A number of possible effects contribute to the environmental hazard potential of TCS. These include acute toxicity to aquatic organisms (however, at concentrations that are typically not reached in real-world scenarios ), chronic toxicity, and endocrine-disrupting effects. Moreover, the antimicrobial TCS may contribute to selection processes that are responsible for the development of antibiotic-resistant bacteria. Due to the frequent presence of relatively low levels of antibiotics and disinfectants in wastewaters and wastewater treatment plants (WTTPs), these have been identified as "hot spots" for the development of microbial resistance. Hence, the frequent presence of TCS in such environments should be a cause for concern, not only due to its potential environmental impact, but also with regard to possible, more indirect consequences for human health. Non-negligible amounts of TCS can also be found in soils amended with biosolids from wastewater treatment plants. Here, TCS and its degradation product methyltriclosan, formed during the wastewater treatment process, may accumulate in terrestrial organisms like earthworms. Other relevant degradation products include highly toxic chlorinated dioxins and chlorophenols, which are produced through photolytic degradation of TCS. Starting with the work of McAvoy et al., several authors have measured TCS concentrations in WWTP influents and effluents, and the results have been compiled in review articles and databases. While concentrations in effluents remain usually below 1 µg L -1 , a few studies reported values above 10 µg L -1 . The reported removal efficiencies of conventional WWTPs also vary widely, ranging from removal rates below 50% to essentially complete removal. Several advanced treatment methods that are under consideration for PPCP removal in general have also been studied for TCS removal in particular, including adsorption-based methods, advanced oxidation processes, and biodegradation. The advantages and drawbacks of individual methods have been discussed in recent reviews. Due to the lipophilicity of TCS (log (𝐾 ) of 4.76 ), hydrophobic adsorbents appear as the most promising materials for the adsorption-based removal of TCS from aqueous solution.