The suburban New Orleans neighborhood hit by a million-gallon oil spill after Hurricane Katrina is still a dangerous, toxic mess, the head of the Environmental Protection Agency said Thursday.

TOM FOX/DMN

Mike Gilfour and Jesse Coffman vacuumed oil sludge in September after a tank at a refinery southeast of New Orleans came loose in the flooding from Hurricane Katrina.

It's not known when the area around Murphy Oil Corp.'s refinery in St. Bernard Parish will be safe or whether some of the 1,700 oil-soaked homes can ever be re-occupied, EPA Administrator Steve Johnson and other officials told reporters.

"We have serious concerns about potential exposure to Murphy Oil contaminated sediment," Mr. Johnson said. New Orleans' Ninth Ward neighborhood is also a concern, he said.

"Avoid direct contact with the sediment," he said. "Avoid direct contact with the floodwater. That has been our message since the very beginning."

A tank at the Murphy Oil refinery in Meraux, southeast of New Orleans, came loose Sept. 4 in the floods after Katrina. Officials estimate that more than 1 million gallons of crude oil spilled.

Murphy Oil, based in El Dorado, Ark., has assured residents that after a planned cleanup, the neighborhood would face no short- or long-term risks from the spilled oil. However, EPA and Louisiana officials said the contamination in the square-mile spill area is a serious health risk.

Parish officials went against the state's recommendation when they let people start repairing their homes, said Dwight Bradshaw of the Louisiana Department of Environmental Quality.

The cleanup is the responsibility of Murphy Oil, under government supervision, said Richard E. Greene, regional administrator of the EPA.

A decision on whether the worst hit homes can be reoccupied "is a work in progress," he said.

A Murphy Oil spokesman declined to comment.

The EPA offered hopeful signs on some other fronts. Monitoring has uncovered few if any problems with toxic air pollution in the Gulf Coast hurricane zone or chemical contamination in gulf bays, the agency said.

Three of the five federal Superfund toxic-waste sites in the hurricane zone came through with no release of contamination, while at two others, no contamination reached drinking water wells, the EPA said.

But, problems remain, Mr. Johnson said. They include contaminated flood sediment, oil spills, mold in formerly flooded buildings, damaged drinking- water and wastewater systems and massive amounts of debris.

E-mail rloftis@dallasnews.com