Ethyl methyl sulphide

Biodegradation in water: screening tests

Description of key information

Ethyl methyl sulphide was found to be inherently biodegradable with 92% of biodegradation obtained in an OECD 301D test with adapted bacteria.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

The biodegradability of ethyl methyl sulphide (EMS) was evaluated according to OECD guideline 301D“Ready biodegradability: Closed Bottle Test” and GLP requirements (Gancet, 2011). The study meets the validity criteria. The study indicates that ethyl methyl sulphide is not readily biodegradable since 41% of biodegradation of the test item was observed after 28days.

Therefore, two enhanced biodegradation screening tests have been performed: with an extended period and adapted bacteria.

Firstly, the biodegradability of EMS was evaluated according to the OECD guideline 301 D during 56 days (Gancet, 2012b). Under the test conditions, the percentage of biodegradation of EMS reached 32 % in 28 days and 33 % of the ThOD at the end of the extended test (56 days).

Secondly, the biodegradability of EMS was evaluated according to the OECD guideline 301 D and using adapted bacteria (Gancet, 2012a). Adaptation was obtained through a first period of 28 days, followed by a second period using the adapted bacteria. Under the test conditions, the percentage of biodegradation of EMS reached 22 % of the ThOD at the end of the first 28 day period and 92 % of the ThOD at the end of the second period with adapted bacteria (31 days after the adaptation period of 28 days). The test substance did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is 58 % higher than 25 % within 14 days of the first period. The validity criteria were fulfilled. According to this result, the test substance can be considered as inherently biodegradable.