Species-related risk assessment of antibiotics using the probability distribution of long-term toxicity data as weighting function: a case study

Abstract

Urban areas are among the main sources which release antibiotics into the environment. The fate of antibiotics during their passage through the human body, the sewer system and the waste water treatment processes can be estimated and used for ecological risk assessment. The present approach deals with the possibility of addressing the ecological impact on individual trophic levels using a probability function to attenuate the classical PNEC approach. The species sensitivity distribution (SSD) is based on available long-term toxicity data and was fitted using the Hill-equation. The species-related toxicity threshold was merged with the slope characteristics gathered from SSD to express the risk probability of each species level. The results for algae and crustaceans show that azithromycin, clarithromycin and ciprofloxacin contribute the highest risk portions to the risk index (RI). The determined RI for fish was found to be below the threshold value of 1 and thus no risk is expected for this species.