Registration Dossier
Registration Dossier
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EC number: 219-863-1 | CAS number: 2554-06-5
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). |
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