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Environmental fate & pathways

Adsorption / desorption

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Endpoint:
adsorption / desorption
Remarks:
other: Estimation of the organic carbon-normalized sorption coefficient for soil and sediment
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Calculated by using peer-reviewed and authorative estimation programs of US EPA 2012. Read-across justification: The substance is hydrolytically unstable. When it comes in contact with water or moisture complete hydrolysis will take place with no significant reaction products other than the particular alcohol and hydrated titanium dioxide. This rapid hydrolysis (hydrolysis half-life < 3 minutes to < 2 hours) is the driving force for the fate and pathways of the substance. The aquatic toxicity testing is considered scientifically unjustified as the substance degrades immediately releasing alcohol and hydrated insoluble titanium dioxides in water. The testing conducted with analogue substances of the category proves that the aquatic toxicity in daphnia and algae studies is similar to the aquatic toxicity of alcohol released to the test water, and the insoluble hydrated titanium oxides precipitated on the bottom of the test vessels. The identification of degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the alcohol released from the target substance, which might change the aquatic toxicity of the target substance compared to the toxicity of the pure alcohol. As there is a mechanistic reasoning to the read-across, the read-across from the degradation product (relevant alcohol) is used to evaluate the aquatic toxicity and the fate and pathways of the target substance in the environment.
Justification for type of information:
The substance is hydrolytically unstable. When it comes in contact with water or moisture, a complete hydrolysis will take place with no significant reaction products other than the particular alcohol and hydrated titanium dioxide. This rapid hydrolysis (hydrolysis half-life < 3 minutes to < 2 hours) is the driving force for the fate and pathways of the substance. The aquatic toxicity testing is considered scientifically unjustified as the substance degrades immediately releasing the particular alcohol and hydrated insoluble titanium dioxides in water.
The testing conducted with analogue substance of the category justifies that the aquatic toxicity in daphnia and algae studies is similar to the aquatic toxicity of the alcohol released to test water as the insoluble hydrated titanium oxide, precipitated on the bottom of the test vessels; lacking bioavailability. The identification of the degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the alcohol released from the target substance which might change the aquatic toxicity of the target substance compared to the toxicity of the pure alcohol.
As there is a mechanistic reasoning to the read-across, the read-across from the degradation product (relevant alcohol) is used to evaluate the aquatic toxicity and the fate and pathways of the target substance in the environment.
Cross-reference
Reason / purpose:
read-across source
Reference
Endpoint:
adsorption / desorption
Remarks:
other: Estimation of the organic carbon-normalized sorption coefficient for soil and sediment
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Calculated by using peer-reviewed and authorative estimation programs of US EPA 2012. Read-across justification: The substance is hydrolytically unstable. When it comes in contact with water or moisture complete hydrolysis will take place with no significant reaction products other than the particular alcohol and hydrated titanium dioxide. This rapid hydrolysis (hydrolysis half-life < 3 minutes to < 2 hours) is the driving force for the fate and pathways of the substance. The aquatic toxicity testing is considered scientifically unjustified as the substance degrades immediately releasing alcohol and hydrated insoluble titanium dioxides in water. The testing conducted with analogue substances of the category proves that the aquatic toxicity in daphnia and algae studies is similar to the aquatic toxicity of alcohol released to the test water, and the insoluble hydrated titanium oxides precipitated on the bottom of the test vessels. The identification of degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the alcohol released from the target substance, which might change the aquatic toxicity of the target substance compared to the toxicity of the pure alcohol. As there is a mechanistic reasoning to the read-across, the read-across from the degradation product (relevant alcohol) is used to evaluate the aquatic toxicity and the fate and pathways of the target substance in the environment.
Justification for type of information:
The substance is hydrolytically unstable. When it comes in contact with water or moisture, a complete hydrolysis will take place with no significant reaction products other than the particular alcohol and hydrated titanium dioxide. This rapid hydrolysis (hydrolysis half-life < 3 minutes to < 2 hours) is the driving force for the fate and pathways of the substance. The aquatic toxicity testing is considered scientifically unjustified as the substance degrades immediately releasing the particular alcohol and hydrated insoluble titanium dioxides in water.
The testing conducted with analogue substance of the category justifies that the aquatic toxicity in daphnia and algae studies is similar to the aquatic toxicity of the alcohol released to test water as the insoluble hydrated titanium oxide, precipitated on the bottom of the test vessels; lacking bioavailability. The identification of the degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the alcohol released from the target substance which might change the aquatic toxicity of the target substance compared to the toxicity of the pure alcohol.
As there is a mechanistic reasoning to the read-across, the read-across from the degradation product (relevant alcohol) is used to evaluate the aquatic toxicity and the fate and pathways of the target substance in the environment.
Reason / purpose:
read-across source
Qualifier:
no guideline required
Principles of method if other than guideline:
Estimation of the organic carbon-normalized sorption coefficient for soil and sediment (Koc) by using KOCWIN™ which estimates KOC. KOC was estimated using the Sabljic molecular connectivity method with improved correction factors; and the traditional method based on log KOW.
GLP compliance:
no
Type of method:
other: Estimation based on the traditional method from log KOW
Media:
other: soil and sediments
Type:
Koc
Value:
35.28
Temp.:
20 °C
Remarks on result:
other: calculated based on MCI; correction factor -1.3179
Type:
Koc
Value:
131.1
Temp.:
20 °C
Remarks on result:
other: calculated based on Log Kow of 2.9

