Long-term exposure to ambient air pollution and serum liver enzymes in older adults: A population-based longitudinal study

To investigate the association of long-term exposure to ambient air pollution with serum liver enzymes in older adults. In this longitudinal study, we investigated 318,911 adults aged 65 years or older and assessed their long-term residential exposure to particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5), particulate matter with an aerodynamic diameter ≤10 µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). Linear mixed models and generalized linear mixed models were implemented for exposure-response analyses. Each interquartile range (IQR) increase of PM2.5, PM10, SO2, NO2, CO, and O3 exposures was significantly associated with a 4.6%, 4.6%, 5.6%, 4.6%, 6.2%, and 3.6% increase in alanine aminotransferase (ALT), and a 4.6%, 5.2%, 3.6%, 3.3%, 6.1%, and 4.0% increase in aspartate aminotransferase (AST), respectively. Each IQR increase of PM2.5, PM10, SO2, NO2, CO, and O3 exposures was significantly associated with a 23%, 24%, 28%, 17%, 31%, and 19% increase in odds of elevated ALT (>40 U/L), and a 32%, 39%, 40%, 32%, 57%, and 25% increase in odds of elevated AST (>40 U/L), respectively. Long-term exposure to ambient air pollution was significantly associated with increased serum liver enzyme levels in older adults, suggesting that air pollution exposures may induce hepatocellular injury.