Dodecanal

Toxicity to aquatic algae and cyanobacteria

Description of key information

The test substance was assessed for toxicity to aquatic algae in 2 studies performed according to OECD guideline 201. The study performed using a conventional system as opposed to sealed vessels is considered more environmentally relevant. Under the conditions of this test, the growth rate and yield of Pseudokirchneriella Subcapitata were not affected by the presence of the test material up to the limit of solubility (0.35 mg/l initial measured concentration). In the absence of toxic effects, this concentration value is taken into account for derivation of PNEC(aquatic).  The substance is considered to exhibit no effects at the limit of solubility for classification purposes.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

0.35 mg/L

Additional information

Two studies were performed on the test substance according to OECD guideline 201. In the first, the test material was tested in a closed system as it was thought that the volatile nature of the test material would result in loss of test material from the test vessel. However, it was demonstrated that the closed system placed undue stress on the test organisms, resulting in a lower EC₅₀value than would occur in a real world scenario. The test was therefore repeated in an open system, which more accurately reflects a real world scenario. This study was used as the key study for chemical safety assessment purposes. The test item was prepared using a preliminary solution in dimethylformamide. The nominal test concentration of 0.48 mg/L was the highest attainable test concentration that could be prepared due to the limited solubility of the test item in water and auxiliary solvent and having due regard to the amount of auxiliary solvent permitted in the study under the OECD Guideline. The growth rate (r) and yield (y) of Pseudokirchneriella subcapitata were not affected by the presence of the test item over the 72-Hour exposure period. Based on 0-Hour measured test concentrations the EC50 was greater than 0.35mg/L and the No Observed Effect Concentration was 0.35 mg/L (the solubility limit of the test item in the test media). Based on the geometric mean measured test concentrations the NOEC was 0.048 mg/L. However, due to unavoidable loss of test substance due to abiotic degradation and the conventional test system the NOEC based on geometric mean measured concentrations should not be used for CSA purposes. Instead, the initial measured soluble concentration of 0.35 mg/L is considered for derivation of PNEC and no effects at solubility for classification.