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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

The removal of parent material was extensive with 99.89 to 99.99% in the CAS system. The concentrations of parent in the sludge ranged from 0.00 to 0.28% of applied test item. The high removal values and low removal via sorption percentages support the high removal via biodegradation.   The observed distribution of the sodium [1-14C] lauryl isethionate and the sodium [1-14C] stearyl isethionate was similar suggesting that all chain lengths would behave in a similar manner in a CAS system.

Key value for chemical safety assessment

Half-life in freshwater:
0.36 h

Additional information

A continuous activated sludge (CAS) test was performed with 14C- lauryl sulfoethyl ester, sodium salt according to guideline OECD 303A, under the spirit of GLP conditions under slightly adapted conditions. The protocol was modified so that the fate of the test substance could be assessed at environmentally realistic concentrations using radiolabelled test substance along with un-labelled test substance. The test substance was exposed to non-adapted micro-organisms maintained by addition of domestic wastewater. The wastewater was spiked at a nominal influent concentration of ~0.5 mg/L for a period of 72 days. The total removal percentage as monitored from day 40 to day 72 range from 99.89 to 99.99% using 14C scintilation counting. This result demonstrates a near complete removal of parent compound at stringent STP considitions (SRT of 6 ± 1 day). Removal of the test substance from the influent through adsorption onto sludge ranged from 0.21 to 0.28%, demonstrating that the test substance was primarily removed by biodegradation (Gore, 2010).