DSpace
 

Researchspace >
General science, engineering & technology >
General science, engineering & technology >
General science, engineering & technology >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/1899

Title: Assessment of microbial infection risks posed by ingestion of water during domestic water use and full-contact recreation in a mid-southern African region
Authors: Steyn, M
Jagals, P
Genthe, B
Keywords: Portable water
Salmonella
Escherichia coli
Recreation water
Observed adverse effect levels
Quantitative microbial risk assessment
Issue Date: 2004
Publisher: International Water Association Publishing
Citation: Steyn, M, Jagals, P and Genthe, B. 2004. Assessment of microbial infection risks posed by ingestion of water during domestic water use and full-contact recreation in a mid-southern African region. Water Science and Technology, vol. 50(1), pp 301-308
Abstract: A customised Water-related Quantitative Microbial Risk Assessment (WROMRA) process was used to determine risk of infection to water ingested by users in the south-eastern Free State, South Africa. The WRQMRA consisted of an observed-adverse-effect-level approach (OAELA) and a quantitative microbial risk assessment (QMRA). The OAELA was based on the occurrence of E coli in the study waters to determine the possible risk of infection and the QMRA probable risk of infection by salmonellae. The WRQMRA was applied to recreational surface resource waters as well as waters from an unprotected spring and waters from the treated municipal supply that were stored in containers for domestic purposes. E. coli numbers were measured against expected infection levels expressed in water quality guidelines, while Salmonella counts were calculated to give the probable infection risk (P-I). Ingestion was based on intake volumes compiled for the various water uses. E coli occurred in numbers <1 06 in the surface waters, while the untreated spring and treated supply water contained E Coliof < 10(2) and <10(1) respectively. Salmonella occurred in numbers of <10(3) in recreational waters, and <10(-1) in water used for domestic purposes. A single exposure to the mean (as well as 95th percentile) risk was calculated using a beta-Poisson dose-response model at ingestion volumes of 100 mL (for full-contact recreation) and 1,318 mL (for domestic water use). Both the OAELA and the QMRA approaches indicated a risk of infection to recreational and domestic water users, even for a single exposure event, with the OAELA either over- or under-estimating the risk of infection for singular exposure events. This indicated that this method, used on its own, could not reliably predict a realistic risk of infection. It is recommended that the full WRQMRA process be used, and further developed to address several uncertainties that became evident during this study.
URI: http://hdl.handle.net/10204/1899
http://hdl.handle.net/10204/1899
ISSN: 0273-1223
Appears in Collections:Water resources and human health
General science, engineering & technology

Files in This Item:

File Description SizeFormat
steyn_2004.pdf475.82 kBAdobe PDFView/Open
View Statistics

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback