Summary of the Public Health Goal for Pentachlorophenol (PCP)
A Public Health Goal (PHG) of 0.4 ppb is developed for pentachlorophenol (PCP) in drinking water. The U.S. Environmental Protection Agency’s (U.S. EPA’s) Maximum Contaminant Level (MCL) and Maximum Contaminant Level Goal (MCLG) for PCP are 1 ppb and zero, respectively. PCP is a chlorinated aromatic organic chemical with low volatility and is used as a wide-spectrum biocide; its main use is as a wood preservative. Because it is so widely used and persistent in the environment, it can be detected at many locations in soil or other environmental samples but it is not often found in California drinking water. PCP has both noncarcinogenic and carcinogenic health effects. PCP is a proven carcinogen in rodent studies and there is some epidemiological evidence that PCP is carcinogenic in humans. U.S. EPA places PCP in class B2, probable human carcinogen, based on inadequate data in humans and adequate data in laboratory animals. The International Agency for Research on Cancer (IARC) places PCP in group 2B, possibly carcinogenic to humans, based on inadequate evidence in humans and sufficient evidence in experimental animals. However, the human data are inadequate for calculation of a PHG. Therefore, the PHG calculation is based on carcinogenic effects (adenoma and carcinoma) in male mice in a 1989 National Toxicology Program (NTP) bioassay. Using these data, the Office of Environmental Health Hazard Assessment (OEHHA) calculated a q1* of 8.34 × 10-2 (mg/kg-day)-1 and a human equivalent oral cancer slope factor (CSF) of 8.11 × 10-2 (mg/kg-day)-1. Based on the CSF, and assuming a 70 kg body weight, a de minimis theoretical excess individual lifetime cancer risk level of 1 x 10-6 and 2 L/day water over a 70-year lifetime for an adult consumption, OEHHA calculates a PHG of 0.0004 mg/L (0.4 ppb) for PCP in drinking water.
- Pentachlorophenol