Arsenic and Chromium Treated Wood

Inorganic arsenic and chromium salts dissolved in water have been/are commonly used in the following formulations:

In 1984, CCA was used as the preservative for 80% of treated wood and the proportion has increased since then.  CCA is a chemical formulation containing chromium, copper, and arsenic.  Primarily because of the arsenic, certain safety issues have been raised regarding specific uses and disposal of CCA treated wood.

The Agency for Toxic Substances and Disease Registry (ATSDR) is an agency of the U.S. Department of Health and Human Services. ATSDR provides ToxFAQsTM for these chemicals and many others. Note that the links lead away from the Department of Ecology Web site. However, the ATSDR is the Federal government's general clearinghouse for toxicity information.

Arsenic is a naturally occurring element widely distributed in the earth’s crust. In the past it has been used in many products, including pigments, pesticides, and herbicides. Because of its potential for poisoning, most uses of arsenic have been discontinued or severely restricted. Currently, most arsenic is used for treating wood, with smaller amounts used by the semiconductor industry. Exposure to large amounts of arsenic can lead to serious illness or death. Ongoing exposure to smaller amounts over a long time can cause many different adverse health effects including skin changes, cardiovascular problems, and increased risk of several forms of cancer.

Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases. Chromium is present in the environment in several different forms. Exposure to chromium occurs from ingesting contaminated food or drinking water or breathing contaminated workplace air.

Copper is an element that is found naturally in the environment. Small amounts of copper are necessary for good health; however, very large amounts can cause dizziness, headaches, diarrhea, abdominal cramps, and liver and kidney damage. Copper-treated lumber turns green as the preservatives dry and react to the sun’s ultraviolet rays.

Arsenic and chromium are regulated by the EPA and the Dangerous Waste and Toxics Reduction (HWTR) Program because they are toxic and are able to leach into the water table if put into a landfill. Dangerous waste levels of arsenic and chromium would be detected with the Toxicity Characteristic Leaching Procedure (TCLP) test. The Dangerous Waste code for arsenic is D004 and the dangerous waste code for chromium is D007. In addition, EPA has reported that arsenic used in wood preserving formulations was typically contaminated with lead (see the December 30, 1988 Federal Register Vol. 53 No. 251 page 53284). Lead has a Dangerous Waste Code of D008.

Related information

Focus on Treated Wood Exclusion is an Ecology publication that clarifies the disposal and recycling options for arsenic-, pentachlorophenol-, and creosote-treated wood.