Treated wood is regulated by the U.S. Environmental Protection Agency (EPA) as a treated article. Treated articles do not have to be registered as a pesticide with the EPA if the treatment is only intended to protect the item or material from microorganisms or mold (fungi). This means that the U.S. EPA registers the treatment chemicals used on the wood as pesticides but does not require registration of the wood once it is treated.

• Wood preservatives may be registered for residential, commercial, or industrial uses. Some wood preservatives are restricted-use pesticides, meaning they are only available to licensed and certified applicators.
• Some treated wood types, such as ACQ, may be used in either residential, commercial, or industrial uses. Others are not for use in homes or residences. There are many types of treated wood.
• Treated wood is sold with end tags that specify what chemicals were used to treat it and the use category for that wood. Use categories indicate the environmental conditions the treated wood can handle. For example, Use Category 4 (UC4) is rated for use with ground or water contact.

In 2004, the wood-preserving industry voluntarily stopped selling wood treated with CCA to homeowners. The EPA was concerned about risks to workers in wood-treatment facilities and residues on the skin. For more information, see our FAQ about Chromated Copper Arsenate (CCA).

Reuse

Reuse and disposal of treated wood is not regulated by the EPA. However, reusing old treated wood may put you at risk of exposure to wood preservatives that are not considered safe for use in or around the home. Reused or recycled treated wood often lacks the end tag that identifies the preservative used. It can be very difficult to identify what was applied to the wood based on its appearance alone.

Disposal

Treated wood is not listed as hazardous waste under federal law. However, sawdust and scraps should be cleaned up after working with treated wood. State and local governments may have specific instructions, rules, or guidance for disposal. If you have treated wood to dispose of:

• Never burn treated wood. The ash and the smoke can contain toxic chemicals.
• Chipping or composting treated wood may release toxic chemicals into the environment.
• Contact your local or state waste management program.

Additional Resources:

• Consumer products treated with pesticides - U.S. Environmental Protection Agency (US EPA)
• Select the right preserved wood for your project - American Wood Protection Association
• Information for homeowners: Codes used for preservatives - American Wood Protection Association
• Treated lumber Draft Guidance for Organic Farms - USDA National Organic Program
• Treated Wood on Organic Farms - University of Tennessee

If you have questions about this, or any pesticide-related topic, please call NPIC at 800-858-7378 (8:00am - 12:00pm PST), or email us at npic@oregonstate.edu.