NIWA-National Institute of Water and Atmospheric Research, P.O. Box 11-115, Hamilton 3251, New Zealand.
Water Res. 2013 Sep 15;47(14):5282-97. doi: 10.1016/j.watres.2013.06.001. Epub 2013 Jun 12.
This study is the first to report a quantitative microbial risk assessment (QMRA) on pathogens detected in stormwater discharges-of-concern, rather than relying on pathogen measurements in receiving waters. The pathogen concentrations include seven "Reference Pathogens" identified by the U.S. EPA: Cryptosporidium, Giardia, Salmonella, Norovirus, Rotavirus, Enterovirus, and Adenovirus. Data were collected from 12 sites representative of seven discharge types (including residential, commercial/industrial runoff, agricultural runoff, combined sewer overflows, and forested land), mainly during wet weather conditions during which times human health risks can be substantially elevated. The risks calculated herein therefore generally apply to short-term conditions (during and just after rainfall events) and so the results can be used by water managers to potentially inform the public, even for waters that comply with current criteria (based as they are on a 30-day mean risk). Using an example waterbody and mixed source, pathogen concentrations were used in QMRA models to generate risk profiles for primary and secondary water contact (or inhalation) by adults and children. A number of critical assumptions and considerations around the QMRA analysis are highlighted, particularly the harmonization of the pathogen concentrations measured in discharges during this project with those measured (using different methods) during the published dose-response clinical trials. Norovirus was the most dominant predicted health risk, though further research on its dose-response for illness (cf. infection) is needed. Even if the example mixed-source concentrations of pathogens had been reduced 30 times (by inactivation and mixing), the predicted swimming-associated illness rates - largely driven by Norovirus infections - can still be appreciable. Rotavirus generally induced the second-highest incidence of risk among the tested pathogens while risks for the other Reference Pathogens (Giardia, Cryptosporidium, Adenovirus, Enterovirus and Salmonella) were considerably lower. Secondary contact or inhalation resulted in considerable reductions in risk compared to primary contact. Measurements of Norovirus and careful incorporation of its concentrations into risk models (harmonization) should be a critical consideration for future QMRA efforts. The discharge-based QMRA approach presented herein is particularly relevant to cases where pathogens cannot be reliably detected in receiving waters with detection limits relevant to human health effects.
本研究首次报告了对受关注的雨水排放中检出的病原体进行定量微生物风险评估（QMRA），而不是依赖于受纳水体中病原体的测量。病原体浓度包括美国环保署确定的七种“参考病原体”：隐孢子虫、贾第鞭毛虫、沙门氏菌、诺如病毒、轮状病毒、肠道病毒和腺病毒。数据来自 12 个具有代表性的排放类型（包括住宅、商业/工业径流、农业径流、合流污水溢流和林地）的地点，主要收集在湿天气条件下，此时人类健康风险会大幅增加。因此，本文计算的风险通常适用于短期条件（降雨期间和降雨后不久），因此，水务管理人员可以使用这些结果来告知公众，即使对于符合当前标准的水体也是如此（因为它们基于 30 天的平均风险）。以一个示例水体和混合源为例，使用 QMRA 模型中的病原体浓度来生成成人和儿童主要和次要接触（或吸入）的风险概况。本文突出强调了 QMRA 分析中的一些关键假设和考虑因素，特别是协调本项目中排放物中测量的病原体浓度与已发表的剂量反应临床试验中测量的（使用不同方法）的病原体浓度。诺如病毒是最主要的预测健康风险，但需要进一步研究其疾病（感染）剂量反应。即使将病原体的混合源浓度降低 30 倍（通过失活和混合），预测的与游泳相关的疾病发病率 - 主要由诺如病毒感染驱动 - 仍可能相当可观。轮状病毒在测试的病原体中引起的风险第二高，而其他参考病原体（贾第鞭毛虫、隐孢子虫、腺病毒、肠道病毒和沙门氏菌）的风险则低得多。与主要接触相比，二次接触或吸入导致风险显著降低。诺如病毒的测量和将其浓度仔细纳入风险模型（协调）应该是未来 QMRA 工作的关键考虑因素。本文提出的基于排放的 QMRA 方法特别适用于在受纳水体中无法可靠检测到与人类健康影响相关的检测限的病原体的情况。
