Blending antibiotic resistance into environmental risk assessment of antibiotics: A case study in coastal waters of the Bohai Bay, China

Antibiotic contamination can result in not only the ecotoxicity but also the antibiotic resistance in the aquatic environment. To characterize the antibiotic resistance risk and ecological risk in coastal waters, water samples were collected from the coastal area of the Bohai Bay during two seasons. The resistance risks were evaluated using the risk quotient (RQ) method based on the predicted no effect concentration for the development of antibiotic resistance. The ecological risk characteristics of antibiotics were assessed based on the species sensitivity distribution. The values of resistance RQ ranged from 6.7 × 10−5 to 5.3 × 10−1, while the values of ecological RQ ranged from 9.7 × 10−5 to 1.7 × 101. The results demonstrated that the resistance risk were slightly lower than the ecological risk in coastal waters of the Bohai Bay. Both the highest resistance risk and ecological risk were caused by fluoroquinolone antibiotics and tetracycline antibiotics. Despite the low concentrations, fluoroquinolone antibiotics exhibited the highest risk to aquatic organisms. Additionally, compared with other coastal areas in China, the resistance risks of antibiotics were relatively higher in coastal waters of the South China Sea and the Bohai Bay, implying the serious problem of the coastal pollution.