Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Hazard for aquatic organisms

Hazard for air

Hazard for terrestrial organisms

Hazard for predators

Additional information

Diphenylsilanediol (CAS 947-42-2) is part of a group of organosilicon substances, the ecotoxicity of which is determined by a non-polar narcosis mechanism of toxicity, and as such log Kow drives toxicity. Substances in this group include silanols and alkoxy- and chloro-silanes having secondary features that do not affect the toxicity of the substances. The side chains of the registered substance are aryl (phenyl). There is evidence that the phenyl groups’ toxicity is related to log Kow alone, as for other neutral organics (narcotics) and thus does not enhance toxicity. Additional information is given in the following supporting report: PFA, 2016y, Peter Fisk Associates, Analogue Report - Ecotoxicity of substances with ‘low-functionality’ side chains attached to silicon ,

PFA.300.003.004, attached in Section 13 of the IUCLID 5 dossier.

The registered substance is a silanediol containing two phenyl groups and is not susceptible to hydrolysis. It has a low predicted log Kow (2 at 20°C) and is moderately soluble in water (predicted water solubility of 510 mg/l), although the concentration dissolved in water is limited to about 25 - 100 mg/l by condensation reactions (see section 4.8 of IUCLID for more information). The substance is not readily biodegradable, based on read-across data.

Reliable measured data are available for the registration substance for short-term toxicity to fish, aquatic invertebrates and aquatic algae.

Conclusion on classification

The substance has reliable short-term E(L)C50values of 39 mg/l in fish, 24 mg/l in invertebrates and 9 mg/l in algae. A reliable NOEC value of 1.1 mg/l with algae is also available. No chronic studies are available for fish or invertebrates.

The substance does not hydrolyse in water and is not readily biodegradable.  

These data are consistent with the following classification under Regulation (EC) No 1272/2008 (as amended) (CLP):

Acute toxicity: Not classified.

Chronic toxicity: Category 2, H411: Hazardous to the aquatic environment