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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Freshwater:

ErC50 (96 h) = 29.8 mg a.i./L (Key, M-001513-01-1, Pseudokirchneriella subcapitata, OECD 201, mean measured)

NOErC (96 h) = 6.4 mg a.i./L (Key, M-001513-01-1, Pseudokirchneriella subcapitata, OECD 201, mean measured)

Marine water:

ErC50 (96 h) = 15.7 mg a.i./L (Key, M-122128-01-2, Skeletonema costatum, OECD 201, mean measured)

NOErC (96 h) = 6.4 mg a.i./L (Key, M-122128-02-2, Skeletonema costatum, OECD 201, mean measured)

Key value for chemical safety assessment

EC50 for freshwater algae:
29.8 mg/L
EC50 for marine water algae:
15.7 mg/L
EC10 or NOEC for freshwater algae:
6.4 mg/L
EC10 or NOEC for marine water algae:
6.4 mg/L

Additional information

Four experimental studies are available investigating the toxicity of the test item to aquatic algae (M-001513-01-1, M-062300-01-1, M-107701-01-1 and M-122128-01-2). All studies were performed according to OECD 201 and GLP with analytical monitoring of the test item concentration. Three studies were performed with different freshwater species: one green algae species (Pseudokirchneriella subcapitata; M-001513-01-1), one diatom species (Navicula pelliculosa; M-062300-01-1) and one blue-green algae species (Anabaena flos-aquae; M-107701-01-1). One study was performed with a saltwater species (Skeletonema costatum; M-122128-01-1).

For the key study (M-001513-01-1) Pseudokirchneriella subcapitata was exposed under static conditions (shaken cultures) for approximately 96 hours to the following nominal concentrations: Control, Buffered Control, 2.56, 6.4, 16.0, 40.0, 100 and Buffered 100.0 mg a.i./L. Mean measured concentrations were based on the recoveries of the test solutions on Days 0 and 4. The mean measured concentrations were 2.6, 6.4, 16.4, 41.4, 107 and 106 mg a.i./L. This represents a range of 100 to 107% of the nominal test concentrations. Based on regression calculations, cell density (standing crop) is the most sensitive endpoint to exposure to the test item. The 96-hour EC50 for cell density was 11.6 mg a.i./L. The 96-hour EC50 value for growth rate was 29.8 mg a.i./L and the NOEC for growth rate was 6.4 mg a.i./L.

In the study with Navicula pelliculosa (M-062300-01-1) the diatom species was exposed under static conditions (shaken cultures) for approximately 96 hours to the following nominal concentrations: Control, Buffered Control, 6.25, 12.5, 25.0, 50.0, 100 and Buffered 100.0 mg a.i./L. Mean measured calculations were based on the recoveries of the test solutions on Days 0 and 4. The nominal (mean measured) concentrations results were 6.25 (5.95), 12.5 (12.4), 25.0 (25.8), 50.0 (51.4), 100 (105) and buffered 100 (106) mg a.i./L. This represents a range of 95 to 106% of the nominal test concentrations. Recoveries for the control test solutions were below the limit of quantitation (0.51 mg/L). Based on 96-hour regression calculations, cumulative biomass is the most sensitive endpoint to exposure to the test item. The 96-hour EC50 value for cumulative biomass was 50.8 mg a.i./L. The LOEC for the study was 12.4 mg a.i./L and the NOEC was 5.95 mg a.i./L based on 96-hour cumulative biomass. The 96-hour EC50 value for growth rate was 87.8 mg a.i./L and the NOEC for growth rate was 51.4 mg a.i./L.

In the study with Anabaena flos-aquae (M-107701-01-1) the blue-green algae species was exposed under static conditions (shaken cultures) for approximately 96 hours to the following nominal concentrations: Control, Buffered Control, 2.56, 6.4, 16.0, 40.0, 100 and Buffered 100.0 mg a.i./L. Mean measured calculations were based on the recoveries of the test solutions on Days 0 and 4. The mean measured concentrations were 2.4, 6.3, 16.3, 40.1, 104 and 102 mg a.i./L. This represents a range of 94 to 106% of the nominal test concentrations. Based on regression calculations, cell density (standing crop) is the slightly more sensitive endpoint to exposure to the test item. The 96-hour EC50 for cell density was 43.5 mg a.i./L. The LOEC for the study was 2.4 mg a.i./L based on 96-hour cumulative biomass. The 96-hour EC50 value for growth rate was 48.8 mg a.i./L and the NOEC for growth rate was 40.1 mg a.i./L. 

The key study of the marine species Skeletonema costatum (M-122128-01-2) was exposed under static conditions (shaken cultures) for 96 hours to the following nominal concentrations: Control, 2.56, 6.4, 16.0, 40.0 and 100.0 mg a.i./L. Mean measured calculations were based on the recoveries of the test solutions on days 0 and 4. The mean measured concentrations were 2.53, 6.4, 16.4, 41.1 and 99.5 mg a.i./L. This represents a range of 99 to 103% of the nominal test concentrations. Based on regression calculations, cumulative biomass is the most sensitive endpoint to exposure to the test item. The 96-hour EC50 for cumulative biomass was 9.2 mg a.i./L. The 96-hour NOEC and LOEC were 6.4 mg a.i./L and 16.4 mg a.i./L, respectively for all endpoints. The 96-hour EC50 value for growth rate was 15.7 mg a.i./L and the NOEC for growth rate was 6.4 mg a.i./L.