New Orleans Soil Poses Hazard

Study Finds Elevated Lead Levels in Neighborhoods

Some New Orleans neighborhoods are covered in a layer of sediment containing lead above the concentration the federal government considers hazardous to human health, a new study has found.

The dirt poses the greatest hazard to small children who might play in it, said Steven M. Presley, a toxicologist at Texas Tech University, who led the soil survey team. The hazard could be reduced by keeping the dirt from becoming dry and airborne, by covering it with uncontaminated soil or, if necessary, by hauling it away.

"These levels are not astronomical. It's not like this is an insurmountable hazard. But we are saying that we did find levels that exceeded these thresholds for human health," Presley said yesterday after the study, which will appear in Environmental Science & Technology, was posted on the American Chemical Society's Web site.

The team sampled 14 sites, 12 of them inside the city limits. In two, lead was above the 400-parts-per-million concentration of the Environmental Protection Agency's "high-priority bright line screening" level, a hazardous designation set by the EPA. One was on Esplanade Avenue downtown (406 ppm) and the other was on the bank of the Industrial Canal (642 ppm).

Slightly elevated levels of arsenic and numerous organic chemicals, including some pesticides, were also found at the Industrial Canal. Presley said that was not surprising because "it was the neck of the funnel for the water being pulled from New Orleans."

The researchers also found slightly elevated concentrations of iron at one site near the Lakefront neighborhood and elevated pesticide residues near City Park, which Presley speculated might have come from a nearby golf course.

Presley thinks the chief implication of the study is that more extensive sediment testing needs to be done, as contamination is likely to vary across the city.

The source of most of the lead was exhaust from a century's worth of leaded gasoline burned by automobiles. In many places, it was under the soil surface and covered with vegetation. Hurricane Katrina and the flood suspended it in the water and then redeposited it, sometimes a long way from where it originated.

The sediment is inside many buildings that will be torn down or renovated, making it a potential hazard to construction workers. They should wear masks in dusty areas and wash their clothing and hands, Presley said.

Eryn Witcher, an EPA spokeswoman, said the new findings are "consistent with the sampling we have done. We have seen elevated levels of lead and arsenic, and we have urged the public to avoid contact with the sediments."

The researchers also sampled water and found high levels of some pathogenic bacteria, including various species of Aeromonas that caused many skin infections in victims of last December's tsunami in Southeast Asia. The sampling was done in mid-September; these organisms would have died as the water evaporated.

They also sampled snakes and an alligator to determine baseline levels of various pollutants the animals acquired before the flood. More will be sampled later to see if the flood increased their levels of toxic substances.