Cow and chicken dung has long been used as fertilizer - but human sewage?!?

With an exploding population, it may be an idea whose time has come - and British scientist Michael Rogers and his colleagues at London's Imperial College are saying it may not be as harmful as it seems.

The main concern has been a strain of bacteria known as E. Coli, recently implicated in a spate of food-borne illnesses in the U.S. earlier this week. The scientists are now saying that the bacteria may actually die off relatively quickly when sewage sludge is applied to crop fields.

Until 1998, the U.K. dumped 25% of its sewage sludge into the North Sea. 50% was spread on farmland, and only 10% was incinerated or put into landfills. That increased to 20% when the EU banned the dumping of sludge into oceans.  Rogers has discovered that the levels of E.Coli drop significantly when the sludge is spread onto fields. At the annual meeting of the UK Society for General Microbiology, Rogers reported that "Within 70 days, they went down to as little as 10 bacteria per gram, from 100,000 per gram initially."