Abstract：
Swimming pools adopt chlorination to ensure microbial safety. Giardia has attracted attention in swimming pool water because of its occurrence, pathogenicity, and chlorine resistance. To control Giardia concentrations in pool water and reduce the microbial risk, higher chlorine doses are required during disinfection. Unfortunately, this process produces carcinogenic disinfection byproducts that increase the risk of chemical exposure. Therefore, quantitatively evaluating the comparative microbial vs. chemical exposure risks that stem from chlorination inactivation of Giardia in swimming pool water is an issue that demands attention. We simulated an indoor swimming pool disinfection scenario that followed common real-world disinfection practices. A quantitative microbial risk assessment coupled with a chemical exposure risk assessment was employed to compare the Giardia microbial exposure risk (MER) and the trihalomethane chemical exposure risk (CER) to humans. The results demonstrated a 22% decrease in MER- and CER-induced health exposure risk, from 8.45E-5 at 8:00 to 6.60E-5 at 19:00. Both the MER and CER decreased gradually, dropping to 3.26E-5 and 3.35E-5 at 19:00, respectively. However, the CER exceeded the MER after 18:30 and became the dominant factor affecting the total exposure risk. Past the 18 hr mark, the contribution of trihalomethane CER far exceeded the risk aversion from microbial inactivation, leading to a net increase in total exposure risk despite the declining MER. Swimmers may consider swimming after 19:00, when the total exposure risk is the lowest. Lowering water temperature and/or pH were identified as the most sensitive factors to minimize the overall health exposure risk.
摘要：
游泳池采用氯化法，以确保微生物安全。贾第鞭毛虫在游泳池水中引起了人们的注意，致病性，和耐氯性。为了控制池水中贾第虫的浓度并降低微生物风险，消毒期间需要更高的氯剂量。不幸的是,这个过程会产生致癌的消毒副产品，增加化学品暴露的风险。因此,定量评估比较微生物与游泳池水中贾第鞭毛虫的氯化失活引起的化学暴露风险是一个需要关注的问题。我们模拟了室内游泳池消毒方案，该方案遵循了常见的现实消毒实践。采用定量微生物风险评估与化学暴露风险评估相结合，比较了贾第鞭毛虫微生物暴露风险（MER）和三卤甲烷化学暴露风险（CER）。结果表明，MER和CER引起的健康暴露风险降低了22％，从8:00的8.45E-5到19:00的6.60E-5。MER和CER均逐渐下降，在19:00分别降至3.26E-5和3.35E-5。然而,18:30后，CER超过MER，成为影响总暴露风险的主要因素。超过18小时标记，三卤甲烷CER的贡献远远超过了微生物灭活的风险厌恶，尽管MER下降，但导致总暴露风险净增加。游泳者可以考虑在19:00之后游泳，此时总的暴露风险最低。降低水温和/或pH被认为是最敏感的因素，以最大程度地降低整体健康暴露风险。
