Health Risk from the Use of Roof-Harvested rainwater in Southeast Queensland, Australia, as potable or nonpotable water, determined using quantitative microbial risk assessment

Warish Ahmed; A Vieritz; A Goonetilleke; Ted Gardner

doi:10.1128/AEM.00944-10

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Health Risk from the Use of Roof-Harvested rainwater in Southeast Queensland, Australia, as potable or nonpotable water, determined using quantitative microbial risk assessment

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Health Risk from the Use of Roof-Harvested rainwater in Southeast Queensland, Australia, as potable or nonpotable water, determined using quantitative microbial risk assessment

Warish Ahmed, A Vieritz, A Goonetilleke and Ted Gardner

Applied and Environmental Microbiology, Vol.76(22), pp.7382-7391

2010

DOI: https://doi.org/10.1128/AEM.00944-10

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Abstract

A total of 214 rainwater samples from 82 tanks were collected in urban Southeast Queensland (SEQ) in Australia and analyzed for the presence and numbers of zoonotic bacterial and protozoal pathogens using binary PCR and quantitative PCR (qPCR). Quantitative microbial risk assessment (QMRA) analysis was used to quantify the risk of infection associated with the exposure to potential pathogens from roof-harvested rainwater used as potable or nonpotable water. Of the 214 samples tested, 10.7%, 9.8%, 5.6%, and 0.4% werepositive for the Salmonella invA, Giardia lamblia β-giardin, Legionella pneumophila mip, and Campylobacter jejuni mapA genes, respectively. Cryptosporidium parvum oocyst wall protein (COWP) could not be detected. The estimated numbers of Salmonella, G. lamblia, and L. pneumophila organisms ranged from 6.5 × 101 to 3.8 × 102 cells, 0.6 × 100 to 3.6 × 100 cysts, and 6.0 × 101 to 1.7 × 102 cells per 1,000 ml of water, respectively. Six risk scenarios were considered for exposure to Salmonella spp., G. lamblia, and L. pneumophila. For Salmonella spp. and G. lamblia, these scenarios were (i) liquid ingestion due to drinking of rainwater on a daily basis, (ii) accidental liquid ingestion due to hosing twice a week, (iii) aerosol ingestion due to showering on a daily basis, and (iv) aerosol ingestion due to hosing twice a week. For L. pneumophila, these scenarios were (i) aerosol inhalation due to showering on a daily basis and (ii) aerosol inhalation due to hosing twice a week. The risk of infection from Salmonella spp., G. lamblia, and L. pneumophila associated with the use of rainwater for showering and garden hosing was calculated to be well below the threshold value of one extra infection per 10,000 persons per year in urban SEQ. However, the risk of infection from ingesting Salmonella spp. and G. lamblia via drinking exceeded this threshold value and indicated that if undisinfected rainwater is ingested by drinking, then the incidences of the gastrointestinal diseases salmonellosis and giardiasis are expected to range from 9.8 × 100 to 5.4 × 101 (with a mean of 1.2 × 101 from Monte Carlo analysis) and from 1.0 × 101 to 6.5 × 101 cases (with a mean of 1.6 × 101 from Monte Carlo analysis) per 10,000 persons per year, respectively, in urban SEQ. Since this health risk seems higher than that expected from the reported incidences of gastroenteritis, the assumptions used to estimate these infection risks are critically examined. Nonetheless, it would seem prudent to disinfect rainwater for use as potable water. © 2010, American Society for Microbiology.

Details

Title: Health Risk from the Use of Roof-Harvested rainwater in Southeast Queensland, Australia, as potable or nonpotable water, determined using quantitative microbial risk assessment
Authors: Warish Ahmed (Author) - Queensland University of Technology
A Vieritz (Author) - Department of Environment and Resource Management
A Goonetilleke (Author) - Queensland University of Technology
Ted Gardner (Author) - Queensland University of Technology
Publication details: Applied and Environmental Microbiology, Vol.76(22), pp.7382-7391
Publisher: American Society for Microbiology
Date published: 2010
DOI: 10.1128/AEM.00944-10
ISSN: 0099-2240; 0099-2240
Copyright note: Copyright © 2010 American Society for Microbiology. The author's accepted version is reproduced here in accordance with the publisher's copyright policy. The definitive version is available at http://aem.asm.org/
Organisation Unit: University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99451090602621
Output Type: Journal article
Research Statement: false