09/27/2008 05:12 am ET | Updated May 25, 2011

Human Waste Used By 200 Million Farmers, Study Says

Facing water shortages and escalating fertilizer costs, farmers in developing countries are using raw sewage to irrigate and fertilize nearly 49 million acres (20 million hectares) of cropland, according to a new report--and it may not be a bad thing.

While the practice carries serious health risks for many, those dangers are eclipsed by the social and economic gains for poor urban farmers and consumers who need affordable food, the study authors say.

Nearly 200 million farmers in China, India, Vietnam, sub-Saharan Africa, and Latin America harvest grains and vegetables from fields that use untreated human waste.

Read more on National Geographic