Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

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Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

I would like to introduce to you the details of a new grant that we are working on, with funding by the Bill & Melinda Gates Foundation:

Title of grant: Unsafe Return of Human Excreta to the Environment - Proof of Concept of Estimates for the Unsafe Return of Human Excreta to the Environment
  • Name of lead organization: The Water Institute at UNC, Gillings School of Global Public Health, UNC (The University of North Carolina at Chapel Hill)
  • Primary contact at lead organization: Pete Kolsky - Co-Principal Investigator; Jamie Bartram- Co-Principal Investigator (or myself for the purposes of this forum)
  • Grantee location: Chapel Hill, North Carolina, USA
  • Countries where the research will be tested: Netherlands, Uruguay, Egypt, Philippines, Burkina Faso, Ghana, and Fiji
  • Start and end date: Feb 2015 to 30 April 2016; Phase 2: 14.10.2016 to 30.09.2018
  • Grant type: Global development
  • Grant size: USD 267,978 (as per grant database here and Phase 2 here )
Short description of the project:
There is need to track human excreta beyond their initial deposit in toilets through to their final return to the environment, to ensure that the population is properly protected from the diseases spread by this waste.

The work of this project is intended to inform the expected Sustainable Development Goal Target to reduce the amount of human excreta unsafely returned to the environment. The “global scorecard” for excreta management developed will assist governments, funding agencies and development agencies to address progress and the need for improvement more effectively, both from an improved understanding of the situation, and from the clearer insight into the global situation.

Methodology:
  • We will model the return of human excreta to the environment through three sanitation technologies: pit latrines, septic tanks, and sewers. Similar to shit-flow diagrams, our model will track human excreta across the entire sanitation chain, including containment, emptying, transport, treatment, disposal/reuse. However, our model will also include both solid (fecal sludge) and liquid (wastewater/effluent) streams.
  • Rather than completing a mass balance of waste, as is done in shit-flow diagrams, our model will incorporate pathogen die-off over time and will therefore be representative of a “hazard balance”. The model will also classify the location of the hazard associated with unsafe return at each step in the sanitation delivery chain according to local, community, and the greater environment.
  • The tool is currently being developed at the national level, using disaggregated data for urban and rural areas and modeling each setting differently. However, it is anticipated that the model could be used at the regional and local level. The output of the model will assist policy makers by identifying where the greatest hazards are within the sanitation delivery chain and where exposure occurs, at the local, community, or environmental level. Policy-makers could then use tools like Sanipath to further identify specific exposure pathways within the local and community level.
Goals: to develop and pilot approaches for the estimation of the fraction of human excreta unsafely returned to the environment

Objectives:
  • to estimate the fraction of human excreta unsafely returned to the environment, and
  • to estimate where in the sanitation chain this occurs
Research or implementation partners: University of Alabama, USA

Links, further readings – results to date: waterinstitute.unc.edu/research/current-projects/unsafe-return/ (contains only a short project description so far).

Current state of affairs:
We have developed a preliminary tool and modeled the hazard flow from the unsafe return of human excreta in two countries using available data. The model will be further refined using information from in-country experts and from public health microbiologists.

Biggest successes so far:
  • Completion of a strategic literature review examining the unsafe return of human excreta into the environment along the sanitation delivery chain
  • Informal elicitation of public microbiologists at the UNC Water Microbiology Conference
Main challenges / frustration:
  • Defining “unsafe return” and modeling pathogen die-off
  • Lack of available data on household pit latrine and septic tank emptying behavior, method of fecal sludge disposal and treatment, and the level of wastewater treatment (primary, secondary, tertiary) at the national level
If you have any questions or comments, please don't hesitate to raise them in this thread.

Regards,
Ashley


Ashley McKinney

Communications Specialist
The Water Institute at UNC
Gillings School of Global Public Health
The University of North Carolina at Chapel Hill
USA
waterinstitute.unc.edu
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  • arno
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Re: Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

Hi Ashley
What criteria are being used to define safe vs unsafe? How then is hazard defined since exposure is a variable when defining hazard. Any indicator pathogens chosen yet? Using epidemiological data, DALYS, morbidity, mortality, age groups, rural/urban, etc? Will be useful to link this up to the other modelled work at UNC regarding estimates of untreated wastewater/sanitation sources.

