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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Ethanol:
FRESHWATER
Chlorella vulgaris; EC50 (72hr) = 275mg/l; EC10 (72hr) = 11.5mg/l
Isopropanol:
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.
Selenastrum capricornutum EC50 (72hr) = 12900mg/l; EC10 (72hr) = 440mg/l
Chlamydomonas eugametos: EC50 (48hr) ~ 18000mg/l NOEC (48hr) = 7900mg/l
SEAWATER
Skeletonema costatum: EC50 (9 day): 10940 mg/l; NOEC (5 days): 3240mg/l

Key value for chemical safety assessment

EC50 for freshwater algae:
675 mg/L
EC50 for marine water algae:
10 943 mg/L
EC10 or NOEC for freshwater algae:
86 mg/L
EC10 or NOEC for marine water algae:
3 240 mg/L

Additional information

There are no data available for the reaction mass. The lowest EC50 value for freshwater species based on growth rate with an exposure time of 72 hrs was derived from a study with ethanol and was 675 mg/l. From that study an EC10 value of 86 mg/l was derived. For saltwater species values were derived from a study with ethanol showing an EC50 value of 10943 mg/l and a NOEC value of 3240 mg/l. These values will be taken forward to the risk assessment, representing a worst-case value for the reaction mass.

Ethanol:

In a study which followed the basic principles of a guideline study, two green algae Chlorella vulgaris and Selenastrum capricornutum were exposed to ethanol at sufficient concentrations to enable EC50 values to be established. Exposure was carried out over 5 days with daily measurements of growth characterised by chlorophyll measurement. The dose response curve obtained was very shallow. The four day data presented showed some evidence that the control had passed the exponential growth phase. Basing the results on the 3 day measurements when exponential growth was still clearly evident, ethanol showed slight toxicity to the Chlorella species but not to the Selenastrum species. EC10 (72hr) values were= 11.5mg/l and 440mg/l respectively.  EC50 (72hr) values were 275mg/l and 12900mg/l respectively.

In a well described study, the marine diatom Skeletonema costatum was exposed to ethanol for a period of 5 days and at concentrations sufficient to derive both an EC50 value and a NOEC. From the results, ethanol was not toxic to this species.

Isopropanol

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 toScenedesmus quadricaudawas 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 1014parts 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 toScenedesmus quadricaudawas 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 toMicrocystis aeruginosawas 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 toScenedesmus quadricaudawas 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.