Abu-Ali Lena, Albert Ryan J, Davis Angela B, Gonsenhauser Rachel, Foreman Katherine
Office of Ground Water and Drinking Water, U.S. Environmental Protection Agency, WA, DC 20460, USA.
Harmful Algae. 2025 May;145:102846. doi: 10.1016/j.hal.2025.102846. Epub 2025 Mar 29.
Cyanotoxins produced by harmful algal blooms (HABs) can negatively impact human health through ingestion of drinking water. Under most circumstances, public water systems (PWSs) have demonstrated that they can successfully manage the removal of low-to-moderate levels of cyanotoxins with conventional treatment. Intense or frequent blooms put some PWSs at higher risk for treatment breakthrough, meaning cyanotoxins can pass through the drinking water treatment process, and there are still some instances of reported cyanotoxin levels in drinking water. This study links cyanotoxin drinking water occurrence data from PWSs sampled under the Fourth Unregulated Contaminant Monitoring Rule (UCMR 4) with qualitative source water HAB information to understand the relationship between source water indicators and drinking water occurrence. During the monitoring period (2018 to 2020), 153 of approximately 110,000 total cyanotoxin analytical results from 67 PWSs were observed at or above the minimum reporting level (MRL), resulting in a 0.14 percent rate of occurrence in drinking water. The associated qualitative data indicated that 23.9 percent of systems with a cyanotoxin reported value ≥ MRL in drinking water also reported the presence of a HAB indicator while 1.7 percent of systems with a reported value ≥ MRL in finished water did not report any HAB indicators. Odds ratio testing revealed that a system is more than twice as likely to have a cyanotoxin detection in drinking water if a HAB indicator is observed. This study demonstrates the importance of monitoring source water changes and observed treatment changes for vulnerable systems, as these can facilitate timely adjustments to treatment and mitigate the risks of cyanotoxin breakthrough in finished water.
有害藻华（HABs）产生的蓝藻毒素可通过饮用水摄入对人类健康产生负面影响。在大多数情况下，公共供水系统（PWSs）已证明它们能够通过常规处理成功去除低至中等水平的蓝藻毒素。强烈或频繁的藻华使一些公共供水系统面临更高的处理突破风险，这意味着蓝藻毒素可能会通过饮用水处理过程，并且仍有一些饮用水中蓝藻毒素水平的报告案例。本研究将根据《第四次未管制污染物监测规则》（UCMR 4）对公共供水系统采样得到的蓝藻毒素饮用水出现数据与定性的水源水藻华信息联系起来，以了解水源水指标与饮用水出现情况之间的关系。在监测期（2018年至2020年）内，67个公共供水系统约110,000个总蓝藻毒素分析结果中有153个在最低报告水平（MRL）或以上被观测到，导致饮用水中出现率为0.14%。相关的定性数据表明，饮用水中蓝藻毒素报告值≥MRL的系统中有23.9%也报告了藻华指标的存在，而成品水中报告值≥MRL的系统中有1.7%未报告任何藻华指标。优势比测试表明，如果观测到藻华指标，系统在饮用水中检测到蓝藻毒素的可能性会增加两倍多。本研究证明了对脆弱系统监测水源水变化和观测到的处理变化的重要性，因为这些可以促进及时调整处理并降低成品水中蓝藻毒素突破的风险。
