Environmental behavior, human exposure, and elimination technology of fluorinated liquid crystal monomers: A review

Abstract

Fluorinated liquid crystal monomers (FLCMs), widely employed in liquid crystal displays, are emerging organofluorine compounds that are characterized by their universal presence, environmental persistence, and potential endocrine/developmental toxicity. This review emphasizes on the existing knowledge on their physicochemical properties, ecological distribution, human-exposure routes, transformation pathways, and elimination technologies. Some FLCMs exhibit atmospheric persistence, bioaccumulation and various toxicities, despite significant deviations between their measured and predicted characteristics. However, their persistence in soil and water remains largely unknown, hindering their comprehensive environmental risk assessment. A narrow array of FLCMs is frequently detected in diverse ecological and biotic matrices; however, monitoring is currently limited to a few countries and regions. E-waste dismantling is recognized as a significant source of FLCMs in the environment, investigate their distribution and exposure risks in developing countries associated with e-waste dismantling is highly needed. Analytical methods combined with nontargeted screening can provide a solution for identifying a wider range of these compounds. Prior evidence has indicated that dietary ingestion is predominant human-exposure pathway, with infants experiencing higher exposure levels than adults. Considering their detection frequency, persistence, bioaccumulation, toxicity, and potential for human exposure, several FLCMs have been selected as priority compounds for future monitoring and research. FLCMs can undergo photo- and biotransformation, which can generate potentially toxic transformation products. The ecological and health risks posed by FLCMs and their transformation products underscore the urgent need for bringing up more effective and environmentally friendly remediation technologies.