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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

3h EC50 (activated sludge, domestic) = 135 mg/L (respiration inhibition test, similar to OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:
135 mg/L

Additional information

Two reliable studies investigating toxic effects of Sodium dodecyl sulfate (CAS 151-21-3) to aquatic microorganisms are available. The key study was performed using activated sludge from a municipal sewage treatment plant (Dutka 1983). The non-GLP test was performed according to a guideline similar to OECD 209. EC50 values of 188 and 135 mg/L (nominal concentrations) were obtained for the endpoint respiration inhibition after 30 minutes and 3 hours of exposure, respectively.

In addition, supporting studies are availabe with (i) the substance itself (CAS 151-21-3) and a read across substance (CAS 90583-18-9) containing C14 alkyl sulfate which is considered to be the most toxic chain length based on the data available for memebers of the alkyl sulfate category.

One non-GLP study with sodium dodecyl sulfate (CAS 151-21-3) was performed by Dutka and Kwan (1984) using synthetic activated sludge as inoculum. The respiration rate was measured after a contact time of 3 hours. The 3h-IC50 value was determined to be 480 mg/L based on the nominal concentration.

One study with the read across substance Sulfuric acid, mono C12-14, alkyl ester, compounds with triethanolamine (CAS 90583-18-9) was performed according to GLP and DIN guideline 38412 part 8 using Pseudomonas putida as test organism (Guhl 1992). The growth inhibition was measured after 16 hours of exposure. The 16-h EC10 value was determined to be 1084 mg a.i./L (nominal concentration).

The supporting studies indicate that the EC50 value of 135 mg/L may overestimate the toxicity of sodium dodecyl sulfate. However, in order to be consistently conservative, the 3-hour EC50 value of 135 mg/L obtained by Dutka (1983) was used as key study and for PNEC STP derivation.