The SODISWATER PROJECT
- Solar Disinfection (SODIS) of
Drinking Water
Dr Kevin McGuigan
Dept. of Physiology & Medical Physics
Royal College of Surgeons in Ireland
Dublin 2, IRELAND
Email: kmcguigan@rcsi.ie
Salgaa,
Nakuru,
Kenya
More than 1 billion people have no access to safe drinking water.
More than 1 million children die from waterborne disease annually
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SODIS Process - Fetch the water
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Wash an
ordinary plastic
Bottle
(supervised by
husband)
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Fill the Bottle
(supervised by
cat and dog)
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Expose the water in the bottle for
6 hours - (supervised by foreman)
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After 6 hrs in the sun, drink the water
(supervised by the rest of the village)
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RCSI group working on Solar Disinfection
since 1992
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2004
Indian
Ocean
Tsunami
Despite >10 years research & > 30 papers, it
became obvious that Aid Agencies were reluctant
to promote SODIS as a method of water
treatment in aftermath of humanitarian disasters.
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In 2006 obtained €2.7M funding (€1.9M EU,
€0.3M Irish Govt. & €0.5M others) for the 3 year
SODISWATER Project to expand knowledge of
solar disinfection (SODIS) and help promote
technology.
1. RCSI
(IRELAND)
2. UUJ
(UK)
3. CSIR
(S AFRICA)
4. EAWAG (SWITZERLAND)
5. IWSD
(ZIMBABWE)
6. PSA CIEMAT
(SPAIN)
7. UL
(UK)
8. ICROSS
(KENYA)
9. USC
(SPAIN)
10. CIC
(CAMBODIA)
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Health Impact Assessment
study model
• Children under age of 5 Years
• 14 month trial
• Control group maintained
usual practices.
• All test group families given
two 2-L bottles per child
• Test group placed bottles in
sun for 6h
• Drink today what was treated
yesterday
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Diarrhoeal disease rates recorded
using “Smiley-Face Diary”
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Health Impact Assessment - A Tale of Four Studies:
“it was the best of studies, it was the worst of studies”
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Zimbabwe Study
Total = 839 children
Control group = 547
Test group = 292
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Results
No Significant Effect
Observed
• Political tension.
• Pre- & post-election (3-4
months) suspension of all
foreign funded projects.
• Economic hyper-inflation.
• Cholera epidemic.
• Fear of interference with
bottle by neighbours.
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South Africa Study
A total of 649 households
were recruited with 386
children in the control group
and 438 in the test group.
Of the total of 824 children
402 were male and 421
female
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Typical S. African brick houses
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S. Africa Results
• Incidence rates were lower in those
drinking solar disinfected water (incidence
rate ratio* 0.64, 95% CI 0.39-1.0, P )
0.071) but not statistically significant
• Solar disinfection was not significantly
associated with non-dysentery diarrhea
risk overall (P = 0.419).
* IRR = Incident rate in test group / Incident rate in control group
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S. Africa Results – cont’d
• Incidence of dysentery was significantly
associated with higher motivation, defined
as 75% or better completion of diarrhea data.
• Compared with the control, participants with
higher motivation achieved a significant
reduction in dysentery (incidence rate
ratio (IRR = 0.36, 95% CI 0.16-0.81, P =
0.014). However, there was no significant
reduction in risk at lower levels of motivation.
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S. Africa Results – cont’d
• A statistically significant reduction in
dysentery was achieved only in
households with higher motivation,
showing that motivation is a significant
determinant for measurable health gains.
• SODIS works but only if you use it!
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Other problems
• Overall compliance rate was poor (~35%).
Many S. African users feared SODIS use
would release local govt. from
responsibility to provide clean water (S.A.)
so they stopped using it!
doi: 10.1021/es103328j.
Kenya Study
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Bondena Urban Slums in Nakuru
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Rural Maasailand, Kenya
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Test Group = 555
children in 404
households using
SODIS.
Control Group = 534
children in 361
households with no
intervention.
Post-election violence,
disruption, interruption.
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Kenya Results
Dysentery and non-dysentery diarrhea
were significantly (P<0.001)
reduced by use of solar disinfection:
1. dysentery days IRR = 0.56 (95% CI
0.40 to 0.79);
2. dysentery episodes IRR = 0.55
(95% CI 0.42 to 0.73);
3. non-dysentery days IRR = 0.70
(95% CI 0.59 to 0.84);
4. non-dysentery episodes IRR = 0.73
(95% CI 0.63 to 0.84).
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Anthropometry – height & weight
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Effect of SODIS on child development?
• Median height-for-age was significantly
increased in those on SODIS, corresponding
to an average of 1.3 cm taller over a 1-year
period over the group as a whole (95% CI
0.54 to 2.2 cm, P=0.001).
• Median weight-for-age was similarly higher in
those on SODIS, corresponding to a 0.4 kg
heavier difference in weight after a year on
SODIS (95% CI 0.16 to 0.64 kg, P<0.001).
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Comment
• Anthropometric benefit only observed in
Kenyan study. Probably because only area
where we saw significant malnutrition.
• This is the first trial to show evidence of the
effects of SODIS on childhood anthropometry
& should alleviate concerns that the lower
disease rates associated with household water
treatment are the product of biased reporting
rather than genuinely decreased incidence.
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Cambodia – Prey Veng &
Svay Reng provinces
Cambodia - results
• Children drinking SODIS water
were at lower risk of dysentery
(IRR = 0.40, 95% CI 0.18 to
0.92, P=0.032). Incidence was
low, hence wide C.I.
• Children drinking SODIS water
were at lower risk of nondysentery diarrhoea (IRR =
0.40, 95% CI 0.31 to 0.50, P <
0.001).
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General SODISWATER Conclusions:
• SODIS significantly reduces incidence of
dysentery (0.36<IRR<0.56) in most study
communities (S Africa, Kenya, Cambodia).
• SODIS associated with height & weight benefit
in child development for Kenyan children.
• No genotoxic risk observed for standard
SODIS method over 6 months (Recommend
replace bottles every 6 months).
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33 countries where SODIS is currently in
daily use by > 4.5 million people
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Acknowledgements
• Health Research Board
(NS/2003/007)
• Irish Aid and Health Research
Board
(GHRA/06/01)
• European Science Foundation
COST Action P9
• European Commission
(FP6-INCO-CT-2006-031650 SODISWATER)
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