An environmental tragedy’s silver lining
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nounced declines occurred in chilcomparative study described here. It is hard to think of anything dren less than 36 months old. “These For this research, the scientists fopositive coming out of the devasare children born in the post-Katrina cused on 46 census tracts, which tation inflicted on New Orleans period, who were exposed to subare defined in the paper as “neighby Hurricanes Katrina and Rita in stantially lower soil-lead conditions,” borhoods delineated by recogniz2005. But the storms did leave Zahran says. “We fully expected able, physical, cultural, economic, one beneficial legacysas floodwathis statistical outcome.” To that, and demographic characteristics.” ters washed over the city, they Nicholas E. Pingatore, a professor of Census tracts were selected from deposited clean sediments geochemistry at the University flowing down from Lake of Texas at El Paso, adds, Pontchartrain, to the north. “You’d also expect these correThose sediments effectively lations in younger children becapped lead (Pb)-contamicause they stay closer to the nated soils throughout New ground. That’s when you get Orleans. In this issue of the most exposure.” ES&T (Environ. Sci. Technol. Both Zahran and Mielke say DOI 10.1021/es100572s), the new findings further indiHoward Mielke and colcate that the EPA’s soil-Pb leagues at Tulane University standard is too high. According in New Orleans, Colorado to Mielke, a soil-Pb level of 400 State University (CSU) in ppm produced a median Fort Collins, and Lead Lab, blood-Pb concentration of 5 Inc., report that soil-Pb µg/dL in children under the levelsswhere measureds Extent of flooding sustained by New Orleans after Hurage of six, which is half the acwere down by an average of ricane Katrina made landfall in late August 2005. This tion threshold of 10 µg/dL set 39% after the floodwaters re- image was taken from the International Space Station by the U.S. Centers for Disease ceded. What’s more, declines on September 8, 2005. Control and Prevention (CDC). in soil-Pb were matched by many parts of metropolitan New “But that’s the median, which means commensurate declines in childOrleans; including high ground, half are above and half are below,” rens’ blood-Pb levels. flooded ground, interior city, and he emphasizes. “And our data from The researchers found that soilouter city locations. According to New Orleans show that at 400 ppm, Pb levels decreased from a meMielke, census tracts offer the best about 10-15% of kids will exceed the dian level of 329 ppm to 203 resolution for soil-to-blood reCDC threshold.” In the current arppm. The median drop in bloodsearch involving Pb. Research areas ticle, the researchers say that a more Pb among children less than six delineated by zip codes, he says, appropriate soil standard is 80 ppm, years old was 33%. According to are too big and do not supply which would be far more protective. coauthor Sammy Zahran of CSU, meaningful demographic informaEmerging research data collected these findings further indicate tion about resident populations, over the last several decades show that soils are the major source of such as their socio-economic adverse health effects from blood-Pb Pb exposure in U.S. children. status. at levels as low as 2 µg/dL. “And insofar as blood-lead levels Before the storms, 15 of the cenMielke points out that the in children impact cognitive outsus tracts exceeded the EPA’s soilcleaner soils covering New Orleans comes like IQ, substantial health lead standard of 400 ppm. in the wake of the storms are not and economic benefits can be reAfterward, only six of them did, there permanently. He expects alized for future cohorts of chiland soil-lead levels dropped in 29 them to blow away with time and dren by remediating soil-lead of the 46 census tracts evaluated. expose the more contaminated layconditions,” says Zahran. Blood-Pb, meanwhile, dropped ers underneath. “But this experifrom a median level of 5.14 µg per Mielke, who is at Tulane Univerment hints at what might be deciliter (µg/dL) to 3.45 µg/dL. sity, says the hurricane allowed for possible,” he says. “There’s plenty Mielke and colleagues used blooda natural, quasi-experiment that of clean soil outside of New OrPb measurements obtained from could not have happened otherleans and we’re working to truck 13 306 children; 11 191 of them wise. Mielke had already been colmore of it into the city.” were measured before the storms, lecting soil-Pb data in the city —CHARLIE SCHMIDT and 2115 were measured afterward. before the storms struck, and those Not unexpectedly, the most prodata supplied a baseline for the
9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / June 15, 2010
10.1021/es1014339
2010 American Chemical Society
4388
Published on Web 05/10/2010
