Several people warned NOT TO ALLOW CHILDREN TO PICK UP THIS FORM OF DEBRIS.
and NEVER BURN THIS TYPE OF PRESSERVED WOOD.
The following information from a fact sheet of the Ecology Center http://www.ecologycenter.org/ offers good explanation for its toxic qualities. High levels of arsenic are a major concern. Here is a brief section of their review:
By far the most common type of pressure treated wood is designated PT CCA (Pressure Treated Chromated Copper Arsenate). The basic elements involved are copper, chromium, and arsenic. In CCA treated wood, the chromium acts as the bactericide, copper as the fungicide, and arsenic as the insecticide. Even though all three are toxic, the chromium and copper don't raise many concerns (although maybe they should). If we don't inhale it, chromium is not particularly harmful, and copper is not very toxic to mammals, although it is to aquatic life. It's the arsenic that is worrisome. All of these compounds are stable and do not break down into other, less harmful substances in the environment.
Pressure treated wood has been in common use for about forty years and much of that is coming out of service and becoming a waste product. The companies that produce this product claim that the compounds are chemically locked to the wood itself and therefore not a hazard to human health and the environment. This statement is mostly true as far as it goes. What they don't tell us is that leaching does occur and that leaching is accelerated by acidic conditions such as is produced by acid rain or occurs during the composting process. A study by the Connecticut Agricultural Experiment Station found an average arsenic concentration of 76 ppm under old CCA treated decks. The state limit is 10 ppm.7 In another East-coast study, soil under an 8-year old deck was found to have 7.7 times the copper concentration, 3 times the chromium concentration, and 31.4 times the arsenic concentration as samples taken at least 15 feet away. It is clear that leaching does occur, at least in areas with high levels of acid rain.
The EPA has developed the Toxic Characteristic Leaching Procedure (TCLP) to set threshold levels for the toxicity of 39 different chemicals, including chromium and arsenic. If the measured leaching from a waste product exceeds these limits it is considered a toxic waste and regulated accordingly. Arsenic-treated wood such as CCA does not have to pass this test. "Why not?" you ask. It turns out that this obviously questionable product enjoys a special exemption from the TCLP rule in 40 C.F.R. 261.4(b)(9). This is likely the result of strong lobbying pressure from the manufactures of these products.9 Because the point is legally moot, actual data is hard to come by, but results of one test obtained by EBN show that CCA-treated wood actually fails the test for arsenic and only barely passes it for chromium.10
There is evidence of leaching from PT CCA structures into the surrounding environment, but the disposal of this product is by far the more serious environmental problem. It should never, ever be burned! The chemical companies don't tell us is that these compounds, and particularly the arsenic, are released when the wood is burned. Some of these compounds are released directly into the air where the can be inhaled and some remain in the ash where they are highly leachable.
I will keep you updated as I discover more, but it appears that few studies have been conducted to determine impacts on marine life. And a lack of regulation by the EPA is troublesome to be sure.
Removing it from the ocean is important, but I think there is another alarming situation..........Beach fires are very popular along our shores. Burning treatedwood releases the toxic chemicals and the ash remains toxic as well.
Hopefully, more information is made available for campers and others who enjoy toasting marshmallows on a fire. While it is theoretically illegal to collect wood for fires on some beaches (State Parks for example), firewood is often gathered. Sadly, milled lumber is fast becoming one of the major components of wood along our shorelines as natural sources decline due to clearing of marine riparian woodlands. Ironically, this toxic woody debris may serve some of the same valuable functions as the branches, stumps, and tree trunks once so prevalent on backshores. Will we see the day when arsenic soaked wood is protected because it is helping to protect our shores from erosion? I know from experience that a lot of creosote soaked wood remains in place along our beaches. It continues to leach toxins, but the large size of this debris makes it nearly impossible to eliminate...........A lot to think about and much work to be done!
Thanks to all who helped me with the immediate concern. I won't be asking kids to pick up any form of treated wood!