Short-term effects of air pollution on liver function among urban adults in China

Urban environmental air pollution has become a serious public issue in China. However, the potential adverse effects of different air pollutants on liver function are still unclear. We aimed to explore the associations of air pollutants exposure with liver function, and analyzed short-term impact in two cities with different levels of air pollution. We included 3892 residents from the Wuhan (high-pollution area)-Zhuhai (low-pollution area) cohort. Liver enzymes including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in fasting peripheral blood were determined by a fully automatic biochemical analyzer. Individual air pollutants inhalation exposure was estimated by combining his/her daily breathing volume and the concentrations of six air pollutants, including particulate matter (PM2.5), inhalable particulate matter (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO) and ozone (O3), from local ambient air monitoring stations. The associations of air pollutants with ALT and AST were evaluated using linear mixed models. We found positive associations of PM2.5 (lag01-lag07), PM10 (lag01-lag07), NO2 (lag01-lag07), SO2 (lag01-lag07), CO (lag01-lag06) and O3 (lag01-lag02) with ALT and PM10 (lag04-lag07) with AST. In Wuhan, exposure to PM2.5 (lag01-lag07), PM10 (lag01-lag07), NO2 (lag01-lag07) and SO2 (lag01-lag07) was associated with increased ALT, and PM10 (lag04-lag07) and NO2 (lag01-lag03) exposure was significantly associated with increased AST. While in Zhuhai, although all six air pollutants (PM2.5 [lag01-lag07], PM10 [lag01-lag02], NO2 [lag01-lag04], SO2 [lag01-lag03], CO [lag01-lag07] and O3 [lag01-lag03]) were significantly associated with increased ALT, no pollutant was significantly associated with increased AST. Our results suggest that short-term exposure to air pollutants has adverse effects on liver function among urban adults. Such adverse effects last longer in high-pollution area than that in low-pollution area.