Persistence of tetrachlorophenol and pentachlorophenol in exposed woodworkers.

The decline in urinary concentrations of pentachlorophenol (PCP) and 2,3,4,6-tetrachlorophenol (TCP) were observed for a group of woodworkers chronically exposed to Permatox 100 (3% PCP, 21% TCP) during a 16 day vacation and plant shutdown. The group was monitored annually for two years, with sampling occurring on the last working day prior to shutdown and on the first day after the shutdown. Among those workers with the highest pre-shutdown levels, uniform TCP reductions of 90 +/- 6% were observed, indicating elimination rates similar to those reported for PCP in a single dose human exposure study. Four workers were sampled on alternate days during the shutdown in the second year. Of these, two workers had significant pre-shutdown levels, and showed declines in urine TCP levels over this period consistent with simple one-compartment first order decay. The possible effect of environmental PCP exposure on observed biological decay rates when occupational PCP exposures are low was indicated by the wide variation in urinary PCP reduction and slight decreases or actual increases observed over the shutdown period.