Assessment of pentachlorophenol exposure in humans using the clearance concept

1. Pentachlorophenol (PeCP), a widely-used wood preservative, is a ubiquitous compound which has been found to be carcinogenic in mice. The objective of this study is to assess the average net daily intake of PeCP in cohorts of individuals who are: (1) not specifically exposed to PeCP, (2) residents of homes made of PeCP-treated logs and (3) occupationally exposed to PeCP. 2. The average net daily intake was calculated using a basic pharmacokinetic principle, the clearance (CL) concept: net daily intake equals CL (in 1 d-1) times the average steady-state concentration of PeCP in plasma (Css). Css values reported in the literature were used for the calculations. 3. Because the two definitive studies on PeCP toxicokinetics in humans have given conflicting results, kinetic information from human exposure to PeCP was reviewed. Plasma clearance was estimated from retrospective analysis of urine and plasma concentrations measured in people after long-term exposure to PeCP. An overall clearance of 0.425 l d-1 was obtained. 4. In groups of individuals who are not specifically exposed to PeCP, net daily intake estimated in eight countries varied from 5 micrograms (Nigeria) to 37 micrograms (The Netherlands). Net intake was between 51 micrograms d-1 and 157 micrograms d-1 in residents of homes made of PeCP-treated logs. In individuals occupationally exposed to PeCP, net daily intake varied widely (from 35 micrograms to about 24,000 micrograms) depending on the type of work.