Waste water and agriculture

We can safely say that the quality of water is a huge factor in the safety of fresh fruits and vegetables. Given that reality, Doug Powell of the Food Safety Network links to this sobering news release about the use of sewage waste water in developing countries. From the news release from the International Water Management Institute:



Most Common in Asia and Sub-Saharan Africa, Wastewater Use is Critical to Farmers Incomes, Urban Food Security but Raises Health Concerns
Stockholm, Sweden (18 August 2008) — As developing countries confront the first global food crisis since the 1970s as well as unprecedented water scarcity, a new 53-city survey conducted by the International Water Management Institute (IWMI) indicates that most of those studied (80 percent) are using untreated or partially treated wastewater for agriculture. In over 70 percent of the cities studied, more than half of urban agricultural
land is irrigated with wastewater that is either raw or diluted in streams. The conclusions of the study, released today at 2008 World Water Week in Stockholm, are based on data gathered from a diverse sample of developing country cities, chosen on the basis of factors such as water scarcity and income levels. Local experts selected by an independent panel completed survey questionnaires, drawing on secondary data as well as interviews with local water management experts and detailed country studies. “Irrigating with wastewater isn’t a rare practice limited to a few of the poorest countries,” said IWMI researcher Liqa Raschid-Sally and lead author of a report on survey results. “It’s a widespread phenomenon, occurring on 20 million hectares across the developing world, especially in Asian countries, like China, India and Vietnam, but also around nearly every city of sub-Saharan Africa and in many Latin American cities as well.” Wastewater is most commonly used to produce vegetables and cereals (especially rice), according to this and other IWMI reports, raising concerns about health risks for consumers, particularly of vegetables that are consumed uncooked.


“The negative and positive implications of wastewater agriculture have only recently received attention,” noted Colin Chartres, director general of IWMI, which is supported by the Consultative Group on International Agricultural Research (CGIAR). “This study offers the first comprehensive, cross-country analysis of the conditions that account for the practice and the difficult tradeoffs that arise from it.” Accra, Ghana’s capital city (with an urban population of nearly 2 million), illustrates those tradeoffs particularly well. An estimated 200,000 of the city’s inhabitants daily purchase vegetables produced on just 100 hectares of urban agricultural land irrigated with wastewater, says the IWMI report. “That gives you an idea,” remarked Raschid-Sally, “of the large potential of wastewater agriculture for both helping and hurting great numbers of urban consumers.”

Farmers too are aware that irrigating with wastewater may pose health risks both for themselves and the consumers of their produce, but they simply have little choice, since safe groundwater is seldom an accessible alternative, according to the IWMI report. Few developing countries reported having official guidelines for the use of wastewater in agriculture. And even if they do, monitoring and enforcement rarely happen and may not be realistic, especially where irrigation with polluted water occurs on a large scale. As a result, though the practice may be theoretically forbidden or controlled, it is in fact “unofficially tolerated.”

TK: It would appear most of the food-related impact of the waste water is confined to urban areas near where the produce is grown in developing countries. However, this report illustrates just how much work needs to be done to improve the quality of life for much of the world's population.