What are treated wood products?
Many Wisconsin residents use wood products to build outdoor structures such as decks,
fences and borders around gardens or flowerbeds. Because wood is naturally susceptible to
decay, it is common to use chemically treated lumber for outdoor projects.
Chemical treatments help preserve the structural integrity and appearance of wooden
structures. Treated lumber can be used safely in many backyard construction projects if
appropriate precautions are taken.
What kind of wood treatments are commonly used?
Wood treatments can be classified into two major categories: oil-based treatments and
- Creosote and pentachlorophenol (PCP) are two oil-based treatments that are
commonly used to treat railroad ties and utility poles. Because of the toxicity of these
chemicals, lumber treated with creosote or PCP should not be used indoors, or for
playgrounds, decks, picnic tables or similar structures.
- Chromated copper arsenate (CCA) and ammonium copper quat (ACQ) are the two
most commonly used water-based treatments. CCA-treated wood is commonly used for
playgrounds, decks and patios, fences, landscaping and in gardens. CCA contains arsenic, a
chemical found to cause skin and lung cancer in people who are exposed over a long period
of time. ACQ is a newer, less toxic product that has gained popularity in recent years.
Are there health concerns related to exposure to
treated wood products?
The chemicals used to treat wood products are applied at high pressure, and most of the
treatment remains effectively bound in the wood. However, recent studies show that
rainwater can wash CCA out of the wood and carry it into surrounding soil.
Additionally, a thin residue coating of CCA was found to exist on the wood's
surface. This residue can easily be picked up on hands or food items resulting in
Children who play on CCA-treated playground equipment can be exposed to significant
amounts of arsenic. To reduce the potential for this type of exposure, the U. S. Consumer
Product Safety Commission (CPSC) recommends that playground equipment be painted or sealed
with an oil-based sealer every two years.
Research on the use of CCA-treated lumber in gardens has shown that treatment chemicals
do not affect the growth or safety of home-grown produce.
How can I reduce exposure to wood treatment
- Avoid using lumber treated with creosote or PCP in any home construction or landscaping
- Dont use treated lumber for any indoor home construction project. Wood treatment
chemicals are too toxic for interior uses.
- Seal decks that are constructed with treated lumber with an oil-based sealer
years. This is consistent with the wood manufacturer's recommendations for maintenance of
CCA-treated wood. Proper sealants will keep the wood from cracking and splintering while
reducing the risk of exposure to CCA residues.
- Do not allow children to play under decks made with treated lumber. Ensure that
children playing on or around structures made with treated lumber wash their hands before
eating. Pets that regularly sleep or live under decks could be exposed to arsenic
and may carry it into your home.
- Sawing or sanding treated wood is hazardous and requires special precautions. Perform
the work outdoors on a dropcloth so the sawdust can be collected and
discarded. Wear a dust mask if there is frequent or prolonged exposure to sawdust.
Wash hands and clothing immediately after completing the work.
- Do not use treated wood for countertops, cutting boards, picnic tables, beehives or for
other applications where treatment chemicals may come into contact with food.
- Never burn treated wood. Burning releases toxic fumes into the air and has been
associated with serious arsenic poisoning.
What should I do if I suspect a problem?
Taking steps such as those outlined above can reduce your familys
exposure to toxic wood preservatives. Ask your contractor or retail supplier for
additional information about the specific materials you are using.
For more information
For health related questions, contact the Division of Public Health,
Environmental and Occupational Health,
PO Box 2659, Madison, WI 53701-2659,
Back to Environmental Health
Department of Natural Resources
July 29, 2013