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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
key 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
Justification for type of information:
- QMRF: see 'Overall remarks, attachments'.
- QPRF: see 'Executive summary'.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Calculation using KOCWIN (v2.00) Molecular Connectivity Index (MCI)
GLP compliance:
no
Type of method:
other: QSAR estimation: KOCWIN v2.00: Koc estimate from MCI
Specific details on test material used for the study:
- Name of test material (from EPISuite CAS inventory): 2-Propenoic acid, 2-hydroxyethyl ester
- Smiles Code: O=C(OCCO)C=C
Test temperature:
25 °C
Key result
Type:
Koc
Value:
1 L/kg
Temp.:
25 °C
Type:
log Koc
Value:
-0.03 dimensionless
Temp.:
25 °C

Koc Estimate from MCI:

KOCWIN Program (v2.00) Results:

SMILES : O=C(OCCO)C=C

CHEM  : 2-Propenoic acid, 2-hydroxyethyl ester

MOL FOR: C5 H8 O3

MOL WT : 116.12

 

Koc Estimate from MCI

First Order Molecular Connectivity Index  

3.808

Non-Corrected Log Koc (0.5213 MCI + 0.60) 

2.5849

Fragment Correction(s)

 

 1  Aliphatic Alcohol (-C-OH)  

-1.3179

 1  Ester (-C-CO-O-C-) or (HCO-O-C)  

-1.2970

Corrected Log Koc  

-0.0299

Over Correction Adjustment to Lower Limit Log Koc 

0.0000

Estimated Koc

1 L/kg 

Executive summary:

QPRF: KOCWIN v2.00 (MCI methodology) (18 Nov. 2013)

 

1.

Substance

See “Test material identity”

2.

General information

 

2.1

Date of QPRF

See “Data Source (Reference)”

2.2

QPRF author and contact details

See “Data Source (Reference)”

3.

Prediction

3.1

Endpoint
(OECD Principle 1)

Endpoint

Adsorption to solid phase of soils etc.

Dependent variable

Organic carbon normalised adsorption coefficient (Koc)

3.2

Algorithm
(OECD Principle 2)

Model or submodel name

KOCWIN

Model version

v. 2.00

Reference to QMRF

QMRF: Estimation of Soil Adsorption Coefficient using KOCWIN v2.00 (EPI Suite v4.11): MCI methodology

Predicted value (model result)

See “Results and discussion”

Input for prediction

- Chemical structure via CAS number or SMILES

Descriptor values

- MCI (first order molecular connectivity index)

- Correction factors

3.3

Applicability domain
(OECD principle 3)

Domains:

1) Molecular weight
(range of test data set: 32.04 to 665.02 g/mol; On-Line KOCWIN User’s Guide, Ch. 6.2.4 Domain)

Substance within range (116.12 g/mol)

2) Correction factors: Number of instances of the identified correction factor does not exceed the maximum number as listed in Appendix D (On-Line KOCWIN User’s Guide)

Fulfilled.

3.4

The uncertainty of the prediction
(OECD principle 4)

Statistical accuracy for training dataset:

n = 516, r² = 0.916, std. dev. = 0.330, average dev.= 0.263

3.5

The chemical mechanisms according to the model underpinning the predicted result
(OECD principle 5)

Adsorption is caused by temporary (reversible) or permanent bonding between the substance and a surface (e.g. due to van der Waals interactions, hydrogen bonding to hydroxyl groups, ionic interactions, covalent bonding, etc.). The organic carbon normalized adsorption coefficient (Koc) is the ratio of a substance concentration sorbed in the organic matter component of soil or sediment to that in the aqueous phase at equilibrium.

MCI methodology: The first-order molecular connectivity index is a measure to describe a variety of properties of chemicals. According to Sabljic (1984; cited in Meylan et al., 1992), the soil sorption potential is highly correlated with the first order MCI. Therefore, it has been used to derive the adsorption coefficient.

 

References

- US EPA (2012). On-Line KOCWIN User’s Guide.

- Meylan, W., P.H. Howard and R.S. Boethling. 1992. Molecular topology/fragment contribution method for predicting soil sorption coefficients. Environ. Sci. Technol. 26: 1560-1567.

Assessment of estimation domain (molecular weight, fragments, correction factors):

Training set: Molecular weights

Training set

Validation set

Minimum

32.04

73.14

Maximum

665.02

504.12

Average

224.4

277.8

Assessment of molecular weight

Molecular weight within range of training and validation set

Training set: Log Kow

Training set

Validation set

Minimum

-2.11

-5.98

Maximum

8.12

8.68

Assessment of log Kow

Log Kow within range of training and validation set

 

Appendix D. MCI & Log Kow Correction Factors for 447 Compound Training Set

Correction Factor Descriptor

Coefficient for Molecular Connectivity Index (MCI) Regression Methodology

Coefficient for log Kow Regression Methodology

Occurrence

No. of instances
of each bond
found for the
current substance

(new model)

 Remark

(number of compounds

(max per structure)

 

Aliphatic Alcohol (-C-OH)

-1.317914

(a)

-0.411443

21

1

1

Ester (-C-CO-O-C-) or (HCO-O-C)

-1.296957

(a)

-0.065594

50

2

1

(a)   Counted up to twice per structure, regardless of number of occurrences.

Description of key information

For 2-hydroxyethyl acrylate the Koc value was calculated to be 1L /kg (log Koc = -0.03) when based on the MCI method (BASF, 2015). Based on a log Koc of <3 adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

QSAR-disclaimer:

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of 2-hydroxyethyl acrylate (Q)SAR results were used for adsorption / desorption.The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.