Web edition: November 23, 2009
NEW ORLEANS No kid should ever play in arsenic. Especially at school. Yet many probably do, according to findings of a study presented today.
Howard Mielke of Tulane University's Center for Bioenvironmental Research and his colleagues were concerned about risks to children posed by old-style pressure treated wood, the type that has been infused with a chromated-copper-arsenic concoction to limit deterioration from rot and insects. This town is a veritable termite capital, so it made a reasonable place to look for treated wood.
Mielke’s group carried a portable X-ray fluorescence instrument into playgrounds to survey for arsenic. And they found it at 36 percent of the sites visited. A pilot study, this investigation only examined 38 playgrounds, but spanned the entire New Orleans metropolitan area.
“The irony,” Mielke contends, “is that if you want to find arsenic in soil, go to a child’s play area with wood structures.” The areas will likely be pressure treated with the CCA combo and leach substantial quantities of this carcinogen and neurotoxic agent into soil.
At each tainted play area, the researchers grabbed a bit of soil and took it back to the lab for digesting in one-molar nitric acid, a solution meant to mimic the pH of a child’s stomach.
“And what we found,” Mielke says, “is that the median arsenic concentration was on the order of 57 parts per million. This compares with the median of 1.5 ppm in soils generally throughout the city of New Orleans.” The play-yard median is also more than four times Louisiana’s permissible limit for arsenic in soil, the scientists reported here at the annual meeting of the Society of Environmental Toxicology & Chemistry.
The most egregious example the scientists turned up happened to be at an elementary school with no pressure-treated wood structures. Here, treated wood had been chipped and used as a cushioning ground surface around slides, swings and other equipment from which a child might fall. That’s not a legal use of such wood, since it’s supposed to be disposed of as hazardous waste. And with good reason. These chips contained 813 to 1,654 ppm of leachable arsenic.
As soon as Mielke’s group informed the school of those sky-high arsenic concentrations, the school replaced the tainted chips with untreated bark.
And Mielke predicts New Orleans’ arsenic hazard will not prove unique: “I would expect to see it all over the country.” For decades, CCA-treated lumber was the wood of choice, nationally, for play structures, picnic tables, decks and fencing.
That CCA-treated wood leaches arsenic is anything but new. I wrote a cover story on concerns about risks that this wood might pose a few years back. It was at the time the federal government was imposing a ban on arsenic-treated wood for structures that might make contact with bare skin. I would have thought playgrounds – especially in schools and daycare settings – would have replaced any of the toxic wood.
Hardly, Mielke says. “There’s been a movement, fairly recent, to ban CCA-treated wood, but we have an enormous amount that is still out there.” The cost of cleaning it up isn’t enormous, perhaps a few grand per playground (his estimate from having worked to clean up several in town), but still beyond the discretionary budgets of cash-strapped parks and schools.
So what should managers of playgrounds do when they find an arsenic problem? Good question, Mielke says, because “if we try to remove that soil, we don’t know where to put it.” Costs of moving it are also extraordinarily high and can prove a public-relations nightmare. “People coming into a play area with moon suits on and special equipment to try to dig contaminated materials out” can scare parents.
In most cases, Mielke says, the most cost-effective treatment may be to simply paint exposed CCA-treated structures. For soil contamination, this biogeochemist recommends tarping the ground with permeable landscape fabric and then covering it with six to eight inches of clean fill dirt. “We’re using Mississippi River silt and sand, which contains very low levels of arsenic, lead and other metals.”
Parents shouldn’t expect to be informed where tainted play areas are suspected. There are no requirements that playground managers survey for arsenic in soil. “And we found that when we were going to take samples at child-care centers, we quickly learned they don’t want to know the results,” Mielke says. At least not until after any remediation was completed. At a minimum, they could face liability issues if they learned they had a problem and didn’t immediately shut down until tests confirmed the area was clean.
“So for our study, we agreed to take the samples and not give them the results until after we were done [cleaning up the site].” Which offered them plausible deniability of any preexisting problem.
“The take-home message, Mielke says, “is that there needs to be a much larger emphasis on the quality of play areas for children.” In this study, where arsenic was found, “78 percent of the soil samples were greater than the state standard. That makes it worthwhile surveying play areas, generally, for this problem.”
U.S. Environmental Protection Agency. Chromated Copper Arsenate (CCA): Consumer Safety Information Sheet: Inorganic Arsenical Pressure-Treated Wood. [Go to]