6,6-dimethoxy-2,5,5-trimethylhex-2-ene

Biodegradation in water: screening tests

Description of key information

The ready biodegradability of Methyl Pamplemousse was determined by the Manometric Respiratory Test according to OECD Guidelines No 301F. Under the conditions of the study, the test substance underwent -3 % biodegradation after 28 days. Thus, the test substance should be regarded as not readily biodegradable according to this test.

The inherent biodegradability of Methyl Pamplemousse was determined by the Manometric Respirometry Test according to the OECD Guidelines for Testing of Chemicals, Method No. 302C. The repeatability between the two replicates was poor. At day 7 the measured biodegradation was 8 and 19%, and at the end of the test -5 and 15%. However, it can be inferred from the results that Methyl Pamplemousse undergoes no significant (i.e. below 20%) biodegradation after 32 days in the test conditions. Thus, Methyl Pamplemousse should be regarded as not inherently biodegradable according to this test.

Based on the above two tests, the conclusion for the chemical safety assessment is that no biodegradation was observed.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

An inhibition control was included in the ready biodegradability test. At the concentration used in the test (100 mg/l), Methyl Pamplemousse was not inhibitory to the micro-organisms. This concentration can be considered as a NOEC for the toxicity to STP microorganisms.

 

Intrinsic shortcomings associated with the above screening tests have been reported (Roberts et al. 2009, Influence of inoculum source in the biodegradability of Propanolol and Atenolol, poster presentation SETAC-Europe meeting Göteburg, Sweden 31 May - 04 June 2009; ECETOC Workshop Report No. 10 - Workshop on biodegradation and persistence, 26 - 27 June 2007, Holmes Chapel, UK), including low diversity in microbial populations of the inoculum, over-exaggerated test concentrations compared to those likely to occur in the environment under realistic use conditions, absence of light, and lack of aeration. The use of high test concentrations in these studies may lead to reduced bioavailability and, in certain cases, can result in either subtle or marked inhibition effects on the microbial population present. As such, these screening tests are considered to represent an extreme worst case situation.