Fluorinated Liquid Crystal Monomers in Human Urine: Occurrence, Demographic Associations, and Health Risk Assessment in a Cohort of 150 Couples

Abstract

Fluorinated liquid crystal monomers (FLCMs) represent an emerging class of environmental contaminants characterized by persistence, bioaccumulation potential, and suspected toxicity; however, knowledge of exposure profiles and associated health risks in the general population remain inadequate. This study systematically investigated the occurrence of 50 FLCMs in 300 urine samples collected from 150 couples living in Tianjin, China. Among the 50 target analytes, 42 were detected, with total FLCM concentrations (∑FLCMs) ranging from 1.59 to 34.60 ng/mL (median: 7.45 ng/mL), which were substantially higher than reported urinary levels in Beijing and Guangdong populations. The predominant compounds identified were DTMTPT (4-[difluoro(3,4,5-trifluorophenoxy)methyl]-2′,3,5-trifluoro-4′-pentyl-1,1′:4′,1′-terphenyl), CFPEB (3-fluoro-4-cyanophenyl 4-ethylbenzoate), EDPBB (1-ethoxy-2,3-difluoro-4-[(trans,trans)-4′-propyl[1,1′-bicyclohexyl]-4-yl]benzene), DPPCB (2,3-difluoro-1-propoxy-4-[(trans,trans)-4′-propyl[1,1′-bicyclohexyl]-4-yl]benzene), and EFPT (4″-ethyl-2′-fluoro-4-propyl-1,1′:4′,1″-terphenyl), with DTMTPT and CFPEB representing the largest contributions at 20.5% and 19.1% of total concentrations, respectively. Demographic analysis revealed that urinary EFPT concentrations were significantly lower in females than in males (P < 0.05), and gender exerted a more pronounced influence on exposure than cohabitation. Individuals aged <30 years exhibited marginally elevated FLCM exposure compared to those ≥30 years, whereas body mass index, smoking status, and alcohol consumption showed no significant associations with urinary FLCM concentrations (P > 0.05). Correlation analysis and molecular docking simulations demonstrated that CFPEB and DTMTPT were significantly positively correlated with serum alanine aminotransferase levels (P < 0.05), and all five major FLCMs exhibited stable binding affinities to the aryl hydrocarbon receptor (AhR), suggesting potential hepatotoxicity. Screening-level hazard quotient (HQ) assessment indicated low health risks under current exposure scenarios. This study addresses a critical data gap regarding FLCM exposure in the general adult population of China and provides foundational data and scientific evidence for characterizing human exposure patterns and informing risk management strategies for this emerging contaminant class.