Pressure-treated lumber and CCA wood (playground equipment, decks, and landscape timbers) — outdoor safety profile

What is this product?

Chromated copper arsenate (CCA) is a wood preservative containing three toxic metals — inorganic arsenic, hexavalent chromium (Cr(VI)), and copper — that was used extensively from the 1940s through 2003 for outdoor wood rot resistance. CCA-treated wood is visually distinctive: a greenish-gray tint imparted by the copper chromate preservative. The wood preservative works by incorporating the toxic metals into the wood structure at levels lethal to wood-rot fungi and insects. These same metals, however, present human health hazards through the surface of the treated wood, which continues to leach arsenic via rainfall and physical contact for decades after treatment. EPA negotiated a voluntary phase-out agreement with CCA wood manufacturers effective December 31, 2003 — CCA-treated wood was withdrawn from the residential-use market for applications including playground equipment, picnic tables, boat docks, decks, and fences in public-accessible areas. CCA treatment remains permitted for industrial applications: highway utility poles, marine pilings, and industrial structures. The legacy problem is substantial: millions of CCA-treated playground structures and residential decks installed before January 2004 remain in service, leaching arsenic from their surfaces and into the surrounding soil. Children's exposure occurs through two primary pathways: hand-to-mouth transfer (hands contact the wood surface, arsenic transfers to hands, child puts hands in mouth — the same pathway documented for lead paint); and incidental soil ingestion (soil beneath CCA structures is arsenic-enriched, and children playing in or near this soil ingest it). Studies measuring urinary arsenic in children who regularly use CCA playground equipment versus children using alternative-material equipment have documented elevated urinary arsenic in the CCA-exposed group. Annual application of oil-based penetrating sealers to CCA wood surfaces substantially reduces arsenic surface transfer and is the practical mitigation for legacy structures not yet replaced.

What's in it

Click any compound name for its full safety profile, regulatory consensus, and exposure data.

Who's most at risk

• Children — Developing endocrine and neurological systems, higher exposure per body weight

How to use it more safely

• Use only for outdoor applications where ground contact is acceptable
• Wear gloves and respiratory protection when cutting or sanding
• Apply sealant annually to minimize arsenic leaching into soil
• Keep away from areas where children play or food is prepared

Red flags — when to walk away

• Playground equipment or residential deck with greenish-gray wood tint — installed before 2004 and not yet replaced or sealed; sandbox with a CCA-wood frame; CCA deck adjacent to vegetable garden (arsenic leaches into adjacent soil) — The greenish-gray tint of CCA-treated wood is the primary visual indicator of CCA treatment. All outdoor wood structures with this tint installed before 2004 should be presumed CCA unless documented otherwise. Sandboxes with CCA wood frames create a direct child-soil-ingestion pathway: the arsenic-enriched sand/soil inside the CCA frame is what children play in and inevitably ingest. CCA decks adjacent to vegetable gardens leach arsenic into garden soil — vegetables grown in arsenic-contaminated soil take up arsenic into the edible portions (leafy vegetables and root vegetables are highest risk).
• Burning CCA wood — indoor fireplace, outdoor fire pit, waste burning, or BBQ with CCA scraps — CCA wood combustion concentrates arsenic and chromium in smoke and ash at toxic levels — arsenic in CCA wood ash can reach several percent by weight; burning CCA wood releases arsenic-laden smoke that is acutely toxic at higher levels and carcinogenic at lower chronic levels. CCA wood should NEVER be burned: not in fireplaces, not in wood stoves, not in outdoor fire pits, not in barrel burners, not as charcoal starter. This is widely unknown by homeowners who may burn scrap deck boards or dismantled CCA playground structures. EPA explicitly prohibits burning of CCA-treated wood in open burning and restricts it in permitted burn facilities.

Green flags — what to look for

• Playground equipment and decks confirmed as post-2003 installation using ACQ, CA-B, or composite lumber; CCA structures that have been professionally sealed with oil-based penetrating sealer within the past year; soil testing below EPA residential soil arsenic standard (0.39 mg/kg in highly sensitive areas, typically <10 mg/kg regional background) under play areas — Post-2003 pressure-treated wood for residential use is ACQ or CA-B — no arsenic, dramatically lower human toxicity. Composite lumber is completely inert with respect to heavy metal leaching. Annual oil-based penetrating sealer on CCA structures has been documented in EPA SFIREG studies to substantially reduce arsenic surface transfer to wipe tests — sealing is meaningful mitigation for legacy structures not yet replaced. Soil arsenic testing below background levels confirms the soil under play areas has not been contaminated by CCA leaching.

Safer alternatives

• ACQ or Copper Azole treated lumber — Safer arsenic-free preservative options approved for playground use
• Naturally rot-resistant wood (cedar, redwood, composite) — No chemical preservatives; suitable for decks and landscape applications
• Composite decking materials — Made from recycled plastic/wood fiber; durable without toxic preservatives

Frequently asked questions