Feb 24, 2003: What is the toxicity of Chromated Copper Arsenate (CCA) treated wood in Playground Equipment?

This is a long answer.  The potential carcinogenic effects of CCA have been hotly debated.  The evidence is far from conclusive but it appears that CCA lumber will not be used in playground equipment.  I’ve also attached background info on CCA.

What is chromated copper arsenate?

  • Chromated copper arsenate or CCA, is a chemical preservative that protects wood from rotting due to insects and microbial agents. CCA contains arsenic, chromium and copper. CCA has been used to pressure treat lumber used for decks, playgrounds (playsets) and other outdoor uses since the 1930’s. Since the 1970’s, the majority of the wood used in residential settings was CCA-treated wood.
  • CCA is a registered chemical pesticide that is subject to U.S. Environmental Protection Agency's (EPA's) regulation under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The playground equipment made with wood treated with CCA is the jurisdictional responsibility of the CPSC and would be subject to the rules of the CPSC's Federal Hazardous Substances Act if found to be a hazardous substance.

CPSC activities on CCA-treated wood playground equipment

  • In June 2001, the U.S. Consumer Product Safety Commission (CPSC) docketed a petition by the Environmental Working Group (EWG) and the Healthy Building Network (HBN) to enact a ban of CCA or chromated copper arsenate-treated wood for use in playground equipment.
  • The staff's report that was developed in response to the petition has been presented to the Commissioners for their review. The Commission is expected to hold a public meeting to discuss the staff report and other related information. The Commissioners will then vote on the petition, which asks the CPSC to initiate a regulatory procedure.

EPA activities and collaboration with CPSC staff

  • Manufacturers of CCA reached a voluntary agreement with EPA to end the manufacture of CCA-treated wood for most consumer applications by December 31, 2003. EPA has indicated that some stocks of wood treated with CCA before this date might still be found on shelves until mid-2004. EPA is expected to finalize this agreement in the near future. Information on this EPA activity can be found on its website (www.epa.gov).
  • CPSC staff and EPA staff have worked together on several issues related to exposure and potential risk to children and will initiate studies to determine effective methods of reducing the amount of arsenic released from CCA-treated wood.

Why is CPSC staff concerned about CCA-treated wood in playground equipment?

  • CPSC staff is concerned about CCA-treated wood in playground equipment because exposures to arsenic in the wood might increase a person's probability (or risk) of developing lung or bladder cancer over their lifetime. Children can be exposed to the arsenic in CCA-treated wood by playing on playgrounds made from this wood.
  • Staff believes that hand-to-mouth behavior is the primary source of exposure to arsenic from CCA-treated wood playsets. Young children who routinely put their hands in their mouths (generally children under 6 years of age) can then ingest the arsenic directly from their hands or indirectly when they touch food or toys, which are then placed in their mouths.

What studies did CPSC staff conduct to assess the potential health risk to children from playing on CCA-treated wood playsets?

  • Staff conducted a series of scientific studies to measure how much arsenic comes off CCA-treated wood playgrounds onto the hand to estimate the potential exposure in children. Staff used this information along with other scientific information to perform a risk assessment of arsenic in CCA-treated playground equipment.
  • As part of the risk assessment, the staff also considered the age of the child using the product, the developmental characteristics of the child that could result in hand-to-mouth behaviors, how many days a year a child might play on the playset, and how many years they might play on the playset during early childhood.
  • The CPSC staff's scientific work was peer reviewed by independent scientific experts in the fields of exposure and risk assessment, and statistical analysis. The CPSC staff considered and addressed the reviewers' comments in its final reports.
  • The CPSC staff has reviewed other exposure and risk assessments from industry and consumer groups. These groups and EPA are continuing to examine the issue of potential risk to children from CCA-treated wood and CPSC staff will review the results of their work when they become available.

What is the exposure to arsenic from CCA-treated playsets?

  • A child’s exposure to arsenic from CCA-treated playsets and the consequent risk of developing cancer depends upon a number of factors, including:
    • the number of days they play on the CCA-treated playset each year;
    • the number of years they play on the CCA-treated playset;
    • the amount of arsenic that is picked up on their hands while they play; and
    • the amount of arsenic they ingest from their hands throughout the day.
  • Children are exposed to a background level of arsenic that comes primarily from food, followed by soil, then water, and air. This background exposure is one of the many exposures that can result in background cancer levels, cancers that have no apparent cause. Based on estimates by ATSDR (the Agency for Toxic Substances and Disease Registry, in the U.S. Department of Health and Human Services), an average daily intake of arsenic for a 2-6 year old child ranges from about 2-46 µg per day depending upon amounts in diet, air, and soil. From the staff’s analysis, arsenic exposure in children from contact with CCA-treated wood playground structures is estimated to be about 3.5 µg each day that includes a playground visit. While exposure to arsenic from background sources could be much higher than the exposure from playgrounds for some children, exposure to arsenic from CCA-treated playgrounds could be a significant source of arsenic for other children on those days that include a playground visit.

