Distinct profiles and elevated exposure to liquid crystal monomers in urban areas: Insights from indoor dust across China.

Liquid crystal monomers (LCMs) added in liquid crystal displays (LCDs) are emerging contaminants. While indoor LCD emissions are a potential exposure source, the correlation between LCM concentrations and device numbers, along with urban-rural differences, remains uncharacterized. In this study, indoor dust samples from 10 provinces in China were collected and 60 LCMs were determined. Significant positive correlation (P < 0.05) was observed between LCM concentrations and the numbers of electronic devices. The concentrations of LCMs in the dust from urban areas (78.7-2730 ng/g, average: 565 ng/g) were statistically higher than those from rural areas (57.8-2050 ng/g, average: 386 ng/g). The compositions of LCMs in dust samples from urban and rural areas were considerably different. Trans-1-ethoxy-4-(4-pentylcyclohexyl)benzene was the dominant LCM in urban dust, while 4-[difluoro(3,4,5-trifluorophenoxy)methyl]-3,5-difloro-4'-propyl-biphenyl was the dominant LCM in rural dust. Median daily intakes of LCMs through dust ingestion were 0.984 and 0.093 ng/kg BW/day for children and adults, while those through dermal absorption were 0.818 and 0.184 ng/kg BW/day. This study highlights the urban-rural disparities, thus providing crucial insights for targeted pollution control strategies and public health interventions.