Halogenated disinfection byproducts (DBPs) are formed during chlorine disinfection of drinking water. The complicated natural organic matter in source water causes the formation of an even more complicated mixture of DBPs. To evaluate the toxicity of a DBP mixture in a disinfected water sample, the sample needs to be pretreated in order to attain an observable acute adverse effect in the toxicity test. During sample pretreatment, volatile DBPs including trihalomethanes, haloacetonitriles and haloketones may be lost, which could affect the toxicity evaluation of the DBP mixture. In this study, we intentionally prepared "concentrated" simulated drinking water samples, which contained sufficiently high levels of volatile and nonvolatile DBPs and thus enabled directly evaluating the toxicity of the DBP mixtures without sample pretreatment. Specifically, the natural organic matter and bromide concentrations and the chlorine dose in the concentrated water samples were 250 times higher than those in a typical drinking water sample. Each concentrated water sample was divided into two aliquots, and one of them was nitrogen sparged to eliminate volatile DBPs; then, both aliquots were used directly in a well-established developmental toxicity test. No significant difference (p > 0.10) was found between the developmental toxicity indexes of each concentrated water sample without and with nitrogen sparging, indicating that the contribution of volatile DBPs to the developmental toxicity of the DBP mixture might be marginal. A reasonable interpretation is that nonvolatile halogenated DBPs (especially the aromatic ones) in the DBP mixture could be the major developmental toxicity contributor that warrants more attention.

中文翻译：

---

挥发性DBP对饮用水DBP混合物对杜氏侧柏的发育毒性贡献很小。

饮用水的氯消毒过程中会形成卤化消毒副产物（DBP）。源水中复杂的天然有机物导致DBP的混合物更加复杂。为了评估消毒水样品中DBP混合物的毒性，需要对样品进行预处理，以便在毒性测试中获得可观察到的急性不良反应。在样品预处理过程中，可能丢失包括三卤甲烷，卤代乙腈和卤代酮在内的挥发性DBP，这可能会影响DBP混合物的毒性评估。在这项研究中，我们有意准备了“浓缩”的模拟饮用水样品，其中包含足够高含量的挥发性和非挥发性DBP，因此无需样品预处理即可直接评估DBP混合物的毒性。具体而言，浓缩水样品中的天然有机物和溴化物的浓度以及氯的剂量是典型饮用水样品中的250倍。将每个浓缩水样品分成两等份，并用氮气鼓泡以除去挥发性DBP。然后，将两份等分试样直接用于成熟的发育毒性试验中。在没有和有氮气鼓泡的情况下，每个浓缩水样品的发育毒性指标之间都没有发现显着差异（p> 0.10），这表明挥发性DBP对DBP混合物的发育毒性的贡献可能很小。