I was unaware of the corrosion issues for fasteners on pressure treated wood. On recent trip to my local home center, I was buying lag fasteners from some pressure treated lumber. A sales associate steered me towards the stainless steel fasteners. I asked why, and he just said that they were "reccomended" for the pressure treated material. There was no mention of the corrosion problem. As a matter of safety, this information should be more readily available to the general public.
This article explains the corrosion issue with ACQ treated wood products quite well. It states that,
"A study done by Simpson Strong-Tie found that ACQ is twice as corrosive to metals as CCA, and some other studies have found it to be three times as corrosive."
Rob: I read your article with great interest, as I publish a website about the health hazards of CCA treated wood, and have done so since 2001. However, I disagree with your points and feel compelled to correct them.
I have studied CCA treated wood at length and have amassed a lot of data about the negative health consequences of CCA treated wood for humans (especially children) and animals. Much of this information can be found on our website: www.bancca.org.
Regarding your comments about corrosion of fasteners and your backyard playset, I believe that the treated wood in question is NOT CCA treated wood, but is ACQ treated wood (Ammonium Copper Quarternary). ACQ treated wood was released in late 2003/early 2004, after the voluntary ban by the treated wood industry on the manufacture of CCA treated wood for residential purposes. It does not contain any arsenic or hexavalent chromium, as CCA treated wood does.
Right away, there were problems reported with the corrosion of fasteners used with ACQ treated wood. This is a well known issue. Treated wood manufacturers and big box retail stores, like Lowes and Home Depot, responded by stocking stainless steel or "double-dipped galvanized" fasteners for use with ACQ treated wood.
Later, MCQ treated wood (Micronized Copper Quarternary) was also released. It is supposed to have a lesser problem with corrosion of fasteners than ACQ treated wood does. MCQ treated wood was sold by Home Depot, (and others), whereas Lowes generally carried (and still carries) ACQ treated wood products. To be clear, both require either the use of galvanized, coated or stainless steel fasteners. And, corrosion continues to be a problem with ACQ treated wood products, and to a lesser extent, the MCQ treated wood.
While I share your concerns about the safety of playground equipment and how it relates to the corrosion of fasteners, there was a bigger issue with CCA treated wood products used in the past, namely that the arsenic in the wood leached to the surface, where it could be picked up by children and, worse, due to frequent hand-to-mouth contact, could pose a serious health risk. Also, CCA treated wood creates a disposal issue, since many municipalities will no longer accept CCA treated wood curbside, due to its arsenic content.
I am not aware that creosote treated wood was EVER used in playground equipment. Creosote treated wood is treated with a coal tar derivative and is primarily used for rail ties and marine pilings. It leaches out benzo-a-pyrenes and other toxic chemicals. Some refer to creosote as a "Witches brew of toxic chemicals". Thus creosote would be too toxic for use in any backyard or playground situation, so your implication that creosote treated wood might be superior is NOT correct.
Moreover, if you will review the health hazards of arsenic, hexavalent chromium and CCA treated wood products, (which contain both chemicals along with copper), you will come to realize that the toxicity of CCA wood is the greater threat than the corrosion of fasteners, due to its arsenic content. While corrosion of fasteners continues to be a problem, and needs to be addressed as a safety issue in playground equipment, we have not heard of any cases of deaths or injuries to humans or animals from corroded fasteners. We do have documented cases of human and animal injuries from exposure to CCA treated wood.
In summary, it sounds like the wood from your playset, especially if purchased after Dec. 2003, is likely ACQ wood, and not CCA treated wood after all. That being the case, corrosion of fasteners is an issue with ACQ wood, and one that the manufacturer should address and pay for, in our humble opinion, since it was known to be a problem for many years.
The use of Chromium Copper Arsenate (CCA) as a wood treatment ceased in North America at the end of 2003 (a). Although most codes still allow the use of hot-dipped or mechanically zinc'd hardware, the use of stainless steel hardware makes more sense. The cost difference from zinc'd hardware is negligent when compared with the cost of replacing the hardware (or worse, an avoidable accident).
a. http://en.wikipedia.org/wiki/Chromated_copper_arsenate
That's quite an eye-opening tale and one many parents and boat owners (I'm both) should really have knowledge of. It surprises me, though, that wasn't caught and addressed as it's a huge safety and liability issue. It seems like there should have been some sort of correlation made and material choice changes invoked to either replace CCA in terms of treating wood or coming up with some cocktail of materials for the hardware that doesn't end up in the same scary place.
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