In Katrina's Wake, An Arsenic Threat

An incredible 72 million m³ of debris was created when Hurricane Katrina wreaked havoc in Louisiana and Mississippi in 2005. A survey of this debris now reveals that an estimated 1,740 metric tons of arsenic could leach into groundwater from unlined landfills where the materials are being disposed (Environ. Sci. Technol., DOI: 10.1021/es0622812).

The arsenic is primarily in the form of chromated copper arsenate (CCA), a chemical once commonly used to pressure-treat lumber for protection against termites and decay. The lumber industry has voluntarily phased out CCA for residential uses in recent years because of public concerns that arsenic leaching could pose health problems. Lumber is now typically treated with quaternary ammonium copper or copper-boron-azole compounds.

To conduct the survey, environmental engineers Helena M. Solo-Gabriele of the University of Miami and Brajesh Dubey and Timothy G. Townsend of the University of Florida used handheld X-ray fluorescence spectrometers to measure arsenic concentrations in hundreds of pieces of debris in the hard-hit areas of New Orleans. On the basis of their findings and state government estimates of the amount of debris, the team calculated the overall amount of latent arsenic.

Besides arsenic, copper and chromium in the treated wood could be a problem and add to elevated levels of metals already detected in the disaster region, the researchers note. They recommend that disaster-management plans include provisions for segregating treated wood for separate disposal or disposing all debris in lined landfills.