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A moving bed biofilm reactor (MBBR) process in wastewater treatment plants (WWTPs) uses plastic carriers, called biofilm carrier, to increase their treatment efficiency. Biofilm carrier is made up of plastic, containing the OPEs as flame retardants or plasticizers, so OPEs in biofilm carrier are possible to release from WWTPs to the river. This study investigated the effect of the MBBR process in WWTP on aquatic environments, focusing on OPEs. OPE eluted from the biofilm carrier by leaching test was tris(2-chloroethyl) phosphate (TCEP), and the concentration of the effluent compared to the influent was increased in the WWTP of the MBBR process. 3609 mg/day of TCEP would be discharged into the water using the second-order model with rate constant [Formula: see text] = 0.000451 (ng L -1 ) -1  h -1 , which is the most suitable for the leaching concentration of TCEP. It was identified that TCEP in biofilm carrier was transformed into oxidative dechlorinated compounds and oxidative compounds by microorganisms in the bioreactor. As a result of the study, it was confirmed that not only TCEP but also transformation products of TCEP emitted into the water from the MBBR process of WWTP., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Bisphenol A (BPA) is a well-known endocrine-disrupting compound that causes several toxic effects on human and aquatic organisms. The restriction of BPA in several applications has increased the substituted toxic chemicals such as bisphenol F (BPF) and bisphenol S (BPS). A native tropical freshwater cladoceran, Moina micrura, was used as a bioindicator to assess the adverse effects of bisphenol analogues at molecular, organ, individual and population levels. Bisphenol analogues significantly upregulated the expressions of stress-related genes, which are the haemoglobin and glutathione S-transferase genes, but the sex determination genes such as doublesex and juvenile hormone analogue genes were not significantly different. The results show that bisphenol analogues affect the heart rate and mortality rate of M. micrura. The 48-h lethal concentration (LC 50 ) values based on acute toxicity for BPA, BPF and BPS were 611.6 µg L -1 , 632.0 µg L -1 and 819.1 µg L -1 , respectively. The order of toxicity based on the LC 50 and predictive non-effect concentration values were as follows: BPA > BPF > BPS. Furthermore, the incorporated method combining the responses throughout the organisation levels can comprehensively interpret the toxic effects of bisphenol analogues, thus providing further understanding of the toxicity mechanisms. Moreover, the output of this study produces a comprehensive ecotoxicity assessment, which provides insights for the legislators regarding exposure management and mitigation of bisphenol analogues in riverine ecosystems., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Fine dust (PM2.5) is generated from various sources, and many studies have reported on the sources of PM2.5. However, the current research on PM2.5 toxicity based on its sources is insufficient. In this study, we developed a framework for the prioritization of fine dust (PM2.5) sources on the basis of the multi-endpoint toxicities using the multi-criteria decision-making method (MCDM). To obtain the multi-endpoint toxicities of PM2.5 sources, cell mortality, reactive oxygen species (ROS), inflammation and mutagenicity were measured for diesel exhaust particles (DEP), gasoline exhaust particles (GEP), rice straw burning particles (RBP), coal combustion particles (CCP) and tunnel dust particles (TDP). The integrative toxicity score (ITS) of the PM2.5 source was calculated using MCDM, which consist of four steps: (1) defining the decision-making matrix, (2) normalization and weighting, (3) calculating the ITS (linear aggregation) and (4) a global sensitivity analysis. The indicator of cell mortality had the highest weight (0.3780) followed by inflammation (0.2471), ROS (0.2178) and mutagenicity (0.1571). Additionally, the ITS based on the sources contributing to PM2.5 resulted in the following order: DEP (0.89), GEP (0.44), RBP (0.40), CCP (0.23) and TDP (0.06). The relative toxicity index (RTI), which represents the ratio of toxicity due to the difference in sources, increases as the contribution of the highly toxic sources increases. The RTI over 1 is closely associated with an increased contribution from highly toxic sources, such as diesel exhaust, gasoline exhaust and biomass burning. It is necessary to investigate the toxicity of various PM2.5 sources and PM2.5 risk based on the sources.

Although particulate matter (PM) is composed of various chemicals, investigations regarding the toxicity that results from mixing the substances in PM are insufficient. In this study, the effects of low levels of three PAHs (benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene) on Ni toxicity were investigated to assess the combined effect of Ni-PAHs on the environment. We compared the difference in cell mortality and total glutathione (tGSH) reduction between single Ni and Ni-PAHs co-exposure using A549 (human alveolar carcinoma). In addition, we measured the change in Ni solubility in chloroform that was triggered by PAHs to confirm the existence of cation-π interactions between Ni and PAHs. In the single Ni exposure, the dose-response curve of cell mortality and tGSH reduction were very similar, indicating that cell death was mediated by the oxidative stress. However, 10 μM PAHs induced a depleted tGSH reduction compared to single Ni without a change in cell mortality. The solubility of Ni in chloroform was greatly enhanced by the addition of benz[a]anthracene, which demonstrates the cation-π interactions between Ni and PAHs. Ni-PAH complexes can change the toxicity mechanisms of Ni from oxidative stress to others due to the reduction of Ni 2+ bioavailability and the accumulation of Ni-PAH complexes on cell membranes. The abundant PAHs contained in PM have strong potential to interact with metals, which can affect the toxicity of the metal. Therefore, the mixture toxicity and interactions between diverse metals and PAHs in PM should be investigated in the future.