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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

72h EC50 (growth rate) = 17 mg/L (OECD 201)
72h EC10 (growth rate) = 1.8 mg/L (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
17 mg/L
EC10 or NOEC for freshwater algae:
1.8 mg/L

Additional information

Since no reliable short-term test with aquatic algae is available for C9AS Na (CAS 1072-15-7), in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to another structurally related category member was conducted. Read-across data from pure homologues C8-isoAS Na (CAS 126-92-1) and C10AS Na (CAS 142-87-0) were used. As the toxicity of alkyl sulfates is dependent on the carbon chain length, it is expected that the toxicity of C9 homologue will be lower than the toxicity of C10 homologue and higher than of C8 homologue.

One study investigating toxic effects of C8-isoAS Na (CAS 126-92-1) to freshwater algae Desmodesmus subspicatus is available (Scholz 1995). The test was performed according to EU Method C.3 and is GLP compliant. Growth inhibition caused by the test substance was determined after 24, 48 and 72 h of exposure to five test concentrations up to 511 mg a.i./L (measured concentration equal to 900 mg a.i./L of nominal concentration). The results show that the 72-hour EC50 value for growth rate was above the highest test concentration of 511 mg a.i./L (measured concentration). The 72-hour EC10 value for growth rate was determined to be 199 mg a.i./L (measured concentration).

One reliable study investigating the effects of C10AS Na (CAS 142-87-0) to the freshwater algae Pseudokirchneriella subcapitata is available (Huntsman 2013). The test was performed according to OECD guideline 201 and is GLP compliant. Growth inhibition caused by the test substance was determined after 24, 48 and 72 h of exposure to seven test concentrations up to 122 mg a.i./L (nominal concentrations were shown to be in accordance with the measured ones with recoveries of 82.6% to 132.1%). The results showed that the 72-hour EC50 value for growth rate was 8.64 mg/L and the EC10 value for growth rate was 0.95 mg/L.

Due to structural and property similarities with the tested category members, it can be concluded that the above results apply also to C9AS Na (CAS 1072-15-7). The EC50 value for algae growth rate will be above 8.6 mg/L and EC10 above 0.95 mg/L. Using the additivity formula stipulated in the EC Regulation 1272/2008, the reliable EC50 value for C9AS Na (CAS 1072-15-7) calculated based on toxicity of C8-isoAS Na (CAS 126-92-1) and C10AS Na (CAS 142-87-0) is 17 mg/L. The EC10 value calculated in the same way is 1.8 mg/L.