Associations Between Urinary Metabolites of Polycyclic Aromatic Hydrocarbons and Liver Enzyme Levels among Korean Firefighters

Abstract

Objectives: Polycyclic aromatic hydrocarbons (PAHs), byproducts of incomplete combustion of organic compounds, have been linked to various adverse health outcomes; however, evidence associating PAHs with liver damage remains inconsistent. This study aimed to investigate the relationship between PAH exposure and liver enzyme levels among firefighters, who have an increased risk of PAH exposure.

Methods: A total of 961 firefighters were included in the study. Urinary concentrations of 4 PAH metabolites (2-naphthol, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxypyrene) were measured and categorized into quartiles. Serum levels of liver enzymes, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were evaluated. Age, smoking status, alcohol consumption, body mass index (BMI), job position, and self-reported disease history were adjusted as covariates. Multivariable linear regression analyses were conducted to assess the association between PAH metabolites and serum AST and ALT levels. Logistic regression analyses evaluated associations between PAH metabolites and abnormal AST and ALT levels, defined as 40 IU/L or higher.

Results: Participants in the highest quartile of urinary 2-naphthol had an increased risk of abnormal ALT levels compared to those in the lowest quartile (odds ratio, 2.00; 95% confidence interval, 1.09-3.65). No significant associations were observed for the other PAH metabolites. The association between urinary 2-naphthol and abnormal ALT levels did not differ significantly by smoking status, alcohol consumption, or BMI.

Conclusions: Elevated urinary 2-naphthol levels were associated with abnormal liver enzyme levels among firefighters, suggesting that monitoring and managing PAH exposure may help protect liver health in this occupational group.

Keywords: Firefighters; Liver function tests; Polycyclic aromatic hydrocarbons.