m-Cresol - ipcs inchem

OECD SIDS
m- / p-CRESOL
√ information available
* evaluation based on human experience
X Testing being performed (o-/m-/p- isomer mixture)
All cresol isomers are well absorbed via all main exposure routes. The main metabolic pathway is
hydroxylation of the benzene ring. p-Cresol can also be oxidized to hydroxybenzoic acid and, at
least in vitro, to a reactive quinone methide. For m- and p-cresol, elimination occurs mainly as
glucuronide and/or sulfate via urine, minor amounts via faeces.
The available acute toxicity data of the two isomers indicate similar toxicity profiles after oral
exposure, and a lesser toxicity of m-cresol in experiments with dermal exposure. m-Cresol and p-
cresol are corrosive substances.
There is no indication of a sensitizing effect of p-cresol from a limited guinea pig study and a
limited human study. However, hypersensitivity reactions of some individuals to cresol (isomer
unspecified) have been mentioned in the literature.
For both isomers, as well as for the mixture of the two the NOAELs in 28- and 90-d feeding studies
are ≥ 50 mg/kg bw/day in rodents. At higher doses, there were indications of a transient impairment
of liver function and a dose dependant increase in liver weight was observed for m-, p- and the
mixture of cresols, but without histopathological correlate. Increases in kidney weight were
observed with p-cresol and at higher doses with the m/p-cresol mixture.
p-Cresol exerted some clastogenic activity in vitro, but this activity was not reproduced in vivo. All
isomers were consistently tested negative in vivo.
There is no adequate data available to assess the carcinogenic potential of m- and p-cresol. Limited
studies gave an indication of a tumour promoting activity of m- and p-cresol. Carcinogenicity
studies in two species with the o-/m-/p-isomer mixture are currently performed within the U.S.
National Toxicology Program.
None of the isomers, and also not the mixture, was a reproductive toxicant. Mild developmental
toxicity was only seen at maternally toxic doses of p-cresol; there was no indication of
developmental effects with m-cresol. Hence, slight developmental toxicity at maternally toxic doses
may also occur with the isomer mixture.
Based on the similarities in the results of studies on m-and p-cresol, inclusion of m/p-cresol mixture
in this report is justified.
UNEP PUBLICATIONS 55