The concern about chromated copper arsenate (CCA)-treated wood is much larger than parents’ worries about poisonous playgrounds. In fact, the research and recent publicity surrounding the issue actually stemmed from — and is focused on — the waste industry.
“When we the started the research here in 1996, it was all based on waste,” says Timothy Townsend, one of the lead researchers studying the effects of CCA-treated wood and associate professor with the Gainesville-based University of Florida department of environmental engineering and science. “It’s a big deal for C&D (construction and demolition) recyclers. And it’s a potentially big deal to municipal disposers. There weren’t any issues in terms of contamination of soils, kids and playgrounds.”
Approximately five years ago, the Florida Department of Environmental Protection (FDEP), Tallahassee, decided to test the ash coming from a co-generation plant in south Florida, according to Bill Hinkley, chief of the bureau of solid and hazardous waste for the FDEP. The industrial facility, which was built next to a sugar mill, had two large wood-fire boilers designed to burn wood to produce electricity from the high-pressure steam, and burn off the water using the low-pressure steam.
The company was taking the waste from the sugar industry, burning the bagasse, which is the fiber that remains after extracting the sugar from the cane, then applying the ash onto the muck fields because it is high in phosphorous, potassium and other nutrients.
To keep the boilers operating at capacity, the company decided to burn wood waste during its slower periods, and Florida’s nearby Dade, Broward and Palm Beach counties were encouraged to take advantage of this opportunity to recover their wood waste.
The facility wanted to continue spreading its ash on the sugar cane fields, but the FDEP was concerned there might be lead-based paint in the recycled wood. To ensure lead levels weren’t too high, the FDEP asked the facility to test the ash, Hinkley says. “When we got the data back, we found 400 to 500 parts per million of arsenic and high levels of chromium in the ash.”
Current federal primary drinking water standards limit arsenic to 50 parts per billion. And U.S. Environmental Protection Agency (EPA) toxicity characteristic leaching procedure (TCLP) limits are 5 milligrams per liter (mg/l).
“This drove us to ask the Florida Center for Solid and Hazardous Waste [Gainesville, Fla.] for help in researching the issue,” Hinkley says. “Eventually the arsenic was traced to CCA-treated wood.” And Townsend and Helena Solo-Gabriele of the University of Miami, teamed up to tackle the CCA-treated wood research from a waste-to-energy, mulch and disposal perspective. Their research is funded by the center.
“Our research grew through a series of studies to determine how much CCA was out there, the potential impacts and how much will be out there in the future,” Townsend says.
Now, five years after the initial research began, concern about CCA-treated wood in playgrounds has made its way into mainstream media.
“When we asked the center to take on the research, we asked them to examine four areas,” Hinkley says, “ash, mulch, landfilling and soil contamination under decks. We asked the center to test for soil contamination under decks because the FDEP operates 150 parks, and most of them have boardwalks and decks [made from CCA-treated wood].”
Data from the deck studies showed average arsenic concentrations in below-deck soils to be 28 milligrams per kilogram of soil (mg/kg) — far above federal and state arsenic restrictions.
EPA soil screening level (SSL) limits for arsenic are 0.4 mg/kg. Florida’s soil clean-up target levels are 0.8 mg/kg for residential areas and 3.7 mg/kg for industrial areas, among the most stringent standards in the country.
“An energetic reporter at the St. Petersburg Times noticed that playground equipment also is made from CCA-treated wood,” Hinkley says, “and the newspaper hired a consultant to sample soil under playground structures.”
“The arsenic levels in playgrounds were higher than Florida’s clean-up target levels, which prompted a huge wave of concern,” Hinkley adds. But because playgrounds don’t fall under the FDEP’s jurisdiction, the Florida Department of Health and the state legislature now are attempting to address the issue.