Environmental Engineering Reference
In-Depth Information
conservative defi nition of SODIS use compared to that in other studies, which record-
ed reported use [9] or the number of bottles exposed to sunlight [34]. Both are indica-
tors that can easily and reliably be measured, but which are prone to over-reporting
due to low specifi city for actual use. Further studies will need to validate different
compliance indicators and formally assess the dimension of reporting bias.
It is possible that respondents would like to please fi eld staff and over-report use
out of courtesy. Also, observing exposed bottles on the roof may overestimate use
(Figure 3), because some households were noted anecdotally to have placed bottles
on the roof to avoid discussions with the SODIS-implementing NGO staff. Figure 3 is
indicative of this phenomenon, as reported use at the beginning and reported use and
satisfaction with the method at the end of the study reached the 80% mark—a usage
fi gure consistent with other studies relying on reported compliance [9] and evaluation
reports from gray literature. We conclude that self-reported SODIS use may overesti-
mate compliance and a combination of reported and objectively measurable indicators
provides more accurate SODIS-compliance data.
There are limitations to our study. As in other studies [24, 35], we observed a
decline in the reporting of child diarrhea during the observational period in both arms
(Figure 2). If true, seasonal variation of diarrhea could be one possible cause; increased
awareness leading to more attention to basic hygiene and hence to illness reduction
may be another reason. Alternatively, the pattern could be due to survey fatigue.
Despite a comprehensive and intensive intervention promotion campaign, we de-
tected no strong evidence for a signifi cant reduction in the IR of diarrhea in children
<5 year in families using SODIS in our trial in a typical setting in rural Bolivia. We
believe that clearer understandings of the discrepancy between laboratory and fi eld re-
sults (obtained under typical environmental and cultural conditions), the role of com-
pliance in effectiveness, and a direct comparison of SODIS to alternate drinking water
treatment methods are needed before further global promotion of SODIS.
EDITORS' SUMMARY
Background
Thirsty? Well, turn on the tap and have a drink of refreshing, clean, safe water. Unfor-
tunately, more than 1 billion people around the world do not have this option. Instead
of the endless supply of safe drinking water that people living in affluent, developed
countries take for granted, more than a third of people living in developing countries
only have contaminated water from rivers, lakes, or wells to drink. Because of limited
access to safe drinking water, poor sanitation, and poor personal hygiene, 1.8 million
people (mainly children under 5 years old) die every year from diarrheal diseases.
This death toll could be greatly reduced by lowering the numbers of disease-causing
microbes in household drinking water. One promising simple, low-cost, point-of-use
water purification method is SODIS. In SODIS, recycled transparent plastic drinks
bottles containing contaminated water are exposed to full sunlight for 6 hr. During this
exposure, ultraviolet radiation from the sun, together with an increase in temperature,
inactivates the disease-causing organisms in the water.
Search WWH ::
Custom Search