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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The EC50 (72 h) for algae is calculated to be 5.2 mg/L with 37.9% active ingredient and 1.97 mg/L for 100% substance . The NOEC was determined to be 3.2 mg/L with 37.9% active ingredient and 1.2 mg/L for 100% substance .

Key value for chemical safety assessment

EC50 for marine water algae:
1.97 mg/L
EC10 or NOEC for marine water algae:
1.2 mg/L

Additional information

No reliable study for freshwater algae species is available, but there is a reliable study with a marine species. However, the toxicity of freshwater and saltwater species are considered to be in the same order of magnitude based on the data for aquatic invertebrates: the EC50(48 h) of the freshwater invertebrate speciesCeriodaphnia dubiaresulted in 4.53 mg/L, the EC50(48 h) of the marine copepode Acartia tonsa was 5.5 mg/L. Therefore, freshwater algae exposed toSulfonic acids, C14-16 (even numbered)-alkane hydroxy and C14-16 (even numbered)-alkene, sodium saltsare expected to exhibit similar sensitivity as marine species, and the study with the marine species Skeletonema costatum is also reliable to cover freshwater species. This assumption is supported by further data on freshwater species which have been tested with longer chain AOS than C14-16. Long-chain AOS are consistently more toxic than those with shorter alkyl chains (Little, 1993). Data for the freshwater alga Selenastrum capricornutum exposed to AOS with a chain length of C14-18 (mean: 16.4) or C16-18, respectively, have been published resulting in an EC50of 45 mg/L (Yamane et al., 1984) and > 20 mg/L (Konno & Wakabayashi, 1987). As the test duration was 48 h (Yamane et al., 1984), the test result (EC50= 45 mg/L) can only be considered as indication for the effect concentration. The chain lengths of the substances tested were longer and therefore expected to be more toxic than AOS with chain lengths of C14-16 considered forSulfonic acids, C14-16 (even numbered)-alkane hydroxy and C14-16 (even numbered)-alkene, sodium salts. Based on these considerations it is justified to use the test with marine algae exposed toSulfonic acids, C14-16 (even numbered)-alkane hydroxy and C14-16 (even numbered)-alkene, sodium saltsfor the hazard assessment of freshwater algae and for classification and labelling purposes.

The 72h-EC50(growth rate) is 5.2 mg/L for Skeletonema costatum (Hushagen, 1997). The 72h-EC10and 72h-NOEC based on growth rate were 3.9 mg/L and 3.2 mg/L for 37.9% substance, respectively. If recalculated for 100% substance the72h-EC50(growth rate) is 1.97 mg/L and the NOEC is 1.2 mg/L.