Perhydroimidazo[4,5-d]imidazole-2,5-dione

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2018

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
Estimation Programme Interface (EPI) Suite programme for Microsoft Windows v4.11
Contact EPISuite:
U.S. Environmental Protection Agency
1200 Pennsylvania Ave.
N.W. (Mail Code 7406M)
Washington, DC 20460

2. MODEL (incl. version number)
KOCWIN v2.00
September 2010 (model development); November 2012 (model publication)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See QPRF attached: ‘QPRF Title: Perhydroimidazo[4,5-d]imidazole-2,5-dione using the model KOCWIN v2.00 for the endpoint: Soil Adsorption Coefficient (Koc)’ version 1.0; dated 12 April 2018.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Full details of the method are provided in the attached QMRF named ‘QMRF Title: KOCWIN v2.00: Soil Adsorption Coefficient (Koc)’ version 1.0; 17 January 2018.

5. APPLICABILITY DOMAIN
See ‘any other information on results incl. tables’.
See QPRF attached: ‘QPRF Title: Perhydroimidazo[4,5-d]imidazole-2,5-dione using the model KOCWIN v2.00 for the endpoint: Soil Adsorption Coefficient (Koc)’ version 1.0; dated 12 April 2018.

6. ADEQUACY OF THE RESULT
1) QSAR model is scientifically valid. 2) The substance falls within the applicability domain of the QSAR model. 3) The prediction is fit for regulatory purpose.
The prediction is adequate contributing information to the environmental fate and transport and distribution assessment of the substance. The prediction is also supporting information for the Classification and Labelling or risk assessment of the substance as indicated in REACH Regulation (EC) 1907/2006: Annex XI Section 1.3. Specifically when combined with further information such as environmental toxicity and environmental fate testing.

Guideline:

other: REACH Guidance on QSARs R.6, May/July 2008.

Principles of method if other than guideline:

Full details of the method are provided in the attached corresponding QMRF named ‘QMRF Title: KOCWIN v2.00: Soil Adsorption Coefficient (Koc)’ version 1.0; 17 January 2018.

- The model applies the following methodology to generate predictions:
(1) MCI model: first-order Molecular Connectivity Index with Fragment (group contribution) correction based QSAR; based on multiple linear-regression modelling
(2) Log Kow Regression mode: thermodynamic relationship model with Fragment (group contribution) correction based QSAR; based on multiple linear-regression modelling

- The model and the training and validation sets are published by US Environmental Protection Agency (USA).
The experimental Koc values in the training set and validation set were measured using one or more methods equivalent or similar to the following guidelines:
- HPLC method (OECD TG 121, 2001)
- Sediment and soil adsorption/desorption isotherm; screening method using three soil types (US EPA guideline OPPTS 835.1220, 1996)
- Batch equilibrium method (OECD TG 106, 2000)
- Leaching in Soil Columns method (Kd) (OECD TG 312, 2002)
- Simulation tests and direct field measurement (OECD Guidance Document 22, 2000)

Relevant EU (1992 as amended) may be also have been used where appropriate. It is understood that the core data of the training set would have been generated by non-HPLC method direct measurements of KOC. Additional data may have been subsequently added utilising estimates from the HPLC method in the model update from PCKOCWIN v1.0 to KOCWIN v2.0 and incorporation of Schuurmann et al. (2006) and other data.
- Justification of QSAR prediction: The result should be considered in relation to corresponding information presented and in accordance with the tonnage driven information requirements of REACH Regulation (EC) 1907/2006 in a weight of evidence.

Specifically the substance is hydrolytically unstable. The substance constituents have short hydrolytic half-lives (scale: hours at neutral pH, ambient temperatures, accelerated in acidic or basic pH conditions by catalytic hydrolysis) they would be considered as fulfilling the criteria for rapid (primary) degradability.

Provision of measured experimental log Koc has been determined as not technically possible under guideline OECD TG 121 HPLC method (under OECD TG 117 HPLC method of Koc that the test item was determined to be too unstable). It is also potentially not possible by other methods. Therefore, in accordance with the tonnage driven information requirements: the calculated method for Log Koc has been adopted.
The calculated predictions are indicative of a substance of low to moderate adsorption potential: blocks of Loc Koc in the range of 2.09 and 2.96. The rapidly formed primary hydrolysis products are of much lower adsorption potential in several blocks of log Koc: -0.042, 0.73 and 1.59, as the hydrolysis products become more water soluble.

Type of method:

other: Calculated.

Specific details on test material used for the study:

Detailed information on the 'test material identity' is provided in the attached QSAR Prediction Reporting Format (QPRF) document including information on individual consituents.

Type:

log Koc

Value:

-0.997 dimensionless

Remarks on result:

not measured/tested

Remarks:

Estimated result from validated (Q)SAR model: KOCWIN v2.00.

Validity criteria fulfilled:

yes

Conclusions:

The results are adequate for the regulatory purpose.

Executive summary:

QSAR Predictions KOCWIN v2.00 model, 2018

Log Koc range: -0.9968 at 25°C

The calculated predictions are indicative of a substance of low to moderate adsorption potential.

References for further information:

1. QMRF Title: KOCWIN v2.00: Soil Adsorption Coefficient (Koc), version 1.0; 17 January 2018; updated 12 April 2018.

2. QPRF Title: Perhydroimidazo[4,5-d]imidazole-2,5-dione using the model KOCWIN v2.00 for the endpoint: Soil Adsorption Coefficient (Koc), version 1.0; dated 12 April 2018.

Description of key information

Log Koc, soil of -0.9968 at 25°C, ca. pH 7, QSAR Predicition - KOCWIN v2.00, 2018. MCI model was not used since the substance lies outside the domain.

Key value for chemical safety assessment

Koc at 20 °C:

0.101

Additional information

QSAR Predictions KOCWIN v2.00 model, 2018

Log Koc range: -0.9968 at 25°C

The calculated predictions are indicative of a substance of low to moderate adsorption potential.

References for further information:

1. QMRF Title: KOCWIN v2.00: Soil Adsorption Coefficient (Koc), version 1.0; 17 January 2018; updated 12 April 2018.

2. QPRF Title: Perhydroimidazo[4,5-d]imidazole-2,5-dione using the model KOCWIN v2.00 for the endpoint: Soil Adsorption Coefficient (Koc), version 1.0; dated 12 April 2018.