Sulfuric acid, C10-12 (even numbered)-alkyl esters, sodium salts

Toxicity to aquatic algae and cyanobacteria

Description of key information

72h EC10 (growth rate) =  1.3 mg/L
72h EC50 (growth rate) = 11.5  mg/L 

Key value for chemical safety assessment

EC50 for freshwater algae:

11.5 mg/L

EC10 or NOEC for freshwater algae:

1.3 mg/L

Additional information

Since no reliable aquatic algae test is available for C10-12AS Na (CAS 85049-86-1), 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).

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. There values were further used for the derivation of EC50 and EC10 values for C10-12AS Na (CAS 85049-86-1).

Moreover, a 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). The study of Nyholm and Damgaard (1990) resulted in more conservative toxicity values, and therefore the EC10 of 12 mg/L and EC50 of 117 mg/L (both for growth rate) are considered as the reliable values for aquatic algae for C12AS Na (CAS 151-21-3). These values were further taken for the calculation of the EC50 and EC10 values of C10-12AS Na (CAS 85049-86-1).

Due to structural and property similarities with the tested category member these results also apply to C10-12AS Na (CAS 85049-86-1). The 72-hour EC50 and EC10 values for the C10-12AS Na (CAS 85049-86-1) were calculated based on the results for both homologues using the additivity formula as stipulated in the EC Regulation 1272/2008. The following values were used in the calculation of the EC50: 8.64 mg/L and 117 mg/L recorded for C10AS Na (CAS 142-87-0) and C12AS Na (CAS 151-21-3) respectively. For the EC10 calculations the values of 0.95 mg/L and 12 mg/L were taken into account; they were recorded for C10AS Na (CAS 142-87-0) and C12AS Na (CAS 151-21-3) respectively. The composition of C10-12AS Na (CAS 85049-86-1) used for the calculations was based on the normalized mean values of provided ranges: C10: 72% and C12: 28%. The EC50 value of C10 -12AS Na (CAS 85049-86-1) is 11.5 mg/L and the EC10 value is 1.3 mg/L.