Triclosan occurrence in European Sewage Treatment Plants and risk assessment for the European rivers

The purpose of this study was to estimate the environmental risk associated with the existence of triclosan (TCS) released from municipal wastewater in the European rivers. A literature review was held to record the concentration levels of TCS in effluents of European Sewage Treatment Plants (STPs), while toxicity data was collected for aquatic organisms (algae, Daphnia magna and fish). Risk assessment was based on both Risk Quotient (RQ) methodology and Monte Carlo simulation. According to the results, TCS monitoring data was available for 349 STPs located in 15 out of the 50 European countries. Its mean concentrations ranged between 2.2 ng L-1 and 47,800 ng L-1. The 95th percentile of RQ was higher than 1 (in algae) for rivers with dilution factors (DFs) equal to or lower than 100, when maximum concentration was used, whereas the 95th percentile of RQ exceeded 1 for rivers with DFs up to 10, in cases where the calculations were based on mean concentration values. The probability that RQ exceeds 1 in rivers (for algae) ranged from 0.2% (DF = 1000) to 45% (DF = 2), when calculations were based on mean concentration values.