Is Pressure Treated Wood Dangerous?
I don't believe Wolmanized (CCA--chromated copper arsenate) treated wood presents any meaningful danger to end users -- people who live, work or play near or on construction that contains CCA treated wood.
Only minimal precautions are recommended even for workers building with the product. I looked into this in the late '90s and concluded even the minimal precautions suggested for these workers probably derive primarily from the intuitive (common sense) idea that the arsenate treatment might present a hazard -- not from any evidence that it's harmful. The EPA recommendation to use a dust mask when sawing is the same for all woodworking that produces sawdust. In spite of the extensive use of this product over the last 40 years, studies don't show harmful effects on users or construction workers. Studies of workers at the treatment plants have not demonstrated hazard. There is evidence for some biochemical differences between such workers and normals, which may suggest some risk, but no actual health differences were seen. These treatment plant workers are exposed to conditions much more intense than construction workers, whose exposure is, in turn, much greater than end users. Treatment plant workers can experience constant daily exposure to the concentrated chemical products and aerosols (airborne amounts) of these chemicals. Even with this intense exposure, it's not obvious there are significant hazards.
CCA preservative reacts with the wood and forms a chemical bond - it becomes "fixed" within the lumber. Once fixation occurs, the preservative is very leach resistant. CCA treated wood gives off no fumes or vapors.
Here's what the EPA said in 2002:
"Do CCA treated wood and any arsenic that might be released from the wood pose risks to human health?
"EPA reviewed the use of CCA in pressure treated wood extensively during the 1980s and concluded that pressure treated wood did not pose unreasonable risks to children or adults, either from direct contact with the wood (e.g., as used for playgrounds and decks) or from contact with surrounding soil where some releases may have occurred. Based on scientific data that EPA has reviewed to date, the Agency has not identified any significant health concerns from short or long-term exposure to arsenic residues from pressure-treated wood. EPA reached this conclusion based on studies that evaluated dermal contact (absorption through the skin), inhalation, and ingestion for both children and adults. EPA also reviewed a study that concluded that CCA does not pose a short or long-term toxic hazard to children playing on playground equipment. However, the Agency was concerned about the health effects on workers who come in contact with CCA on a daily basis. Based on these concerns, the Agency issued new requirements for protecting workers."
Caution suggests you not burn CCA treated wood, as some think the smoke can present a hazard and, to be safe, don't use it for surfaces in direct contact with food.
Here's the information sheet the EPA urges be available anywhere CCA treated wood is sold:
Some other references:
All this doesn't mean there cannot possibly be any danger, but clearly there's no blatant or obvious or even apparent hazard to end user exposure. I wouldn't eat it or smoke it, though.
Follow-up: Since I wrote the last sentence above, I've read that because objects in stables are sometimes made from CCA treated wood, horses eat it. So, they did some studies -- the studies showed there's no ill effect on the horses. So, maybe you can eat it after all. But, I'm still abstaining -- well, perhaps a nibble now and then.
Follow-up Two: Manufacturers of CCA wood voluntary stopped manufacturing CCA-treated wood for most consumer applications December 31, 2003. They did not do this because they believe there is any danger associated with the product in ordinary use -- they do not believe there is any danger, and neither do I. In about 2001, a press fed hysteria, absent evidence, caused attorneys and plaintiffs to line up to makie unsubstantiated claim for damages from exposure to CCA. As a result the industry became afraid of these ill founded, expensive lawsuits and voluntary changed to a different treatment. The replacement treatment has not been in use or studied long enough to know if it presents actual dangers. The replacement product does not last/protect as long as CCA wood, thus increasing the demand for it. I have no way to know if this increased demand was a factor in the industry's decision to stop making the safe, long lasting CCA treatment. CCA treated wood is still used in Canada.