The University of Florida has issued a press release setting forth some of the details of a study by researchers from the University of Miami, the University of Florida, and Florida International University that “examined the potential consequences of arsenic leaching from chromated copper arsenate, or CCA-treated wood, from a real deck as well as from simulated landfills.”
The troubling conclusions of the two research papers published in the online version of the journal Environmental Science & Technology Research are that: (1) “Arsenic from treated lumber used in decks, utility poles and fences will likely leach into the environment for decades to come, possibly threatening groundwater; and (2) “The deck wood leached high levels of arsenic into rainwater runoff and the soil and treated wood only continued leaching arsenic while sitting in simulated landfills.”
“What’s important for people to realize is that arsenic is relatively mobile, so it’s something we have to be relatively concerned about how to manage this huge stock of CCA wood that remains to be disposed of,” said Tim Townsend, a UF associate professor of environmental engineering.
Previous studies relating to the arsenic leaching problem prompted the wood-products industry to phase out CCA-products for residential use in 2003, but CCA-wood can still be used in utility poles and industrial timbers.
One of the conclusions of a study conducted by Helena Solo-Gabriele, a professor of environmental engineering at the University of Miami, Townsend studied rainwater runoff from a CCA-treated deck for a year. Their conclusion: Arsenic contamination was 100 times higher than runoff from an untreated deck.
In addition, “a layer of sand underneath the deck had arsenic levels 15 to 30 times higher than background levels, while water that percolated through the sand also was contaminated by the toxic metal.”
While it was found that only “a small fraction leaches in any given year,” the problem was that the treated wood can be in the ground for several years and, thus, “the impacts can be significant, especially given the high concentrations of arsenic in the wood itself.”
By their calculations, the researchers estimated that by 2000, Florida had already imported some 28,000 metric tons of arsenic, of which, 4,600 metric tons has already leached into the environment. They projected up to 11,000 additional tons of arsenic will leach from decks and other structures over the next 40 years.
All of this raises the suggestion that those charged with the removal and disposal of CCA-treated wood may want to be cautious in selecting whether the final resting place for the contaminated wood once it is taken out of service should be lined or unlined landfills.
These future considerations do not, however, address the serious problem posed by a mathematical model based on the researchers’ experiments that estimated between 20 and 50 tons of arsenic may have already leached into construction and demolition landfills in Florida before 2000, with an expected increase of between 350 and 830 tons of the heavy metal by 2040.
Under current Florida law, construction-and-demolition landfills are not required to be equipped with linings. This could pose a long-term contamination problem with respect to groundwater around those landfills, according to John Schert, director of the Florida Center for Solid and Hazardous Waste Management.
“The leaching research conducted by the team suggests that arsenic contamination of the groundwater under these landfills may be a large future problem that future generations have to deal with,” Schert said.
One possible solution is to require linings, Schert said. However, that might put many of the landfills out of business.
“This would probably lead to much more illegal dumping of construction-and-demolition waste in remote, rural, and agricultural locations,” he said. “Illegal dumping of construction and demolition waste in Florida is already a big problem.”
In addition to the results of the recent Florida studies, however, are the broader problems posed by arsenic-treated lumber across the U.S. especially in playground building materials and other wood used in applications where it comes into direct contact with humans in general and children in particular.
Arsenic is a naturally occurring element that is found throughout the environment. It is usually combined with other elements such as oxygen, chlorine, and sulfur to form inorganic compounds. When combined with hydrogen and carbon, arsenic forms organic compounds.
Although most people are aware of pure arsenic when it is intentionally used as a poison, it is when inorganic arsenic compounds are used to preserve wood and organic arsenic compounds are used as pesticides (particularly on cotton plants) that arsenic can present a serious health threat.
In 2001, several articles were written regarding the dangers of arsenic-treated wood used for decks, patio furniture, benches, and playground equipment. About 80% of outdoor lumber is treated with chromated copper arsenate (CCA) composed of copper and arsenic used to repel insects, kill molds and fungi and retard rot, and chromium used to stabilize the two other chemicals.
While the chemicals can stay in the wood for 10 years or more, they can also slowly leach out of the wood and become dangerous to both children and adults. In the environment, arsenic cannot be destroyed; it can only change its form. Arsenic in the air settles to the ground on its own or is washed to the ground by rain. Many arsenic compounds are water soluble.
Ninety-eight percent of outdoor wood sold in the U.S. is treated with CCA and in Florida alone; nearly 30,000 tons of arsenic is believed to be at large.
