This study assessed the die-off of Escherichia coli (E. coli) and Ascaris suum on lettuce (Great Lakes 118) and cabbage (Brassica oleracea var capitata) in wastewater-irrigated fields using comparative mathematical die-off models. The study revealed that none of the survival curves of E. coli and A. suum was best fitted with the log-linear model, indicating that the classical first-order kinetic approach is inadequate in many cases. The biphasic die-off model best described the die-off of E. coli on lettuce (kmax1 = 2.62 day−1 and kmax2 = 0.22 day−1) and cabbage (kmax1 = 1.06 day−1 and kmax2 = 0.53 day−1). The die-off of A. suum on lettuce was best described by the biphasic model (kmax1 = 0.48 day−1 and kmax2 = 0.01 day−1) and best described by log linear + tail (kmax = 0.44) on cabbage. A comparative health risk assessment associated with the consumption of lettuce showed significant underestimation of the number of days of irrigation cessation required to achieve E. coli O157:H7 and Ascaris tolerable annual infection risk when using biphasic die-off rates compared with other die-off rates. The study stresses the need to test different die-off models as inputs for quantitative microbial risk assessment (QMRA) particularly for interventions associated with health risk reduction.
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Research Article|
September 01 2013
Modeling the die-off of E. coli and Ascaris in wastewater-irrigated vegetables: implications for microbial health risk reduction associated with irrigation cessation
Razak Seidu;
1Water, Sanitation Engineering and Health Group, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Postboks 5003, N-1432, Ås, Norway
E-mail: [email protected]; [email protected]
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Ingrid Sjølander;
Ingrid Sjølander
1Water, Sanitation Engineering and Health Group, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Postboks 5003, N-1432, Ås, Norway
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Amina Abubakari;
Amina Abubakari
1Water, Sanitation Engineering and Health Group, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Postboks 5003, N-1432, Ås, Norway
2Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Private Mail Bag, Kumasi, Ghana
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Dennis Amoah;
Dennis Amoah
2Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Private Mail Bag, Kumasi, Ghana
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John A. Larbi;
John A. Larbi
2Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Private Mail Bag, Kumasi, Ghana
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Thor Axel Stenström
Thor Axel Stenström
1Water, Sanitation Engineering and Health Group, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Postboks 5003, N-1432, Ås, Norway
3SARChI, Institute for Water and Wastewater Treatment, Durban University of Technology, P.O. Box 1334, Durban, South Africa
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Water Sci Technol (2013) 68 (5): 1013–1021.
Article history
Received:
November 05 2012
Accepted:
April 15 2013
Citation
Razak Seidu, Ingrid Sjølander, Amina Abubakari, Dennis Amoah, John A. Larbi, Thor Axel Stenström; Modeling the die-off of E. coli and Ascaris in wastewater-irrigated vegetables: implications for microbial health risk reduction associated with irrigation cessation. Water Sci Technol 1 September 2013; 68 (5): 1013–1021. doi: https://doi.org/10.2166/wst.2013.335
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