Sanitation: Controlling problems at source:
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People and waste: The size of the problem
Worldwide 2.4 billion people do not have access to basic sanitation: they lack safe means of disposal of excreta and waste water
Despite continued efforts to promote sanitation 40% of the world's population is still without basic sanitation. This number does not tell the whole story, sanitation coverage is often much lower in rural areas than in urban areas. For example, in Africa 84% of urban but only 45% of rural residents have access to basic sanitation. The numbers are similar in Asia where 78% of urban and 31% of rural residents have access to basic sanitation (WHO, 2000). In many cases, improving sanitation can be as simple as installing a well-designed ventilated improved pit latrine (VIP) or composting latrine. However, in other cases, improving sanitation will be more challenging, particularly in rapidly growing urban slums. Moreover, while building improved sanitation facilities is a crucial health intervention, the full health benefits will not be realized without proper use and maintenance of the facilities and good personal and domestic hygiene (Carr and Strauss, 2001).
Sanitation facilities interrupt the transmission of faecal-oral disease at its most important source by preventing human faecal contamination of water and soil. Poor waste disposal practices are responsible for a significant proportion of the world's infectious disease burden. Diseases due to poor water supply, sanitation, and personal and domestic hygiene cause 4.0% of all deaths and 5.7% of all disability or ill health in the world. This burden is not distributed equally; waterborne illnesses predominantly affect the poor and the young. However, when basic water, sanitation, and hygiene interventions are applied, waterborne illnesses can be effectively reduced. Low cost interventions such as composting latrines can be used to reduce the transmission of many diseases.
Municipal sewage is a mixture of human excreta and household wastewater that is transported via pipes to a treatment or disposal point. In many areas, municipal sewage is often mixed with industrial waste. Sewerage systems are common in industrialised countries and often occur in urban areas of less-industrialised countries. In some regions very little wastewater receives treatment before it is discharged into the environment. In Africa, virtually no wastewater receives treatment before it is discharged. In other regions, rates of treatment are not much better, for example, in the Latin America and Caribbean Region only 14% of wastewater is treated, while in Asia approximately 35% of wastewater is treated before it is disposed of in the environment (WHO 2000b). Problems in waste disposal are not confined to less-industrialised countries. Industrialized countries also need to improve their sewage, excreta, and sludge management practices. In North America 10% and in Europe 34% of wastewater is not treated before it is discharged into the environment (WHO, 2000b). In the United States of America, the number of detected waterborne disease outbreaks and the number of affected individuals per outbreak has increased since 1940 (Hunter, 1997). Similarly, water quality monitoring of major European rivers indicates that average coliform levels - the organism present in human, animal and bird excreta - have been steadily increasing for decades (Meybeck et al. 1990).
Currently, water-borne sanitation systems typically use 50 to 100 litres of water to remove 1-1.5 litres of human excreta per person per day (Jönsson, 1997; Van der Ryn, 1995). Moreover, most of this water is used to remove urine (urine makes up 90% of the volume of excreta) which poses little threat to human health (Esrey, 2000). In this type of system, a small amount of faeces then contaminates a large amount of water and nutrients that could be useful locally are washed away into other areas (or removed at great expense in a treatment system) where they concentrate. High levels of nutrients cause environmental damage and exacerbate the growth of potentially toxin-producing algae. Clearly, sustainable sanitation alternatives are needed.
Toilets and latrines: a basic right and an essential way of controlling sanitation problems at source
In examining the larger issues of waste disposal, we should not forget the role played by the humble latrine. Far more people lack access to a properly managed toilet or latrine, than to water. In a recent survey in Uganda, only a third of schools had adequate sanitation and separate toilets for girls (Box 1). In another study in Ecuador, latrines designed for use by 30 to 40 pupils, in reality served as many as 180 (WHO, 1994). A lack of separate sanitation facilities for girls has been cited as a prime cause of girls leaving school before finishing their studies (WHO, 1997b).
Box 1: Sharing toilets in Uganda
A recent survey by the Ministry of Health in Uganda suggested that there is only one toilet for every 700 Ugandan pupils, compared to one for every 328 pupils in 1995. Out of 8000 schools surveyed, only 33% of the 8000 schools sampled have separate latrines for girls. The deterioration in sanitary conditions was attributed to increased enrolment in schools. UNICEF surveyed 90 primary schools in crisis-affected districts of north and west Uganda: only 2% had adequate latrine facilities (IRIN, 1999).
Sanitation: Controlling problems at source:
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