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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The substance was not toxic to algae when tested according to non-specific methods, the substance was determined to possess a 7 day toxicity threshold, approximately equivalent to the LC3, of 1800 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
1 800 mg/L

Additional information

Four studies addressing toxicity to aquatic algae and cyanobacteria are presented in the dossier.

Toxicity to aquatic algae and cyanobacteria.001- scenedesmus – 1980 – key: Acute toxicity to Scenedesmus quadricauda was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements).  Algae were exposed to the substance at a range of concentrations in dilution water (1 part v/v of pollutant solution in 2 to 2 x 1014 parts v/v mixture). The toxic effect measured during the assay was the mean extinction over a time period of 7 days. The study was performed under static conditions using 300 mL glass Erlenmeyer flasks, containing 50 mL of test solution with the algal suspension of the preliminary culture having a known adjusted extinction value.  Test flasks were stoppered with metal caps, incubated at 27°C, and shaken once each day. The extinction value of monochromatic radiation at 578 nm for a 10-mm layer of algal suspension was determined. The toxicity threshold (approximately equivalent to the LC3) based on mean extinction value was determined to be 1800 mg/L.

Toxicity to aquatic algae and cyanobacteria.002 Scenedesmus – 1976: Acute toxicity to Scenedesmus quadricauda was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements). Algae were exposed to the substance under static conditions for 8 days. The toxicity threshold based on growth inhibition was determined to be 1800 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.003 – Microcystis – 1978: Acute toxicity to Microcystis aeruginosa was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements). Algae were exposed to the substance under static conditions for 8 days. The toxicity threshold based on growth inhibition was determined to be 1000 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.004 – Scenedesmus – 1978: Acute toxicity to Scenedesmus quadricauda was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements). Algae were exposed to the substance under static conditions for 8 days. The toxicity threshold based on growth inhibition was determined to be 1800 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.