Pentachlorophenol (C6HCl5O) is a man-made (i.e., it does not otherwise occur in nature) fungicide which is a organochloride. It is toxic to humans.
It was once used as a pesticide and wood preservative.
In 1984 (or 1987 — references vary), the purchase and use of pentachlorophenol was restricted in the United States, and the general public may no longer buy it. It is has industrial use as a wood preservative for utility poles, railroad ties, and wharf pilings.
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