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EC number: 217-496-1
CAS number: 1873-88-7
Controls (C) and Decamethyltetrasiloxane (T): pH, oxygen
concentration, oxygen consumption and percentage inhibition of the
at the start
¹: Negative values indicate stimulation
of the respiration rate of the sludge. The values are considered as not
Toxicity to microorganisms: 3 hour EC50 >100 mg/l (ASRI), read-across
from a structurally-related substance.
There are no reliable microorganism toxicity data available for
A category approach is applied to this endpoint and is detailed in the
Siloxane Category report (PFA, 2017). The hypothesis for read-across
is that siloxane substances exhibit no evidence of significant
toxicity to sewage treatment plant microorganisms. This is consistent
with a non-polar narcosis mode of action. Therefore, good
quality data for the structurally-related substance,
decamethyltetrasiloxane, L4, (CAS 141-62-8), have been read across.
H-L3 and L4 are structurally-similar substances, both are linear
H-L3 and L4 are members of the Reconsile Siloxanes
Category within which, in general, there is no evidence of
significant toxicity to microorganisms.
The table below presents microorganism toxicity data available for
substances within the Siloxanes Category.
Table: Microorganism toxicity data for substances within the
Reconsile Siloxane Category
Result: E(I) C50
Result: NOEC (or EC10/ EC20)
>10 000 mg/l
ISO 8192 (Test for Inhibition of Oxygen Consumption by Activated Sludge)
Little or no toxicity (24 h): 0.1 g/g solution test mat. based on: reduction in number of viable bacteria
Toxicity toEscherichia coliandStaphylococcus aureusat 37°C for 24 hours
Siloxanes and Silicones, di-Ph, Ph (trimethylsilyl) oxy
Nitrification control indicated no heterotrophic inhibition of respiration rate
dimethyl, methyl(3-aminopropyl) siloxane, trimethylsiloxy-terminated
> water soluble fraction
≥ water soluble fraction
dimethyl, (aminoethylaminopropyl) methyl siloxane, trimethylsiloxy-terminated
It is, therefore, considered valid to read-across the results for
L4 to fill the data gap for the registered substance. Additional
information is given in a supporting report (Peter Fisk Associates,
2017) attached in Section 13 of the IUCLID 6 dossier.
In the study with L4, an activated sludge respiration inhibition
3h EC50value of >100 mg/l was reported.
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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