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A104 could be considered as a vPvB candidate based on data provided under 67/548/EEC. However, before initiating additional studies such as methods OECD 305 and 308 suggested by BERPC, the registrant sought to generate additional biodegradation data on Additiv 104. The biodegradability study (OECD 301B: Ready Biodegradability by the CO2 Evolution method (Modified Sturm Test)) in the original 1993 notification is not considered to be a relevant test for poorly water soluble substances because of limited bioavailability under these test conditions.  A further investigation of biodegradation according to OECD 301B in association with ISO 10634 (Water Quality: Guidance for the preparation and treatment of poorly water-soluble organic compounds for the subsequent evaluation of their biodegradability in an aqueous medium)or some equivalent means of preparing a testable solution of A104 was proposedin our dossier update of January 2012*. This new investigation was considered more appropriate than a standard OECD 301B because it was developed specifically for substances which are poorly water-soluble, and would therefore give a more accurate assessment of biodegradability. On this basis it was proposed to defer OECD 305 and 308 tests until further clarity on the biodegradation properties wa obtained, since if evidence of biodegradation was identified using this more appropriate method, then the studies initially proposed by BERPC might not be necessary. However, on further consideration, and given the possibility that an OECD 305 might be requested, the registrant commissioned synthesis of a [14C]-radiolabelled A104, facilitated lower concentrations to be tested in a standard OECD 301B, which was commissioned in January 2012.

The latest OECD 301B using [14C] A104 concluded that approximately 13% of the test material mineralised during 61 days of exposure (based on radiochemical measurements), and that it did not exert a toxic effect on the biota present at 30 and 300 mg/L. The bioavailable amount of radioactivity and, therefore, potentially the biodegradation rates were substantially reduced as a result of the radioactivity dosed into the test system strongly adhering to the glassware and was not removed during the course of the study. Overall, the study was inconclusive due a lower than 90% recovery of total radioactivity added to the test system, but these results do reveal that the radiolabelled test material is biodegradable to some extent.

Furthermore a data waiver is proposed for adsorption/ desorption based on the following grounds:

OECD 106 is unsuitable for poorly soluble substances. Furthermore, log Kow of A104 is estimated as >= 8.5 using EPIWIN prediction; OECD 106 is considered to be unsuitbale for substances with log Koc > 4. Likewise, OECD 121 is not appropriate for this substance as the methodology is not suitable for surface active substances.

In lieu of conducting OECD 106 study it is considered that toxicity tests for the soil environment would be the most appropriate and the registrant proposes to conduct an OECD 207 (Earthworm Acute Toxicity Test) and an OECD 208 (Terrestrial Plan Test: Seedling Emergence and Seedling Growth Test). In fact, following the recommendations of ECHA in 2011, the registrant commissioned the long-term equivalent of these tests, i.e. an OECD 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei)) and an ISO 22030 (Chronic toxicity in higher plants). These studies are complete and the results of these are included in the updated dossier and summarised in IUCLID Section 6.

Overall, the data are not suggestive that the registered substance will persist in the environment sufficiently to meet the very Persistent criteria.

UPDATE of January 2012:

* Text in italics above added.

  • Communication received from ECHA (28 September 2011; Decision number: TPE-D-0000001608 -71 -03/F) approving testing programme for earthworm and seedling emergence tests.
  • OECD 106 feasibility assessment added to Section 5.4.1 as Endpoint.
  • See Section 13 for full text of letter sent from registrant to ECHA, via evaluation-compliance-check@echa.europa.eu, dated 28 October 2011.

 

UPDATE of May 2013

  • Summary of latest OECD 301B biodegradation test included.