Koc estimate from MCI (KOCWIN v.2.00) results:

First-order molecular connectivity index: 4.346

Non-corrected Log Koc (0.5213MCI+0.60): 2.8654

Fragment Correction(s):

Aliphatic alcohol (C-OH): -1.3179

Corrected Log Koc: 1.5475

Estimated Koc: 35.28 L/kg

Validity criteria fulfilled:
not applicable
Conclusions:
Estimated organic carbon-normalized sorption coefficient for soil and sediment (Koc) for ethylhexanol is 35.28 L/kg based on the Sabljic molecular connectivity method with improved correction factors.
Executive summary:

Testing is scientifically unjustified as this substance is hydrolytically unstable. Therefore, the estimated Koc of the main degradation product was calculated by using KOCWIN v.2 (US EPA. 2012, Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10).

This value is considered reliable with restrictions, as this is an estimated value, to be used as a key value in CSA and to derive the PNECs to sediment and soil compartment by using equilibrium partioning method.

Data source

Reference
Reference Type:
other: Estimation programs
Title:
Estimate of the organic carbon-normalized sorption coefficient for soil and sediment using KOCWIN v.2
Author:
US EPA
Year:
2012
Bibliographic source:
Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10. United States Environmental Protection Agency, Washington, DC, USA.

Materials and methods

Test guideline
Qualifier:
no guideline required
Principles of method if other than guideline:
Estimation of the organic carbon-normalized sorption coefficient for soil and sediment (Koc) by using KOCWIN™ which estimates KOC. KOC was estimated using the Sabljic molecular connectivity method with improved correction factors; and the traditional method based on log KOW.
GLP compliance:
no
Type of method:
other: Estimation based on the traditional method from log KOW
Media:
other: soil and sediments

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 1-Hexanol, 2-ethyl-
- Molecular formula (if other than submission substance):C8 H18 O1
- Molecular weight (if other than submission substance): 130.23 g/mol
- Smiles notation (if other than submission substance): OCC(CCCC)CC

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
35.28
Temp.:
20 °C
Remarks on result:
other: calculated based on MCI; correction factor -1.3179
Type:
Koc
Value:
131.1
Temp.:
20 °C
Remarks on result:
other: calculated based on Log Kow of 2.9

Any other information on results incl. tables

Koc estimate from MCI (KOCWIN v.2.00) results:

First-order molecular connectivity index: 4.346

Non-corrected Log Koc (0.5213MCI+0.60): 2.8654

Fragment Correction(s):

Aliphatic alcohol (C-OH): -1.3179

Corrected Log Koc: 1.5475

Estimated Koc: 35.28 L/kg

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
Estimated organic carbon-normalized sorption coefficient for soil and sediment (Koc) for ethylhexanol is 35.28 L/kg based on the Sabljic molecular connectivity method with improved correction factors.
Executive summary:

Testing is scientifically unjustified as this substance is hydrolytically unstable. Therefore, the estimated Koc of the main degradation product was calculated by using KOCWIN v.2 (US EPA. 2012, Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10).

This value is considered reliable with restrictions, as this is an estimated value, to be used as a key value in CSA and to derive the PNECs to sediment and soil compartment by using equilibrium partioning method.