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Environmental fate & pathways

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Biodegradation in water: screening tests

The test substance diisotridecyl adipate was demonstrated to be readily biodegradable in three OECD guideline 301-tests.

An OECD 301F-study (Flach, 2014, key study) (guideline suitable for poorly soluble and volatile substances) with the test substance has been conducted, showing that DITA is readily biodegradable (69 % biodegradation based on ThOD after 28 days). The inoculum used in this study was neither adapted, nor pre-exposed (confirmation of the test institute attached). Two more studies (OECD 301B) are available, showing that DITA is readily biodegradable. In the first OECD 301B study, 81 % biodegradation were achieved within 28 d, fulfilling the 10d-window criterion (although not required for an UVCB). A second OECD 301B-test resulted in a biodegradation extent of 69.6 % after 28 days. The other studies reported for DITA clearly indicate the ready biodegradability of the substance, by almost reaching the 60% biodegradation threshold. In the respective study according to OECD guideline 301B, a biodegradation of 56.6% within 28 days was obtained with DITA. Similar biodegradation was found in the other 301F study (58.53% biodegradation within 28 days). Supporting all these findings, the read-across substance diisotridecyl dodecanedioate was found readily biodegradable in an OECD 301B-test. All of the studies mentioned above are considered valid.

 

Biodegradation in water and sediment: simulation tests

In accordance with column 2 of REACH Annex IX No 9.2.1.2, the study does not need to be conducted as the substance is regarded as readily biodegradable and to be highly insoluble in water (see Sect. 4.8).DITA is readily biodegradable and therefore a sediment simulation test is not required. The available studies on the biodegradation behavior of DITA, particularly the key study of Flach (2014), clearly show that the substance fulfills the criteria for Ready biodegradability. The inoculum used in these studies was neither adapted, nor pre-exposed. This applies also to the latest OECD 301F (Flach, 2014) study with DITA and was confirmed by the respective test institute (please see attachment: " issue2_OECD301FcommentsInoculum_diisotridecyladipate __studyno892.pdf"). Based on the data, direct and indirect sediment deposition is unlikely.

 

Biodegradation in soil

In accordance with column 2 of REACH Annex IX No 9.2.1.2, the study does not need to be conducted as the substance is regarded as readily biodegradable. DITA is readily biodegradable and therefore a soil simulation test is not required. The available studies on the biodegradation behavior of DITA, particularly the key study of Flach (2014), clearly show that the substance fulfills the criteria for Ready biodegradability. The inoculum used in these studies was neither adapted, nor pre-exposed. This applies for the latest OECD 301F study with DITA and was confirmed by the respective test institute (please see attachment: " issue2_OECD301FcommentsInoculum_diisotridecyladipate __studyno892.pdf").

Direct and indirect soil exposition is therefore unlikely.

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