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 fields. 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. The 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.
Highlights
It is estimated that 2.7 billion people use on-site sanitation word-wide and of these 1.77 billion use some kind of a pit latrine
There has been an emphasis on the use of Ecological Sanitation (EcoSan) as it appears to overcome most of the problems faced by the water closet toilets and the traditional pit latrines
The colony forming units for Salmonella were higher for Urine Diverting Dry Toilets (UDDTs) than for Fossa Alternas (FAs) (509.1 versus 346.2 CFUs, p = 0.35) while that for E. coli was similar in FAs and in UDDTs (1007.7 versus 859.1 CFUs, p = 0.79)
Summary
It is estimated that 2.7 billion people use on-site sanitation word-wide and of these 1.77 billion use some kind of a pit latrine. Of those using some form of pit latrines, 65% are found in Sub-Saharan Africa [1]. Water closet toilet is the most common and came into use in the 1880s with the aim of reducing the transmission of sanitation related diseases especially cholera epidemics [2]. There has been an emphasis on the use of Ecological Sanitation (EcoSan) as it appears to overcome most of the problems faced by the water closet toilets and the traditional pit latrines. Studies have shown that sludge produced from these latrines is unsafe for use in agriculture and increases the health risks to the communities [2, 10, 11]
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