Best wishes
--Arno

Arno Rosemarin PhD
Stockholm Environment Institute
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Current project affiliation: www.susana.org/en/resources/projects/details/127
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Re: Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

I also am interested in this 'safety' aspect. It seems to me there is a chronic lack of agreement as to what 'safe' is (as measured by DALYS, QMRA etc) - who is going to make that call and how?

Also my observation from the UN debates on the Sustainable Development Goals is that the moves are away from universal standards and indicators and pressure towards locally defined targets. Of course, these are only preliminary discussions, but the tone seems to be that the mountain of targets and indicators will be impossible to deliver.

So what happens if this system suggests that a country is releasing a high percentage of unsafe faeces into the environment when the local targets (which might be based on the MDG improved sanitation standard) are met?

Without political agreement as to what is 'safe', I can't see that scientific methods of measurement (which in themselves are going to be dependent on good data collection..) are going to lead us anywhere very quickly.
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Re: Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

The results of the literature review are now available for download at waterinstitute.unc.edu/publication/unsaf...t-literature-review/ and www.susana.org/en/resources/library/details/2304

The review has a wide scope encompassing diverse technologies and all stages of the sanitation delivery chain and was solicited to add to the discussion on global sanitation monitoring and the agenda for the Sustainable Development Goals (SDGs). The Water Institute believes the review has value to the WaSH sector and has made it publicly available for comment in order to incorporate questions and comments from WaSH professionals and practitioners. We encourage you to download the document and provide feedback via e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it..
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Re: Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

Hi Ashley,

Thank you for the post which provides a good review and lessons. I would be interested in your follow-up studies especially in Ghana where we are located.

You cited Cofie et al (2009) and concluded that "while pathogen concentration was not measured as part of the study, the authors assumed the compost materials were sanitized since internal temperatures were above 45°C and composting occurred over 90 days". Indeed the authors monitored helminth die off as reported in Kone et al (2007) which you also cited on the same page. So it was not an assumption but evidence-based statement.

I would be happy to provide more insight into that project if necessary.
Best wishes.
Funke

Olufunke Cofie
Principal Researcher, Resource Recovery and Reuse Group
Head, IWMI West Africa Office.
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Re: Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

Hi Arno and Joe,

Thank you both for your comments. In terms of what is deemed "safe", this is a difficult thing to define, especially because there are many pathogens present in excreta that presents a risk to human health. We have piloted a survey to ask expert public health microbiologists to try and identify which pathogens are the most important to look at and have attempted to use expert elicitation to develop an estimate of pathogen die-off over time under various circumstances. We have not ironed out the question of "what is safe?" and we admit that even at the end of the project we may not have the most satisfactory answer, but we are trying to move away from simply a mass balance to a "hazard balance".

Our effort focuses at the national level rather than at the local level, and we are hopeful that the SDG 6.2 will encompass "safely managed sanitation" and not settle at simply the improved/unimproved user interface. Rather than only focusing on a binary indicator, our model is intended to reveal the need for safe management along the entire sanitation delivery chain in order to safeguard public health. We see our model as a tool for national policymakers and planners to identify areas along the sanitation delivery chain where excreta is not being safely managed and thereby target resources to improve their services.

Thank you again for your questions,

Ashley
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Re: Estimates for the Unsafe Return of Human Excreta to the Environment (The Water Institute at UNC, USA)

Hi Funke,

Thank you very much for your comment and for pointing out they are the same study. I went back to Cofie et al. 2009 and I see that he cited Kone et al. 2007 in the introduction "In terms of microbial population, pathogen inactivation in the FS/SW co-composting has been reported by Omanhene (2003) and Kone et al. (2007)."

Thank you for bringing this to our attention.

Warm regards,

Ashley
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