Water Quality District - Hazardous Waste
What is the Problem?
Treated wood contains chemical preservatives (pesticides) to inhibit fungal decay and extend the life of the wood. The wood-treating industry estimates treated wood will last 20 to 30 times longer than untreated wood in challenging outdoor environments. While treating the wood lengthens its useful life and conserves trees, some of the chemicals used in treating wood are toxic.
Types of Treated Wood:
- Pentachlorophenol (PCP or Penta), typically used for telephone poles.
- Creosote, a tar-like substance that is used for railroad ties and construction pilings, now banned.
- Chromated copper arsenate (CCA) , or other preservatives containing arsenic and heavy metals.
- Other copper-containing treatments, such as ammoniacal copper quaternary (ACQ), copper azole or ammoniacal copper citrate, which are formulated with less toxic chemicals.
Chromated Copper Arsenate (CCA)
- CCA treated wood, also known as green-treated wood, is the most commonly used type of treated wood. It is commonly used for children’s play equipment, gazebos, decks and other residential building products.
- Studies have shown that rainwater leaches (releases) CCA from the treated wood. This can lead to contamination of soil beneath the wood structure. Also, a pesticide residue (fine coating) can be left on the wood’s surface, which can easily be wiped from the wood surface and picked up on hands or clothing.
- The most toxic part of the CCA pesticide formulation is the arsenic. Arsenic is a known human carcinogen. An important health concern with CCA-treated wood is arsenic exposure to children. See the safety notes below for ways to minimize arsenic exposure from CCA-treated wood.
Minimize exposure to your family and children by following these guidelines:
- Seal existing CCA-treated structures every two years with a penetrating sealant such as a shellac or oil-based stain.
- Never burn CCA or any type of treated wood. The fumes and resultant ash are toxic and very harmful to children and pets.
- Avoid breathing dust from cutting treated wood. Dispose of treated wood sawdust, see below for options. Never put sawdust from treated wood in your compost and or leave on the ground.
Consider alternatives to treated wood when selecting building materials for your next outdoor structure or project:
- Recycled plastic material.
- Redwood and/or Cedar, which are naturally rot-resistant.
- Wood-plastic composite materials.
- Wood treated with less toxic preservatives, such as ammoniacal copper quaternary (ACQ), copper azole or ammoniacal copper citrate.
- Waste Hauler: Call BFI (728-9572) for disposal options of treated wood, or treated wood sawdust.
- Do not burn treated wood. The fumes and resultant ash are toxic and very harmful to children and pets.
- Treated wood of any kind is not accepted at Haz Waste Days.
The Residential Disposal Guide is provided by the Missoula Valley Water Quality District as a public service and is not an endorsement of specific businesses, services or products. Any omissions or inaccuracies are unintentional. Please contact us with corrections or additions. Call businesses or agencies to confirm hours, locations and charges for services, if any. For information on disposal of items not listed, email or call the Water Quality District at 406-258-4890, M - F, 8 am to 5 pm.
Much of the information provided is from the Washington County, MN, Dept. of Public Health and Environment website.
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