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Ecotoxicology and Human Environmental Health
Adherence to point-of-use water treatment over shortterm implementation: parallel crossover trials of flocculation-disinfection sachets in Pakistan and Zambia Ameer Shaheed, Sohail Rathore, Andy Bastable, Jane Bruce, Sandy Cairncross, and Joe Brown Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b00167 • Publication Date (Web): 07 May 2018 Downloaded from http://pubs.acs.org on May 8, 2018
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Adherence to point-of-use water treatment over short-term implementation: parallel crossover trials of flocculation-disinfection sachets in Pakistan and Zambia Shaheed, A.1, Rathore, S.2, Bastable, A.3, Bruce, J.1, Cairncross, S.1, Brown, J.4* 1
Department of Disease Control, Faculty of Infectious and Tropical Diseases, London
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School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, United
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Kingdom
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Mehran University of Engineering and Technology, Jamshoro, Sindh 76062, Pakistan
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Oxfam GB, Oxfam House, John Smith Drive, Oxford, OX4 2JY, United Kingdom
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School of Civil and Environmental Engineering, Georgia Institute of Technology,
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Atlanta, GA 30332
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*corresponding author.
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Contact details: School of Civil and Environmental Engineering, Georgia Institute of
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Technology, 311 Ferst Drive, Atlanta, GA 30332. Tel: +1 (404) 385-4579. Email:
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[email protected] 17
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[TOC art]
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ABSTRACT
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The health benefits of point-of-use (POU) water treatment can only be realized through
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high adherence: correct, consistent, and sustained use. We conducted parallel randomized,
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longitudinal crossover trials measuring short-term adherence to two single-use flocculant-
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disinfectant sachets in Pakistan and Zambia. In both trials, adherence declined sharply for
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both products over the eight-week surveillance periods, with overall lower adherence to
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both products in Zambia. There was no significant difference in adherence between the
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two products. Estimated median daily production of treated water dropped over the
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crossover period from 2.5 to 1.4 l person-1 day-1 (46% decline) in Pakistan, and from 1.4
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to 1.1 l person-1 day-1 (21% decline) in Zambia. The percentage of surveillance points
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with detectable total chlorine in household drinking water declined from 70% to 49% in
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Pakistan and rose marginally from 28 to 30% in Zambia. The relatively low and
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decreasing adherence observed in this study suggests that these products would have
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provided little protection from waterborne disease risk in these settings. Our findings
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underscore the challenge of achieving high adherence to POU water treatment, even
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under conditions of short-term adoption with intensive follow-up.
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INTRODUCTION
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Water quality improvements, including point-of-use (POU) water treatment, are intended
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to deliver health benefits by reducing exposure to waterborne pathogens1-3. POU water
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treatment is often recommended for short-term deployment, such as in emergency
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response, where interim strategies are required to reduce potentially elevated waterborne
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disease risks when safe water supplies are unavailable4-6. The degree to which POU
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methods provide protection against disease depends on several factors, including (i)
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whether drinking water is an important source of pathogen exposure and (ii) effectiveness
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of the technology in reducing the presence or viability of waterborne pathogens under
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real-world use conditions.
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Protective effects are also a function of the consistency of treatment over time, since even
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brief periods of exposure to high risk water can control overall risk7-9. POU compliance
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or adherence has been defined as the correct and consistent adoption of a given method10 10
, or the percentage of total water consumed that is treated7, 8. Previous studies have
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explored the relationship between POU adherence and health outcomes using
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Quantitative Microbial Risk Assessment (QMRA), modeling probabilities of infection
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and estimating the resulting burden of disease7-9. Under most modeling scenarios where
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waterborne disease risk is high, POU interventions require exclusive or nearly exclusive
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use to deliver substantial health benefits.
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Despite the critical role of adherence in achieving health gains via water quality
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interventions, adherence has not been consistently measured in field trials2, 3, 11, 12. Where
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measured, adherence ranges from very low (2 – 5 >5 – 8 >8 Household primary drinking water source Public standpipe On-plot piped water Shallow well Household sanitation None/open defecation Own pit latrine Shared pit latrine
Zambia 214 17 (8%) 6 (2 – 17) 1211 51% 17% 17 (
