Department of Civil and Environmental Engineering, ‡Department of Crop Sciences, and §Safe Global Water Institute, University of Illinois , Urbana, Illinois 61801, United States.
Environ Sci Technol. 2017 Aug 15;51(16):9297-9304. doi: 10.1021/acs.est.7b02345. Epub 2017 Jul 25.
Water reuse is receiving unprecedented attention as many areas around the globe attempt to better-manage their fresh water resources. Wastewaters in coastal regions may contain elevated levels of bromide (Br) and iodide (I) from seawater intrusion or high mineral content in the source waters. Disinfection of such wastewater is essential to prevent the spread of pathogens; however, little is known about the toxicity of the treated wastewater. In this study, we evaluated the genotoxicity to Chinese hamster ovary (CHO) cells induced by municipal secondary wastewater effluent amended with elevated Br and I after disinfection by chlorine, chloramines, or ozone. We calibrated and applied an N-acetylcysteine (NAC) thiol reactivity assay as a surrogate for thiol reactivity with biological proteins (glutathione) of wastewater samples. Chlorination of wastewaters produced CHO cell genotoxicity comparable to chloramination, 3.9 times more genotoxic than the nondisinfected controls. Ozonated wastewater was at least 3 times less genotoxic than the samples treated with chlorine-based disinfectants and was not significantly different compared with the nondisinfected controls. Positive and significant correlations were observed among genotoxicity, cytotoxicity, and NAC thiol reactivity for all disinfected samples. These results indicate that the ozonation of wastewater with high Br and I levels may yield organics with lower genotoxicity to CHO cells than chlorine-based disinfection. NAC thiol reactivity, although excluding the possible effect of bromate from ozonation in this work, could be used as a rapid in chemico screen for potential genotoxicity and cytotoxicity in mammalian cells exposed to disinfected wastewaters.
水资源再利用正受到前所未有的关注，因为全球许多地区都试图更好地管理其淡水资源。沿海地区的废水可能含有来自海水入侵的溴（Br）和碘（I）升高水平，或者水源中含有高矿物质。对这些废水进行消毒对于防止病原体传播至关重要；然而，对于处理后的废水的毒性知之甚少。在这项研究中，我们评估了经氯、氯胺或臭氧消毒后，添加了升高的 Br 和 I 的市政二级废水处理厂出水对中国仓鼠卵巢（CHO）细胞的遗传毒性。我们校准并应用了 N-乙酰半胱氨酸（NAC）巯基反应性测定法，作为废水样品与生物蛋白质（谷胱甘肽）的巯基反应性的替代物。废水的氯化作用产生的 CHO 细胞遗传毒性与氯化作用相当，比未消毒对照物的遗传毒性高 3.9 倍。臭氧化废水的遗传毒性至少比用基于氯的消毒剂处理的样品低 3 倍，与未消毒对照物相比无显著差异。所有经消毒的样品的遗传毒性、细胞毒性和 NAC 巯基反应性之间均存在正相关和显著相关性。这些结果表明，对高 Br 和 I 水平的废水进行臭氧化处理可能会产生对 CHO 细胞遗传毒性较低的有机物，而不是基于氯的消毒。NAC 巯基反应性虽然排除了本工作中臭氧化过程中溴酸盐的可能影响，但可用于快速筛选哺乳动物细胞暴露于消毒废水中的潜在遗传毒性和细胞毒性。
