Emerging organic contaminants of liquid crystal monomers: Environmental occurrence, recycling and removal technologies, toxicities and health risks

Abstract

Liquid crystal monomers (LCMs) are a family of synthetic organic chemicals applied in the liquid crystal displays (LCDs) of various electric and electronic products (e-products). Due to their unique properties (i.e., persistence, bioaccumulative potential, and toxicity) and widespread environmental distributions, LCMs have attracted increasing attention across the world. Recent studies have focused on the source, distribution, fate, and toxicity of LCMs; however, a comprehensive review is scarce. Herein, we highlighted the persistence and bioaccumulation potential of LCMs by reviewing their physical–chemical properties. The naming rules were suggested to standardize the abbreviations regarding LCMs. The sources and occurrences of LCMs in different environmental compartments, including dust, sediment, soil, leachate, air and particulate, human serum, and biota samples, were reviewed. It is concluded that the LCMs in the environment mainly originate from the usage and disassembly of e-products with LCDs. Moreover, the review of the potential recycling and removal technologies regarding LCMs from waste LCD panels suggests that a combination of natural attenuation and physic-chemical remediation should be developed for LCMs remediations in the future. By reviewing the health risks and toxicity of LCMs, it is found that a large gap exists in their toxicity and risk to organisms. The fate and toxicity investigation of LCMs, and further investigations on the effects on the human exposure risks of LCMs to residents, especially to occupational workers, should be considered in the future.

Keywords

• Liquid crystal monomers
• Occurrences
• Removal
• Human exposure
• Toxicity