EPA announces ban on CCA wood for residential useThe US EPA has announced a transitional ban on the production of CCA wood for residential use. Read the full text at the EPA Website by clicking on this link.What is CCA pressure treated wood?Most woods are susceptible to attack by fungus and insects. To make wood more resistant to attack, insecticides and anti-fungal agents can be added.CCA wood - also called pressure treated wood - is the green-tinged lumber sold in almost every home center and lumberyard in America. It has the indisputable benefit of being highly resistant to rot and insects. The lumber is treated with a pressurized solution containing Copper, Chromates and Arsenic, hence the name CCA lumber. It is sometimes sold under the brand name "Wolmanized" Lumber. Soft wood is injected with an aqueous solution of Copper, Chromate and Arsenic under pressure. The arsenic is chemically bound in the wood by the chromate, and the copper gives it that slight greenish tint. The solution is water based, which is why the wood often feels damp at the lumberyard. CCA treatment leaves about one ounce of inorganic arsenic in each 12 foot 2 x 6. This is enough arsenic, if released, to kill about 250 adults.
 How is arsenic released?CCA pressure-treated wood contains arsenic which can be released from the wood in several ways:
Even more astonishing, minute amounts of 'fly ash' from burning CCA pressure treated wood, can have serious health consequences. The Journal of the American Medical Association reported on a family that burned CCA in a wood stove for winter heating. Their hair fell out, all family members suffered severe, recurring nosebleeds, extreme fatigue and debilitating headaches. The parents complained about 'blacking out' for periods of several hours, followed by long periods of extreme disorientation. Both children suffered frequent seizures described as 'grand mal'. The symptoms were finally traced to breathing minute amounts of arsenic laden dust leaking from the furnace as fly ash. The family's houseplants and fish died, too, victims of copper poisoning from the same dust. Peters HA, et al: Seasonal exposure to arsenic from burning CCA wood. JAMA 251:(18)2393-96, 1984) Mechanical abrasion: CCA wood particles are released when the wood is sawed, sanded or shaped. So far, no studies have been done on these effects, but the warning card stapled to each bundle of CCA wood warns about avoiding sawdust. Direct Contact: In a study conducted by the Connecticut Agricultural Experiment Station, the authors found that arsenic is released to the child's hand by direct contact with arsenic-treated wood. The amount ingested per day was estimated to be about 7 micrograms per day. This should be compared against an estimated 5 micrograms estimated in food and 5 to 100 micrograms (ppb) in drinking water. Acid release: The same Connecticut Agricultural Experiment Station study found an average Arsenic concentration of 76 ppm under old CCA treated decks. The range was from 3 to 350 ppm, and the state limit is 10 ppm. It is suspected that acid rain and acidic deck washes can hasten release of arsenic from the wood. How does arsenic affect me?Back to you: The concern is that released arsenic can find its way into our bodies, the food chain and groundwater. Will arsenic in CCA ash leech out of landfills into water supplies? No one knows. Arsenic can be absorbed through the skin, inhaled or ingested. One-tenth of a gram accumulated over a two month period can produce death, and arsenic is carcinogenic at much lower levels. The EPA limit in water is currently 50 ppb, and proposals to lower it to 2 ppb are in place.Besides release of arsenic, another concern is the release of Arsine gas. Arsine gas has been used as a nerve gas, and is made by reacting zinc and arsenic in the presence of an acid. Building a deck using galvanized nails in an area of acid rain could theoretically cause this reaction, although the volume of Arsine gas would be expected to be low. Storing CCA wood ash in a galvanized bucket may be asking for trouble, however. Click on the 'Arsenic' tab to the left to read more about arsenic toxicity, Signs of Arsenic poisoning, and Arsenic poisoning treatment.
How much should I be concerned?More than a little. Besides the extreme toxicity of CCA ash, newer studies have shown that arsenic can be rubbed off by contact with CCA wood and leech out of CCA wood in significant amounts.
