Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

MTDID 15670 and its hydrolysis products are not expected to be persistent in aquatic systems.

Additional information

MTDID 15670 is hydrolytically active, but was not meaningfully degraded in an ready biodegradation test. It could not be determined whether MTDID 15670 was inhibitory to biodegradation. QSAR modeling of the two organic hydrolysis products, crotononitrile and dodecyl ethyl sulfide, showed that the crotonitrile should be readily biodegradable while dodecyl ethyl sulfide would be more resistant to degradation. The predicted biodegration pathways for dodecyl ethyl sulfide involve mercaptan (thiol) formation. Since free sulfhydril groups are toxic to many microorganisms but would only be created over time, inhibition of activated sludge would not be shown during a short-term OECD 209 respiration inhibition test. In fact, MTDID 15670 did not reach 50% inhibition to activated sludge respiration even at a loading rate of 1000 mg/L. However, organisms capable of metabolizing sulfoethers are widespread in the environment. The training set of the QSAR model included the structural analog dihexyl sulfide, which was 57% degraded in an OECD 301C assay, and was inherently biodegradable (information from Japan Chemicals Collaborative Knowledge database[1]). By multiple lines of evidence, dodecyl ethyl sulfide is also not expected to be persistent.

1] http://www.safe.nite.go.jp/jcheck/searchresult.action?cas_no=6294-31-1&request_locale=en