New Orleans has authorised the forced removal of residents who refuse to leave their homes, as health risks increase in the flood-ravaged city.About 60 percent of it is under water – down from 80 percent last week. But the combination of toxic waste and rotting corpses poses serious dangers to those who stayed behind when Hurricane Katrina struck. “I will emphasise that I would like everyone to get out because it’s a health risk,” said Mayor Ray Nagin. “There are toxins in the water. There are gas leaks where we might have explosions.” The presence of gas makes fighting fires almost as vital as getting the water out. Nagin has said that an estimated death toll of 10,000 would not be unreasonable. Most of the survivors that are now being found are elderly people in desperate need of medical care. The White House is set to ask Congress for an extra 40 to 50 billion dollars in aid to the stricken areas – that is the equivalent of up to 40 billion euros. President George W Bush, who has come under strong criticism for his response to the disaster, has announced he will lead an investigation into what went wrong. Congress also plans a probe. Politicians of all persuasions say the handling of the tragedy has raised doubts about America’s ability to cope with a major terrorist attack. More than 273,000 people displaced by the Hurricane have been given shelter across 16 states.