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Long-term toxicity to aquatic invertebrates

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Description of key information

On the basis of a QSAR-model a NOEC for the substance is calculated to be 0.479 mg/L

Key value for chemical safety assessment

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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 -16 alkyl sulfate sodium salt mixture (CAS 73296 -89 -6) 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 73296 -89 -6) with an amount of 60 -71%.

In the non-GLP study of Memmert (Hansa, 1991), which was conducted equivalent to OECD guideline 202, part 2,Daphnia magnawas 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 testCeriodaphnia dubiawas 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 -16 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) 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 65% C12, 25% C14 and 10% C15 (C15 is used as worst-case assumption as the model does not contain data for C16 AS which are expected be lower toxic as C15) for the mixture C12-16 alkyl sulfate sodium salt the QSAR-calculation resulted in a NOEC value for reproduction of 0.479 mg/L. This value is used by taking into account an assessment factor of 5 for the PNEC-calculation.

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 SIAM 25, 17 -18 October 2007, SIDS initial assessment profile, Chemical Category Alkyl Sulfates, Alkane Sulfonates and

a-Olefin Sulfonates