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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

72h EC50 (Pseudokirchneriella subcapitata, growth rate) = 8.64 mg/L (measured concentration, OECD 201)
72h EC10 (Pseudokirchneriella subcapitata, growth rate) = 0.95 mg/L (measured concentration, OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
8.64 mg/L
EC10 or NOEC for freshwater algae:
0.95 mg/L

Additional information

Since no reliable aquatic algae test is available for C9-11AS Na (CAS 84501-49-5), in accordance to Regulation (EC) 1907/2006 Annex XI, 1.5, a read-across to other structurally related category member was conducted. Toxicity of alkyl sulfates is dependent on the carbon chain length and therefore read-across data from the following substances were used: C10AS Na (CAS 142-87-0) and C12AS Na (CAS 151-21-3).

A key GLP study investigates the effects of C10AS Na (CAS 142-87-0) to the freshwater algae Pseudokirchneriella subcapitata (Huntsman 2013). The test was performed according to OECD guideline 201. 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.

Moreover, a supporting GLP compliant study was performed with C12AS Na (CAS 151-2-3) according to guideline DIN 38412, part 9 (Rieche 1994). Aquatic algae Desmodesmus subspicatus were exposed for 72 hours to four test concentrations up to 120 mg/L (nominal concentrations). Analytical check of test concentrations showed that the nominal concentrations were in agreement with the measured ones and therefore the nominal concentrations were used. The 72-hour EC50 value for growth rate was above 120 mg/L (nominal concentration). The NOEC value for biomass was 30 mg/L (nominal concentration). These results are supported by a publication of Nyholm and Damgaard (1990). The non-GLP test was performed with Pseudokirchnerella subcapitata exposed to six test concentrations. No special guideline was followed and analytical monitoring of test concentrations was not performed. Growth rate measurement after 96-h resulted in the ErC50 value of 117 mg/L (nominal concentration). EC10 for growth rate was 12 mg/L (nominal concentration).

Due to structural and property similarities with the tested category member these results also apply to C9-11AS Na (CAS 84501-49-5). The worst case 72-hour EC50 and EC10 values are assumed to be 8.64 mg/L and 0.95 mg/L respectively.