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Endpoint:
adsorption / desorption: screening
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
The study is technically not feasible since the substance is hydrolytically unstable (half-life < 1h).
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
According to OECD Guideline 121.
Qualifier:
according to guideline
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Qualifier:
according to guideline
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Type of method:
HPLC estimation method

An experimental determination of the adsorption coefficient Koc could not be performed, because:

1) the test substance rapidly degrades with a half-life time of <1 hour at 25°C, see separate report on the hydrolysis and,

2) the test substance is a mixture of several compounds and reacts with water as part of the eluent.

Validity criteria fulfilled:
not applicable
Conclusions:
The adsorption coefficient Koc of test item Wasox-MMAC2 using HPLC could not be determined due to rapid hydrolysis (half-life < 1h) of the substance.
Executive summary:

An experimental determination of adsorption coefficient Koc of test item Wasox-MMAC2 using HPLC could not be performed, because 1) the test substance rapidly degrades with a half-life time of <1 hour at 25°C, and 2) the test substance is a mixture of several compounds and reacts with water as part of the eluent.

Endpoint:
adsorption / desorption, other
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Internationally accepted method, EPI-Suite, EPA (USA)
Justification for type of information:
See attached the QMRF and QPRF for the QSAR model.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992).
SRC.1991. Group Contribution Method for Predicting Soil Sorption Coefficients. William Meylan & Philip H. Howard, Syracuse Research Corporation (June 3, 1991). EPA Contract No. 68-D8-0117 (Work Assignment 2-19); SRC F0118-219.
Type:
Koc
Value:
60.7 L/kg
Remarks on result:
other: QSAR predicted value (KOCWIM v2.00, MCI method, no data on temperature and organic carbon is provided)
Type:
log Koc
Value:
1.783 dimensionless
Remarks on result:
other: QSAR predicted value (KOWMIN v2.00, MCI method, no data on temperature and organic carbon is provided)
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of acetone oxime is 60.7 and 1.783 respectively.
Executive summary:

The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of acetone oxime is 60.7 and 1.783 respectively.

Endpoint:
adsorption / desorption, other
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Internationally accepted method, EPI-Suite, EPA (USA)
Justification for type of information:
See attached the QMRF and QPRF for the QSAR model.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992).
SRC.1991. Group Contribution Method for Predicting Soil Sorption Coefficients. William Meylan & Philip H. Howard, Syracuse Research Corporation (June 3, 1991). EPA Contract No. 68-D8-0117 (Work Assignment 2-19); SRC F0118-219.
Specific details on test material used for the study:
SMILES: CO[Si](C)(O)OC
Type:
Koc
Value:
168.6 L/kg
Remarks on result:
other: QSAR predicted value (KOCWIM v2.00, MCI method, no data on temperature and organic carbon is provided)
Type:
log Koc
Value:
2.227 dimensionless
Remarks on result:
other: QSAR predicted value (KOWMIN v2.00, MCI method, no data on temperature and organic carbon is provided)
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of dimethoxymethylsilanol is 168.6 and 2.227 respectively.
Executive summary:

The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of dimethoxymethylsilanol is 168.6 and 2.227 respectively.

Endpoint:
adsorption / desorption, other
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Internationally accepted method, EPI-Suite, EPA (USA)
Justification for type of information:
See attached the QMRF and QPRF for the QSAR model.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992).
SRC.1991. Group Contribution Method for Predicting Soil Sorption Coefficients. William Meylan & Philip H. Howard, Syracuse Research Corporation (June 3, 1991). EPA Contract No. 68-D8-0117 (Work Assignment 2-19); SRC F0118-219.
Specific details on test material used for the study:
SMILES: CO[Si](C)(O)O
Type:
Koc
Value:
86.03 L/kg
Remarks on result:
other: QSAR predicted value (KOCWIM v2.00, MCI method, no data on temperature and organic carbon is provided)
Type:
log Koc
Value:
1.935 dimensionless
Remarks on result:
other: QSAR predicted value (KOWMIN v2.00, MCI method, no data on temperature and organic carbon is provided)
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of methoxymethylsilanediol is 86.03 and 1.935 respectively.
Executive summary:

The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of methoxymethylsilanediol is 86.03 and 1.935 respectively.

Endpoint:
adsorption / desorption, other
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Internationally accepted method, EPI-Suite, EPA (USA)
Justification for type of information:
See attached the QMRF and QPRF for the QSAR model.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992).
SRC.1991. Group Contribution Method for Predicting Soil Sorption Coefficients. William Meylan & Philip H. Howard, Syracuse Research Corporation (June 3, 1991). EPA Contract No. 68-D8-0117 (Work Assignment 2-19); SRC F0118-219.
Specific details on test material used for the study:
SMILES: [Si](O)(O)(O)C
Type:
Koc
Value:
43.89 L/kg
Remarks on result:
other: QSAR predicted value (KOCWIM v2.00, MCI method, no data on temperature and organic carbon is provided)
Type:
log Koc
Value:
1.642 dimensionless
Remarks on result:
other: QSAR predicted value (KOWMIN v2.00, MCI method, no data on temperature and organic carbon is provided)
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of methylsilanetriol is 43.89 and 1.642 respectively.
Executive summary:

The estimated soil adsorption coefficients Koc and Log Koc (KOCWIN v2.00, MCI method) of methylsilanetriol is 43.89 and 1.642 respectively.

Description of key information

The Log Koc and Koc of test item should be understood based on its degradation products since it undergoes rapid hydrolysis (half-life < 1h) in water to acetone oxime (log Kow = 1.783 and Koc = 60.7, KOCWIN v2.00) and silanols (Log Kow  in the range of 1.642-2.227 and Koc 43.89-168.6 KOWWIN v1.68). Moreover, it should be pointed out that the corresponding silanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable. Therefore, the Key value for chemical safety assessment would be the adsorption coefficient of acetone oxime.

Key value for chemical safety assessment

Koc at 20 °C:
60.7

Additional information

Data waiving (study technically not feasible): An experimental determination of adsorption coefficient Koc of test item Wasox-MMAC2 using HPLC could not be performed, because 1) the test substance rapidly degrades with a half-life time of <1 hour at 25°C, and 2) the test substance is a mixture of several compounds and reacts with water as part of the eluent.

It should be also taken into account that the substance undergoes rapid hydrolysis (half-life < 1h) in aqueous to acetone oxime and the corresponding silanols. The estimated partition coefficients log Koc and Koc for the degradation products acetone oxime and silanols were estimated to be in the range of 1.642 -2.227 and 43.89 -168.6 L/kg (EPI-Suite, KOCWIN v2.00) respectively (log Kow < 3, low bioaccumulation for adsorption). Moreover, it should be pointed out that the corresponding silanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable. Therefore, the Key value for chemical safety assessment would be the adsorption coefficient of acetone oxime, i.e. Koc of 60.7 L/kg and Log Koc of 1.783.