Health Risk Management
Published on SSWM (http://www.sswm.info/)

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Health Risk Management

Compiled by:
Gina S. Itchon (Xavier University), Robert Gensch (Xavier University)

Sanitation systems should serve as a barrier or a series of barriers against different types of waterborne and excreta related pathogens in order to reduce the associated health risk to an acceptable minimum. It is recognised that a sanitation system including the treatment, safe disposal and reuse of human excreta and wastewater should not be based on a single barrier (such as treatment alone) but that a multi-barrier approach is required to effectively eliminate and/or inactivate the various types of hazardous microorganisms present in excreta. Achieving the objective of the multi-barrier approach requires a paradigm shift from the assessment of sanitation technologies as mere technological units to one that encapsulates the health risk and mitigation, institutional, socio-cultural, environmental and financial dimensions of sanitation technologies (adapted from STENSTROEM et al. 2010).

Multi-Barrier Approach

A barrier is a part of the treatment or handling chain of a sanitation system that substantially reduces the number of pathogens present in excreta. The barrier function is normally expressed in log-terms, where one log is similar to a 90% reduction, two logs similar to 99% reduction and so on. In the technical barriers, the reduction can be simplified to occur through different treatment processes. There is an additional risk of disease transmission related to the usage of sanitation system as well as the handling or use of the end products. These relate to environmental persistence and die-off, dilution factors, exposure and the dose that humans are exposed to (see also waterborne diseases pathogens and contaminants).

Barriers to protect oneself from infection are needed at all different points of exposure and for different exposure groups, i.e., those using the system, those handling the end products or those consuming crops fertilised with them.

A system for the safe disposal and reuse of human excreta and wastewater should not be based on a single barrier such as treatment, but that a multi-barrier approach is required to effectively eliminate and/or inactivate the different hazardous microorganisms spread through various routes as shown in the figure below (CARR 2001) and to obtain a high level of reliability. Achieving the objective of the multi-barrier approach requires a paradigm shift from the assessment of sanitation technologies as technological units, to one that encapsulates the system itself and human behaviour.

Transmission Routes of Excreta-Related Diseases

The transmission routes of excreta related disease, exposure points and the health risk factors involved are directly interlinked. The transmission of excreta related pathogens may be either primary (direct exposure) and/or secondary, (exposure through an external route). Primary transmission includes person to person contact, including short distance airborne transmission. Secondary transmission includes vehicle-borne (food, water etc.), vector borne and airborne long-distance transmission.

 transmissen routes

The spread of pathogens from excreta of an infected individual to a healthy individual – The faecal oral pathogen transmission routes. Source: CARR (2001) 

Critical Questions to Identify Severity of Health Risks

Closely related to the various transmission pathways are the following critical questions that need to be addressed in identifying the severity of the health risk associated with a particular pathway:

 

Groups Affected

In addition, different user and non-user groups may be affected. In this context these groups can be defined as users, workers, farmers and  the community. Special consideration should be given to vulnerable groups like children, the elderly or people with other underlying disease.

Mitigating Health Risks

Sanitation is considered as a system comprising technical (functional groups) and non-technical components that work in synergy to safeguard human health. Each sanitation technology is related to this grouping or components.

Technologies are defined as the specific infrastructure, methods, or services that are designed to contain, transform, or transport products to another functional group or component. Five main functional groups make up a full sanitation systems. These are

  1. user interface (e.g. toilet systems)
  2. storage and treatment
  3. conveyance collection
  4. secondary treatment 
  5. disposal and/or reuse

Each of the functional groups may be represented by different technologies that are chosen depending on the local context. The selected technology within each of the functional groups will govern the overall reduction efficiency and the likelihood of disease transmission. Each is linked to critical points where pathogens may be transmitted or controlled (see also toilet systems).

Non-Technical Aspects

Furthermore, the extent of human health protection by the sanitation system relates to non-technical socio-cultural aspects linked to specific features of the system, e.g. traditions, local believes, behaviours or taboos, or also predominant hygiene practices. These may further reduce (or sometimes elevate) exposure to pathogens at these critical points or as end-use related risks.

An example of such socio-cultural aspects are the Koranic edict where excreta are regarded as impure (najassa) and its use only permitted when the najassa is removed (FARUQUI 2001). Similarly, the Luo of western Kenya dispose of children’s faeces by digging and burying. This further relates to raining. Infants are trained to defecate in a special place and inform their care-takers so that the faeces are disposed of (ALMEDOM 1996) (see also sociocultural issues).

 monse fit for school

This picture was taken by Robert Gensch during Global Handwashing Day 2008 activities and the simultaneous launching of the Essential Health Care Package (EHCP) for Filipino Children (includes handwashing, tooth brushing and twice a year deworming). Source: SuSanA on Flickr (2008)

Cultures or traditions may also involve perception that exposes people to disease causing pathogens. This is the situation with child faeces which in other cultures are perceived as harmless, also when diarrhoeal diseases are prevalent. When mothers in areas with high prevalence of childhood diarrhoea are asked about the cause of the disease, they often blame it another factors than the poor handling of child faeces or poor hand washing practices (see also hygiene frameworks and approaches).


References

ALMEDOM, A. (1996): Recent Developments in Hygiene Behaviour Research: An Emphasis on Methods and Meaning. Tropical Medicine and International Health.

FARUQUI, N.; BISWAS, A.; BINO, M. (2001): Water Management in Islam. Tokio, New York, Paris: IDRC and UNU Press.

STENSTROEM, A.; SEIDU, R.; EKANE, M.; ZURBRUEGG, C. (2011): Microbial Exposure and Health Assessments in Sanitation Technologies and Systems. (= EcoSanRes Series, 1). Stockholm: Stockholm Environment Institute (SEI). URL [Accessed: 28.11.2011].

CARR, R. (2001): Excreta-related Infections and the Role of Sanitation in the Control of Transmission. In: FEWTRELL, L. ; BARTRAM, J. (2001): Water Quality: Guidelines, Standards and Health. London, 89-113. URL [Accessed: 06.10.2010].

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