Wastewater and Excreta Use In Aquaculture

By The World Health Organisation - This volume of the World Health Organization's (WHO) Guidelines for the safe use of wastewater, excreta and greywater describes the present state of knowledge regarding the impact of waste-fed aquaculture on the health of product consumers, workers and their families and local communities. Health hazards are identified for each group at risk, and appropriate health protection measures to mitigate the risks are discussed.

Wastewater and Excreta Use In Aquaculture - By The World Health Organisation - This volume of the World Health Organization's (WHO) Guidelines for the safe use of wastewater, excreta and greywater describes the present state of knowledge regarding the impact of waste-fed aquaculture on the health of product consumers, workers and their families and local communities. Health hazards are identified for each group at risk, and appropriate health protection measures to mitigate the risks are discussed.


1. Introduction
1.1 Objectives and general considerations
1.2 Target audience, definitions and scope
1.3 Organization of this Guidelines document
1.4 Driving forces affecting wastewater and excreta use in aquaculture
1.5 Historical overview of waste-fed aquaculture
1.6 Current waste-fed aquacultural practice
1.6.1 Bangladesh
1.6.2 China
1.6.3 India
1.6.4 Indonesia
1.6.5 Viet Nam
1.6.6 Africa
1.6.7 Europe
1.6.8 The Americas
1.6.9 Western Pacific
2. The Stockholm Framework
2.1 A harmonized approach to risk assessment/management
2.2 Assessment of environmental exposure
2.3 Assessment of health risk
2.4 Tolerable risk
2.5 Health-based targets
2.6 Risk management
2.7 Public health status
2.7.1 Excreta-related diseases
2.7.2 Foodborne trematodes and schistosomiasis
2.7.3 Vector-borne diseases
2.7.4 Measuring public health status
3. Assessment of health risk
3.1 Microbial evidence
3.1.1 Microbial pond water quality
3.1.2 Evidence of product contamination: Fish
3.1.3 Evidence of product contamination: Plants
3.2 Epidemiological evidence
3.2.1 Skin diseases
3.2.2 Product consumption and other exposures
3.3 Chemicals
3.4 Health benefits
4. Health-based targets
4.1 Protection of product consumers
4.1.1 Trematodes
4.1.2 Other pathogens
4.1.3 Chemicals
4.2 Protection of aquacultural workers and local communities
4.2.1 Pathogens
4.2.2 Skin irritants
4.2.3 Vector-borne diseases
4.3 International guidelines and national standards
4.3.1 Food exports
4.3.2 National standards
5. Health protection measures
5.1 Health protection measures for different exposed groups
5.1.1 Product consumers
5.1.2 Workers (and their families)
5.1.3 Local communities
5.2 Effectiveness of health protection measures
5.2.1 Excreta treatment
5.2.2 Wastewater treatment
5.2.3 Produce restriction
5.2.4 Waste application withholding period
5.2.5 Depuration
5.2.6 Food handling and preparation
5.2.7 Produce washing/disinfection and cooking of food
5.2.8 Health and hygiene promotion
5.2.9 Immunization and chemotherapy
5.2.10 Exposure control measures for workers, product handlers and local communities
5.2.11 Control of vector-borne diseases
5.3 Trematodes: Special considerations
5.3.1 Reducing trematode contamination of ponds and interrupting trematode life cycles
5.3.2 Control of intermediate hosts
5.3.3 Post-harvest health protection measures
5.3.4 Chemotherapy of humans and animals
5.3.5 Schistosomiasis
6. Monitoring and system assessment
6.1 Monitoring
6.2 Monitoring functions
6.3 System assessment
6.4 Validation
6.5 Operational monitoring
6.6 Verification monitoring
6.7 Small systems
6.8 Other types of monitoring
6.8.1 Food inspection
6.8.2 Public health surveillance
7. Sociocultural, environmental and economic aspects
7.1 Sociocultural aspects
7.1.1 Public perception
7.1.2 Excreta use
7.1.3 Wastewater use
7.1.4 Food-related determinants
7.2 Environmental concerns
7.3 Economic and financial feasibility
7.3.1 Economic appraisal
7.3.2 Financial feasibility
8. Policy aspects
8.1 Policy
8.1.1 International policy
8.1.2 National wastewater and excreta use policies
8.1.3 Wastewater and excreta in integrated water resources management
8.2 Legislation
8.2.1 Institutional roles and responsibilities
8.2.2 Rights of access
8.2.3 Land tenure
8.2.4 Public health
8.3 Regulations
8.4 Developing a national policy framework
8.4.1 Defining objectives
8.4.2 Assessment of the policy environment
8.4.3 Developing national approaches based on the WHO Guidelines
8.4.4 Research
9. Planning and implementation
9.1 Reporting and communication
9.2 Interaction with community and consumers
9.3 Use of data and information
9.4 Project planning criteria
9.4.1 Support services
9.4.2 Training
Annex 1: Wastewater-fed fish pond design
Annex 2: FAO Code of Conduct for Responsible Fisheries: Aquaculture and environmental impact
Annex 3: Health impact assessment
Annex 4: Glossary of terms used in the Guidelines


