CCA Pressure-Treated Wood:
Arsenic in Older Decks, Play Sets, and Garden Beds

What changed in 2003

On February 12, 2002, EPA announced that manufacturers would move consumer treated lumber off CCA by December 31, 2003. The list of uses covered play structures, decks, picnic tables, landscaping timbers, residential fencing, patios, and walkways. EPA said that by January 2004 it would not allow CCA products for any of those residential uses.

Two details get lost in the retelling. First, it was a voluntary industry agreement, not a ban. The CPSC’s own guidance says plainly that “a ban on CCA-treated wood was never imposed.” Second, CCA is still made for other uses. EPA lists commercial poles, posts, shakes, shingles, permanent foundation support beams, and pilings.

So the rule of thumb works backward from the build date. Lumber bought for a backyard project after 2003 shouldn’t be CCA. Lumber from before, including salvaged boards, might be.

Why arsenic in wood is a concern

The arsenic doesn’t stay locked in the wood. Small amounts come to the surface, rub off on hands, and wash into the soil underneath.

The CPSC looked at this closely for children’s play sets. In 2003, CPSC staff estimated an increased lifetime risk of bladder or lung cancer of roughly 2 to 100 per million for children who played on CCA play sets. The main route was arsenic picked up on hands and then put in mouths. The Commission voted not to ban CCA playground equipment, since the EPA phase-out was already underway.

That’s a statistical risk, and it depends on how much contact a child has. It’s also why most of the advice below is aimed at hands, food, and soil.

How to tell if it’s CCA

Not by color. Copper is in CCA and in the newer treatments that replaced it, and either can leave wood with a greenish tint.

What the agencies point to instead:

• The build date. The CPSC says a structure built before 2004 that isn’t cedar or redwood was “most likely” CCA.
• An end tag or stamp. Look on the ends of boards and on the undersides. Some tags name the preservative.
• The builder or seller. If the deck came with the house, the sellers may know when it went in, and a permit record can sometimes show the date.

The National Pesticide Information Center, run by Oregon State University with EPA, says treated wood is “very difficult to identify” by appearance and that reused wood often lacks the end tag. If you need to know for certain, the CPSC suggests asking your local health department about testing.

Living with an older CCA deck

EPA doesn’t recommend tearing it out. Its 2002 announcement said it was not recommending removal of existing structures or the soil around them, and its 2008 final risk assessment said there’s no reason to remove or replace CCA structures.

What EPA and the CPSC do recommend:

• Wash hands after touching the wood or playing on it, and especially before eating.
• Don’t set food directly on the wood. No CCA cutting boards or countertops.
• Keep kids and pets from playing in the dirt under the deck.
• Don’t sand it, pressure-wash it, or clean it with bleach or oxalic-acid deck brighteners.
• Apply a penetrating oil- or water-based stain or sealant. The CPSC playground handbook says to do it at least once a year and to skip film-forming finishes, which crack and peel.
• Never burn it, and don’t use the sawdust for mulch or compost.

For garden beds, OSU Extension says there’s no evidence CCA lumber raises arsenic levels in vegetables, but manufacturers don’t recommend it there, and lumber salvaged from a project more than 20 years old may be CCA. The CPSC says to put a plastic liner in an existing CCA planter before filling it.

Getting rid of it

When an old deck comes down, the boards can’t go in a backyard burn pile. Oregon DEQ lists treated wood among the materials that can’t be open-burned anywhere in the state, and EPA and the CPSC both say never to burn CCA wood.

In the Portland area, Metro’s transfer stations take treated wood as garbage, not in the clean-wood stream, which has to be free of paint, stain, and treatments. In Washington, the Department of Ecology says used CCA wood isn’t a dangerous waste and can go to a permitted, lined solid waste landfill. Call your hauler or transfer station before you load the trailer, since rules and fees change.

What a home inspection covers on a deck

Russ doesn’t test wood for arsenic, and no home inspection does. What he looks at on a deck is condition: rot at posts, joists, and boards, wood in contact with soil, the ledger connection to the house, missing or rusted hardware, and guards and stairs that aren’t safe to use.

Age still counts, in a practical way. The CPSC notes that the treatments that replaced CCA corrode some metals faster, so the hardware has to be rated for them when an old deck gets rebuilt. And if the deck dates from before 2004, the cleaning, sealing, and disposal steps above are worth knowing before anyone starts sanding.

Russ’s post on what gets checked in a deck inspection covers the structure side, and the deck ledger attachment guide explains the connection that holds the whole thing up. If you’re replacing old boards with composite, see composite decking recalls and class actions. For other older-house materials, the guide to checking a house for recalled products is a good starting point. To book an inspection in the Portland metro or Southwest Washington, schedule online.