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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Hydrolysis product: Stearic acid: Acutely harmful to aquatic algae. No toxic effects within range of water solubility.
Hydrolysis product: HCl: Acutely very toxic to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
11.72 mg/L

Additional information

No data on the toxicity of stearoyl chloride is available. However, since the test substance rapidly hydrolyses in water, algae are mainly exposed to the hydrolysis product stearic acid.

The toxicity of stearic acid to algae is assessed via a study with the green alga Pseudokirchneriella subcapitata. Solvent (DMSO) was used to achieve the desired test concentrations. The 72 -h EC50 (cell number) of 11.72 mg/L indicates that stearic acid is acutely harmful to aquatic algae (Kamaya et al., 2003). The determined EC50 lies clearly above the water solubility limit (0.6 mg/L). Therefore it can be assumed that no toxic effects will occur within the range of water solubility.

The hydrolysis product hydrochloric acid (HCl) was tested in an algae growth inhibition test according to OECD 201 with Pseudokirchneriella subcapitata. The 72-h ErC50 was 0.492 mg/L (acid equivalent to pH 5.3), the 72 -h NOEC was 0.097 (acid equivalent to pH 6; OECD 2002).