Emission Dynamics and Global Exposure Risks of Liquid Crystal Monomers from Indoor Electronic Devices

Liquid crystal monomers (LCMs) are emerging indoor pollutants of global concern. Indoor surface reservoirs can affect the capacity of indoor environments to emit and transport LCMs, together with increasing exposure for indoor residents. This study investigates the complex dynamics of LCM emissions in indoor surface environments through field investigations and environmental modeling. Emission profiles of LCMs from indoor electronic devices (e-devices) to source and nonsource surface environments follow different transfer behaviors. The physicochemical properties of LCMs and the characteristics of surface environments collectively influence their emission and persistence. Surface environments can re-emit LCMs, leading to prolonged and multiple exposure scenarios for residents. The annual global unintentional emissions of LCMs from indoor e-devices are estimated using the obtained emission factors for the first time. Results indicate that while substantial emissions originate from North America and Europe, high exposure risks occur in low-income nations. Past usage and disposal of e-devices have contributed to an underreported accumulation of LCMs in the global environment. Our findings provide a critical foundation for developing strategies to reduce emissions and migration of LCMs indoors, thereby minimizing human exposure.