Pentachlorophenol(pcp) Risk Characterization Document

Pentachlorophenol is a pesticide used to protect wood products against microbial degradation andinsect infestation. A dermal absorption value of 29.2% was obtained from a study using monkeys.A default inhalation absorption of 100% was used in the estimation of absorbed dosages.Elimination of PCP in humans is primarily by urinary excretion of free and glucuronide-conjugatedpentachlorophenol. Total (acid hydrolyzed) urinary pentachlorophenol can be used for biologicalmonitoring. Attributed to protein binding or enterohepatic recirculation, is a lag of a day or morein maximal pentachlorophenol urinary elimination following absorption. Following a single oraldose in human the half-lives for urinary elimination of PCP ranged from one to 20 days.Pentachlorophenol exposure in pressure-treating facilities is estimated by the Worker Health andSafety Branch as resulting in an absorbed daily dosage (ADD) of 1.2 μg/kg/day whenloading/unloading retorts. Long maintenance work for retorts is estimated as leading to an ADDof 2.5 μg/kg/day, and mixing and loading to 1.8 μg/kg/day. The ADD for a worker performingmixing/loading and short maintenance work is 2.9 μg/kg/day and that for a worker performingretort loading/unloading and short maintenance work is 2.3 μg/kg/day. This report was prepared as part of the Department's risk characterization document onpentachlorophenol pursuant to SB 950 and Proposition 65. Possible adverse effects associatedwith pentachlorophenol exposure in animals include oncogenicity in mice and immunotoxicity inmice and rats. The U.S. EPA has classified PCP as a B2 probable human carcinogen. * Present address: Pesticide and Environmental Toxicology Section, Office of Environmental Health HazardAssessment, 301 Capitol Mall, Sacramento, California 95814-4327.** This document was revised by Thomas Thongsinthusak