Sulfuric acid, mono-C12-14-alkyl esters, sodium salts

Long-term toxicity to aquatic invertebrates

Description of key information

On the basis of a QSAR-model a NOEC for the substance is calculated to be 0.508 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.508 mg/L

Additional information

A weight of evidence approach is performed using experimental data of two chronic invertebrate studies available for alkyl sulfate sodium salts. In the first study daphnids (Daphnia magna) were exposed to a C12-15 alkyl sulfate sodium salt mixture (CAS 68890-70-0). In the second study the pure homologue C12 alkyl sulfate sodium salt (CAS 151-21-3) was tested on another daphnid species (Ceriodaphnia dubia). As the C14 -chain length is regarded to be the most toxic in chronic tests on aquatic organisms (OECD SIDS, 2007), the C12-15 alkyl sulfate sodium salt mixture (CAS 68890-70-0) is expected to be comparable to the C12 -14 alkyl sulfate sodium salt mixture (CAS 85586 -07 -8) and thus a read-across is possible. The data available for the pure homologue C12 were evaluated since this chain length is the main component of the mixture C12-14 alkyl sulfate sodium salts (CAS 85586-07-8) with an amount of 45-80%.

In the non-GLP study of Memmert (Hansa, 1991), which was conducted equivalent to OECD guideline 202, part 2, Daphnia magna was exposed to C12-15 alkyl sulfate sodium salts over 21 days in a static system. The test resulted in a NOEC of 0.14 mg/L for mortality and in a NOEC of 1.2 mg/L which is more relevant for a chronic test conducted to evaluate sublethal effects. This NOEC is within the same range as the result reported in a reproduction study of Lauth (P&G, 1996) conducted with the pure homologue C12. In that test Ceriodaphnia dubia was exposed in a flow-through system over 7 days. The resulting NOEC for reproduction was 0.88 mg/L.

From the reported data it could be concluded that the NOEC for the mixture C12-14 alkyl sulfate sodium salts would be in the same range as the NOEC values summarized above. Nevertheless, a QSAR-calculation is conducted by using a model reported by Dyer et al. (1997) and Dyer et al. (2000) evaluated on the basis of chronic tests on Ceriodaphnia dubia. In the chronic tests the daphnids were exposed to alkyl sulfates of different chain lengths and the resulting NOEC-values were used in the model. By taking into account a mixture composition of maximum contents of 70% C12, 25% C14 and 5% C15 for the mixture C12-14 alkyl sulfate sodium salt the QSAR-calculation resulted in a NOEC value for reproduction of 0.508 mg/L.

Additionally, the 2 day chronic toxicity of C14 alkyl sulfate to rotifer (Brachionus calyciflorus) was determined under the static test conditions. The effect parameters observed were number of live, swimming rotifers and reproduction. The results were based on measured test substance concentration. At 48 hour, mean number of rotifer young found in replicate vessels at 0.047, 0.093, 0.186, 0.373 and 0.746 mg/L were 44.33, 42.0, 43.0, 25.66 and 3.66 respectively and mean number of rotifer young found in control replicates was 41.66. Under the conditions of this test, the 2 day EC10 value of C14 alkyl sulfate to rotifer (Brachionus calyciflorus) was 0.24 mg/L (95% CI 0.18 -0.33 mg/L), based reproduction and survival of rotifers.

References:

Dyer et al. (1997). Development of a chronic toxicity structure-activity relationship for alkyl sulfates.Environmental Toxicology and Water Quality 11, 335-343.

OECD SIDS Initial Assessment Report For SIAM 25, 19. October 2007