Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Read-Across is claimed between BT4 (target) and SE7B (Source), according to the justification attached to the target record, and based on structural and physical/chemical similarities.

Analogue diesters (SE7B, SE6B) and BT4 contain the same functional groups, i.e the ester group adjacent to the ethylhexane side chain, and the ester group at the opposite end of the molecules. The carbon range in the main backbone of the molecules is all the same (C18) though the acetate moiety is attached at slightly different positions (C12 for BT4, C9/10 for the analogue diesters). The analogue diesters have the additional alkane chain attached to the acetate cap. The alkane chains themselves are not typically considered to be functional groups, per se, as they are relatively inactive biologically. Thus the parent molecules BT4 and the analogue diesters are similar enough to allow for read across in that there are no differences with respect to functional groups, and their only real difference is number of, and length of, saturated hydrocarbon chains.

Four screening test for biodegradation in water were performed for SE7B.

In the key study, OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test), the degradation extent of the test item at the end of the test was 89.5% (28 d after acidification, mean value of three replicates).

The mean degradation extent on day 11 was already higher than 60% (81.1%, mean value of three replicates). Therefore the criteria for ready biodegradation was met (10-d window).

In an  OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test), the test item attained 72% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No. 301F the test item cannot be considered to be readily biodegradable as the test item failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation exceeding 10%. However, the test item has exhibited the potential for rapid degradation. In terms of the classification and labelling requirements (EU Directive for Dangerous Substances, L110A), the test item may be considered as readily biodegradable as evidence of >70% degradation has been shown over a 28-day period in a standard biodegradation study.

In an OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)), under the conditions of the study, most of the test item underwent biodegradation and two degradation intermediates were detected after the end of incubation. Because the percentage biodegradation by BOD was very high (average 96%) and the BOD curves wererising at the end of the incubation, theintermediates will finally undergo biodegradation.

In an OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test), SE7B gave a positive result (> 60% degradation relative to the COD value) with a maximum of 75% recorded on day 21. It may therefore be concluded that there is a potential for biodegradation under environmental conditions.

Hydrolysis of BT4 would yield acetic acid plus 12-hydroxystearic acid (C18), versus either lauric acid (C12) or the coconut oil fatty acid mixture (C8-18) for SE6B and SE7B, respectively.

These substances are not expected to persist in the environment, consistent with the hazard assessment presented in the OECD SIDS (2009) for the category “Aliphatic Acids Category” where aliphatic fatty acids with a carbon chain length in the range of C8 – C22 were judged to be readily biodegradable.