Dodecanal

Short-term toxicity to aquatic invertebrates

Description of key information

The test substance was assessed for acute toxicity to aquatic invertebrates according to OECD guideline 202.  The test material was not toxic to Daphnia magna at the limit of solubility. To avoid unnecessary chronic testing, the highest measured soluble concentration of 0.42 to 0.53 mg/L was taken into account for derivation of PNECaquatic.

Additional information

The test substance was assessed for acute toxicity to aquatic invertebrates according to OECD guideline 202. A semi-static test design with test medium renewal at 24 hours in completely filled and sealed vessels was chosen to ensure that the concentration of the test item remained as high as possible over the 48-Hour test period. To avoid the potential photolytic degradation of the test item, the test was carried out in the dark and all test item preparation was performed under laboratory safety lighting and/or shielded from the light.

Pre-study solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e.g. ultrasonication. A pre-study media preparation trial indicated that the use of a prolonged stir saturated solution method of preparation was inappropriate since it resulted in the presence of an additional peak which was considered to be due to the autoxidation of the test item. The results obtained from a solvent spike method of preparation indicated that a maximum dissolved test item concentration of approximately 0.48 mg/l was obtained indicating this to be the solubility limit of this test item under test conditions. The concentration and stability of the test item in the test preparations was verified by chemical analysis at 0 and 24 hours (fresh media) and at 24 and 48 hours (old media).

No immobilisation or adverse effects were observed at the maximum nominal concentration of 0.48 mg/l (the solubility limit of test item in the test media). Thus the 48-hour EC50 was greater than 0.48 mg/L and the corresponding NOEC was 0.48 mg/L based on nominal concentrations.

Chemical analysis of the freshly prepared test media at 0 and 24 hours showed measured test concentrations to range from 0.42 mg/L to 0.53 mg/L (equivalent to 87% to 121% of nominal). A decline in measured test concentration was observed at 24 and 48 hours in the range of 56% to 75% of nominal at 24 hours and less than the limit of quantitation (LOQ) of the analytical method employed, which was determined to be 0.035 mg/l at 48 hours. Based on time-weighted mean measured concentrations, the No Observed Effect Concentration was 0.27mg/L. However, the decline in measured concentrations were a result of unavoidable loss of test substance due to abiotic degradation and therefore cannot be used to derive an EC50 or NOEC.

To avoid unnecessary chronic testing, the initial measured soluble concentrations of 0.42 to 0.53 mg/L were taken into account for derivation of PNECaquatic.