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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Not readily biodegradable: 20.7 - 45%  (CO2 evolution) in 28 days based on read across (EU method C.4-C)
Enhanced ultimately biodegradable: 71.4 - 78% (CO2 evolution) in 40 - 50 days based on read-across (EU method C.4-C)

Key value for chemical safety assessment

Additional information

Two studies for the category member 2,4-Benzenetricarboxylic acid, tri-C9-11-alkyl esters (CAS No. 94279-36-4) are available. However, these studies are not appropriate to assess the biodegradability of 1,2,4-Benzenetricarboxylic acid, tri-C9-11-alkyl esters (CAS No. 94279-36-4), because (i) a product is tested and no further information about the tested substance is given, (ii) a method is used which substantially differ from current guidelines (CEC-L-33-T-82) and (iii) only a short abstract is available which makes it impossible to verify the reliability and accuracy of the provided test results. 

Therefore, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances, a read-across to the structurally related category member 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters (CAS No. 90218-76-1) was conducted.The read across is justified due to a) the structural similarity of the category members and b) similar physico-chemical properties resulting in a similar environmental fate and ecotoxicity profile. Further justification is given within the endpoint summary 6.1 and within the category justification section 13.

For 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters (CAS No. 90218-76-1) two ready biodegradability studies are available. Both GLP studies were performed according to EU method C.4-C (Diefenbach, 1995; Mitterer, 1997). Initial test concentrations of 14.8 and 14.95 mg/L (TOC) were applied. Based on CO2 evolution mean degradation rates of 45% and 20.7% were observed after 28 days. Hence, the substance is not readily biodegradable according to OECD criteria.Nevertheless, the test duration was extended to 43 and 48 days, respectively, resulting in overall biodegradation rates of 71.4 - 78% in the enhanced ready biodegradation test.

Conclusion:

Based on the data above, 1,2,4-Benzenetricarboxylic acid, tri-C9-11-alkyl esters (CAS No. 94279-36-4) can be considered as not readily biodegradable according to OECD criteria. However, it could be demonstrated that the biodegradation continued beyond the 28 day test period, which resulted in a biodegradation rate above the pass level of > 60% (CO2 evolution) after a test period of 43 and 48 days, respectively. This indicates that the test substance is enhanced ultimately biodegradable according to the criteria described on pages 179 -180 of the "Guidance on information requirements and chemical safety assessment -Chapter R.7b: Endpoint specific guidance" (ECHA, 2012).

As the screening criteria for persistency listed in table R.11-2 of the “Guidance on information requirements and chemical safety assessment: chapter 11: PBT assessment (ECHA, 2012) are passed under the strict conditions of enhanced biodegradation tests, it can be concluded that the test substance is not persistent in the environment.

Due to the structural and property similarities with the tested category member 1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters (CAS No. 90218-76-1) the results are applicable to read across to 1,2,4-Benzenetricarboxylic acid, tri-C9-11-alkyl esters (CAS No. 94279-36-4).