Occurrence of pentachlorophenol in enclosed environments.

The pentochlorophenol (PCP) and tetrachlorophenol (TCP) obtained in untreated samples indicate that the contamination of all objects in closed rooms after use of pentachlorophenol-containing-woodprotecting compounds cannot be avoided. The measured values in plaster, wood, and other objects vary between 0.2 and 26.0 mg/kg for PCP and between 0.4 and 5.5 mg/kg for TCP, and thereby present further sources of contamination themselves. Furthermore, it is certain that PCP, TCP, and other chlorinated impurities of the wood-protecting compound are transported through the room air. In the first model experimental series, the correlation between PCP concentration and humidity in the air was satisfying. One can consider the humidity as a solvent for pentachlorophenol and can explain the fluctuation of PCP values as a result of different extraction yields. In contrast, in the second model experiment the PCP concentrations cannot be presented satisfactorily. However, it can be seen as certain that the vapor released and absorbed by the system is partly responsible for these fluctuations. Besides, a temperature increase causes an increase in the diffusion rate of pentachlorophenol. The model study, in which the concentrations of 1-160 μg PCP/M3 air were measured, indicates that under unfavourable conditions the daily uptake of PCP can comprise 4.8 mg. This value corresponds approximately to the PCP concentration which was calculated on the basis of the MAK value. How these concentrations are to be considered in the toxicological judgement of PCPs is still open and demands a thorough toxicological long-term study of this compound under partical conditions