Air pollution and bone health outcomes: Periods of susceptibility from pregnancy to childhood

Background: 

Early life exposure to environmental factors can impact skeletal development. We aimed to identify periods of susceptibility to air pollution in early life in relation to bone health outcomes at age six. 

Methods: 

Data were from the Generation R study, a population-based pregnancy cohort study, The Netherlands. We estimated daily concentrations of nitrogen dioxide (NO2) and particulate matter (PM10, PM2.5 and PM2.5 absorbance) at the home addresses during pregnancy and childhood, using land-use regression models. Bone mineral density and area-adjusted bone mineral content were measured by dual-energy x-ray absorptiometry at age six. We performed distributed lag modelling (DLM) adjusted for several socioeconomic characteristics to assess the associations between bone health and air pollution, using 28-day averaged exposure levels, and identify windows of susceptibility. 

Results: 

Among 5966 children, we identified windows of susceptibility from ∼ 1 to ∼ 4 years of age for PM2.5 and PM2.5 absorbance with bone mineral density (e.g., −10.3; 95 % CI −15.8 to −4.7 per 5 µg/m³ increase in PM2.5) and for all air pollutants with bone mineral content (e.g., −14.6; 95 % CI −20.7 to −8.4 per 5 µg/m³ increase in PM2.5). Also, we identified an association between NO2 and PM2.5 absorbance during pregnancy and higher bone mineral content (e.g., 4.0; 95 % CI 1.4 to 6.6 per 10^-5 m⁻¹ increase in PM2.5 absorbance). In the sex-stratified analyses, associations across all exposures and outcome measures were in the same direction for both sexes, and similar to the main analyses, but statistically significance was observed only in boys. 

Conclusions: 

Our findings suggest that exposure to air pollutants during childhood may already lead to poorer bone health outcomes.