The Truth About Treated timber (Lumber), IS IT TOXIC? CARCINOGENIC? BAD FOR THE ENVIRONMENT? A lot of people have questions about the toxicity and safety of treated wood/lumber these days. Here are some quick facts about modern treated wood.
Pressure treated lumber milled BEFORE 2004 contained a truly toxic component–Arsenic (CCA). But the EPA essentially outlawed the use of arsenic and chromium in treated lumber at the end of 2003.
Now, lumber is pressure treated with Alkaline Copper Quaternary (ACQ) and Copper Azole (CA-B), two less harmful copper-based emulsions. But, these chemicals are less fungi-and rot resistant as well.
To keep cost down, mills started producing GROUND CONTACT and NON-GROUND CONTACT lumber. GC has a higher copper content, making it more rot-resistant. NON-GC has a lower copper content, so it can not stay in contact with the wet ground surface.
Most companies state that these treated lumbers are suitable for raised garden beds, but organic gardeners disagree.
Also, many carpenters and contractors feel that these newer lumbers don’t resist rot for very long–maybe less than 12 years–so more lumber is winding up in the dump.
All the same, it does seem that newer lumber poses less risk of toxicity to humans and ground soils
Article by The Honest Carpenter: https://www.youtube.com/@TheHonestCarpenter