Children are particularly vulnerable to CCA poisoning as they are more likely to play on floorboards or playground equipment and then put their hands in their mouths. Arsenic has been linked to birth defects in animals exposed to inorganic arsenic.
Adults, especially workers and do-it-your-selfers are also at risk as the inhalation or ingestion of the sawdust can be harmful. Other sources of arsenic exposure are smoke from burning (treated) wood, eating or drinking contaminated food or water, hazardous waste dumps, living in areas with high natural levels of arsenic in rocks.
Prolonged exposure to CCA can lead to nerve damage, dizziness, numbness, and an increased risk of bladder, lung, and skin cancer. The World Health Organization (“WHO”), the Department of Health and Human Services (“DHHS”) and the EPA have all determined that inorganic arsenic is a human carcinogen. Arsenic can give you sore throats and irritated lungs.
It may cause nausea and vomiting, decreased production of red and white blood cells, abnormal heart rhythm, and “pins and needles” sensation in the hands and feet. Arsenic may cause small corns or warts on the palms, soles, and torso. In sufficient quantities, arsenic will cause death.
Consumers should remember to ask retailers if the wood they are purchasing is arsenic-treated as the warnings provided by suppliers may be discarded with the packing material before the wood is sold.
A report issued by the National Academy of Sciences in September of 2001 showed that the Environmental Protection Agency had completely underestimated the cancer risks of arsenic in drinking water. The reports claimed that cancer risks are high even for seemingly low levels of arsenic in tap water.
The current standard of 50 parts per billion of arsenic in drinking water, which was established in 1942, is no longer acceptable as the risk of bladder and lung cancer is high even at just 3 ppb. The report also addressed other serious arsenic-related health effects such as heart disease, high blood pressure, and diabetes.
There are tests to determine the exact level of arsenic in the blood, hair, urine, and finger nails. The urine test is used to detect recent exposure while the hair and nail tests are used to measure long term exposure and past exposure (6-12 months before).
Children are particularly vulnerable to arsenic exposure since they spend much of their time playing on wooden playground structures and on decks. These surfaces, a Canadian Study revealed, may expose children to significant levels of arsenic.
Until 2003, the wood used to make such structures was treated with the preservative chromated copper arsenate (CCA). A study published in the October 2004 issue of Environmental Health Perspectives found that children who play on wooden structures treated with CCA were left with more arsenic on their hands than children playing on other wooden sets.
To collect data, researchers from University of Alberta examined the hands of 66 children playing in 8 CCA playgrounds and compared them to the hands of 64 kids playing in 8 CCA-free playgrounds. After play, children washed their hands in a bag containing water. The solution was then analyzed for the presence of arsenic.
On average, the researchers found that kids playing in CCA playgrounds had more arsenic on their hands (.5 mcg compared to .095 mcg) than the other children. The amount found from CCA playgrounds ranged as high as 3.5 mcg.
exposure to higher concentrations of arsenic (200 mcg/L) in drinking water have been tied to an increase cancerous tumor growth, and to the existence of skin and bladder cancer. Below that level, meaningful research on the subject remains to be conducted.
Also unknown is how exposure to arsenic in drinking water compares to children’s exposure to small doses of arsenic on the playground.
Still, any level of exposure to a known carcinogenic toxin is unsettling, particularly if the exposure is occurring in a location where children spend a lot of time and are presumed to be safe.
But what are the possibilities for reducing the risk of illness and health problems to children due to exposure to the poisons and pesticides around them?
The researchers from University of Alberta urge parents to have their kids always wash their hands thoroughly after playing on structures that are coated with CCA.
Another possible solution is to coat the wood with an oil or water-based sealant so that the arsenic cannot get onto children’s’ hands.
The Environmental Protection Agency (EPA) revealed in May of 2004 that an ongoing study with the Consumer Products Safety Commission (CPSC) found that a yearly coating of such a sealant could cut down on arsenic exposure.
Such preventative steps are surely worth taking, given the potential hazards of arsenic exposure. According to Dr. James Roberts, M.D., M.P.H., an associate professor of pediatrics at the Medical University of South Carolina in Charleston; “Arsenic in children’s bodies is a long-term exposure and the outcomes are often caner at a much later age.”
Physicians, Roberts said, must be aware of the risks children’s exposure to the poison so that they can urge families to follow EPA recommendations on treating CCA-coated wood. At this point, it’s the only type of protection available.