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

Abstract

Purpose: To investigate the association of long-term exposure to ambient air pollution with serum liver enzymes in older adults.

Methods: 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 (PM_2.5), 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.

Results: Each interquartile range (IQR) increase of PM_2.5, 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 PM_2.5, 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.

Conclusions: 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.

Keywords: Alanine aminotransferase; Ambient air pollution; Aspartate aminotransferase; Liver enzymes; Older adults.