WHO Issues Third Edition Of Its Guidelines For The Safe Use Of Wastewater

In many parts of the world, good quality fresh water resources are becoming increasingly scarce. At the same time, wastewater is produced in ever larger quantities, mainly as a result of the continued growth of the human population and the process of rapid urbanization.

In reality, wastewater is a water resource of ever-growing importance, particularly for the urban and peri-urban poor whose livelihoods depend on agricultural products that can be marketed locally. However, its use for crop and fish production carries important health risks and the disease burden that can be attributed to its unsafe use is considerable.

The third edition of the World Health Organization's (WHO) "Guidelines for the Safe Use of Wastewater, Excreta and Greywater in Agriculture and Aquaculture" is published in four volumes, addressing, respectively, policy and regulatory aspects, wastewater use in agriculture, wastewater and excreta use in aquaculture and excreta and greywater use in agriculture. It supersedes the second edition of the guidelines, which was published in 1989.

"This third edition of the Wastewater Guidelines marks an important departure from the previous edition," said Susanne Weber-Mosdorf, assistant director-general for the Cluster of Sustainable Development and Healthy Environments. "The rigid and prescriptive character of the second edition has evolved to a more contemporary and flexible approach based on scientific evidence and process-oriented risk assessment and management. The guidelines reflect a strong focus on disease prevention and public health principles. Water quality regulators will have to work towards attaining health-based targets through an integrated approach."

Parallel to this new thinking on handling risks in an integrated manner, the guidelines also reflect new thinking in the field of sanitation. This has evolved in part in response to the sanitation target within the Millennium Development Goals. Volume 4 of this third edition elaborates on this issue and the links to safe use of excreta and greywater in agriculture.

"Eco-sanitation is scaling up from a stage of pilot studies to extensive use in a number of countries, for example China and South Africa," said Professor Thor Axel Stenstroem who holds positions at the Swedish Institute for Infectious Disease Control and the Stockholm Environment Institute. "Now, for the first outcomes of a recently initiated WHO/Sida study provides proof of a significantly reduced health impact. In a comparative study, the Nelson Mandela School of Medicine of the University of KwaZulu Natal (Durban) and the Ethekwini Municipality measured the incidence of diarrhoea, vomiting, skin infections and worms in six cohorts of a total of more than 7,000 people from 1,337 households. The study now provides evidence of significant correlations between disease outcome in relation to sanitation interventions, outcomes for disease per area, incidence rates of health outcome and incidence rate ratio of disease outcome."

The guidelines reflect regional differences in wastewater use and in associated public health issues. The WHO "Guidelines for the Safe Use of Wastewater, Excreta and Greywater in Agriculture and Aquaculture" reflect the knowledge and experience of a unique group of scientists, regulators and public health specialists brought together by the Water, Sanitation and Health Programme of the WHO, officials said. The guidelines, announced on Sept. 11, are available online at http://www.who.int/water_sanitation_health/wastewater/gsuww/en/index.html.

This article originally appeared in the 09/01/2006 issue of Environmental Protection.

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