미량유기물질 차이에 따른 염소소독 부산물 변화 및 제브라피쉬 독성평가 연구 Changes in the chlorine disinfection byproducts of trace organic substances its toxicity evaluation by zebrafish원문보기
Many trace organic substances entering water treatment plants react with the chlorine during the disinfection stages to produce various disinfection byproducts. Among them are trihalomethanes (THMs) and haloacetic acids (HAAs), the most well known, and small amounts of other low-molecular substances...
Many trace organic substances entering water treatment plants react with the chlorine during the disinfection stages to produce various disinfection byproducts. Among them are trihalomethanes (THMs) and haloacetic acids (HAAs), the most well known, and small amounts of other low-molecular substances. Especially during summer when the rainfall intensity and temperatures are higher, the changes in fresh water characteristics entering the water treatment plant become diverse, and the generation of disinfection by-products could also be affected. Despite these changes, toxicity assessment using the conventional Daphnia magna test report no toxicity from the treated water other than from effect of residual chlorine. However, recently, uncertainties and limitations of existing toxicity assessment due to errors in animal experiments such as humidifier disinfectants have become clear, and novel methods are needed to evaluate the toxicity caused by trace pollutants. In this study, the concept of adverse outcome pathway was introduced along with the quantification of disinfection byproducts, and the changes in toxicity due to the varying trace organic matter (OM) was observed through the toxicity assessment using zebrafish. The results indicate that the tendency to produce toxic byproducts was different for each type of OM. The byproduct from water-soluble natural OM (NOM) was more toxic compared to the byproducts of microcystin-LR and humic acid, causing the cognitive function of zebrafish to decrease by 20% and the activity time by 90%. In addition, zebrafish exposed to water after chlorination of each NOM showed several changes in lipid metabolism. It was confirmed that the Chuso water sample and the Suwannee river NOM also caused changes in the metabolic process. In the analysis of the metabolic and behavioral changes of the zebrafish, it was observed that the indicators related to inflammation and membrane fluidity had an influence on the behavior. In the case of the inflammation related indicators, the influence of the zebrafish on the activity time and speed and the membrane fluidity index is thought to affect cognitive function. This study provides understanding of the toxicity mechanisms and results at low concentrations which were not provided by existing toxicity assessment methods, and approached the toxicity experiment in the concept of adverse outcome pathway (AOP). In conclusion, it was confirmed that the toxicity results are different from each NOM type as the contact time increases after chlorination disinfection by natural organic materials, and is a much more sensitive test than the conventional Daphnia magna experiment. Although it is in its early stages and may be difficult to standardize, if the research progresses, this method can be used as a new index for toxicity evaluation.
Many trace organic substances entering water treatment plants react with the chlorine during the disinfection stages to produce various disinfection byproducts. Among them are trihalomethanes (THMs) and haloacetic acids (HAAs), the most well known, and small amounts of other low-molecular substances. Especially during summer when the rainfall intensity and temperatures are higher, the changes in fresh water characteristics entering the water treatment plant become diverse, and the generation of disinfection by-products could also be affected. Despite these changes, toxicity assessment using the conventional Daphnia magna test report no toxicity from the treated water other than from effect of residual chlorine. However, recently, uncertainties and limitations of existing toxicity assessment due to errors in animal experiments such as humidifier disinfectants have become clear, and novel methods are needed to evaluate the toxicity caused by trace pollutants. In this study, the concept of adverse outcome pathway was introduced along with the quantification of disinfection byproducts, and the changes in toxicity due to the varying trace organic matter (OM) was observed through the toxicity assessment using zebrafish. The results indicate that the tendency to produce toxic byproducts was different for each type of OM. The byproduct from water-soluble natural OM (NOM) was more toxic compared to the byproducts of microcystin-LR and humic acid, causing the cognitive function of zebrafish to decrease by 20% and the activity time by 90%. In addition, zebrafish exposed to water after chlorination of each NOM showed several changes in lipid metabolism. It was confirmed that the Chuso water sample and the Suwannee river NOM also caused changes in the metabolic process. In the analysis of the metabolic and behavioral changes of the zebrafish, it was observed that the indicators related to inflammation and membrane fluidity had an influence on the behavior. In the case of the inflammation related indicators, the influence of the zebrafish on the activity time and speed and the membrane fluidity index is thought to affect cognitive function. This study provides understanding of the toxicity mechanisms and results at low concentrations which were not provided by existing toxicity assessment methods, and approached the toxicity experiment in the concept of adverse outcome pathway (AOP). In conclusion, it was confirmed that the toxicity results are different from each NOM type as the contact time increases after chlorination disinfection by natural organic materials, and is a much more sensitive test than the conventional Daphnia magna experiment. Although it is in its early stages and may be difficult to standardize, if the research progresses, this method can be used as a new index for toxicity evaluation.
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