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EC number: 252-161-3
CAS number: 34708-08-2
Table 1. Test results
EC50 (24 h): 29
mg/l (nominal), based on mobility of Daphnia magna (OECD
A 24-hour EC50
value of 29 mg/l (nominal) has been determined for the effects of the
registered substance, triethoxy(3-thiocyanatopropyl)silane (CAS
34708-08-2; EC No. 252-161-3), on mobility of Daphnia magna (TNO,
1990b). In view of the test media preparation method and exposure regime
it is likely that the test organisms were exposed to a mixture of the
parent substance and its hydrolysis products.
The exposure duration during
this test was only 24 hours rather than 48 hours as recommended by OECD
TG 202. It is therefore possible that the toxicity of the substance
could have been underestimated and the EC50 value may have
been lower, had the test duration been 48 hours. A long-term toxicity to
aquatic invertebrates study is ongoing, conducted according to OECD TG
211 and in compliance with GLP. In this study it is proposed to conduct
a Dose Range Finding study, the results of which will be compared with
the current short-term aquatic invertebrate toxicity study by TNO
The test solution was
prepared using tert-butyl alcohol (TBA) as a solvent. The recommended
solvent concentration (100 mg/l) was exceeded during the test, with TBA
at a concentration of approximately 250 mg/l (based on a density of
0.781 g/ml). However, TBA is a low molecular weight (MW = 74.123 g/mol),
highly water soluble (1000 g/l at 25°C) solvent with a low log Kow
value (0.32 at 22.5°C) (ECHA Substance Evaluation Conclusion
document, 2019). The substance is not classified as toxic to the aquatic
environment according to the harmonised classification and labelling
(CLP) or CLP inventory for this substance and E(L)C50 values
are >100 mg/l, indicating low toxicity (WHO, 1987; ECHA Substance
Evaluation Conclusion document, 2019). The lowest E(L)C50
value according to the REACH disseminated dossier is 933 mg/l for
invertebrates, which is higher than the concentration of TBA used in
this study (ECHA, 2022). It is therefore unlikely that TBA significantly
affected the results of the test.
In addition, the test
substance is susceptible to hydrolysis and it is likely that the test
organisms were exposed to a mixture of the parent compound and the
hydrolysis products of the substance.
Above a concentration of
approximately 1000 mg/l, dimeric/oligomeric, cyclic or cross-linked
condensation products could potentially form over time in the aqueous
test media. There was no report of undissolved material (parent
substance or precipitated by products) indicated in the study report for
A functional group
associated with ecotoxicity by a specific mode of action (thiocyanate)
is present in both the registration substance and the silanol hydrolysis
product, and the effects seen are attributed to this. It is therefore
reasonable to conclude that both the parent and hydrolysis product could
contribute to any effects observed.
WHO (1987) International
Programme on Chemical Safety, Environmental Health Criteria 65,
Butanols: Four Isomers. World Health Organisation, Geneva. Report date:
1987. Available at:
ECHA (2019) Substance
Evaluation Conclusion as required by REACH Article 48 and Evaluation
Report for 2-methylpropan-2-ol (tertiary butyl alcohol) EC No 200-889-7,
CAS No 75-65-0. Evaluating Member State(s): United Kingdom. Report date:
October 2019. Available at:
2-methylpropan-2-ol. Available at:
Date accessed: 3 May 2022.
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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