A review of ecotoxicity and developmental toxicity of disinfection byproducts (DBPs): Are aromatic DBPs more toxic than aliphatic DBPs?

Aromatic disinfection byproducts (DBPs) were suggested to exhibit greater ecotoxicity and developmental toxicity than regulated DBPs. However, a systematic comparison of ecotoxicity/developmental toxicity between aromatic and aliphatic DBPs remains lacking. Herein, we aim to provide a comprehensive evaluation of the ecotoxicity and developmental toxicity of DBPs by analyzing epidemiological evidence, aquatic toxicity data (EC50), TIC-Tox calculations, and quantitative structure-activity relationship (QSAR) modelling. Epidemiological evidence suggests that DBP exposures are associated with low birth weight, small for gestational age, and neurodevelopmental defects. In terms of aquatic ecotoxicity studies, ecotoxicity data of aliphatic DBPs has been studied more extensively than aromatic DBPs. Overall, the ecotoxicity of aromatic DBPs is significantly higher than that of aliphatic DBPs, both in aquatic animals (median: 0.09 mmol/L vs. 1.34 mmol/L) and green algae (median: 0.04 mmol/L vs. 0.24 mmol/L). TIC-Tox calculations showed that aliphatic DBPs in drinking water, wastewater, and surface water generally contribute more to ecotoxicity than known aromatic DBPs. Currently published QSAR models typically focused on a specific class of DBPs and a specific type of species, limiting their generalizability. To address this limitation, we developed nine universal QSAR models based on existing data, fitting multiple classes of DBPs and various species, which can be used for cross-species ecotoxicity prediction. Our findings suggest that in aliphatic DBPs, the sum of valence degrees (SVD) may be a significant molecular descriptor, while in aromatic DBPs, radius may play a crucial role.