(Beyond Pesticides, February 9, 2007) The effects of Hurricane Katrina are still being felt in the Gulf Coast, a year and a half after it hit. Research shows one of the secondary effects of Katrina is increased arsenic levels, largely due to debris treated with the wood preservative chromated copper arsenate (CCA).
The debris, mostly originating from damaged and destroyed residential buildings, total 72 million cubic meters, of which 16% has been estimated to be wood, and all of which must be added to landfills. The resulting risk to groundwater is an estimated 1,740 metric tons of arsenic, much of which has been deposited into unlined landfills. The source of this arsenic is primarily from chemically treated lumber, as chromated copper arsenate (CCA) was once commonly used to pressure-treat wood. The Environmental Protection Agency (EPA) has since banned the use of CCA in residential projects, but many older structures still contain the treated wood.
A study, released online in the January 2007 issue of Environmental Science & Technology, led by Helena Solo-Gabriele, Ph.D., of the University of Miami and Brajesh Dubey, Ph.D., of the University of Florida, surveyed debris in New Orleans. Out of 225 pieces of lumber tested in seven sites, 52 contained arsenic (roughly 23%).
Prior to Hurricane Katrina, arsenic-treated wood was legally required to be disposed of in lined landfills. With the unprecedented amount of waste resulting from the storm and its aftermath, the ban has been lifted, leaving the estimated 1,740 metric tons of arsenic free to leach into groundwater. The researchers concluded, after factoring in the surface area of Louisiana and Mississippi and volume of Lake Pontchartrain (next to New Orleans), that this amount of arsenic had the potential to raise levels in surface soil by 0.17 mg/kg and the level in the lake to 28 times the allowable limit for drinking water. In their findings, they stated, “This disposal practice should be re-evaluated with respect to the potential for leaching of arsenic from pressure-treated wood and in light of studies which suggest that such leaching can potentially impact groundwater quality. The need to consider the potential for arsenic leaching from disposed treated wood is further emphasized by the recent reduction of the drinking water limit.”
John H. Pardue, Ph.D., an environmental engineer at Louisiana State University, said that the report “confirms that large amounts of arsenic are making their way into debris landfills.” Environmental scientist John D. Schert, of the University of Florida in Gainsville, confirms that disposal of CCA wood is “way down the list” of priorities following a disaster like Katrina, and that it “is a really difficult, complicated waste-management problem.” Dr. Pardue, putting it more starkly, commented, “I believe the storm-debris landfills will be the environmental legacy of these storms. While many environmental issues were handled well after the storm, the way debris has been handled has been abysmal.”