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EC number: 201-251-0
CAS number: 80-10-4
The registered substance is part of a group of organosilicones,
the toxicity of which is determined by a non-polar narcosis mechanism of
toxicity, and as such log Kow drives toxicity. Substances in
this group include alkoxy- and chloro- silanes having secondary features
that do not affect the toxicity of the substances. The side chain of the
registered substance is an aryl. There is evidence that the phenyl
(aryl) group’s toxicity is related to log Kow alone as
for other neutral organics and thus does not enhance toxicity.
Additional information is given in a supporting report Application of
Category - Analogue - QSAR for Reconsile (PFA, 2016b) attached in
Section 13 of the IUCLID dossier.
In order to reduce animal testing read-across is proposed to
fulfil up to REACH Annex IX requirements for the registered substance
from substances that have similar structure and physico-chemical
properties. Ecotoxicological studies are conducted in aquatic medium or
in moist environments; therefore the hydrolysis rate of the substance is
particularly important since after hydrolysis occurs the resulting
product has different physico-chemical properties and the structure is
In the following paragraphs the read-across approach
fordichloro(diphenyl)silaneis assessed for each surrogate substance
taking into account structure, hydrolysis rate and physico-chemical
from diphenylsilanediol to dichloro(diphenyl)silane:
Measured data were not available for dichloro(diphenyl)silane for
aquatic toxicity. However, as the substance hydrolyses very rapidly
(half-life of 10 seconds at pH 7) it is more environmentally relevant to
consider the toxicity of the hydrolysis product, diphenylsilanediol (CAS
947-42-2) as organisms will predominately be exposed to the hydrolysis
product.Therefore, the hazard assessment for the environment, including
sediment and soil compartments, is based on the properties of the
hydrolysis product,diphenylsilanediol, in accordance with REACH
Measured data were available for diphenylsilanediol. The lowest
reported effect concentration was an EC50of 9.0 mg/l for the
effect on growth rate on the algae Pseudokirchnerella subcapitata.
For fish an LC50of 39 mg/l was reported and for invertebrates
an EC50of 24 mg/l. These studies were conducted according to
OECD Guidelines 201 (Alga, Growth Inhibition Test), 203 (Fish, Acute
toxicity test) and 202 (Daphnia sp. Acute Immobilisation Test),
respectively and are considered reliable for assessment.
QSAR predictions for the hydrolysis product diphenylsilanediol
confirm the low short-term toxicity of the substance to aquatic
organisms. QSAR calculated LC50of 31.6 mg/l for fish,
17.9 mg/l for Daphnia and an EC50of 8.6 mg/l for algae.
on the non-silanol hydrolysis products:
Effects on aquatic organisms arising from exposure to hydrochloric
acid are thought to result from a reduction in the pH of the ambient
environment (arising from an increase in the H+concentration)
to a level below their tolerable range. Aquatic ecosystems are
characterized by their ambient conditions, including the pH, and
resident organisms are adapted to these conditions. The pH of aquatic
habitats can range from 6 in poorly-buffered ‘soft’ waters to 9 in
well-buffered ‘hard’ waters. The tolerance of aquatic ecosystems to
natural variations in pH is well understood and has been quantified and
reported extensively in ecological publications and handbooks (e.g. OECD
SIDS for CAS 7647-01-0, hydrochloric acid). It is not considered
appropriate or useful to derive a single aquatic PNEC for hydrochloric
acid because any effects will not be a consequence of true chemical
toxicity and will be a function of, and dependent on, the buffering
capacity of the environment.
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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