The global use of untreated waste water from cities to irrigate crops is much more widespread than previously estimated, says a new report.
According to this updated assessment, nearly 30 million hectares are now using untreated water within 40km of an urban centre
Some 800 million people, including farmers, vendors and consumers are said to be exposed to serious health risks.
China, India, Pakistan, Mexico and Iran account for most of the treated land.
The huge populations in big cities across the developing world make very attractive markets for farmers.
The lack of refrigeration and transport means that crops need to be grown close to these consumers. Being close to cities also provides a key element for the crops – plentiful amounts of nutrient-rich waste water.