Bg. Reigner et al., PENTACHLOROPHENOL CARCINOGENICITY - EXTRAPOLATION OF RISK FROM MICE TO HUMANS, Human & experimental toxicology, 12(3), 1993, pp. 215-225
1 Pentachlorophenol (PCP) has been found to be carcinogenic in mice. T
he objective of this study was to extrapolate to humans the risk of ca
ncer from data obtained in mice using information on disposition, seru
m protein binding and metabolism of PCP across species. 2 A review of
the literature indicates that neither PCP nor a mutagenic metabolite,
tetrachlorohydroquinone (TCHQ), has been specifically identified as re
sponsible for the carcinogenicity. In addition, the occurrence of TCHQ
as a metabolite of PCP in humans is still questionable. Therefore, ca
ncer risk assessment is performed on the assumption that PCP itself is
responsible for the carcinogenicity. 3 For interspecies extrapolation
, a new method in which interspecies differences in clearance and seru
m protein binding are taken into account is used. The method gives est
imates of equivalent human doses of PCP which are up to 4 times smalle
r than those obtained using body surface area. For both interspecies e
xtrapolation methods, the estimated virtually-safe doses of PCP are sm
aller than the average daily intakes reported in groups of subjects no
nspecifically exposed to PCP. Corresponding extra risks of cancer for
lifetime exposure are from 20 to 140 times greater than the acceptable
extra risk (10(-6)). The results obtained with this approach indicate
that PCP is a possible public health hazard.