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 elemental 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 health concerns. Lumber is now typically treated with quaternary ammonium copper or copper boron azole compounds. To conduct the survey, environmental engineer Helena M. Solo-Gabriele of the University of Miami and her coworkers 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.