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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable according to OECD criteria: 95% after 28 days based on CO2 evolution (OECD 301 B).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Since no reliable ready biodegradability tests are available for C9-11AS Na (CAS 84501-49-5), in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5, a read-across to other structurally related category members was conducted. Read-across data on the following substances were used: C10AS Na (CAS 142-87-0) and C12AS Na (CAS 151-21-3).

The key study with C12AS Na (CAS 151-21-3) was performed according to OECD 301 B and is GLP compliant (Brunswik-Titze 2005). Non-adapted activated sludge coming from a municipal wastewater treatment plant was used as inoculum and the initial concentration of the test substance was 20 mg/L as DOC. Biodegradation measured as CO2 evolution reached 95% after 28 days and passed a 10-day window (81.5% after 10 days). A supporting study with C12AS Na (CAS 151-21-3) was performed according to OECD guideline 301 D and GLP (Börner 1996). Effluent of domestic sewage treatment plant was used as inoculum and the initial concentrations of the test substance were 2 mg/L and 5 mg/L. Biodegradation after 28 days measured as O2 consumption reached 97% at the concentration of 2 mg/L and 94% at the concentration of 5 mg/L. It can be concluded that C12AS Na (CAS 151-21-3) is ready biodegradable according to OECD criteria.

Two further supporting studies are available for C10AS Na (CAS 142-87-0). One non-GLP study assessing biodegradation of C10AS Na (CAS 142-87-0) was performed according to OECD guideline 301 D (Richterich 2001). Effluent of the sewage treatment plant handling predominantly domestic sewage was used as inoculum. The initial concentrations of the test substance were 2 mg/L and 5 mg/L. Biodegradation of 98% measured as oxygen demand was observed after 30 days at the initial concentration of 2 mg/L and 92% at the concentration of 5 mg/L. The test substance was biodegraded by more than 60% in both cases within five days. Based on these results it can be concluded that C10AS Na (CAS 142-87-0) is readily biodegradable. This result was confirmed by a supporting non-GLP study performed according to OECD guideline 301 E (Sanchez Leal et al. 1991). Biodegradation reached ca. 90% after 8 days of testing.

Due to structural and property similarities with the tested category member these results also apply to C9-11AS Na (CAS 84501-49-5). This substance is considered to be readily biodegradable according to OECD criteria.