Pressure Treated Wood – A Potential Health Hazard
Both CCA and CA-based pressure treated wood pose many dangers to humans and animals. Use of CCA was discontinued after 2003, but with a use-life of over 20 years, CCA is still commonly found in existing decks, walkways, fences, picnic tables, raised garden beds, dog houses, and other applications.
WHAT IS PRESSURE TREATED WOOD?
CCA PRESSURE TREATED WOOD
CA-BASED PRESSURE TREATED WOOD
PRESSURE TREATED WOOD AND RAISED GARDEN BEDS
HOW TO IDENTIFY PRESSURE TREATED WOOD
HEALTH AND SAFETY RECOMMENDATIONS
WHAT IS PRESSURE TREATED WOOD?
Pressure Treated Wood is any wood product (lumber) subjected to a high pressure infusion of chemicals to increase it’s resistance to fungi, bacteria and termites; it does not inhibit damage from weathering. The most common forms of Pressure Treated wood in the United States are:
- Prior to 2004: Chromated Copper Arsenate (CCA)
- Since 2004: Copper-based Amine Copper Quat (ACQ) and Copper Azole (CA)
CCA PRESSURE TREATED WOOD
CCA is an extremely toxic chemical and carcinogen and toxicity can be caused by:
- inhalation of gas created by burning CCA treated wood in a fire
- a dog eating the wood, dust (cutting/sanding) or ashes (One tablespoon of ash from CCA wood contains a fatal dose of arsenic.)
- touching the wood and then ingesting the residue.
CA-BASED PRESSURE TREATED WOOD
The alternatives to arsenic-based preservatives since 2004 are copper-based (with fungicide added) preservatives such as amine copper quat (ACQ) and copper azole (CA). This is less toxic because the human body is less able to absorb these poisons. While safer then CCA treatments, Cooper-based treated wood may present hazards if burned, where wood dust particles are generated (cutting and sanding) or where treated wood comes into direct contact with food and agriculture.
PRESSURE TREATED WOOD AND RAISED GARDEN BEDS
CCA treated woods is not recommend for garden beds used to grow food; although human health risks appear to be extremely small.
HOW TO IDENTIFY PRESSURE TREATED WOOD
If your play structures, decks, picnic tables, landscaping timbers, residential fencing, patios, and walkways/boardwalks were made prior to 2004, unless it was made of cedar or red wood, it was probably made with arsenic treated wood.
You can usually recognize pressure treated wood by its greenish tint (when new), especially on the cut end, and are incised (staple-sized slits) over the surface of the wood. However, the greenish tint fades with time, and not all pressure treated wood has the slits.
The newer CA treated lumber has a brown color.
PRESSURE TREATED WOOD HEALTH AND SAFETY RECOMMENDATIONS
- Currently installed CCA (such as decks and fencing) if in good shape are potentially safe for people and animals (see following safety precautions) and, in fact, unnecessarily tearing them out may release more chemical than leaving them in place.
- The EPA states that applying a penetrating oil-based wood preservative (not paint or decorative opaque stain) helps seal in the chemical preservative in pressure treated wood and can lessen or eliminate human and animal exposure to CCA in existing decks. Studies show a dramatic decrease in arsenic at the surface of the wood for periods up to two years after oil finish is applied. Re-applying the preservative coating every year or two (once the rain stops beading).
- Don’t use pressure treated wood for dog house
- Do not allow your dogs to chew pressure treated wood. If you can not prevent your dog from chewing the wood, it is safer to replace with cedar or plastic composite wood alternatives.
- Do not burn pressure treated wood.
- If you cut pressure treated wood, cut over a plastic tarp, collect the dust and dispose in the trash. Wear a mask when cutting, wash hands after handling.
- Keep decks and structures in good condition to prevent splinters. (Splinters from pressure treated wood can cause inflammation and infections.)
- If you do not use penetrating oil-based wood preservative on your deck consider:
- Make sure there is no standing water on your deck after a rainstorm and while watering the grass or washing decks.
- Never feed, water or give treats to your pet on the deck, and keep their toys off the deck.
- Limit their access to the deck or cover with a rug for them to lie on.
- Laundering rugs that have been in contact with the deck separately to prevent contaminating other items.
- Wash your pet’s paws and fur after their contact with the deck. Don’t let your pet play in wood chips or soil under or around CCA treated wood.
- Consider vinyl alternatives or naturally resistant woods like cedar or redwood for future building projects or repairing existing structures.
- If CCA is used for raised garden beds, consider covering CCA treated wood with plastic to prevent direct contact with garden soil.