Environmental Engineering Reference
In-Depth Information
Why was This Study Done?
SODIS has been promoted as an effective method to purify household water since
1999, and about 2 million people now use the approach (www.SODIS.ch). However,
although SODIS works well under laboratory conditions, very few studies have inves-
tigated its ability to reduce the number of cases of diarrhea occurring in a population
over a specific time period (the incidence of diarrhea) in the real world. Before any
more resources are used to promote SODIS—its effective implementation requires
intensive and on-going education—it is important to be sure that SODIS really does
reduce the burden of diarrhea in communities in the developing world. In this study,
therefore, the researchers undertake a cluster-randomized controlled trial (a study in
which groups of people are randomly assigned to receive an intervention or to act as
controls) in 22 rural communities in Bolivia to evaluate the ability of SODIS to reduce
diarrhea in children under 5 years old.
What Did the Researchers Do and Find?
For their trial, the researchers enrolled 22 rural Bolivian communities that included
at least 30 children under 5 years old and that relied on drinking water resources that
were contaminated with disease-causing organisms. They randomly assigned 11 com-
munities (225 households, 376 children) to receive the intervention—a standardized,
interactive SODIS promotion campaign conducted by Project Concern International (a
NGO)—and 11 communities (200 households, 349 children) to act as controls. House-
holds in the intervention arm were trained to expose water-filled plastic bottles for
at least 6 hr to sunlight using demonstrations, role play, and videos. Mothers in both
arms of the trial completed a daily child health diary for a year. Almost 80% of the
households self-reported using SODIS at the beginning and end of the study. However,
community-based field workers estimated that only 32.1% of households on average
used SODIS. Data collected in the child health diaries, which were completed on more
than three-quarters of days in both arms of the trial, indicated that the children in the
intervention arm had 3.6 episodes of diarrhea per year whereas the children in the
control arm had 4.3 episodes of diarrhea per year. The difference in episode numbers
was not statistically significant, however. That is, the small difference in the incidence
of diarrhea between the arms of the trial may have occurred by chance and may not be
related to the intervention.
What do these Findings Mean?
These findings indicate that, despite an intensive campaign to promote SODIS, less
than a third of households in the trial routinely treated their water in the recommended
manner. Moreover, these findings fail to provide strong evidence of a marked reduc-
tion of the incidence of diarrhea among children following implementation of SODIS
although some aspects of the study design may have resulted in the efficacy of SODIS
being underestimated. Thus, until additional studies of the effectiveness of SODIS in
various real world settings have been completed, it may be unwise to extend the global
promotion of SODIS for general use any further.
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