Just How Bad Is Nola's Sludge?

From Wired:

Before Hurricane Katrina even reached New Orleans, scientists warned of a "toxic gumbo" that would fill the giant soup bowl of a city. Now that their predictions have come true, specialists are turning their attention to the next big challenge: the leftovers.

As the water recedes, a disgusting muck coats the surfaces of buildings and streets. But it might be less dangerous than first feared.

The simple passage of time will cure the Big Easy of many of its ills, according to specialists in germ and chemical threats. To say New Orleans has become a giant toxic waste dump is "too strong," said Danny Reible, chair of Environmental Health Engineering at the University of Texas at Austin.

One reason for the optimism is that the nature of the New Orleans flood might actually result in less thick mud for residents and workers to cope with. In typical floods, "you've got this river that has been rampaging and carrying soil from everywhere in the watershed with it," said Reible, a former professor of chemical engineering at Louisiana State University. "Here, in a way it was a slow trickle, by comparison, that came through a breech in the levee. As a result it probably didn't bring in nearly as much ... mud."

It's also promising that the chemical components of some pollutants, like oil and gasoline, will float to the top and either evaporate or be washed away during the pumping of the city, Reible said.

Still, heavier components of oil and gas will simply sink into the muck, along with chemicals in pesticides and herbicides. But Reible and others think there will be an even bigger hazard -- germs.

Dire predictions about huge outbreaks of disease in New Orleans haven't come true, despite the hundreds or thousands of residents who continue to wade through the polluted water every day. Still, there will be plenty of hazards even when the flooding is gone, said Dr. Philip M. Tierno, director of microbiology and clinical immunology at New York University Medical Center and author of The Secret Life of Germs.