Pentachlorophenol ("Penta") is a highly effective and economical wood preservative. The principal use in the United-States and Canada is pressure-treatment of wood; major applications are for railroad ties, pilings, posts, cross arms, and poles. Treatment of wood products with pentachlorophenol typically extends the functional life of wood by at least eight times. Because of the presence of certain trace impurities produced during the pentachlorophenol manufacturing process, notably hexachlorodioxins ("HxCDDs"), the use of pentachlorophenol has been subject to intense regulatory scrutiny. Animal studies have shown that HxCDDs, when administered in toxic amounts, are fetotoxic, teratogenic, and carcinogenic. In the United States, the Environmental Protection Agency ("EPA") instituted a regulatory proceeding in October 1978 that considered cancellation of all pentachlorophenol pesticide registrations. After extensive review, the EPA declined to take such action. Instead, in 1986, EPA decided to limit the HxCDD levels to no more than 4 ppm per batch with an average of no more than 2 ppm for all batches shipped per month. EPA took additional measures to ensure that use of pentachlorophenol for wood preservation would not cause unreasonable risks to the public or the environment. A parallel proceeding in Canada resulted in the Canadian Government adopting a regulatory program essentially identical to that of the United States. The U.S. and Canadian experience reflects recognition by these regulatory bodies that the appropriate mechanism for addressing pentachlorophenol concerns is not to ban the important uses of the pesticide, but to ensure that those uses are properly managed to minimize exposures. The agencies arrived at that determination after a comprehensive evaluation of the inherent toxicity of pentachlorophenol, reductions in risk achievable through appropriate risk management measures, and the significant economic and societal benefits of pentachlorophenol as a wood preservative. Since that time there have been a number of new studies on pentachlorophenol that further confirm that Penta can be safely and responsibly used for wood preservation without causing adverse effects to health or the environment.

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