Epidemiological study of swimming-associated illnesses relating to bathing-beach water quality

1995 ◽  
Vol 31 (5-6) ◽  
1995 ◽  
Vol 31 (5-6) ◽  
pp. 1-4 ◽  
Author(s):  
C. S. W. Kueh ◽  
T.-Y. Tam ◽  
T. Lee ◽  
S. L. Wong ◽  
O. L. Lloyd ◽  
...  

The water quality objective or indicator of bathing beaches is established on the basis of epidemiological data of swimming-related illnesses in the local population. It needs to be updated and refined in light of changes in the composition, health status and recreational activities of the community. A major epidemiological study was conducted in Hong Kong in 1992 involving interviewing 25000 beach-goers on the health effects of exposure to bathing water. The results indicated that the total incidence of swimming-related illness symptoms was 41 per 1000, higher than the 30 per 1000 found in 1987. Eye, skin and respiratory symptoms were 2-20 times more prevalent in swimmers than in non-swimmers. Only gastrointestinal (GI) symptoms were directly related to the pollution level and bacterial content of beach water. Turbidity of beach water was closely linked with GI and highly credible GI symptoms and might be used as a monitoring tool and a parameter in the beach water quality objective. There was also a direct correlation between GI symptoms and the number of Clostridium perfringens, Aeromonas spp., Vibrio cholerae (non-O1) in beach water. No direct relationship between GI symptoms and E. coli or faecal coliforms could be identified in this study.


1991 ◽  
Vol 23 (1-3) ◽  
pp. 243-252 ◽  
Author(s):  
W. H. S. Cheung ◽  
R. P. S. Hung ◽  
K. C. K. Chang ◽  
J. W. L. Kleevens

A prospective epidemiological study was undertaken in Hong Kong in 1987, in which 18,741 usable responses were obtained. It showed bathing in the coastal beaches of Hong Kong poses an increased risk of developing gastrointestinal, ear, eye, skin, respiratory and total illness. Swimmers immersed in the more polluted beach waters are exposed to a significantly higher risk of contracting swimming-associated gastrointestinal, skin, respiratory and total illness. E. coli was found to be the best indicator for swimming-associated gastroenteritis and skin symptoms amongst the bathers, and a linear relationship could be established. Staphylococci was a good indicator for ear, respiratory and total illness, and should be used in complementary to E. coli. Beach water quality objectives for both E. coli and staphylococci have been proposed. A 4-tier classification system (rather than a single acceptability criterion) based on swimming-associated health risks has been developed for the beaches of Hong Kong. Information on the bacterial water quality and health risk levels of individual beaches is reported to the public both annually and fortnightly, so that beach-goers can choose where to go for swimming based on health effects data.


2021 ◽  
Author(s):  
Ramien Sereshk

It is commonly assumed that the persistence model, using day-old monitoring results, will provide accurate estimates of real-time bacteriological concentrations in beach water. However, the persistence model frequently provides incorrect results. This study: 1. develops a site-specific predictive model, based on factors significantly influencing water quality at Beachway Park; 2. determines the feasibility of the site-specific predictive model for use in accurately predicting near real-time E. coli levels. A site-specific predictive model, developed for Beachway Park, was evaluated and the results were compared to the persistence model. This critical performance evaluation helped to identify the inherent inaccuracy of the persistence model for Beachway Park, which renders it an unacceptable approach for safeguarding public health from recreational water-borne illnesses. The persistence model, supplemented with a site-specific predictive model, is recommended as a feasible method to accurately predict bacterial levels in water on a near real-time basis.


2012 ◽  
Vol 6 (3) ◽  
pp. 164-180 ◽  
Author(s):  
W. Thoe ◽  
S.H.C. Wong ◽  
K.W. Choi ◽  
J.H.W. Lee

2015 ◽  
Vol 14 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Wai Thoe ◽  
King Wah Choi ◽  
Joseph Hun-wei Lee

A beach water quality prediction system has been developed in Hong Kong using multiple linear regression (MLR) models. However, linear models are found to be weak at capturing the infrequent ‘very poor’ water quality occasions when Escherichia coli (E. coli) concentration exceeds 610 counts/100 mL. This study uses a classification tree to increase the accuracy in predicting the ‘very poor’ water quality events at three Hong Kong beaches affected either by non-point source or point source pollution. Binary-output classification trees (to predict whether E. coli concentration exceeds 610 counts/100 mL) are developed over the periods before and after the implementation of the Harbour Area Treatment Scheme, when systematic changes in water quality were observed. Results show that classification trees can capture more ‘very poor’ events in both periods when compared to the corresponding linear models, with an increase in correct positives by an average of 20%. Classification trees are also developed at two beaches to predict the four-category Beach Water Quality Indices. They perform worse than the binary tree and give excessive false alarms of ‘very poor’ events. Finally, a combined modelling approach using both MLR model and classification tree is proposed to enhance the beach water quality prediction system for Hong Kong.


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