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Chromated copper arsenate (CCA) is a wood preservative containing compounds of chromium, copper, and arsenic, in various proportions. It is used to impregnate timber and other wood products, especially those intended for outdoor use, in order to protect them from attack by microbes and insects .
On December 31, 2003, the U.S. wood treatment industry stopped treating residential lumber with arsenic and chromium (chromated copper arsenate, or CCA). This was a voluntary agreement with the United States Environmental Protection Agency. CCA was replaced by copper-based pesticides, with exceptions for certain industrial uses. [2]
One disadvantage of ACQ is that significant amounts of air pollution, in the form of ammonia, are released from treatment plants and freshly treated wood in storage yards. While the CCA components are far more toxic in a weight basis, being non-volatile solids they can be effectively contained.
The treatment was patented in Britain from 1934 and in the US from 1938. It also went by the name of Chromated Copper Arsenate or CCA in the United States of America from around the 1950s. In his treatment, copper is a fungicide, arsenic is a secondary fungicide and insecticide, while chromium is a fixative which also provides ultraviolet (UV ...
In the 1930s, a process of treating wood with chromated copper arsenate (also known as CCA or Tanalith) was invented, and for decades, this treatment was the most extensive industrial use of arsenic. An increased appreciation of the toxicity of arsenic led to a ban of CCA in consumer products in 2004, initiated by the European Union and United ...
Ruby has a laser transition at 694.3 nanometers, in a deep red color. [83] Chromium(VI) salts are used for the preservation of wood. For example, chromated copper arsenate (CCA) is used in timber treatment to protect wood from decay fungi, wood-attacking insects, including termites, and marine borers. [84]
Scaling and root planing, also known as conventional periodontal therapy, non-surgical periodontal therapy or deep cleaning, is a procedure involving removal of dental plaque and calculus (scaling or debridement) and then smoothing, or planing, of the (exposed) surfaces of the roots, removing cementum or dentine that is impregnated with calculus, toxins, or microorganisms, [1] the agents that ...
MIT Press, 2018. Chapter 2 contains a detailed treatment of PAC-learnability. Readable through open access from the publisher. D. Haussler. Overview of the Probably Approximately Correct (PAC) Learning Framework. An introduction to the topic. L. Valiant. Probably Approximately Correct. Basic Books, 2013.