Estimating the health risk associated with the use of ecological sanitation toilets in Malawi

Save Kumwenda, Chisomo Msefula, Wilfred Kadewa, Bagrey Ngwira, Tracy Morse

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Abstract

Use of Ecological Sanitation (EcoSan) sludge is becoming popular due to increasing price of organic fertilizers in Malawi; however, there is little evidence on the associated risks. Quantitative microbiological risk assessment (QMRA) was done to determine health risks associated with use of EcoSan. Pathogens considered included Escherichia coli (E. coli), Salmonella, and soil transmitted helminths (STHs). Exponential and Beta Poisson models were used to estimate the risk from helminthic and bacterial pathogens, respectively. Main exposure pathways were through poor storage of sludge, contamination of foods during drying, walking barefoot on the ground contaminated with sludge, pit emptying without protection, and application of sludge in the elds. Estimated annual risk for Ascaris lumbricoides, Taenia, and hookworms was approximately over 5.6 × 10−1 for both Fossa Alternas (FAs) and Urine Diverting Dry Toilet (UDDTs). Risk from E. coli and Salmonella was 8.9 × 10−2 and above. e risks were higher than WHO acceptable risk for use of faecal sludge in crops of 10−4 infections per year. Promoters and users of EcoSan latrines need to consider advocating for strict guidelines to reduce the risk.
Original languageEnglish
Article number3931802
Number of pages13
JournalJournal of Environmental and Public Health
Volume2017
DOIs
Publication statusPublished - 8 Nov 2017

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Keywords

  • ecological sanitation sludge
  • Malawi
  • quantitative microbiological risk assessment
  • health risk
  • E. coli
  • salmonella
  • soil transmitted helminths (STHs)
  • bacterial pathogens

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