Water Quality Criteria for Freshwater Organisms and Ecological Risk Assessment of Clarithromycin

Clarithromycin (CLA) belongs to the macrolide class of antibiotics, which has a broad-spectrum antibacterial effect. The residue of CLA in the environment may pose potential hazards to aquatic organisms, while China lacks a freshwater biological water quality criteria for CLA. This study collected and screened acute and chronic toxicity data of CLA on freshwater organisms, obtaining 15 acute toxicity data from 5 phyla, 8 families, and 16 chronic toxicity data from 5 phyla, 6 families. Subsequently, the species sensitivity distribution method (SSD) and species sensitivity ranking method (SSR) were used to derive the water quality criteria of CLA. The short-term water quality criteria (SWQC) and long-term water quality criteria (LWQC) derived by SSD method were 0.581 and 0.071 μg·L^-1, respectively. The criterion maximum concentration (CMC) and criterion continuous concentration (CCC) derived by the SSR method were 3.741 and 0.919 μg·L^-1, respectively. Hence, the result of SSD method was adopted as the water quality criterion for protecting freshwater organisms in China. Subsequently, the ecological risk assessment of some water bodies in China was conducted using chronic toxicity zone analysis, entropy method, and safety threshold method. Based on the chronic toxicity zone analysis, it was found that the risk of CLA chronic poisoning was at highly danger level; Based on the entropy method, it was found that CLA poses certain ecological risks in some water bodies in China; Based on the safety threshold method, it was found that CLA posed almost no risk in typical water bodies in China. Due to the limited data volume in the safety threshold method assessment, the impact of many factors of the aquatic ecological environment on the distribution of CLA was not fully considered. The results of entropy method and chronic toxic zone analysis were similar, and the results of entropy method show that all the studied water bodies presented certain ecological risks. The estimation results can better draw attention to the ecological risks of CLA in freshwater environments. Therefore, the ecological risk assessment results of entropy method were taken as the final results The risk assessment level of Guanzhong section of Weihe River, the Beiyun River Basin, the Shenzhen River in the Pearl River Basin, the Guangzhou section of Pearl River, the Nanming River and the Honghu Lake were at moderate risk, while the rest of the water areas presented low risk. The research results of this paper can provide scientific basis for the formulation of CLA water quality criteria and the management of watershed water ecological environment.