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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Abiotic degradation

Vi4-D4is expected to hydrolyse with a predicted half-life of approximately63 hour at pH 7 and 20-25°C (QSAR),see Section 4.1.1.1.

Vi5-D5 (Impurity 1) has a predicted hydrolysis half-life ofapproximately 1600 hours at pH 7 and 20 - 25°C; Vi3-D3 (Impurity 2)has a predicted hydrolysis half-life ofapproximately 0.6 hours at pH 7 and 20 - 25°C.

The half-lives refer to degradation of parent substance by ring-opening of the siloxane. Full hydrolysis will take longer. The intermediate hydrolysis products are linear siloxanediols.

The ultimate hydrolysis product is methylvinylsilanediol.

A half-life of 0.2 days for reaction with hydroxyl radicals in air has been calculated forVi4-D4. For Vi5-D5 the calculated half-life is 0.1 days; for Vi3-D3 the calculated half-life is 0.2 days.

Biotic degradation

Vi4-D4 and the impurities Vi5-D5 and Vi3-D3 are not expected to undergo any significant biodegradation in ready biodegradation tests. 3.7% biodegradation in 29 days has been read-across from a structurally-related substance for Vi4-D4.0.14% biodegradation in 28 days in 28 dayshas been read-across from a structurally-related substance for Vi5-D5;0.06% biodegradation in 28 dayshas been read-across from a structurally-related substance for Vi3-D3.

For Vi4-D4 and Vi5-D5, data are available for degradation in soil simulation testing, read across from structurally-related substances.

Half-lives at ~22°C in Wahiawa soil of 0.04 to 0.89 days (dependent on relative humidity) and on Londo soil of 3.54 and 5.25 days (dependent on relative humidity) have been rea-across for Vi4-D4.A half-life in Wahiawa soil incubated at 32% RH and ~22°C in closed tubes of 0.08 dayshave been rea-across for Vi5-D5. Soil degradation data are not relevant for Vi3-D3 as it hydrolyses rapidly.

For sediment simulation testing, data are read-across from structurally-related substances D4 and D5 to the registration substance Vi4-D4 and impurity Vi5-D5. Sediment simulation data are not relevant for Vi3 -D3 as it hydrolyses rapidly.

Table: Degradation rates

Degradation rate in water:

Hydrolysis half-life: approximately 63 hour at pH 7 and 20 - 25°C (QSAR), for removal of parent(read-across).

Degradation rate in sediment:

A half-life of 365 days has been determined for a structurally related substance (worst-case, based on anaerobic conditions).

Degradation rate in soil:

Half-lives of 0.04 to 5.25 days (dependent on relative humidity and soil type)at ~22°Chave been determined for a structurally-related substance.In EUSES a half-life value of 5 days at 20°C will be used.

Degradation rate in air:

Half-life for reaction with hydroxyl radicals in air: 0.2 days (calculated).