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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key 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 the five (5) constituents (Ethyl 2,2,3,4-tetramethylpentanoate, Ethyl 2,2,3,3-tetramethylpentanoate, Pentanoic acid, 2,2,4,4-tetramethyl-, ethyl ester, Butanoic acid, 2,3-dimethyl-2-(1-methylethyl)-, ethyl ester and Butanoic acid, 2-ethyl-2,3,3-trimethyl-, ethyl ester) of the test item, (Q)SAR results were used for the toxicity to aquatic organisms. 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.


Therefore, and for reasons of animal welfare further experimental studies on aquatic toxicity are not provided


 


Based on the (Q)SAR calculations of the five constituents, the lowest predicted EC50 value of 0.774 mg/L is taken as the worst case EC50 for the test item. The constituents are within the applicability domain of the model.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.744 mg/L

Additional information

The acute toxicity results of the five constituents to Algae are based on a calculation using EPISuite v4.11. All five (5) constituents belong to the ECOSAR class of “Esters”. All constituents contain the same fragments except for constituents 1 and 4 which have two additional fragments (-CH2- (linear)) and (-CH- (linear)). The five (5) constituents have the same molecular weight (186.30 g/mol), but varied slightly in their water solubility (Constituents 2, 3 & 5: 16.82 mg/L; Constituents 1 & 4: 18.05 mg/L) and logKow (Constituents 2, 3 & 5: 4.080; Constituents 1 & 4: 4.044). According to the results of ECOSAR v1.11, the 96-hr EC50 of constituents 2, 3 and 5 was calculated to be 0.744 mg/L while the 96-hour EC50 of constituents 1 & 4 was calculated to be 0.820 mg/L. Based on the (Q)SAR calculations of the five constituents, the lowest predicted EC50 value of 0.774 mg/L is taken as the worst case EC50 for the test item. The constituents are within the applicability domain of the model. Thus, the calculation is accurate.


 


The adequacy of a prediction depends on the following conditions:



  1. a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

  2. b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

  3. c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

  4. d) the (Q)SAR model is relevant for the regulatory purpose.


 


For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and included to this study record.


 


Description of the prediction model


The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the “Overall remarks, attachments – Remarks on results including tables and figures”. 


 


Assessment of estimation domain


The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the “Executive summary” for the details of the prediction and the assessment of the estimation domain.