In Vivo Bioavailability of Liquid Crystal Monomers (LCMs) in Indoor Dust: Implications for Human Oral Exposure

Liquid crystal monomers (LCMs), widely detected in indoor dust at elevated levels, have been scarcely investigated for their relative bioavailability (RBA) via oral exposure. This study classified 35 typical LCMs into three groups based on structure, namely, fluorinated LCMs (Group A, without ether or nitrile groups), cyanated LCMs (Group B, with nitrile functional groups), and others with ether bonds or unsubstituted benzene rings (Group C). For the distribution in mice, LCMs predominantly accumulated in adipose tissue, with mean concentrations of 502 ng g^-1 (Group A) > 159 ng g^-1 (Group B) ≈ 147 ng g^-1 (Group C). All 35 LCMs were detectable in feces, with a log K_ow of 9 as a critical threshold distinguishing gradual versus rapid excretion. Nine stable, frequently detected LCMs were selected for RBA assessment in indoor dust using adipose tissue as the biological end point. The RBA of the 9 LCMs in dust ranged from 8.32 to 108%, highlighting that assuming 100% bioavailability would overestimate the exposure risk of LCMs in dust. A significantly negative correlation (p < 0.01) was found between the total organic carbon (TOC) content of dust and RBA, likely due to the strong adsorption of LCMs by TOC.