Assessing the Impact of Cyanuric Acid on Bather’s Risk of Gastrointestinal Illness at Swimming Pools

Falk, Richard A.; Blatchley, Ernest R.; Kuechler, Thomas C.; Meyer, Ellen M.; Pickens, Stanley R.; Suppes, Laura M.

doi:10.3390/w11061314

Cited by 10 publications

(9 citation statements)

References 56 publications

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“…This study has generated quantitative data on the occurrence and concentration of Cryptosporidium oocysts in leisure pools in the UK, which will enable contextualisation of test results and provide data to contribute to QMRA of infection risk for the UK population. These data could be used, for example, to validate the approaches developed by Suppes and colleagues [8] and Falk and colleagues [40] to quantify the risk of illness associated with the introduction of Cryptosporidium oocysts into pool water by swimmers. Preliminary modelling of oocyst concentration and temporal inputs can be used to guide future studies, for which simultaneous measurements of the filter removal efficiency in the appropriate size range using particle counting would aid the interpretation and modelling of results [12].…”

Section: Discussionmentioning

confidence: 99%

Occurrence of Cryptosporidium Oocysts in Leisure Pools in the UK, 2017, and Modelling of Oocyst Contamination Events

Chalmers

Simmonds²,

Wood³

et al. 2021

Water

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Cryptosporidium is a major cause of diarrhoea outbreaks linked to swimming pools, but little is known about the frequency of contamination. The primary aim was to investigate the occurrence and concentration, through sampling and modelling, of Cryptosporidium oocysts in leisure pools. Secondary aims were to compare detections with operational parameters, provide the evidence-base for guidance, and improve sampling capacity and interpretation for public health investigations. Up to 1000 L pool water was sampled during swim sessions once weekly for 10 weeks from 8th August 2017 at six volunteer pools. Oocysts were detected by microscopy in 12/59 (20%) pool water samples, at least once in each pool; 8/12 (66%) detections were in August when bather loads were highest. At three pools, 1 L filter backwash was sampled weekly and oocysts were detected in 2/29 (7%) samples, following detections in pool water. The probabilities of a bather contaminating the pool ranged from 1 in 1000 to over 1 in 10,000. Monte Carlo analysis showed that when high bather numbers caused contamination on over 70% of days, multiple events per day were more likely than single events. In these generally well-managed leisure pools, Cryptosporidium risk related to high bather loads. We conclude that public awareness campaigns for bather hygiene, and reminding pool operators of current guidance for managing faecal accidents, should be ahead of peak swim season.

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Section: Discussionmentioning

confidence: 99%

Occurrence of Cryptosporidium Oocysts in Leisure Pools in the UK, 2017, and Modelling of Oocyst Contamination Events

Chalmers

Simmonds²,

Wood³

et al. 2021

Water

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“…The above is a simplistic exercise, and there is urgent need for more refined Quantitative Microbial Risk Assessment (QMRA) for Cryptosporidium. For example, the filtration modelling provides a sufficiently simple approach that can be used to incorporate filtration removal into the QMRA modelling, as recently developed by Falk et al [22], but this is beyond the scope of this paper.…”

Section: Discussionmentioning

confidence: 99%

Revisiting the Gage–Bidwell Law of Dilution in Relation to the Effectiveness of Swimming Pool Filtration and the Risk to Swimming Pool Users from Cryptosporidium

Simmonds¹,

Simmonds²,

Wood³

et al. 2021

Water

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The transfer of water from a swimming pool to the treatment location is key in determining the effectiveness of water treatment by filtration in removing turbidity and managing the risk from particulate material, including microbial pathogens, such as Cryptosporidium spp. A key recommendation for pool operators when dealing with an accidental faecal release (the likely main source of high Cryptosporidium oocyst concentrations in pools) is that the pool water should be filtered for at least six turnover cycles prior to use. This paper briefly outlines the theoretical basis of what has become known as the Gage–Bidwell Law of Dilution, which provides a basis for this recommendation, and extends the idea to account for the impact of filter efficiency. The Gage–Bidwell Law reveals that for each pool turnover 63% of the water resident in the pool at the start of the turnover period will have been recirculated. Building on this, we demonstrate that both filter efficiency and water-turnover time are important in determining filtration effectiveness and can be combined through a single parameter we term ‘particle-turnover’. We consider the implications of the Gage–Bidwell Law (as referred to in the original 1926 paper) for the dynamics of the ‘dirt’ content of pool water, whether in terms of a specific particle size range (e.g., Cryptosporidium oocysts) or turbidity.

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“…For example, when CYA reacts with melamine (MEL), it can induce high nephrotoxicity and aggravate renal toxicity ( Wang et al, 2012 ; Chang et al, 2014 ; Zhu and Kannan, 2018 , 2019c , b ). In addition, when abundant CYA was present in water, the disinfection efficacy of FC became lower toward Cryptosporidium oocysts ( Murphy et al, 2015 ) and Giardia ( Falk et al, 2019 ). In fact, CYA has been detected frequently in human urine samples ( Sathyanarayana et al, 2019 ; Zhu and Kannan, 2019a ).…”

Section: Introductionmentioning

confidence: 99%

Green detection of trace cyanuric acid and free chlorine together via ion chromatography

et al. 2022

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Chlorinated cyanurates (CCAs) are a type of disinfectants currently used worldwide for fight of Coronavirus. However, CCAs upon dosed into water can release not only free chlorine (FC), a strong disinfectant, but also cyanurate (CYA), a persistent compound potentially harmful to human and environment. Therefore, detecting CYA and FC in water are very important not only for ensuring sufficient disinfection but also for monitoring the impacts of FC and CYA on receiving watershed. However, conventional analytical methods for them are mostly based on colorimetric methods, which have high method detection limits (MDLs) and rely on chemical reactions that are likely sensitive to coexisting chemicals. To overcome these issues, we herein proposed a facile and reaction-free method to detect CYA and FC together in just one run by ion chromatography (IC) equipped with both conductivity and ultraviolet absorbance detectors. The method features obvious advantages over colorimetric methods in being lower MDLs (3.6 μg/L for CYA and 9.0 μg/L for FC), environmental-friendly (i.e., no organic solvent involved), and more resistant to alkaline solution. With this method, trace levels of CYA (i.e., 34–44 μg/L), which were nondetectable by conventional method, were found in two river water samples, implying that the local environment was already polluted by CCAs during the pandemic period. Overall, this study demonstrates a robust tool that may assist better understanding and monitoring the fate and transport of trace CCA derivatives in water.

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Assessing the Impact of Cyanuric Acid on Bather’s Risk of Gastrointestinal Illness at Swimming Pools

Cited by 10 publications

References 56 publications

Occurrence of Cryptosporidium Oocysts in Leisure Pools in the UK, 2017, and Modelling of Oocyst Contamination Events

Occurrence of Cryptosporidium Oocysts in Leisure Pools in the UK, 2017, and Modelling of Oocyst Contamination Events

Revisiting the Gage–Bidwell Law of Dilution in Relation to the Effectiveness of Swimming Pool Filtration and the Risk to Swimming Pool Users from Cryptosporidium

Green detection of trace cyanuric acid and free chlorine together via ion chromatography

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