Floodwaters a Soup of Pathogens, EPA Finds
The floodwaters that spilled into New Orleans contain extremely high levels of sewage-borne bacteria, posing an immediate health threat to people who remain in the city, according to data released Wednesday by the Environmental Protection Agency.
Federal health authorities urged all remaining residents to leave the flood-ravaged city, saying the tests confirmed that the foul-smelling water that has soaked its neighborhoods is contaminated with unsafe levels of pathogens that could transmit diseases such as hepatitis A and salmonella. No disease outbreaks have been reported in the region, but there have been several isolated deaths blamed on water-borne bacteria.
“For the evacuees who haven’t left the city yet, you must do so,” said Dr. Julie L. Gerberding, director of the Centers for Disease Control and Prevention.
The E. coli and coliform bacteria detected in large amounts in the water covering residential areas of New Orleans are not dangerous, themselves, but they indicate that raw sewage has flowed into city neighborhoods.
The counts of E. coli and coliform exceeded the ability of testing equipment, which is designed for sampling the safety of recreational waters, to measure them. The levels were so high that “every single one of the samples hit the maximum,” said EPA Administrator Stephen L. Johnson.
Lead in New Orleans’ floodwaters also exceeded health standards for drinking water. Low levels of lead, when ingested by a child, can damage the developing brain and cause learning disabilities.
“These [lead] levels are of greatest concern for children. This may seem obvious: No one should drink the floodwaters, especially children,” Johnson said.
There was good news, too. The EPA tested floodwaters for more than 100 other chemicals, including pesticides, hydrocarbons, metals and polychlorinated biphenyls, but so far none except lead has exceeded concentrations that pose human health risks if the water is ingested, EPA officials said.
The findings announced Wednesday are the first preliminary data from the EPA’s sampling for contaminants in the aftermath of Hurricane Katrina.
The chemical tests so far have focused on New Orleans’ residential areas, not the sprawling industrial area along the Gulf Coast that is home to about 140 oil refineries and chemical plants. But EPA officials say that its environmental emergency teams in boats and aircraft have reported no major spills at chemical plants and only two fairly large oil spills.
Health and environmental experts say that the sewage poses a more immediate and serious risk than the chemicals.
“I wouldn’t be too concerned about things like lead,” said Rick Gersberg, a professor at San Diego State University’s Graduate School of Public Health who specializes in water quality. “No one’s going to drink [the floodwater], and if anyone does, it will be so unappetizing that they aren’t going to drink much.” Hazardous levels of chemicals in drinking water are based on drinking two liters per day.
Instead, “the major problem is infectious disease,” he said. “It doesn’t take much to get one virus on your hand and then put your hand in your mouth.”
Sewage contains an array of viruses and other pathogens that can cause illnesses, such as hepatitis A, shigella, giardia, salmonella, and can induce diarrhea, vomiting, fever and other gastrointestinal symptoms. Water-quality experts said it is virtually certain that the floodwaters contain viruses that can make people sick.
The pathogens that infect people in the New Orleans area end up in the streets because the sewage treatment systems are inoperable, sewer lines are leaking and people are defecating in the streets. More than 200 sewage-treatment plants in Louisiana, Mississippi and Alabama were affected by the hurricane, the EPA said. Contact with the bacteria-laden floodwaters can be especially hazardous to the elderly, children or people with compromised immune systems.
The lack of clean water for bathing and drinking poses one of the biggest health threats. More than 1,000 water systems in Louisiana, Mississippi and Alabama were affected by the hurricane, and many of them were disabled, the EPA said. In Louisiana, nearly 400 drinking water systems are not operating and another 48 are in a state that has lead officials to advise people to boil their water.
The CDC reported that four people, evidently evacuees, had died after being infected with Vibrio vulnificus bacteria, a water-borne pathogen common in the Gulf of Mexico. One death was in Texas, which has received evacuees from Louisiana, and three were in Mississippi and Alabama.
Despite some media reports, CDC officials stressed that the Vibrio bacterium was not the agent that caused cholera. Cholera is not found in U.S. waters and spreads by hand-to-hand contact. The bacteria found in the Gulf Coast area is associated with exposure to saltwater, especially by people with skin wounds. Gerberding said it was not an outbreak.
“We see it from time to time along the coast,” she said.
Also, in the shelters, evacuees have reported gastrointestinal illnesses, including noravirus, the same virus sometimes found on cruise ships. It is not usually life-threatening and symptoms last a day or two.
The long-term effects of the contamination remain unknown. Even when the water recedes, chemical and bacterial contaminants will be left behind, and the cleanup job could be massive if soil and debris reach hazardous waste levels. Experts said they would be surprised if continued testing does not detect high levels of some chemical compounds, enough to qualify as hazardous materials.
The EPA has only released data that compare the levels of chemicals in the floodwaters to drinking water standards, not other long-term or chronic risks and routes of exposure. Johnson said the EPA was focusing on immediate health threats but soon would assess the long-term environmental risks and the need for cleanup of Lake Pontchartrain and the Mississippi River.
Although no major industrial spills have been reported, an array of solvents, gasoline, pesticides and other compounds from cars, houses, yards and businesses will taint floodwaters, soil and groundwater.
“You have, potentially, runoff from all the buildings and houses that has been washed into the water, that could be sitting in New Orleans, whether it’s lead paint, or chemicals from chemical processing,” said Roger Lewis, director of the Saint Louis University School of Public Health’s Environmental Health Research Lab.
“I believe there will be found some pretty high levels of organics like benzene,” a toxic substance in crude oil, Lewis said. “Just the water sweeping over all the gasoline stations, all the marketing terminals, things like that.”