Agriculture Reference
In-Depth Information
Chapter IV Additional Information, Results, FAQs, Resources
Section 1: Is Pressure Treated Wood Safe to Use in Your Garden?
There have been many concerns and much has been written about chemicals used to treat
wood getting into vegetables.
Priorto2003,lumberwastreatedwithchromatedcopperarsenate(CCA),whichistoxicand
the EPA issued warnings about even touching arsenate treated wood.
TherehasbeenanerroneousbeliefthattheEPAbannedthesaleoflumbertreatedwithchro-
mated copper arsenate (CCA) in 2003 (12/31/2003). Not true. CCA treated lumber is no
longer approved for residential construction, but it is still approved for sale for industrial,
commercial and agricultural uses.
Chances are any treated lumber you buy today at your local building supply store is one of
the new EPA approved alternatives to CCA:
• Alkaline Copper Quaternary (ACQ)
• Copper Azole (CA)
• Micronized Copper Quaternary (MCQ)
But you should make sure before buying it.
Ireadinsomeofthegardeningforumsthatthenewtreatedwoodproductsareperfectlysafe
to use for raised garden bed frames, but I needed to do the research for myself.
Alkaline Copper Quaternary (ACQ) -
the Copper is the primary active ingredient and is
described as being similar to chemicals used to keep swimming pools clean and primarily
prevents fungal growth. The Quat formulation is similar to other bio-degradable cleaners
and preservatives and is a back up for Copper resistant fungi and termites.
There are no EPA listed carcinogens in ACQ. Research has not identified any direct threats
to humans, but the products do leach copper, which is very toxic in aquatic systems. Brand
Names include YellaWood, Preserve® and NatureWood®.
Copper Azole (CA) -
as with ACQ, the Copper is the primary ingredient (98%) and the
tebuconazole fungicide is the backup (<1%). Brand names are Wolmanized, Tanalith®, or
Tanalised® and Residential Outdoor®.
Micronized Copper Quaternary (MCQ) -
is the same chemical formula as ACQ, but it is
first ground into tiny particles (micron sized) then are injected into the cellular structure of
the wood under high pressure. This process releases 90-99% less copper into the environ-
ment, which is good news for aquatic environments.
