Bioaccumulation, metabolic transformation and toxicity mechanisms of typical fluorinated liquid crystal monomer in earthworms.

Abstract

Liquid crystal monomers (LCMs) have emerged as a class of environmental contaminants of global concern, with fluorinated LCMs raising particular alarm due to their higher detection frequencies and generally greater persistence and biotoxicity. Herein, we systematically investigated the bioaccumulation, metabolic transformation, and toxicological mechanisms of 4-[difluoro(3,4,5-trifluorophenoxy)methyl]-3,5-difluoro-4'-propylbiphenyl (DTMDPB), a representative fluorinated LCM, using the soil invertebrate model Eisenia fetida. Results showed that DTMDPB exhibited dose-dependent bioaccumulation across earthworm tissues, with preferential enrichment in the intestine, and induced excessive reactive oxygen species production and oxidative damage. We identified 23 potential transformation intermediates and elucidated dominant Phase-I (e.g., defluorination, and ether bond cleavage) and Phase-II (e.g., O-glycosylation, and malonylation) metabolic pathways of DTMDPB in E. fetida, revealing a potential dual detoxification-bioactivation effect during biotransformation. Intestinal metabolomics further demonstrated dose-dependent metabolic dysregulation, primarily involving carbohydrate, amino acid, and lipid metabolisms. Concomitantly, high-throughput sequencing uncovered marked gut microbiota dysbiosis, characterized by a compositional shift from Bacillota to Actinomycetota, increased microbial diversity and network complexity at low doses, and significantly reduced diversity and simplified microbial networks at high doses. This study provides the first comprehensive characterization of LCM bioaccumulation, biotransformation, and multi-level toxicological responses in soil invertebrates, offering a scientific foundation for LCM risk assessment in soil environments.

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