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Point-of-Use Drinking Water Treatment in Cambodia: A Randomized, Controlled Trial of Locally Made Ceramic Filters. Joe Brown University of Alabama, New College | Departments of Biological Sciences and Civil and Environmental Engineering Mark Sobsey

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Point-of-Use Drinking Water Treatment in Cambodia: A Randomized, Controlled Trial of Locally Made Ceramic Filters

Joe Brown

University of Alabama, New College | Departments of

Biological Sciences and Civil and Environmental Engineering

Mark Sobsey

University of North Carolina School of Public Health,

Department of Environmental Sciences and Engineering

2008 International Symposium on Household Water Management


Outline
Outline Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Overview of ceramic filters

  • Study design

  • Data collection and analysis

  • Results

  • Brief discussion


10L Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Ceramic Water Purifier (CWP)

  • Potters for Peace design from Latin America

  • Uses gravity-driven porous ceramic microfiltration, with rice husk burnout material

  • Food-grade plastics, local materials and manufacture

1-3 L/hr


Study overview
Study overview Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Intended to independently assess the CWP (CWP1, CWP2) in field use in Cambodia via RCT

  • A rural/peri-urban village on the Bassac River near Phnom Penh

    • Prek Thmey, Kandal

    • Criteria for village selection were proximity to lab, poor quality drinking water & no treatment, high diarrheal disease burden, emerging market for CWPs

  • Just downstream from the Phnom Penh wastewater canal

  • Education and training done with RDI, no messages about diarrhea to bias study – promote clean, beautiful, and tasty drinking water


The 2 interventions
The 2 interventions Randomized, Controlled Trial of Locally Made Ceramic Filters

  • The CWP currently promoted in Cambodia by the NGO Resource Development International (CWP1)

    • Uses Ag coating

    • 2-3 liter/hour flowrate

    • Sales of approximately 20,000 per year in Cambodia

    • Retail cost of US$7 (unskilled labor rate $1-$2.50/day)

  • A modified version we developed in our lab using an alternative ceramic mixture, also made in the RDI factory (CWP2)


Data collection overview
Data collection overview Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Identification of 300 households in Prek Thmey

    • NGO survey

  • Recruitment of 180 eligible households in cluster-randomized order

    • Criteria: child under 5, willingness to participate, never owned CWP, no bottled water

  • Baseline data collection: WSH, water quality, covariates

  • Randomization to 1 of 3 groups: CWP1, CWP2, control

  • Follow all 180 households for 22 weeks

    • Water quality data, including: E. coli/100ml from untreated and treated household water samples

    • Scoring for diarrheal disease for all family members based on 7-day recall, and other health data

    • Other detailed data on filter use, WSH, and other factors


The study
The study Randomized, Controlled Trial of Locally Made Ceramic Filters


The study1
The study Randomized, Controlled Trial of Locally Made Ceramic Filters

Determine eligibility of village and households based on NGO-led community survey


The study2
The study Randomized, Controlled Trial of Locally Made Ceramic Filters

Map all houses, work with community leaders, WQ survey


The study3
The study Randomized, Controlled Trial of Locally Made Ceramic Filters

1

12

7

3

1

Visiting eligible households in cluster-randomized order

2

10

9

8

1

11

5

6

4


The study4
The study Randomized, Controlled Trial of Locally Made Ceramic Filters

Baseline data collection: 2 visits over 4 weeks


The study5
The study Randomized, Controlled Trial of Locally Made Ceramic Filters

CWP1

CWP1

CON

CWP2

Randomization to one of three groups of 60 households each: CWP1, CWP2, control

CWP1

CWP1

CWP2

CWP2

CWP1

CON

CON

CWP2

CON

CON


The study6
The study Randomized, Controlled Trial of Locally Made Ceramic Filters

CWP1

CWP1

CON

CWP2

Follow for 18 weeks with biweekly follow up

CWP1

CWP1

CWP2

CWP2

CWP1

CON

CON

CWP2

CON

CON


Prek Thmey Randomized, Controlled Trial of Locally Made Ceramic Filters


Health data analysis
Health data analysis Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Data on diarrheal disease longitudinal prevalence (7 day recall, binary) computed for each group using Poisson extension of GEE: log-risk regression using longitudinal data

  • Stratified estimates of longitudinal prevalence ratios

  • Controlling for clustering within households and in individuals over time

  • Controlling for other variables using an a priori 10% change in effect estimate criterion

  • Regression models applied to determine important predictors of diarrheal illness, including water quality


Results overview
Results: overview Randomized, Controlled Trial of Locally Made Ceramic Filters

  • CWP1 & CWP2 reduced E. coli concentrations in treated water by a mean 2.0 log10 (99%)

    • Filter effectiveness up to 99.9999%

    • Similar to boiled water samples (98% reduction)

  • Two-thirds of effluent water samples from filters were <10 E. coli/100ml (low risk)

    • Similar to data for stored boiled water

  • Filters associated with a mean 40% reduction in diarrheal disease in users versus non-users

    • Positive but weak relationship between E. coli concentrations and diarrheal disease


E. coli Randomized, Controlled Trial of Locally Made Ceramic Filters in drinking waterstratified by group


Health effects diarrheal disease
Health effects: diarrheal disease Randomized, Controlled Trial of Locally Made Ceramic Filters

  • CWP1, all persons: LPR = 0.51 (0.41-0.63)

  • CWP1, under 5s: LPR = 0.58 (0.41-0.82)

  • CWP2, all persons: LPR = 0.58 (0.47-0.71)

  • CWP2, under 5s: LPR = 0.65 (0.46-0.93)


Diarrhea lp 7 day recall
Diarrhea LP, 7-day recall Randomized, Controlled Trial of Locally Made Ceramic Filters


Other associations diarrheal disease and measured covariates
Other associations Randomized, Controlled Trial of Locally Made Ceramic FiltersDiarrheal disease and measured covariates


Principal findings
Principal findings Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Use of the CWP1 or CWP2 can reduce diarrheal prevalence by approximately 49% and 42% respectively

  • A weak but positive association was observed between diarrhea and increasing levels of E. coli in drinking water, consistent with other studies (data not shown)

  • Diarrheal disease outcomes also associated with sanitation, hygiene, socio-economic measures

  • No significant difference was observed between filters but study was not powered to sort this out


Study limitations
Study limitations Randomized, Controlled Trial of Locally Made Ceramic Filters

  • Not blinded: subject to bias in health data collection

  • Does not capture full seasonality

    • No data from January/February

  • Little data on long term effectiveness

    • This was the focus of a previous study we did

  • No data on actual human pathogens


Acknowledgements
Acknowledgements Randomized, Controlled Trial of Locally Made Ceramic Filters

Uon Virak, Choun Bunnara, Lim Kimly, Michelle Molina, Oum Sopharo, Song Kimsrong, and Van Sokheng for conducting interviews and analyzing water samples

Financial support: US Environmental Protection Agency and the National Science Foundation

Laboratory space and logistical support was generously provided by Resource Development International-Cambodia

Mickey Sampson

Jan-Willem Rosenboom

Ministry of Rural Development, Kingdom of Cambodia

Douglas Wait and the UNC Environmental Microbiology and Health group


Results water quality
Results: water quality Randomized, Controlled Trial of Locally Made Ceramic Filters


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