m-Cresol - ipcs inchem

OECD SIDS
m- / p-CRESOL
Available Physico-Chemical Data for Cresols:
Substance m-Cresol p-Cresol m/p-Cresol
Vapour pressure (25°C) 0.147 hPa 0.147 hPa
Log Kow 1.96 1.94 1.94 -1.96
Water solubility (25°C) 22.7 g/l 21.5 g/l 24.4 g/l
Dissociation constant pKa 10.09 10.26
Vapour pressure and log Kow were determined for both isomers, the water solubility for both
isomers and the m/p-cresol mixture. The values are nearly identical for the pure isomers, so the
isomer mixture can be assessed as well.
Cresols are weak acids. The pKa values of 10.09 and 10.26 resp. indicate that at environmentally
relevant pH values (5 - 9) both substance are largely non-dissociated.
For the assessment of the removal in biological treatment plants and degradation in environmental
compartments, results from biodegradation tests are crucial.
Available Data on Ready Biodegradability
Method Duration m-Cresol p-Cresol Reference
OECD 301 D 28 d 65 - 90 % Bayer AG (1988)
OECD 301 C 40 d 80 - 95 % 80 - 95 % Desai et al. (1990)
The OECD 301 D test reveals that m-cresol is readily biodegradable. As demanded by the OECD
guideline, the oxygen consumption was above 60 % after 28 days and the 10d window was fulfilled.
In a test comparable to OECD 301 C test biodegradation in the range of 80 – 95 % for both
compounds occurred. The oxygen uptake curves are not reported. However, the authors state that all
test compounds revealed the lag phase, biodegradation phase and the plateau region within a period
of 10 days. Therefore, it can be concluded from this test that m- and p-cresol are readily
biodegradable. In addition, the rate constants for both m- and p-cresol were determined and found
to be similar.
Available Ecotoxicity Data
For the acute toxicity of cresols on aquatic species a large number of experimental results from tests
with fish, daphnids and algae are available. Long-term tests were conducted with fish, algae and
invertebrates.
In the following table only those tests are reported where both isomers have been tested in parallel.
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