What precautions can I take?Fortunately, several are effective.Use a pressure treated wood which does not contain arsenic: Several pressure treated wood formulations which do not contain arsenic are available right now. Your lumberyard may carry these under the trade names of "ACQ" or "Kodiak Wood", or they may be listed as preserved with ACQ (Ammoniacial Copper Quaternary), copper azole and/or copper citrate. All are arsenic-free and effective against rot and insects: the US EPA says they are safe, and the American Wood Preservers Association says they work. If your lumberyard does not stock these, they can order them. You might be interested to know that these are the wood-preservation formulas used in Japan and Europe, where CCA treated wood is banned. Seal existing construction: If you already have a CCA wood structure, seal it every two years with a waterproof sealant, paint or stain. Do NOT use acid deck wash or brighteners as these have been suspected to accelerate release of arsenic from CCA wood. Sealing your deck can reduce arsenic leeching by 90% (reference). Never burn CCA wood! The resulting ash is highly toxic. Read more about CCA ash effects on humans and animals on the 'Arsenic' tab to the left. At this point, CCA wood can only be disposed of in special land fills. Check with your local waste agency for precautions and regulations. Let's all hope that arsenic in the wood stays in place as it decomposes. Take precautions when cleaning up after a CCA wood fire If you have a fire of a CCA wood structure, like a deck or gazebo, you MUST treat the ash as toxic, because it is. Again, ingestion, inhalation or absorption through the skin of 1 Tablespoon of this ash can be lethal to an adult. Wear a respirator rated for asbestos dust, and fully cover all exposed skin including hands and face. Disposable Tyvek suits are available through most Industrial supply companies like Grainger.com, McMaster.com, etc. have your clothing rinsed down before disrobing. New construction: Don't add arsenic to your backyard. In particular, plants can take up arsenic from the soils, so it may not be a good idea to use CCA wood in gardens. See the paragraph above on arsenic-free alternatives. Make your local lumberyard aware of the dangers of arsenic.
What can I do?The only reason that CCA wood is still used is economics: it is 5 to 10% cheaper than other wood treatments. Using this logic, it would be sound practice to use asbestos as an insulation material in schools because it's really cheap at the moment. I am informed by the local Home Depot that they are switching away from CCA wood. We'll see.Contact your local elected representative about the unnecessary dangers of living with arsenic in your backyard. Propose tariffs, taxes or a levy on CCA lumber. The added expense will make the safer treatments more widely available, and provide a handy financial resource for what could become the biggest cleanup operation in history. Write your state or Federal Environmental agency make them aware of the dangers of arsenic in CCA wood, and tell them we the risk outweighs the benefit since safer alternatives are available. Get an arsenic test of your soil. Do you have small children who may play under the deck? Concerned about a house with an old deck that you are looking at? Do you live in an area of Acid Rain (which may leech arsenic out of CCA Wood)? Get an arsenic test of the soil under the deck. Click on the Test Labs' to the left.. Look into Arsenic Abatement. Click on the 'Alternatives' tab to the left. CCA wood in GardensThere are very few studies on gardening and plant exposure to CCA wood and wood ash. In a study conducted by the Connecticut Agricultural Experiment Station, the authors found that Romaine lettuce grown in containers with varying degrees of CCA wood sawdust picked up arsenic from the soil, in proportion to the concentration of arsenic in the soil. The amount of arsenic per 50 gram serving of lettuce was measured at < 1 µg (the control) and 10 µg of arsenic for lettuce grown in the heaviest arsenic/soil concentrations.While these are not alarming in themselves - the usual dietary intake of inorganic arsenic is between 4-12 µg/day - this test does confirm that arsenic can be taken up from the soil by plants. It certainly raises questions about the uptake of other plants, and raises the question of what might happen with root crops.
LinksLinks Here is a page of links to other sites on CCA lumber, including a link to the Wood treatment industry page.It is our intention to have this a completely factual forum for the discussion of the risks and benefits of CCA and other pressure treated woods. If you would like to contribute, correct errors, have an idea, gripe, link or comment, contact me, Richard Martin . I want to make this a balanced public forum, and as factual as possible. I would be happy to add your comments or counterpoint to our comment page.
Liability: This site is intended as a discussion site only to present only factual information about arsenic and its effects on the environment. This site is not intended to either promote or denigrate any product over any another. The Author assumes no liability beyond the liability to correct material facts in error.
Richard Martin |