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Toxicity to aquatic algae and cyanobacteria

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Description of key information

There are no experimental data available for the test item. Therefore, a read-across approach is applied. The following threshold values were obtained for toxicity to aquatic algae for the respective source substance:

 

ErC50 > 56.2 mg LAS TEA/L

EC10 = 17.3 mg LAS TEA/L

NOEC = 3.4 mg LAS TEA/L

 

ErC50 = 128 mg LAS Na/L (Scholz RL1)

EC10 = not determined

NOEC = 2.4 mg LAS Na/L (Scholz RL1)

 

ErC50 = 14.9 mg DEA/L

EC10 = 2.4 mg DEA/L

NOEC = not determined

Key value for chemical safety assessment

EC50 for freshwater algae:
128 mg/L
EC50 for marine water algae:
12.8 mg/L
EC10 or NOEC for freshwater algae:
2.4 mg/L
EC10 or NOEC for marine water algae:
0.24 mg/L

Additional information

No experimental data on toxicity to aquatic algae is available for the test item. However, experimental data for three source substances is available and a read-across approach is applied. Please refer to read-across justification document attached in IUCLID Section 13. Furthermore, only key studies are taken into account here. For further supporting information please refer to respective REACH registration dossier of each source substance.

LAS TEA (CAS 121617 -08 -1)

Scenedesmus subspicatus was exposed to concentrations of 0, 0.8, 1.7, 3.4, 7.0, 14.1, 28.1 and 56.2 mg/L of Benzenesulfonic acid, C10-13-alkyl derivs., compds. with triethanolamine (CAS no. 68411-31-4) for 72 hrs. The cell concentration was measured at 24, 48, and 72 hrs. The 72-hr NOEC for algae was 3.4 mg/L. The 72 -hr EbC50 was 52.8 mg/L, and the 72-hr ErC50 was > 56.2 mg/L for algae.

LAS NA (CAS 68411 -30 -3)

In a 96 hour algae growth inhibition test, the green algae Microcystis aeruginosa was exposed to Linear Alkylbenzene Sulfonate (C11.9 LAS) in accordance with USEPA OPPTS 850.5400. The nominal test concentrations were 0 (control), 0.01, 0.05, 0.1, 0.5, 1.0 and 1,000 mg a.i./L. The 96 hour EC50, based on cell number, was 0.91 mg a.i./L (0.84 -10.0). The NOEC is estimated to be 0.35 mg/L for C11.6 LAS (van de Plassche et al., 1999). This algal growth inhibition test satisfies the guideline requirements of the USEPA OPPTS 850.5400.

 

Scenedesmus subspicatus was exposed to concentrations of 0, 0.6, 2.4, 10, 40, or 160 mg/L of test substance for 72 hrs. The cell concentration was measured at 24, 48, and 72 hrs. The 72-hr NOEC for algae was 2.4 mg/L. The 72-hr EbC50 was 47.3 mg/L, and the 72-hr ErC50 was 127.9 mg/L for algae. The NOEC of 2.4 mg/L does not require normalization since the compound tested was C11.6 LAS.

 

This study was done to determine the toxicity of the test substance to aquatic algae. Selenastrum capricornutum was exposed to the test substance for 96 -hrs. During this time, the cell density of the algae was measured. The 96 -hr NOEC was 0.5 mg/L. The 96 -hr LOEC was 1 mg/L. The 96 -hr EC50 was 29.0 mg/L based on cell density. Normalized to C11.6 LAS, the value is 0.58 mg/L for the NOEC (method: van de Plassche et al., 1999).

 

Chlorella kessleri algae was exposed to concentrations of 0, 0.01, 0.03, 0.1, 0.3, 1, 3, 10, 30, 100, 300, and 1000 mg/L (nominal) of test substance for 15 days. The number of cells were counted to determine the toxicity of the test substance. The NOEC was 3.1 mg/L active ingredient, and the FOEC was 10 mg/L active ingredient. The data are for C11.6 LAS and no normalization is required.

 

DEA (CAS 111 -42 -2)

The effect of neutralised test solutions with DEA was examined in a screening study with Desmodesmus subspicatus in 72-hour static tests following the German Industrial Standard DIN 38412, part 9. The following nominal test substance concentrations were set up in each of the four tests: 0, 0.78, 1.56, 3.13, 6.25, 12.5, 25.0, 50.0, and 100.0 mg/L. Test concentrations were not verified analytically. The pH values were measured in all concentrations including control using a separate sample without algae at the beginning and the end (72 h) of the test. At the end of the test, pH measurements were also done in the inoculated samples. With neutralised samples, the pH values ranged from 7.7 - 8.1 at test start to 8.0 - 8.5 (without algae), respective 8.3 - 9.0 (with algae) after 72 h. In the non-neutralised samples, the pH values ranged from 7.4 - 8.8 at test start to 7.9 - 8.5 (without algae), respective 8.3 - 9.0 (with algae) after 72 h. The algal biomass was determined with a fluorimeter at the onset of the test and after 48 and 72 h. The measured data of the screening tests were re-evaluated with ToxRat v2.10 (BASF SE, 2015). The respective 72-h ErC50 values for Desmodesmus subspicatus were 14.9 mg/L (neutralised).