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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The performance of the adsorption/desorption screening test is scientifically unjustified. REACH Regulation (EC) No 1907/2006, Annex VIII Sect. 9.3.1., Col. 2, states as follows: 
"9.3.1. The study does not need to be conducted if:
– based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient); or
– the substance and its relevant degradation products decompose rapidly."
Due to the low logKow value of the test substance estimated to be 1, measurement of the adsorption behaviour of the test substance is technically not feasible.
A log Koc of 4.15 was calculated by EPIWIN for completeness.

Key value for chemical safety assessment

Koc at 20 °C:
14 020

Additional information

A Waiver is used to address this endpoint.

The performance of the adsorption/desorption screening test is scientifically unjustified. REACH Regulation (EC) No 1907/2006, Annex VIII Sect. 9.3.1., Col. 2, states as follows:

"9.3.1. The study does not need to be conducted if:

– based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient); or

– the substance and its relevant degradation products decompose rapidly."

Due to the low logKow value of the test substance estimated to be 1, measurement of the adsorption behaviour of the test substance is technically not feasible.

Further supporting QSAR calculations were available. The following logKoc values were determined which were representative for the different chain length of the test item.

For C12 species: 4.15

For C15 species: 4.95

For C18 species: 5.75

As worst case the C12 log Koc value of 4.15 (leading to lower PNECs) was chosen for this endpoint.

For the assessment of the test item (Q)SAR results were used for Adsorption / desorption

In order to generate a reliable and adequate prediction to fulfil or to supplement the information requirements under REACH, a (Q)SAR result should meet the conditions listed in REACH Annex XI (1.3):

(i) (Q)SAR model should be used whose scientific validity has been established and

(ii) the substance should fall within the applicability domain of the (Q)SAR model,

(iii) the prediction should be fit for the regulatory purpose, and

(iv) the information should be well documented.

In order to fulfil these requirements and in accordance with ECHA guidance IR/CSA R.6 QSARs and grouping of chemicals and ECHA practical guidance 5 How to report (Q)SARs; the validity, the applicability and the relevance of the used QSAR model was assessed.

Assessment of the Validity of the QSAR Model

The validity of (Q)SAR models for regulatory purposes was characterised and documented according to the five agreed OECD principles,

1. The (Q)SAR model should be associated with a defined endpoint.

2. The (Q)SAR model should be expressed in form of an unambiguous algorithm.

3. The (Q)SAR model should be associated with a defined domain of applicability.

4. The (Q)SAR model should be associated with appropriate performance of the model.

5. The (Q)SAR model should be associated with a mechanistic interpretation for human health and ecotoxicological endpoints, if possible.

These points were addressed in the respective (Q)SAR Model Reporting Form (QMRF) attached to the endpoint study record. It was verified that the substance falls within the applicability domain of the model. Thus, the prediction was regarded as reliable.

Assessment of the prediction of the QSAR Model

The following information was provided to assess the QSAR prediction:

1. Information on the validity of the (Q)SAR model;

2. Verification that the substance falls within the applicability domain of the (Q)SAR model;

3. Assess the adequacy of the results for the purpose of classification and labelling and/or risk assessment.

The information on these three points was compiled according to the (Q)SAR Prediction Reporting Format (QPRF) and was provided as attachment to the endpoint study record.

Conclusion

The validity, the applicability and the relevance of the used QSAR model was assessed, the outcome of the assessment was documented and provided as QMRF and QPRF files attached to the study record. It was concluded that the substance lies within the applicability domain of the model, the results are adequately for the purpose of risk assessment.

Thus, the criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint sufficiently covered and suitable for risk assessment.

Therefore, further experimental studies on adsorption / desorption are not provided.

[LogKoc: 4.15]