Arsenic-treated wood is the result of a chemical process in which wood is treated with a pesticide/preservative called chromated copper arsenate (CCA) to prevent rotting in lumber designed for outdoor use. CCA contains arsenic, chromium, and copper and was widely used for residential purposes in the United States from the 1970s until the U.S. Environmental Protection Agency (EPA) phased it out in 2003.
CCA-treated wood can be hazardous to human health because arsenic is classified as a known carcinogen. Exposure to arsenic can cause cancer of the lung, bladder, skin, kidney, prostate, and nasal passage. Data released in November 2003 by the U.S. Environmental Protection Agency (EPA) show that 90% of children repeatedly exposed to arsenic-treated wood face a greater than a one-in-one-million risk of cancer. (One in one million is the EPA’s historic threshold of concern about the carcinogenic effects of toxic chemicals.) Arsenic exposure can also lead to nerve damage, dizziness, and numbness. Arsenic has been linked to immune diseases, cardiovascular disease, diabetes, and changes in hormone function. Lung and bladder cancer are the two health effects most often related to exposure to CCA-treated wood.
CCA-treated wood can be found virtually anywhere outdoor lumber is being utilized. Due to the increased risk to children, the uses currently receiving the most attention are play sets, decks, and picnic tables. Arsenic can leach to the surface of the treated wood, becoming accessible for absorption through exposed hands and skin touching the wood surface and, especially in the case of children, ingestion through normal hand-to-mouth behavior. The arsenic can also leach into the ground surrounding the location of the treated wood, providing yet another exposure pathway for children playing in the area.
Government and public attention to the issue of health hazards from CCA-treated wood, both national and international, has been growing steadily over the past few years. In March 2003, EPA finalized a voluntary agreement with preservative manufacturers to ban the production of CCA-treated wood for most residential uses as of December 31, 2003. However, the ban does not prohibit the sale of CCA-treated wood produced prior to December 31, 2003, nor does the measure address existing structures. With regard to retail sales, a warning label must be displayed in locations where CCA-treated wood is sold. The EPA has also removed chromated copper arsenate from its list of approved chemical pesticides.
The Consumer Product Safety Commission (CPSC) is also involved in the regulation of arsenic-treated wood. The CPSC has officially stated that there is an increased lifetime risk of developing lung or bladder cancer from exposure to arsenic for the individual who plays on CCA-treated wood play sets during early childhood. However, in November 2003, CPSC declined to ban the use of CCA-treated wood in playground equipment, citing the EPA-industry voluntary agreement to phase out the manufacture of CCA-treated wood.
In research that is still underway, the EPA and CPSC are studying whether wood sealants could effectively prevent arsenic from leaching out CCA-treated wood.
Informed individuals need not wait for government action on CCA application. Alternatives do exist to using arsenic-treated wood in new construction, and there are recommendations to reduce exposure from existing structures.
When purchasing new materials, some of the available alternatives include wood treated with non-arsenic preservatives; wood that does not require pressure-treatment; and non-wood alternatives such as metal, cement, and plastic. The pros and cons for such alternatives (other potentially hazardous chemical treatments, sustainable harvesting, durability, etc.) should be examined prior to making a purchasing decision.
- A company called Timber Treatment Technologies announced in April 2006 that a new wood treatment process will replace CCA and other pesticide wood treatments in wood used for decks, porches, fences, and other outdoor home-related structures. The new treatment process, called TimberSil, uses a sodium silicate solution, which is infused into the wood. The solution, which is essentially a type of liquid glass, and the wood are heated, rendering the solution water insoluble. This creates a barrier and makes the wood inedible to insects, microbes, and molds.
When dealing with existing structures that cannot be replaced, general recommendations include:
- Applying a sealant to the wood at least once a year
- Washing hands after coming into contact with arsenic-treated wood, particularly before eating
- Avoiding toy storage under arsenic-treated decks
- Keeping children and pets away from dirt beneath and surrounding arsenic-treated materials, as rains can transfer leached arsenic to these locations
- Not eating at an arsenic-treated picnic table.
Arsenic-Treated Wood Resources
BANCCA.org – comprehensive online health resource on CCA pressure-treated wood
Environmental Working Group – Arsenic – includes news, history and links to databases
Healthy Building Network – Pressure Treated Wood
Healthy Child Healthy World – Avoid Arsenic Exposure From CCA-Treated Wood
U.S. Agency for Toxic Substances and Disease Registry – ToxFAQ for Arsenic
U.S. Environmental Protection Agency – CCA Fact Sheet
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