Urinary exposure to liquid crystal monomers (LCMs) in children near e-waste recycling sites: Occurrence and implications for physical growth

Liquid crystal monomers (LCMs) are emerging contaminants extensively used in electronic displays, yet human exposure assessment studies remain scarce, particularly among children. This study presents the first comprehensive assessment of urinary LCMs in 194 children living near e-waste recycling areas in South China. Eighteen of thirty target LCMs were detected, with significantly higher concentrations in exposed children (median = 8.76 ng/mL) than in the reference group (median = 5.36 ng/mL, p = 0.013). Cyanobiphenyls (CBA) were the predominant LCMs, followed by biphenyls (BA), with substantially lower levels of fluorinated biphenyls (FBA). Urinary LCM levels were negatively correlated with log Kow (r = -0.76, p = 0.007) and molecular weight (r = -0.74, p = 0.008), indicating preferential urinary excretion of LCM with lower weight and hydrophobicity. School-age children (≥5 years) showed significantly higher total urinary LCM concentrations, and the estimated daily excretion in exposed children reached 210.5–256.0 ng/kg bw/day, with FBA excretion 45 % higher than reference group. Crucially, higher urinary FBA/CBA levels were positively associated with head and chest circumferences, especially in girls and preschoolers (<5 years). These findings provide timely evidence of significant LCM exposure burdens in children, highlighting the vulnerability of pediatric development health to emerging contaminants.