Zhang Chiqian, Lu Jingrang
Pegasus Technical Services, Inc., Cincinnati, OH, United States of America.
Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH, United States of America.
Sci Total Environ. 2021 May 20;770:145356. doi: 10.1016/j.scitotenv.2021.145356. Epub 2021 Jan 23.
This Discussion argues that municipal water utilities may need to consider the health risks of both opportunistic pathogens (OPs) and disinfection by-products (DBPs) while selecting disinfectant residual dosages or levels in engineered water systems. OPs are natural inhabitants in municipal water systems and the leading cause of drinking-water-related disease outbreaks threatening public health. DBPs in water systems are genotoxic/carcinogenic and also significantly affect public health. Disinfectant residuals (such as free chlorine and chloramine residuals) dictate OP (re)growth and DBP formation in engineered water systems. Therefore, regulating the dosages or levels of disinfectant residuals is effective in controlling OP (re)growth and DBP formation. Existing effects assessing optimal disinfectant residual dosages focus solely on minimizing OP (re)growth or solely on DBP formation. However, selecting disinfectant residual dosages aiming to solely limit the formation of DBPs might compromise OP (re)growth control, and vice versa. An optimal disinfectant residual level for DBP formation control or OP (re)growth control might not be optimal for minimizing the overall or combined health effects of OPs and DBPs in drinking water. To better protect public health, water authorities may need to update the current residual disinfection practice and maintain disinfectant residuals in engineered water systems at an optimal level to minimize the overall health risks of OPs and DBPs.
本讨论认为，市政供水企业在选择工程水系统中的消毒剂残留剂量或水平时，可能需要考虑机会性病原体（OPs）和消毒副产物（DBPs）的健康风险。OPs是市政供水系统中的天然存在物，也是威胁公众健康的与饮用水相关疾病暴发的主要原因。水系统中的DBPs具有遗传毒性/致癌性，也会对公众健康产生重大影响。消毒剂残留（如游离氯和氯胺残留）决定了工程水系统中OPs的（再）生长和DBP的形成。因此，调节消毒剂残留的剂量或水平对于控制OPs的（再）生长和DBP的形成是有效的。现有的评估最佳消毒剂残留剂量的方法仅侧重于将OPs的（再）生长降至最低或仅关注DBP的形成。然而，选择仅旨在限制DBP形成的消毒剂残留剂量可能会损害对OPs（再）生长的控制，反之亦然。用于控制DBP形成或OPs（再）生长的最佳消毒剂残留水平，对于将饮用水中OPs和DBPs的总体或综合健康影响降至最低而言，可能并非最佳。为了更好地保护公众健康，水务部门可能需要更新当前的残留消毒做法，并将工程水系统中的消毒剂残留维持在最佳水平，以将OPs和DBPs的总体健康风险降至最低。
