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EC number: 276-038-9
CAS number: 71808-53-2
The test substance, cocobis(2-hydroxyethyl)methylammonium chloride was biodegraded by 70% at day 28 in the Closed Bottle test, and can therefore be classified as readily biodegradable.
In order to assess the biotic degradation, five ready biodegradability
tests are performed which allow the biodegradability to be measured in
aerobic aqueous media. Four out of five studies were performed with
(modified) Closed Bottle Tests (CBT, according to OECD TG 301D) with the
substance as registered. For the other study no information on test
method was reported. Various biodegradation results were reported.
In the oldest study (1974) a biodegradation percentage of 82.3% was
reported for the substance. Details on test method are lacking. In the
absence of a full study report, the study was assigned reliability 4.
In another study (1989), a biodegradation percentage of 20-23% was
reported (OECD TG 301D, GLP, reliability 2). The low biodegradation
results were explained by the very poor solubility and therefore very
poor bioavailability. Inhibition of respiration was not observed at the
test concentration. It was concluded that the biodegradation of the
substance should be assessed using a test design with a slow release
method. This study can be used as evidence of biodegradability and this
report can be considered reliable with restrictions.
In a third study (2009) a combination of a semi-continuous activated
sludge test with the closed bottle test was employed to search for a
suitable screening test method taking into account the poor solubility
and poor bioavailability of the substance. The tests were performed
according to OECD guidelines with acceptable minor deviations (non GLP).
The biodegradation percentage was reported to be 63% after 28d. The
results can be used as supporting evidence. The optimal conditions found
in this screening work were used in two subsequent GLP studies.
In the key study (2009), the ready biodegradability was determined in
the Closed Bottle test performed according to slightly modified OECD
TG301D and in compliance with GLP. Ammonium chloride was omitted from
the medium to prevent oxygen consumption due to nitrification (omission
did not result in nitrogen limitation as shown by the biodegradation of
the reference compound) and river water was used as inoculum. The test
was performed in the presence of silica gel to allow for a slow release
of the test substance.
Cocobis(2-hydroxyethyl)methylammonium chloride did not cause a reduction
in the endogenous respiration. The test substance is therefore
considered to be noninhibitory to the inoculum.
Cocobis(2-hydroxyethyl)methylammonium chloride was biodegraded 70% at
day 28 in the Closed Bottle test. Hence this compound should be
classified as readily biodegradable. The test is valid as shown by an
endogenous respiration of 1.4 mg/L and by the total mineralization of
the reference compound, sodium acetate. Sodium acetate was degraded 70%
of its theoretical oxygen demand after 14 days. Finally, the most
important criterion was met by oxygen concentrations >0.5 mg/L in all
bottles during the test period.
In the fifth test (2009), a biodegradation percentage of 64% at day 28
was reported in a CBT (OECD 301D, GLP) under similar conditions as the
key study. The test substance did not meet the 10-day window validation
criteria as mentioned in the OECD guideline 301D, but this concept is
not considered valid to quantify biodegradation rates of mixtures of
homolgue surfactants as the cocobis(2-hydroxyethyl)methylammonium
chlorides.The 10-day window concept assumes that biodegradation of a
single organic compound in a ready biodegradability test is a
growth-linked process which follows an S-shaped growth curve.
Cocobis(2-hydroxyethyl)methylammonium chlorides are mixtures of
homologues with C12-C18 alkyl chains. The biodegradation kinetics (lag
period, growth rate, yield etc.) of the individual homologues in the
mixture are not necessarily the same. The biodegradation of a surfactant
consisting of a mixture of homologues is therefore an addition of
different biodegradation curves. It is thus possible that individual
compounds meet the 10-day time window criterion whereas the
biodegradability curve of the mixture of homologues suggests that the
surfactant is not readily biodegradable.
Based on the latter two studies (OECD 301D, GLP, reliability 1) it can
be concluded that the substance fullfills the criterion for readily
biodegradability. Therefore, the biodegradation half lives proposed in
the REACH guidance for readily biodegradable substances are used in the
Chemical Safety Assessment.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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