Microbial Exposure and Health Assessments in Sanitation Technologies and Systems

The report provides a comprehensive health risk assessment of sanitation technologies, categorizing them into functional groups: user interface, collection and storage/treatment, conveyance, semi-centralized treatment, and reuse/disposal. It identifies critical exposure points for users, workers, farmers, and the community, emphasizing that technical barriers (like storage time and pH elevation) must be combined with socio-cultural behavioral changes (such as hand-washing) to effectively break the cycle of disease transmission. The document analyzes specific technologies—ranging from open defecation and pit latrines to advanced wastewater treatment plants—and provides epidemiological evidence on their impact on diarrhoeal diseases and helminth infections.

• The primary objective of a sanitation system is to protect human health by breaking the cycle of disease transmission through containment and reduction of pathogenic organisms.
• A multi-barrier approach is necessary for the safe disposal and reuse of human excreta and wastewater to eliminate or inactivate hazardous microorganisms and account for performance variations over time.
• Open defecation is identified as the most significant environmental factor in the transmission of excreta-related diseases, with high risks of direct contact, water contamination, and vector breeding.
• In a study in Southern Tanzania, households practicing open defecation were 11.4 times more likely to develop cholera than those with toilet facilities.
• Flush toilets are associated with lower infection risks than dry toilets; users are 2.1 times less likely to be infected with Ascaris and 1.5 to 4.2 times less likely to develop diarrhoea.
• The health risk of using urine-diverting dry toilets (UDDTs) is significantly reduced when combined with safe water and hygiene education, with one study showing a 41 per cent reduction in diarrhoea episodes.
• Dehydration vaults can achieve significant pathogen reduction (up to 6 logs for bacteria and 4 logs for viruses) if combined with low moisture, a pH of 8.5-10.3, and storage for 6-12 months.
• Waste stabilization ponds (WSPs) can remove 1-6 log units of bacteria and 1-4 log units of viruses, but poorly maintained ponds can increase malaria risk for residents living within 300m.
• The use of treated wastewater for irrigation carries significant risks for consumers of raw vegetables; a 6-7 log reduction of pathogens is estimated as necessary to achieve a tolerable health target.
• The application of dehydrated faeces can lead to high helminth infection risks if storage times are insufficient; in El Salvador, those burying dehydrated faeces in yards were 8.3 times more likely to be infected with Ascaris.
• Conventional gravity sewers significantly reduce direct contact with pathogens in the public domain, reducing hookworm infection risk by 2.7 times in some urban Brazilian studies.

APA

Stenström, T. A., Seidu, R., Ekane, N., & Zurbrügg, C. (2009). Microbial Exposure and Health Assessments in Sanitation Technologies and Systems. Stockholm Environment Institute. https://www.sei.org/mediamanager/documents/Publications/SEI-Report-Stenstrom-MicrobialExposureAndHealthAssessmentsInSanitationTechnologiesAndSystems-2011.pdf

Chicago

Stenström, Thor Axel, Razak Seidu, Nelson Ekane, and Christian Zurbrügg. Microbial Exposure and Health Assessments in Sanitation Technologies and Systems. Stockholm Environment Institute, 2009. https://www.sei.org/mediamanager/documents/Publications/SEI-Report-Stenstrom-MicrobialExposureAndHealthAssessmentsInSanitationTechnologiesAndSystems-2011.pdf.

Wikipedia

{{cite report |last1=Stenström |first1=Thor Axel |last2=Seidu |first2=Razak |last3=Ekane |first3=Nelson |last4=Zurbrügg |first4=Christian |title=Microbial Exposure and Health Assessments in Sanitation Technologies and Systems |publisher=Stockholm Environment Institute |date=2009 |url=https://www.sei.org/mediamanager/documents/Publications/SEI-Report-Stenstrom-MicrobialExposureAndHealthAssessmentsInSanitationTechnologiesAndSystems-2011.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stenstrm2009microbial, author = {Stenström, Thor Axel and Seidu, Razak and Ekane, Nelson and Zurbrügg, Christian}, title = {{Microbial Exposure and Health Assessments in Sanitation Technologies and Systems}}, institution = {Stockholm Environment Institute}, year = {2009}, url = {https://www.sei.org/mediamanager/documents/Publications/SEI-Report-Stenstrom-MicrobialExposureAndHealthAssessmentsInSanitationTechnologiesAndSystems-2011.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }