, −0.008 to 0.001 g/cm²per 3 μg/m³increase in PM_2.5). Exposure to BC was associated with lower BMC in the spine (mean difference, −1.13 g per 1 μg/m³increase in BC; 95% CI, −2.81 to 0.54 g per 1 μg/m³increase in BC) and hip (mean difference, −0.35 g per 1 μg/m³increase in BC; 95% CI, −0.96 to 0.25 g per 1 μg/m³increase in BC), although the confidence intervals were wider. There was no association between biomass fuel use and spine BMC (mean difference, 0.12 g; 95% CI, −0.45 to 0.68 g).

Conclusions and Relevance

In a cross-sectional analysis of a population-based cohort, ambient air pollution was associated with lower BMC in a young adult population in a peri-urban area of South India.

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References