National Institute for Public Health and the Environment, Laboratory for Zoonoses and Environmental Microbiology, PO Box 1, 3720 BA Bilthoven, The Netherlands.
Water Res. 2011 Mar;45(7):2392-400. doi: 10.1016/j.watres.2011.01.025. Epub 2011 Mar 1.
Bathing water compliant with bathing water legislation may nevertheless contain pathogens to such a level that they pose unacceptable health risks for swimmers. Quantitative Microbiological Risk Assessment (QMRA) can provide a proper basis for protective measures, but the required data on swimmer exposure are currently limited or lacking. The objective of this study was to collect exposure data for swimmers in fresh water, seawater and swimming pools, i.e. volume of water swallowed and frequency and duration of swimming events. The study related to swimming in 2007, but since the summer of 2007 was wet and this might have biased the results regarding surface water exposure, the study was repeated relating to swimming in 2009, which had a dry and sunny summer. Exposure data were collected through questionnaires administered to approximately 19 000 persons representing the general Dutch population. Questionnaires were completed by 8000 adults of whom 1924 additionally answered the questions for their eldest child (< 15 years). The collected data did not differ significantly between 2007 and 2009. The frequency of swimming and the duration of swimming were different for men, women and children and between water types. Differences between men and women were small, but children behaved differently: they swam more often, stayed in the water longer, submerged their heads more often and swallowed more water. Swimming pools were visited most frequently (on average 13-24 times/year) with longest duration of swimming (on average 67-81 min). On average, fresh and seawater sites were visited 6-8 times/year and visits lasted 41-79 min. Dependent on the water type, men swallowed on average 27-34 ml per swimming event, women 18-23 ml, and children 31-51 ml. Data on exposure of swimmers to recreational waters could be obtained by using a questionnaire approach in combination with a test to measure mouthfuls of water for transformation of categorical data to numerical data of swallowed volumes of water. Previous assumptions on swimmer exposure were replaced with estimates of exposure parameters, thus reducing uncertainty in assessing the risk of infection with waterborne pathogens and enabling identification of risk groups. QMRA for Cryptosporidium and Giardia was demonstrated based on data from previous studies on the occurrence of these pathogens in recreational lakes and a swimming pool.
尽管符合浴场法规的浴场用水可能含有病原体，但这些病原体对游泳者的健康构成了不可接受的风险。定量微生物风险评估（QMRA）可以为保护措施提供适当的依据，但目前有关游泳者暴露的数据有限或缺乏。本研究的目的是收集淡水、海水和游泳池中游泳者的暴露数据，即吞咽水量、游泳事件的频率和持续时间。该研究涉及 2007 年的游泳活动，但由于 2007 年夏季多雨，这可能会影响有关地表水暴露的结果，因此，该研究于 2009 年再次进行，该年夏季干燥晴朗。通过向代表荷兰普通人群的大约 19000 人发放问卷收集暴露数据。8000 名成年人填写了问卷，其中 1924 人还回答了其最大孩子（<15 岁）的问题。2007 年和 2009 年收集的数据没有显著差异。男性、女性和儿童以及不同水类型之间游泳的频率和持续时间不同。男女之间的差异较小，但儿童的行为不同：他们游泳更频繁，在水中停留时间更长，更频繁地将头浸入水中，吞咽更多的水。游泳池是最常去的地方（平均每年 13-24 次），游泳时间最长（平均 67-81 分钟）。平均而言，新鲜水和海水浴场每年访问 6-8 次，访问时间为 41-79 分钟。根据水的类型，男性每次游泳平均吞咽 27-34 毫升，女性 18-23 毫升，儿童 31-51 毫升。通过问卷调查结合测量一口水量的方法，可以获得游泳者接触娱乐用水的暴露数据，从而将分类数据转换为吞咽水量的数值数据。用这种方法可以取代以前对游泳者暴露的假设，用暴露参数的估计来代替，从而减少评估与水传播病原体相关的感染风险的不确定性，并确定风险群体。基于先前关于这些病原体在娱乐湖泊和游泳池中发生情况的研究数据，对隐孢子虫和贾第鞭毛虫进行了 QMRA。
