And disease.

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. . .

"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. But at the same time, wastewater agriculture contributes importantly to urban food supplies and helps provide a livelihood for the urban poor, especially women, and recent migrants from the countryside. . .

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."

"And it isn't just affluent consumers of exotic vegetables whose welfare is at stake," she added. "Poor consumers of inexpensive street food also depend on urban agriculture." Moreover, in Asia, rice-based farming systems, irrigated mainly with wastewater, figure importantly in urban food production, Raschid-Sally explained. . .

Survey results on the forces driving wastewater use in urban agriculture suggest that it is not only widespread but practically inevitable. As long as developing countries lack suitable transport for delivering large quantities of perishable produce to urban areas, vegetable production in urban agriculture will remain important. And in the face of water scarcity generally and a lack of access to clean water, urban farmers will have no alternative except to use diluted or untreated wastewater or polluted river water.

Consumers across the 53 cities said they would prefer to avoid wastewater produce. But most of the time, they have no way of knowing the origin of the products they buy. 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 . . .

Charles The Dim is pleased since the produce is organic.