A Toxicity Equivalent Scheme of Caenorhabditis elegans for Assessing the Risk of Wastewater

This is the authors' abstract. We don't add key points for this paper.

Effect-based methods for water-quality evaluation attract increasing attention. However, most of them lack an effective toxicity measurement medium, which hinders their comparability across batches and laboratories. This study proposes a toxicity-equivalent scheme for Caenorhabditis elegans for mixed pollutants in wastewater. First, effluent samples from municipal and industrial wastewater treatment plants (WWTPs) were used to determine the effect intervals on body length, mean amplitude, swimming speed, and activity of C. elegans. Transcriptomic analysis revealed that wastewaters induced toxicity by activating defense responses and disturbing cuticle structure and function. Subsequently, the effect intervals of 29 compounds were evaluated, among which triclocarban showed the highest overlap with those of the wastewaters. Molecular docking and gene expression profiles showed that triclocarban induced toxicity by activating defense responses and cuticle sensors, primarily through receptors such as TPH-1, SKN-1, SOD-3, and GST-4, which were consistent with those of wastewaters. Thus, triclocarban was used to establish a biological equivalence concentration scheme. This scheme was applied to evaluate 83 wastewaters, revealing hidden health risks that traditional chemical indicators overlooked. This study offers a paradigm for determining toxicity-equivalent schemes for in in vivo bioassays and effect-based quantitative evaluations of water quality risks.