Removal of chloramphenicol antibiotics in natural and engineered water systems: Review of reaction mechanisms and product toxicity

Chloramphenicol antibiotics are widely applied in human and veterinary medicine. They experience natural attenua-tion and/or chemical degradation during oxidative water treatment. However, the environmental risks posed by the transformation products of such organic contaminants remain largely unknown from the literature. As such, this re-view aims to summarize and analyze the elimination efficiency, reaction mechanisms, and resulting product risks of three typical chloramphenicol antibiotics (chloramphenicol, thiamphenicol, and florfenicol) from these transforma-tion processes. The obtained results suggest that limited attenuation of these micropollutants is observed during hydro-lysis, biodegradation, and photolysis. Comparatively, prominent abatement of these compounds is accomplished using advanced oxidation processes; however, efficient mineralization is still difficult given the formation of recalcitrant products. The in silico prediction on the multi-endpoint toxicity and biodegradability of different products is systema-tically performed. Most of the transformation products are estimated with acute and chronic aquatic toxicity, genotox-icity, and developmental toxicity. Furthermore, the overall reaction mechanisms of these contaminants induced by multiple oxidizing species are revealed. Overall, this review unveils the non-overlooked and serious secondary risks and biodegradability recalcitrance of the degradation products of chloramphenicol antibiotics using a combined exper-imental and theoretical method. Strategic improvements of current treatment technologies are strongly recommended for complete water decontamination.

Automated summary

This review summarizes the elimination efficiency, reaction mechanisms, and resulting product risks of chloramphenicol antibiotics during different environmental treatment processes. It reveals the non-overlooked secondary risks and biodegradability recalcitrance of the degradation products.