Independent and Combined Associations of Serum Lead, Mercury, Cadmium, Along with Fluoride and Liver Function Among Adolescents in NHANES 2013-2016

Although growing evidence suggests that lead (Pb), mercury (Hg), cadmium (Cd), and fluoride (F) might induce liver impairment, the combined effects of these environmental pollutants on adolescent liver function remain unknown. To explore the independent and combined correlations between Pb, Hg, Cd, and F exposure and liver function in adolescents, we used data among 1001 adolescents from the National Health and Nutrition Examination Survey (NHANES) 2013-2016. We investigated the independent and combined association between four serum environmental pollutants and seven serum indicators of liver function: alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), total bilirubin (TB), total protein (TP), and albumin (ALB). Multivariate linear regression was performed to assess the independent associations between exposure and altered liver function. The weighted quantile sum (WQS) regression model and the quantile g-computation model (qgcomp) were applied to estimate the combined association between environmental pollutants exposure and liver function. We found a statistically significant positive association between Pb and ALP as well as Hg and TBIL, while negative association between F and both TP and ALB. The WQS analysis showed that the WQS index was positively correlated with ALP and TBIL but negatively correlated with TP and ALB. Additionally, the qgcomp analysis showed that the qgcomp index was adversely associated with TP and ALB. Furthermore, in the combined exposure model, F was the leading contributor to the TP and ALB reduction. Our findings provide new evidence that exposures to Pb, Hg, Cd, and F might be adversely associated with liver function alterations in adolescents, either independently or in combination. Given the cross-sectional nature of the NHANES, more prospective research to elaborate on these findings is necessary.