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Endpoint:
adsorption / desorption, other
Remarks:
adsorption
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
Justification for type of information:
1. SOFTWARE
EPIWIN software by US-EPA

2. MODEL (incl. version number)
KOCWIN v2.00

3. SMILES
CC(C)OCC1CO1

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: log Koc – soil adsorption coefficient of organic compounds
- Unambiguous algorithm: log Koc = 0.5213 MCI + 0.60 + ΣPfN
MCI – molecular connectivity index, ΣPfN - summation of the products of all applicable correction factor coefficients available in the data set multiplied by the number of times (N) that factor is counted for the structure.
- Defined domain of applicability: Currently, there is no universally accepted definition of model domain. The training set of the model contains diverse molecules, so that the fragment library is abundant. It is however possible that a compound has functional groups or other structural features that are not represented in the training set and for which no fragment coefficients were developed. Additionally, there can be more instances of a given fragment than the maximum for all training set compounds. These points should be taken into consideration while interpreting test results.
Molecular weight limits of the training set: 32 - 665 g/mol
Log Kow limits: -2.11-9.10
- Appropriate measures of goodness-of-fit and robustness and predictivity: for the statistics, training data set has been split up into two subsets: the one containing non-polar substances with no fragments subjected to corrections (i.e. those with ΣPfN = 0) and the one containing the remaining ones. For the non-polar set: N = 69 compounds, correlation coefficient R2 = 0.967, standard deviation sd = 0.247 and average deviation ad = 0.199. For the second set: N = 447 compounds, correlation coefficient R2 = 0.9, standard deviation sd = 0.34 and average deviation ad = 0.273. For the external validation data set: N = 158 compounds, correlation coefficient R2 = 0.85, standard deviation sd = 0.583 and average deviation ad = 0.459. For the 516 compounds in the training set, 93% are within 0.6 log units and 100% within 1 log unit.
- Mechanistic interpretation: The methodology and relationship between the first order molecular connectivity index (MCI) and adsorption coefficient is outlined in the reference paper: 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). MCI was initially successfully used to predict soil sorption coefficients for non-polar organics, and the developed new estimation method based on MCIand series of statistically derived fragment contribution factors made it useful also for the polar ones.

5. APPLICABILITY DOMAIN
Molecular weight of ca. 116.16 in molecular weight limits of the training set: 32 - 665 g/mol; log Kow of 0.8 @25°C in log Kow limits: -2.11-9.10; applicability domain fulfilled

6. ADEQUACY OF THE RESULT
The organic substance 2,3-epoxypropyl isopropyl ether lies within the applicability domain with a molecular weight of 116.16 and a log Kow of 0.8; the result seems reasonable and considering the low log kow and log koc as calculated in this QSAR, it is considered as adequate and acceptable to use this result for risk assessment purposes.
Qualifier:
according to guideline
Guideline:
other: REACH guidance on QSARs Chapter R.6 , May 2008
Deviations:
not applicable
Principles of method if other than guideline:
The estimation for soil adsorption of the test material was performed with US-EPA software EPIWIN/KOCWIN v2.00. Two different models are used for this estimation: the Sabljic molecular connectivity (MCI) method as well as the so-called traditional method, which is based on the LogPow.
GLP compliance:
no
Remarks:
(not applicable)
Type of method:
other: QSAR calculation
Media:
soil
Radiolabelling:
no
Test temperature:
Not applicable
Details on study design: HPLC method:
Not applicable
Analytical monitoring:
not required
Details on sampling:
No details available
Details on matrix:
No details available
Details on test conditions:
No details available
Computational methods:
Using the computer tool KOCWIN v2.00 by US-EPA (EPIWIN) the organic-normalized sorption coefficient for soil (soil adsorption, Koc) can be estimated. The following two different models are used: Salbjic molecular connectivity method (MCI) and the traditional method, which is based on the logPow value of the substance. In general, the MCI method is taken more seriously into account, due to the fact that it includes improved correction factors.
Phase system:
other: KOC
Type:
other: KOC
Value:
6.778 L/kg
Remarks on result:
other: MCI method, includes improved correction factors - most relevant
Phase system:
other: KOC
Type:
other: KOC
Value:
10.75 L/kg
Remarks on result:
other: LogPow-based estimate (traditional method)
Details on results (HPLC method):
Not applicable
Adsorption and desorption constants:
Not applicable
Recovery of test material:
Not applicable
Concentration of test substance at end of adsorption equilibration period:
Not applicable
Concentration of test substance at end of desorption equilibration period:
Not applicable
Details on results (Batch equilibrium method):
Not applicable
Statistics:
Not applicable
Validity criteria fulfilled:
yes
Remarks:
(Scientifically accepted calculation method.)
Conclusions:
The study report describes a scientifically accepted calculation method for the soil absorption characteristics using the US-EPA software KOCWIN v2.00. No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable.
Executive summary:

The prediction for soil adsorption property of the test substance was determined by the computer program KOCWIN v2.00 (EPIWIN software) by US-EPA .The program estimates the organic-normalized sorption coefficient for soil, which is designated as Koc. The following two models are used: the Salbjic molecular connectivity (MCI) method as well as the traditional method which is based on the logPow value of the substance.

The MCI method is taken more seriously into account, due to the fact that is includes improved correction factors, resulting in a Koc value of 6.778 L/kg (corrected log Koc = 0.8311).The traditional method gives a value of 10.75 L/kg (corrected log Koc = 1.03).

Endpoint:
adsorption / desorption: screening
Data waiving:
other justification
Justification for data waiving:
the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
As log Pow-values of the substance are well below 3, the study does not need to be conducted:
0.8 [exp. result ; Yu.A. Boikov, V.I. Shibaev, V.V. Gaidamaka and K.A. V'yunov; Zh. Prikl. Khim. (Leningrad) 62(1), 177-179 (1989)]
0.52 [est. with KOWWIN v 1.68 (EPIWIN v 4.1)]
0.712 [est. with ACS Labs v11.02)
Reason / purpose for cross-reference:
data waiving: supporting information

Description of key information

Calculation with KOCWIN v2.00 (EPIWIN software by US-EPA), organic-normalized sorption coefficient (Koc): 6.778 L/kg (MCI method estimation)

Key value for chemical safety assessment

Koc at 20 °C:
6.778

Additional information

The substance has a log Pow and the absorption potential of the substance is related to this parameter. Hence, the conduction of the study has been waived and the key value was determined by QSAR estimation [with KOCWIN v2.00 (EPIWIN software by US-EPA)]. The program estimates the organic-normalized sorption coefficient for soil, which is designated as Koc. The following two models are used: the Salbjic molecular connectivity (MCI) method as well as the traditional method which is based on the logPow value of the substance.

The MCI method is taken more seriously into account, due to the fact that is includes improved correction factors, resulting in a Koc value of 6.778 L/kg (corrected log Koc = 0.8311).The traditional method gives a value of 10.75 L/kg (corrected log Koc = 1.03).

[LogKoc: 0.8311]