A study of the correlation between urinary perchlorate, nitrate, thiocyanate, and serum liver function indices

This study explored relationship between concentrations of perchlorate, nitrate, and thiocyanate and serum liver function markers using data from 3366 adults in the 2013-2018 National Health and Nutrition Examination Survey (NHANES) of the United States. Generalized linear model (GLM), restricted cubic spline (RCS) regression model, and quartile g-computation (Qgcomp) regression model were used to assess the relationship. The median concentrations of perchlorate, nitrate, and thiocyanate in urine were 2.33, 42,900, and 1060 ng/mL. The median concentrations for serum liver function indicators were albumin (ALB, 4.2 g/dL), alkaline phosphatase (ALP, 67 IU/L), aspartate aminotransferase (AST, 22 U/L), alanine aminotransferase (ALT, 20 U/L), globulin (GLB,2.9 g/dL), gamma-glutamyl transferase (GGT, 20 IU/L), lactate dehydrogenase (LDH, 132 IU/L), total bilirubin (TBIL, 0.5 mg/dL), total protein (TP, 7.1 g/dL). Adjusted GLM results showed perchlorate was positively correlated with AST and ALT, but negatively with ALP, GLB, GGT, LDH, and TP. Nitrate correlated positively with ALB, AST and ALT, and negatively with GLB and GGT. Thiocyanate was positively correlated with ALP, and negatively with AST, ALT, GLB, LDH, TBIL, and TP. RCS analysis, adjusted for confounders, revealed non-linear relationships for perchlorate with LDH, TBIL, and TP (P-overall < 0.0001, P-nonlinear < 0.05), for thiocyanate with ALB, ALP, ALT, and TBIL (P-overall < 0.0001, P-nonlinear < 0.05). Qgcomp results suggested that exposure to these chemicals was negatively correlated with GLB, TBIL and TP. The study found complex correlations between chlorate, nitrate and thiocyanate concentrations and serum liver function indices.