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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Link to relevant study record(s)

Description of key information

Weight of evidence data:

A) Ready biodegradability test according to OECD 301 C / EU C.4-F, GLP (details under endpoint record 5.2.1.002, study performed by Laus laboratory), test substance: isopentyl acetate. Result: A plateau of degradation of approximately 40 % was reached after 15 days. After 28 days 44 % of isopentyl acetate was biodegraded. The conclusion was "inherently biodegradable".

B) Ready biodegradability study according to OECD Guideline No. 301F (details under endpoint record 5.2.1.003, test facility: Givaudan Suisse SA).

Test substance: 3-methylbutyl acetate.

Results: 90 % biodegradation after 37 days (88 % after 28 days). Biodegradation started on day 1 and reached 74 % at end of 10-day-window.

The conclusion was "readily biodegradable".

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

In the study report of Laus (endpoint record 5.2.1.002), isopentyl acetate was classified as not readily biodegradable following OECD 301 C / EU C.4-F. A plateau of degradation of approximately 40 % was reached after 15 days and degradation of 44 % had occurred after 28 days. Based on this result, the substance would be regarded as not readily biodegradable and also as not rapidly degradable according to "Guidance on the application of the CLP criteria" (ECHA, Version 3, Nov 2012).

However, a biodegradation above 20 % may be regarded as evidence of inherent, primary biodegradability of test substances in the inherent biodegradation test "Modified MITI Test (II) (OECD 302 C)" and other official inherent biodegradation tests. Reference: R.7.9.4 Evaluation of available information on degradation/ biodegradation, p.183, in: Guidance on information requirements and chemical safety assessment Chapter R.7b: Endpoint specific guidance (ECHA, Nov 2012). As the study was a ready biodgradability test and was therefore more stringent than a inherent biodegradability test, it may be assumed that the test substance exhibits inherent, primary biodegradability.

According to R.7.9.4.4 Remaining uncertainty for degradation/biodegradation, in: Guidance on information requirements and chemical safety assessment Chapter R.7b: Endpoint specific guidance (ECHA, Nov 2012) also the following applies: "Chemicals that fulfil the criteria for ready biodegradability are likely to undergo rapid degradation in the environment under most conditions (OECD, 2006). However, it must be recognised that these tests are very stringent and most chemicals will not fulfil the pass criteria for ready biodegradability. For chemicals that exhibit between 40 and 60 % mineralisation in ready biodegradability test, extensive primary biodegradation would have occurred..."

In a further OECD test guideline ready biodegradability study of Givaudan (endpoint record 5.2.1.003), 3-methylbutyl acetate showed much better biodegradation. As the substance was found to be degraded at 90 % after 37 days (88 % after 28 days) and as biodegradation started on day 1 and reached 74 % at end of 10 -day-window, the conclusion was "readily biodegradable".

The overall conclusion for the biodegradation of isopentyl acetate is therefore "readily biodegradable".