Sodium 2-sulphonatoethyl laurate

Endpoint summary

Additional information

For the aquatic ecotoxicity endpoints a number of results have been read-across from Fatty acids, C12-18 and C18-unsatd., 2-sulfoethyl esters, sodium salts and coco fatty acids 2 -sulfoethyl sodium salt to lauric acid, 2 -sulphethyl, sodium salt.. Read-across from the source chemical Fatty acids, C12-18 and C18-unsatd., 2-sulfoethyl esters, sodium salts (CAS no 85408-62-4) and coco fatty acids 2-sulfoethyl sodium salt to the target chemical is considered to

be justified as the substances are very similar and the source chemicals contains a higher content of longer alkyl chain products which are known to be more toxic than the shorter alkyl chain products. The conclusion that the source chemical is more toxic than the target chemical is considered sufficient to select the more toxic derivative as the worst-case representative in the hazard assessment of both substances. For this reason read-across of ecotoxicity results of the source chemicals (C12-18 and C18-unsatd and coco) to the target chemical (lauryl) is considered to be justified without the introduction of an additional safety factor.

An overview of the most relevant results is provided in the table.

Method	Results	Results, converted to active ingredient	Remarks	Reference
Acute fish 96h OECD 203	LC50 > 25 mg/L	LC50 > 9.9 mg/L (geomean)	Reliability 2	Unilever, 1982
Acute Daphnia 48h OECD 202	EC50 > 50 mg/L	EC50 ca 229.7 mg/L	Reliability 2 QSAR	Roberts, J 2008
Algae 72h OECD 201	ErC50 > 4.8 mg/L	ErC50 > 4.8 mg/L	Reliability 1 Read-across	Roberts, J 2008
Activated sludge OECD 209	EC50 = 1000 mg/L	EC50 = 687 mg/L	Reliability 2	Reinhardt, J 1994
Algae 72h OECD 201	ErC10 = 0.31 mg/L	ErC10 = 0.3 mg/L	Reliability 1 Read-across	Roberts, J 2008
Chronic Fish (FELS)OECD 210	NOEC= 0.045 mg/L	NOEC= 0.4 mg/L	Reliability 2  Calculation	Hurd, 2009
Chronic Daphnia OECD 211	NOEC= 0.154 mg/L	NOEC= 1.1 mg/L	Reliability 2  Calculation	Roberts, J 2010

 

 

Conclusion

Acute toxicity results are available for three taxonomic groups (fish, invertebrates and algae). Solubility of fatty acid 2-sulfoethyl esters differs strongly with the alkyl chain length. The test substance has as for many other surfactants a specific Krafft point/cmc relation which means that at certain temperatures and concentrations cristallinic gels can be formed. 

Great effort has therefore being paid in preparing the test solutions and in quantifying the dissolved fraction of the different alkyl chain 2-sulfoethyl esters during the aquatic ecotoxicity tests. Most of the Key datapoint for the PNEC derivation is the algae study which is read-across from Fatty acids, C12-18 and C18-unsatd., 2-sulfoethyl esters, sodium salts to lauric acid 2 -sulfoethyl sodium salt. The lauric acid 2-sulfoethyl sodium salt contains a lower content of the more toxic but also less soluble longer alkyl chain 2-sulfoethylesters. Due to this lower solubility of the longer alkyl chain 2-sulfoethyl esters and evaluating the solubility data for each alkyl chain 2-sulfoethyl ester it is very likely that the fraction of the toxicity determining longer alkyl chains is almost equal for both substances when dissolved under the same conditions.

Further to the above, chronic toxicity values for lauric acid 2 -sulfoethyl sodium salt have been calculated for both Fish Early Life Stage and Daphnia using a toxic unit approach. The predicted toxicity of each chain length was calculated using a polar narcotic QSAR relevent for the respective species and the relative toxicities of thedifferent molecular species expressed as a ratio of the molar dissolved fraction to thepredicted toxicity. The results show that the lauroyl species contributes to 4% and 5.3% of the overall toxicity of the tested substances in the FELS and daphnia studies respectively.