Poison on the Playground
“It is an uncanny thought that this lurking poison (arsenic) is everywhere about us, ready to gain unsuspected entrance to our bodies from the food we eat, the water we drink and the air we breathe.” – Karl Vogel, 1928
Arsenic has been used since 3,000 B.C. for various medicinal and practical reasons. However, this substance is also acutely toxic and is a known carcinogen that has been the cause of bladder and lung cancer in countless cases. Surprisingly, it is also one of the components used to treat wood that is used in play structures on playgrounds all across the country.
Chromated copper arsenate (CCA) is a chemical preservative that protects wood from rotting due to microbial agents and insects. CCA contains arsenic, chromium and copper and has been used to pressure-treat lumber since the 1930s. Ever since the 1970s, the majority of the wood used in residential settings has been CCA-treated.
The Cancer Connection
According to a report issued by the Consumer Products Safety Commission (CPSC), the scientific evidence regarding health consequences of long-term arsenic exposures comes from cases of cancer found in Taiwan from people who drank water that was contaminated with arsenic. Epidemiological studies in that matter demonstrated a direct connection between arsenic in drinking water and increased incidences of lung and bladder tumors. Because of these findings, it was a concern that regular contact with wood treated with CCA could also lead to lung or bladder cancer.
Because of this strong connection between arsenic and cancer, various organizations became concerned for the health of children who regularly play on wooden play structures. The Environmental Working Group (EWG) and the Healthy Building Network (HBN) petitioned the CPSC to ban CCA-treated wood for use in playground equipment.
Acting directly to the petition, the CPSC began research to verify the health risks to children. As the CPSC staff reviewed their findings, they calculated the increased risk of cancer resulting from exposure to a given level of arsenic and the probability of a child developing lung or bladder cancer over his or her lifetime from exposure to arsenic in CCA-treated wood.
The CPSC released a fact sheet that summarized the criteria they used in their scientific research. According to that information, the following factors were considered in assessing the increased risk of cancer for children.
- The number of days children play on the CCA-treated play set each year;
- The number of years children play on the CCA-treated play set;
- The amount of arsenic that is picked up on their hands while they play;
- The amount of arsenic children ingest from their hands throughout the day.
Research Results
CPSC researchers determined that hand-to-mouth behavior is the primary source of exposure to arsenic from CCA-treated wood play sets. Young children who often put their hands in their mouths ingest the arsenic directly from their hands or indirectly when they touch food or toys, which are then placed in their mouths.
They also determined that there are no known risks of developing skin cancer from touching CCA-treated wood, and there are no known risks from inhaling CCA fumes while playing on the structures.
After reviewing the findings from their research, Ken P. Giles of the CPSC believes there is an increased risk of cancer for children who frequently play on CCA-treated play sets. “CPSC’s study showed that a series of ‘exposure’ steps can make it possible for a child to get enough arsenic over a few years of exposure to have an increased lifetime cancer risk,” Giles says.
Giles explains that for most federal agencies, the risk level of concern is one in a million. “If the risk is less than two in a million, we aren’t concerned,” he says. “However, if it is more than a one in a million, we are concerned. Children who play on CCA-treated playground wood are at an increased lifetime cancer risk ranging from two in a million to 100 in a million. In other words, there is a measureable increased lifetime cancer risk for children who spend time on CCA-treated wood.”
Although they have determined there is an increased risk of lung or bladder cancer from frequently contact with CCA-treated wood, to their knowledge there have been no reported cases of lung or bladder cancer in relation to CCA.
Parents need to remain calm when considering the real impact of CCA on their child’s health. “Don’t panic,” says Giles. “The simplest, easiest thing to do is make your kids wash their hands with soap and water after every time they play on the CCA wood. And don’t let the kids eat food while playing on the playground, because they won’t wash hands and will transfer some arsenic.” He also reminds parents that not every child who plays on a CCA-treated wood will contract cancer.
Environmental Protection Agency
The CPSC is not the only agency that is evaluating the cancer risk of CCA-treated wood. Dave Deegan, spokesperson for the Environmental Protection Agency (EPA), explains that the manufacturers of CCA-treated wood approached the EPA over a year ago with the idea of phasing out the use of CCA.
