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9 Watsan Hygiene n Environmental Health

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Water, sanitation, hygiene & environmental health Pete Kolsky Energy and Water Department
  • Water, sanitation, hygiene & environmental healthPete KolskyEnergy and Water Department

  • OutlineSome facts about water, san and healthHistorical evolution Classification by transmissionThe Literature of impact studiesThe nature of the problemConclusions for practitioners

  • Some water, sanitation and health numbersFaecal-oral (focus of this presentation)Diarrhoeal disease2 million deaths/year from diarrhoea, mostly under 5Jumbo jet crash every hour and a halfOne billion cases/year4.3% of Burden of Disease DALYs88% (?) attributable to inadequate WSH1/3 of developing world popn carry intestinal worms200 million infected by schistosomiasis (bilharzia)6-9 million blind from trachoma (1/4 reduced by adequate water supply)

  • Natural chemical hazardsArsenicSkin lesions, various cancers20 to 60 million exposed in BangladeshMajor problem other parts of S. Asia, also Argentina, Chile, China, Hungary, Mexico, PeruFluorosis Dental damage, crippling bone damageaffects millions (WHO) but often of mild form

  • Historical evolution: water quality and healthJohn Snow Cholera Broad Street Pump 1854 Water Companies' StudiesWilliam Budd Typhoid in 1850's-60'sKoch Cholera vs.Pettenkoffer Hamburg/Altona 1892 1937 Croydon TyphoidAnd many more

  • Characteristics of these (and other) waterborne outbreaksTrue outbreakssudden spikesVery visible and dramatic!!Politically hot!Common sourcethe water supplyIf youre a water engineeryou dont want one on your watch!Cholera is the water engineers best friendMoney for chlorine suddenly becomes availableUntil 1970s, water quality dominated environmental health perception of diarrhoea

  • Classifications of disease Classification usually by organism (viral, bacterial, etc) or organ (diseases of head, heart, liver etc.)Classification by transmission routeBradleys great innovation in 1970sIf you know how its spread, you know how to stop itso engineers loved it!

  • The F-Diagramme

  • The great debates of the 80sWater-borne or water-washed?Is water quality or water quantity more important?Review of epi in 83 revealed fundamental challenges Blum, D. and R. Feachem, Int J Epidemiol 1983, 12, pp. 357-365Lack of controlOne-to-one (clustreing)Confounding variables (inc. age)RecallDiarrhoeal definitionUsageSeasonalityThese issues are real, and are still grave threats to quick and dirty project level impact assessments!!

  • Results from Esrey, 1985(Esrey, S.A. et al., WHO Bull, 63(4): 757-772, 1985)

    Type of InterventionNo ofResultsMedianReductionAll interventions53 22Water quality916Water availability1725Water qualityand availability837Excreta disposal1022


  • Esrey (1985) by disease

    Disease or infectionNo of resultsMedian reductionCholera1141Shigella2748Entamoeba histolytica172Giardia lamblia 10 0


  • Esreys update in 1991

    Esrey et al., WHO Bull, 69(5): 609-621 (1991)All StudiesRigorous Studies

    InterventionNoMed %reductNoMed % reductWater & San720230Sanitation1122536Water Quality and Quantity2216217Water Quality717415Water Quantity727520Hygiene633633

  • 2004 Fewtrell, Colford updateWhy do more?More studiesStatistically rigorous meta-analysisHH water treatment new player

    Water, sanitation and Hygiene: Interventions and diarrhoea A systematic review and meta-analysis, Lorna Fewtrell and John M. Colford, Jr. HNP Discussion Paper, World Bank 2004.

    Water, sanitation, and hygiene interventions to reducediarrhoea in less developed countries: a systematic reviewand meta-analysis, L. Fewtrell, R. Kaufmann, et al. Lancet Infectious Diseases, Vol 5, pp 42-52. Jan 2005.

  • Some of the main resultsAbove are highlights Strong, detailed report and bibliography, and documentation of approach

  • Previous reviews:a dEsrey SA et al. (1991) Bull WHO 69 (5): 609-621eCurtis V, Cairncross S (2003) Lancet Inf Dis 3: 275-281.Taken from S. Cairncross RWSSTG BBL The Health Impact of Sanitation, Aug 2004.







    Previous reviews

    Fewtrell et al. (2004)

    Reduction in diarrhea morbidity (%)


    Previous consensusFewtrell et al. (2004)

    Good studiesAll studiesminusplusminmax

    (a) Sanitation363219151347

    (b) Water availability20251613938

    (c) Water quality153120161147

    (d) Hygiene promotion333714112348

    (e) Hand washing42443723767



  • Major new conclusions from Fewtrell, Colford, KaufmannWater quality at HH is shown as significant further reviews forthcomingsome skeptics remainHygiene is reconfirmed as an effective interventionCombining interventions does not appear to have synergistic effect, contrary to popular public health belief

  • A step back from all of thisWe dont live in an average worldMountains of Peru are different from slums of South Asiae.g. soil and food contamination risks higher in China, Vietnam than in AfricaBriscoe (Briscoe, J., Am J Epidemiol 1984;120:449-55) sheds even more light in a non-linear worldIf disease incidence not linearly proportional to transmission, then impact attribution easily skewed

  • The F-diagramme revisited

  • How people see their city

  • An environmental view

  • A public health view

  • Take home messagesDiarrhoea is a huge problem in child healthWater, sanitation and hygiene can reduce diarrhoea between 25-50%Very broad consensus that:Focus on the householdHygiene matters!Water quality matters, but its not just water qualityfaecal contamination gets around many waysSanitation, WS infrastructure can make hygiene possible!Health studies are toughlive with indicators rather than health outcomeHH water treatment continues to be a growing focus of attentionperhaps even more relevant for chem. contam.

  • Thank you for your attention!