costs, to safeguard public health, and to obtain the maximum possible agricultural benefit from nutrients and organic matter contained in wastewater (Mara and Cairncross, 1989).

Possible steps to help develop a strategic plan for implementing health risk reduction measures are (adapted from Carr _et al._ , 2004):

1.  Design and conduct a survey of wastewater and excreta use practices throughout the country or in specific districts. The survey could contain questions concerning:

- The availability, types and status of wastewater treatment available

- The types of crops grown in the area (whether they are eaten cooked or raw)

- Techniques for wastewater and excreta application, e.g. bucket, furrow, sprinkler, drip, other

- Options for protecting or controlling quality along the food supply chain from farm to fork

- An assessment of human exposure to wastewater and excreta during agricultural practices, e.g. Do fieldworkers wear protective clothing? Do they practice good hygiene?

2. Evaluate and prioritize health risks, in the context of the national burden of disease, associated with the use of wastewater and excreta in agriculture.

- Conduct interviews with health staff (doctors, nurses, pharmacists), farmers, families, community workers, teachers, consumer advocate groups, etc.

- Review scientific studies of disease, clinical data, outbreak information, prevalence data, etc.

- Conduct, if possible, a QMRA-MC risk simulation (see Chapter 4 and Annex A) to assess the safety of local practices for wastewater use in irrigation, and recommend appropriate pathogen reduction targets. If a QMRA is not possible then semi-quantitative risk ranking can be done, or if crops irrigated with severely polluted water are eaten raw the maximum risk reduction level can be targeted, as in the Ghana case (Box 5.2).

3. Based on steps 1 and 2, conduct national or district-level workshops to formulate appropriate (realistic) strategies for mitigating health impacts that include relevant stakeholders, e.g. farmers, traders, and consumer advocate groups 4. Develop national or other action plan and policies for the safe use of wastewater and excreta in agriculture considering cost-effectiveness of possible interventions that include both treatment and multiple barrier options. The plan should include time-bound interim health targets for the steady improvement in health outcomes over the medium and long term.

5. Strengthen institutional capacities – designate a responsible authority (or authorities) to monitor and enforce safe wastewater and excreta use practices.

6. Review and revise national strategy, action plan, and policies as needed.

A sample strategy and an action plan for the incremental application of the 2006 WHO Guidelines is presented in Box 5.1.

When developing a strategic plan it is important always to consider the alternative to this step-wise approach, which may be inaction if standards are set too high and cannot be achieved in a reasonable period of time. In Ouagadougou, for example, crop restrictions for using treated wastewater on a demarcated farming site near the treatment plant are so severe that food crop farmers returned to their informal sites using untreated wastewater (Drechsel, personal communication) **.** The step-wise approach includes the acceptance of wastewater irrigation at a standard much lower than required in developed countries given that post-treatment options for reducing risk can be added through a multibarrier approach.

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