The companies knew the EPA would be performing a study on CCA-treated wood and suggested the products be removed from the market while the assessment was being performed. “We supported taking the wood products off the market,” says Deegan. “Regardless of our future findings, we feel that reducing exposure to arsenic is a good thing.”
Within the next five months the EPA plans to have a preliminary version of their risk assessment for the public and their scientific peers for review and comment. “Then based on comments we receive and reviews we are given on the work we have completed at that point, we will finalize the assessment,” Deegan says.
The EPA then hopes to have its risk assessment completed by the end of 2003. In order to research the impact of CCA on children, the EPA is examining freshly-treated wood and older wood that was treated with the chemicals years earlier. According to Deegan, they are proceeding with guidelines that were established by a scientific advisory commission that met to discuss the methodology the EPA should follow to assess children’s exposure to the chemicals. “The panel gave us a whole set of recommendations that we have been following,” says Deegan.
Regardless of their future findings, the EPA will enforce the new safety standards as of January 1, 2004. CCA will no longer be used to treat wood. Alternative wood preservatives which do not contain arsenic will then be used for wood that will be used in all manufacturing and retail sectors. Although the EPA has not concluded that there is unreasonable risk to the public from CCA products, they feel that a reduction in exposure to arsenic is important.
Minimize Exposure
Parents who remain concerned about the long-term impact of CCA products and want to limit or avoid contact with such products may want to take a few simple precautions. If they or their children spend time on the CCA-treated play sets, they should wash hands thoroughly afterward and keep food from touching the wood directly.
Parents should keep in mind that the EPA does not recommend removing the soil or replacing existing structures made with CCA-treated wood or the soil surrounding those structures. But parents may take steps to reduce and even eliminate CCA exposure to their children.
Some studies suggest that applying certain penetrating coatings such as oil-based or semi-transparent stains on a regular basis may reduce the migration of CCA chemicals from the wood. Non-penetrating stains on outdoor surfaces such as decks and fences are not recommended, because peeling and flaking of the wood in the future may have an impact on durability as well as exposure to the preservatives in the wood.
There are also several non-arsenic containing wood preservatives that have been registered with the EPA. Of the various forms, ammonium copper quaternary (ACQ) and copper boron azole (CBA) are the most common. Some wood treated with these preservatives is already available at retail outlets and home improvement stores.
Characteristics of CCA-Treated Wood
Beginning in the 1970s a majority of the wood used in play sets was treated with CCA. Therefore, it is likely that any pressure-treated wood purchased after that time was treated with CCA. If it is not certain that the wood is CCA treated, a call to the play set manufacturer might help determine if the wood used was CCA treated.
For other wood products in question, the following suggestions may be helpful. Wood that is freshly treated with CCA has a greenish tint. This color will be apparent unless the wood has also been coated with an additional colored stain. Any untreated wood such as redwood and cedar does not contain CCA. Consumers can assume that any wooden structures that were not constructed with redwood or cedar were most likely created with CCA-treated wood.
There are always risks in life. As parents contemplate the chances their children take in playing on wooden play structures, they should keep in mind that arsenic exposure can be dramatically limited by frequent hand washing and avoiding direct food-to-wood contact. However, the odds of 100 in a million of contracting cancer from exposure to CCA-treated wood may be higher than most families are willing to pay in order to play at the park.
More Information
Consumers who want to be rid of their wooden play sets should use caution when disposing of them. The EPA cautions homeowners that treated wood should never be burned in open fires, fireplaces or stoves, as the arsenic fumes may prove toxic. Concerned individuals should contact the EPA or a state or local solid waste management office to receive instructions on how to dispose of CCA-treated wood.
Consumers who would like to read extensive reports published by the EPA on CCA-treated wood can visit the EPA Web site.
To have questions regarding CCA answered directly by the preserved wood industry, call 800-282-0600. Extensive reports submitted by several independent researches on the topic of CCA-treated wood can also be viewed at PreservedWood.com.