What is the risk from arsenic exposure in CCA-treated playgrounds?

  • The scientific evidence about the health consequences of long-term arsenic exposures in humans is found in studies of drinking water. Epidemiological studies have been conducted in Taiwan where there are high levels of arsenic in drinking water. These studies have demonstrated an increased incidence of lung and bladder tumors in that population from drinking water containing arsenic.
  • From these epidemiological studies, staff can calculate the increased risk of lung or bladder cancers resulting from exposure to a given level of arsenic. The data from these studies were used to calculate the probability of a person developing lung or bladder cancer over his/her lifetime from exposure to arsenic in CCA-treated wood.
  • There are many risk factors which contribute to a person's risk for developing cancer over their lifetime, such as environment, genetics, diet and behaviors such as smoking.
  • Staff calculated the increased lifetime risk of developing lung or bladder cancer from exposure to arsenic for the individual who plays on CCA-treated wood playsets during early childhood. This increased cancer risk ranges from about 2 in a million to 100 in a million. The staff used a range of values to estimate the increased number of lung or bladder cancer cases that could result from a specific level of exposure because there is some uncertainty about the amount of arsenic dose (exposure) that is necessary to cause cancer.
  • Cancer does not appear immediately upon exposure to a particular cancer-causing agent. There is a lag time between the time of exposure and the ultimate development of cancer. This lag time could be decades. It is difficult to determine exactly what causes a particular cancer in an individual because individuals are often exposed to many cancer-causing agents either at the same time or over their lifetime. For these reasons, the staff calculated the additional chance or probability that an individual will develop lung or bladder cancer during his or her lifetime because of exposure to arsenic from CCA-treated wood playsets. Not every exposed individual will get cancer at some time during his/her life.

Reducing exposure to arsenic from CCA-treated playground equipment

  • It is difficult to distinguish CCA-treated wood from non-CCA-treated wood. A call to the playset manufacturer might help determine if the playset contains CCA-treated wood. Since the 1970's the majority of the pressure-treated wood used in residential settings was treated with CCA. Therefore, if you are not sure if the playset is composed of CCA-treated wood, you should assume it is.
  • Parents and caregivers should be aware that children are exposed to arsenic through their hand-to-mouth activity while playing on and after playing on CCA-treated wood playsets. To minimize the risk of exposure to arsenic from CCA-treated playsets, parents and caregivers should thoroughly wash the child’s hands with soap and water immediately after outdoor play, especially before eating. Children should also be discouraged from eating while on CCA-treated playgrounds.
  • Based on limited data, some groups suggest that applying certain penetrating coatings such as oil-based, semi-transparent stains on a regular basis (once a year or every other year depending upon wear and weathering) may reduce the amount of arsenic that comes out of the wood.
  • CPSC staff has not evaluated these data, however, CPSC staff and EPA staff will initiate studies to determine effective methods of reducing the amount of arsenic released from CCA-treated wood.
  • If you decide to remove your CCA-treated wood playset, the EPA states that CCA-treated wood should never be burned in open fires, stoves, fireplaces, or residential boilers. Contact EPA (www.epa.gov) or your state or local solid waste management offices to receive instructions on how to dispose of CCA-treated wood.

Are there alternatives to CCA?

  • There are a number of non-arsenic containing preservatives that have been registered by EPA to pressure-treat wood for consumer applications. ACQ (ammonium copper quaternary) and copper boron azole (CBA) are common ones. Some wood treated with these preservatives is already available at retail outlets such as home improvement stores. In addition, playground equipment made of other non-arsenic containing components is also available (e.g. woods such as cedar and redwood and non-wood alternatives such as metals and plastics).

Below are the links to the CPSC Briefing Package regarding Petition HP 01-3 to ban chromated copper arsenate (CCA)-treated wood in playground equipment, that contains the CPSC staff's detailed evaluation of this issue. All of the documents below are in portable document format (pdf) and require the Adobe(TM) Acrobat(TM) Reader to view them.


        Part II follows next week.


As always, if there are any questions, call the MTPC.


I am interested in any questions that you would like answered in “Question of the Week.”  Please e-mail me with any suggestions at donna.seger@Vanderbilt.edu



Donna Seger, M.D.

Medical Director, Middle Tennessee Poison Center