The primary aim of the Guidelines is to maximise public health protection and the beneficial use of important resources, The purpose of this volume is to ensure that waste-fed aquacultural activities are made as safe as possible so that the nutritional and household food security benefits can be shared widely in affected communities, Thus, the adverse health impacts of waste-fed aquaculture should be carefully weighed against the benefits to health and the environment associated with these practices. Yet this is not a matter of simple trade-oils. Wherever waste-fed aquaculture contributes significantly to food security and nutritional status, the point is to identify associated hazards, define the risks they represent to vulnerable groups and design measures aimed at reducing these risks

This volume of the Guidelines is intended to be used as the basis lor the development of international and national approaches (including standards and regulations) to managing the health risks from hazards associated with waste-fed aquaculture as well as providing a framework for national and local decision-making, The information provided is applicable to intentional waste-fed aquacultural practices but also should be relevant to the unintentional use of Faecally contaminated waters for aquaculture.

The Guidelines provide an integrated preventive management framework for safety applied from the point of waste generation to the consumption of products grown with the wastewater and excreta. They describe reasonable minimum requirements of good practice to protect the health of the people using wastewater or excreta, or consuming products grown with wastewater or excreta and provide information thai is then used to derive health-based targets. Neither the minimum good practices nor the health-based targets are mandatory limits. The preferred approaches adopted by national or local authorities towards implementation of the Guidelines, including health-based targets, may vary depending on local social, cultural, environmental and economic conditions, as well as knowledge of routes of exposure, the nature and severity of hazards and the effectiveness of health protection measures available.

The revised Guidelines for the safe use of wastewater, excreta and greywater will be useful to all those concerned with issues relating to the safe use of wastewater, excreta and greywater, public health, water resources development and wastewater management. The target audience may include environmental and public health scientists, educators, researchers, engineers, policy-makers and those responsible for developing standards and regulations.


A number of forces are both negatively and positively impacting the development of waste-ted aquacultural production. Many of the areas where waste-fed aquaculture has been traditionally practised are shrinking due to urbanization, increasing surface water pollution and the development of high-input aquaculture to produce cash crops. Most of the traditional waste-fed aquacultural production has occurred in parts of Asia, Although intentional waste-fed aquaculture is in decline, the unintentional use of contaminated water in aquaculture may be increasing in some areas.

The Stockholm Framework

The Stockholm Framework is an integrated approach that combines risk assessment and risk management to control water-related diseases. This provides a harmonised framework for the development of health-based guidelines and standards in terms of water- and sanitation-related microbial hazards. The Stockholm Framework involves the assessment of health risks prior to the setting of health-based targets and the development of guideline values, defining basic control approaches and evaluating the impact of these combined approaches on public health. The Stockholm Framework provides the conceptual framework for these Guidelines and other WHO water-related guidelines.

Assessment of health risk

Three types of evaluations are used lo assess risk: microbial and chemical laboratory analysis, epidemiological studies and quantitative microbial (and chemical) risk assessment. Overall, there are limited data on the health impacts associated with waste-fed aquacultural practices, The evidence suggests thai pathogens are often present at significant levels in untreated wastewater and excreta; pathogens can survive long enough in the environment to be transmitted to humans; and waste-fed aquaculture-associated disease transmission can occur. Foodborne trematode parasites, where they occur, pose significant health risks to consumers of raw or inadequately cooked fish or plants. Priority should be given to implementing control measures against the transmission of food borne trematode infections, where relevant, Excreta-related pathogens pose health risks to product consumers and people who may have contact with the contaminated water. For product consumers much of the health risk may be associated with poor fish cleaning practices thai lead to cross-contamination between the gut contents and the edible flesh. Thus improving market hygiene and fish processing/cleaning is on important health protection intervention.

Health-based targets

Health-based targets define a level of health protection that is relevant to each hazard. A health-based target can be based on a standard metric of disease, such as the disability adjusted life year or DALY (e.g. 10-6 DALY) or it can be based on an appropriate health outcome, such as the prevention of the transmission of foodborne trematode infection associated with waste-fed aquacultural practices, To achieve a health-based target, health protection measures are developed. Usually a health-based target can be achieved through a combination of health protection measures targeted at different components of the waste-fed aquacultural system.

Further Information

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September 2006

the Fish Site Editor

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