Occurrence and Environmental Risk of Liquid Crystal Monomers - An Emerging Group of E-waste Pollutants Found in Municipal Wastewater

Project: Research

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Global LCD panel production is continuously growing due to increasing demand for consumer electronic devices (e-devices), such as cellphones, tablets, laptops, and smart televisions. During the lifecycle of LCD panels, many organic compounds can be released as environmental contaminants, including liquid crystal monomers (LCMs). LCMs are the critical materials used in manufacturing LCD panels, which have recently been proposed as an emerging group of persistent, bioaccumulative, and toxic pollutants. LCMs have been detected in indoor air, household dust, and sediment near e-waste recycling facilities. Based on the structure and physicochemical properties, it has been proposed that LCMs exposure could cause adverse effects on animals. However, relevant studies of LCMs regarding their unknown analogs, analytical methods, contamination levels, distributions, sources, fates, and ecotoxicity in aquatic environments are extremely limited. We conducted a preliminary study that indicates LCMs pollutants could enter the marine environment through the effluent of wastewater treatment plants (WWTPs) and propose that this may cause adverse impacts on marine organisms. Herein, a combined chemical and ecotoxicological study is proposed. Using GC-Orbitrap-MS/MS, we will develop the analytical methods for quantifying 64 target LCMs and establish suspect and nontarget screening methods for identifying unknown LCMs analogs in aqueous and particulate phases of municipal wastewater. Second, we will test the hypothesis that WWTP effluent is a significant source of LCMs entering the environment by quantifying LCMs/LCMs analogs in the influent, effluent, and sludge of municipal wastewater collected from 3 local WWTPs. Moreover, we will determine LCMs removal efficiencies under different WWTP treatment processes. In concert, we will conduct an ecotoxicological risk assessment on “LCMs of concern” using both computational estimation and a battery of in vivo bioassays on marine microalgae, copepods, and medaka fish. Finally, the top 3 acutely toxic LCMs will be tested for chronic toxicity using medaka fish to address their potentials for bioconcentration and elucidate their toxic mechanism(s) by investigating altered gene expression profiles using transcriptomic sequencing analysis. The results of this study will advance our understating of the occurrence of LCMs in municipal wastewater and their environmental risks to marine organisms. The results of our environmental risk assessment will inform the regulation and management of LCMs, enabling better protection of coastal marine ecosystems in highly urbanized estuaries like Hong Kong and the Pearl River Estuary. This study will place Hong Kong at the forefront of regional and global research efforts to assess and manage emerging e-device/e-waste organic pollutants. 


Project number9043378
Grant typeGRF
StatusNot started
Effective start/end date1/01/23 → …