My take on pressure treated wood is don't use it for edibles and don't eat anything that was grown close to it as well. This article by the Connecticut Agricultural Experiment Station was written in 2004 and last updated in 2007. I'm including selected quotes. http://www.ct.gov/caes/cwp/view.asp?a=2815&q=376678 a
"Arsenic and Pressure Treated Wood
INTRODUCTION
Prior to January of this year, the most common wood preservative formulation in use was CCA (containing copper, chromium, and arsenic). Recent findings that arsenic can be released from this wood by leaching and physical dislodgement has prompted a phase out on its sale for most residential applications, effective January 1, 2004.
WHAT ARE THE HEALTH AND ENVIRONMENTAL CONCERNS?
The arsenic used in the CCA formula is in the inorganic form which is a class A carcinogen, number 1 in EPA’s priority list (CERCLA), on the Z-list of toxic substances (OSHA), and is a potential endocrine disrupter. Moreover, this arsenic leaches from the wood, winding up in the soil, and it is dislodged from the surface upon physical contact. For example, elevated arsenic has been found near CCA structures in Connecticut, in soils under decks and highway traffic sound barriers, in Florida in soils under decks and playscapes, in New Jersey in soils under wetland boardwalks, and in Canada in soils near utility poles.
Arsenic can also be dislodged from CCA wood surfaces such as those commonly found on playground equipment, decks, and picnic tables. In this case the exposure is by hand to mouth contact. Evidence that there is physical dislodgement of arsenic from wood surfaces is illustrated by 2 studies, one done here at the station, the other by the US Consumer Products Safety Commission (CPSC).
study on arsenic dislodged from surfaces was completed by the Consumer Product Safety Commission in early 2003. In this study 8 decks and 12 playscapes in the Washington DC area were tested for dislodgeable arsenic. The commission staff also compared wet and dry wipe methods to direct hand contact. Based on their study they determined that the amount of arsenic dislodged onto the hand, and subsequently ingested, could result in an increased risk of between 2-100 in a million of bladder and lung cancers.
THE REPLACEMENT PRESERVATIVES
After January 2004 the CCA preservative will be replaced with ones that contain no arsenic or chromium. There are two major replacement formulations. One is ACQ, sold under the trademark Preserve Wood. This formulation is a combination of copper and didecyl dimethyl ammonium chloride (quat). The other is copper azole, sold under the trademark Natural Select. This formulation contains copper and tebuconazole. Borates can be added to the copper azole formulation, and may be approved for other uses, depending on the application.
These new preservative formulations do not contain EPA listed compounds, nor do they contain known or suspected carcinogens. The ACQ formulation was given the green chemistry award in 2002. Unfortunately, the toxicity of copper to some beneficial marine organisms presents problems for the use of these preservatives in marine applications."
There are helpful links at the above site as to where to go for more info and a discussion about painting any CCA wood surfaces.
