m-Cresol - ipcs inchem

OECD SIDS
m- / p-CRESOL
extensive study was conducted by Shelton and Tiedje (1981). Primary anaerobic sludges from 12
treatment plants receiving mainly domestic waste water were diluted to 10% in a mineral salt
medium and incubated with 30 mg cresol/l. Triplicate samples were incubated for 8 weeks.
Degradation was related to the theoretical CH4 and CO2 production. With m-cresol as the test
substance, no degradation was observed in 4 sludges, while in 6 sludges the degradation ranged
from 55 to 103 % after lag-periods of 4-6 weeks. For the experiments with 2 sludges the data were
insufficient. In tests with p-cresol a degradation in the range of 62-101% was observed after lagperiods
of 2 - 5 weeks (data for 1 sludge were insufficient). No explanation for the high variability
of degradation results is given by the authors (Most of the results of this extensive study were also
published in a journal; Shelton and Tiedje 1984). Monitoring the formation of methane and carbon
dioxide, Battersby and Wilson (1989) obtained about 75 % of the theoretical yield of methane and
carbon dioxide from m-cresol during a > 60 days incubation period including a lag phase of 40
days. For p-cresol the theoretical yield was 96 % during the same incubation period including a lag
phase of 7 days.
As concluded above, m- and p-cresol can be considered as being readily biodegradable under
aerobic conditions, thus it is unlikely that cresols released into waste waters or into surface waters
will reach the anaerobic zones. Therefore the anaerobic degradation is expected to be of minor
importance for the hazard assessment of cresols.
2.1.4 Bioaccumulation
Freitag et al. (1985) determined bioconcentration factors (BCF) of 14C-labelled m-cresol in fish
(Leuciscus idus melanotus). The fish were exposed to a 0.05 mg/l solution of the tests compound.
After the test period of 3 days radioactivity was measured in water medium and fish. A substancespecific
analysis was not applied. BCF values of 20 were obtained.
In the same study BCF-values of 40 and 4900 for algae are reported without explanation for the
difference. Higher BCF values with algae may be obtained due to adsorption of test substance to the
surface of the algae and due to the high surface-volume ratio in the test. Thus the algal data were
not used in the assessment of the bioaccumulation potential.
The low BCF value for fish is supported by a BCF, estimated on the basis of the log Kow. Based on
the equation log BCFfish = 0.85. log Kow – 0.70 (EC 1996), a bioaccumulation factor (BCF) of 9.3
is calculated from the log Kow of 1.96 (m-cresol).
Experimental data for p-cresol are not available. Because of the similar log Kow, a similar
accumulation behaviour is expected. For m-, p-cresols and the mixture the bioaccumulation
potential is considered to be low.
2.2 Human Exposure
2.2.1 Occupational Exposure
The primary occupational exposure during manufacture and processing is via skin contact and, to a
lesser extent, through inhalation of the vapours. No information is readily available on the total
number of sites, which manufacture, process, or use cresols.
In Germany the workplace limit concentration is 22 mg/m³ (= 5 ppm) as TWA for the sum of all
cresol isomers (TRGS 900, 2002). The German exposure limit value is in accordance with that of
the other European countries limit values and with the US-TLV value.
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