Fluorinated liquid-crystal monomers distribution in paired urine from mothers and infants

Fluorinated liquid-crystal monomers (FLCMs) are widespread environmental contaminants with potential endocrine-disrupting effects. Infants are particularly vulnerable, yet their exposure remains unclear. This study analyzed FLCMs in urine samples from 190 paired mothers and infants in Beijing, detecting 34 and 35 FLCMs, respectively. Median creatinine-corrected concentrations were 1.83 μg/g (unadjusted concentrations: 1.28 ng/mL) for mothers and 3.28 μg/g (0.60 ng/mL) for infants. 1-butoxy-2,3-difluoro-4-(trans-4-propylcyclohexyl) benzene (BDPrB) and 1-ethyl-4-[(4-fluorophenyl) ethynyl] benzene (EFPEB) were identified as the primary detected contaminants. A significant positive correlation in urine concentrations between mothers and infants was observed only for 2'-Fluoro-4″-propyl-[1,1':4',1″-terphenyl]-4-carbonitrile (FPTC) (r_s = 0.23, p = 0.023). Certain FLCMs were associated with infant feeding patterns, maternal parity, and environmental exposure, including dust and cleaning frequency (p < 0.05). The results of the study showed that the median estimated daily intakes (EDIs) of ∑FLCMs for mothers and infants were 526 and 425 ng/kg bw/day, respectively, with no significant difference between them (p > 0.05). Further stratification of the data by sex revealed that for male infants, the EDI values for BDPrB and EFPEB were greater (p < 0.05). These findings emphasize the need for greater research on the health effects of FLCMs on infants, particularly considering gender differences.