The floodwaters that inundated New Orleans following Hurricane Katrina were not as toxic as some had feared, according to a new study.

Researchers at Louisiana State University in Baton Rouge found that the water was similar in content to the city's normal storm water. The findings are published in the online edition of the journal Environmental Science & Technology.

"What we had in New Orleans was basically a year's worth of storm water flowing through the city in only a few days," said study leader John Pardue, director of the Louisiana Water Resources Research Institute at LSU. "We still don't think the floodwaters were safe, but it could have been a lot worse. It was not the chemical catastrophe some had expected."

Some experts had predicted that the floodwaters from Katrina could destroy chemical plants and refineries in the area, releasing a deadly brew containing toxic levels of benzene, hydrochloric acid and chlorine.

Instead, high levels of bacteria and viruses were the biggest human threat, not exposure to chemicals, the researchers said.

But the researchers said the floodwaters, which were pumped back into Lake Pontchartrain, could wreak environmental havoc in the long term.

The water contains high levels of some toxic metals, especially copper and zinc. That could pose a long-term danger to the area's aquatic life, which are more sensitive to the metals than humans. Pardue also said the low oxygen levels in the water could kill fish.

What else was in the water? In 38 samples, the researchers found high levels of bacteria, most likely from fecal contamination resulting from sewage. They also found high levels of lead, arsenic and chromium, as well as chemical compounds from aerosol paints, insecticides, caulking compounds, rubber adhesives and other common household substances.

Additional Resources:

• Overview: New Orleans floodwater is not "toxic soup"
• Full Study: Chemical and Microbiological Parameters in New Orleans Floodwater Following Hurricane Katrina