Disodium adipate

Short-term toxicity to aquatic invertebrates

Description of key information

Based on the absence of data for disodium adipate, results from the corresponding acid are taken into account for this endpoint. Assessing the toxicity to aquatic invertebrates, Daphnia magna was exposed to adipic acid for 48 hours. The experiment was conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test). The test gave a 48-h EC50 value of 46 mg/L (MITI, 1997).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

46 mg/L

Additional information

Based on the absence of data for disodium adipate, a read-across approach with adipic acid is applied. In aqueous media, disodium adipate and adipic acid acid dissociate into the corresponding anion (1,6-hexandioic acid ion) and the sodium ion and hydrogen ion (proton), respectively. Fate, behavior and the ecotoxicological properties of adipic acid and its disodium salt are thought to be an effect of the di-carboxylate ion rather than of the sodium ion or the hydrogen ion (proton), which are normal constituents in environmental systems and have no relevant ecotoxic properties in low concentrations. Therefore a read-across between disodium adipate and adipic acid is justified.

Preparing the SIDS-dossier within the scope of the ICCA/HPV-program the study conducted by the National Institute of Technology and Evaluation, Japan was not available. The following study was taken into account.

With the invertebrate Daphnia magna one acute test according to the European guideline 79/831/EEC, method C.2 is available. For a test period of 24 hours an EC50 value of 85.6 mg/l was obtained. The same effect concentration was reported after a test period of 48 hours (BASF AG 1988b). pH values in the test solutions ranged from 4 (500 mg/l) to 7.7 (15.6 mg/l) and pH related effects on the daphnids cannot be excluded.

This study on daphnids was characterized by a concentration-dependant decrease of pH. During the test on Daphnia, the treatments testing adipic acid's concentrations near the EC50 value presented a pH markedly inferior to the control treatment. At the end of the 48-hour exposure period, the pH in the control treatment was 7.95, whereas it decreased from 7.2 to 5.26 in the range of concentrations (62.5 - 125 mg/L) covering the EC50 value (85.6 mg/L). Furthermore, it should be noticed that the pH value in the control treatment is high compared to the guideline's requirements. Based on this observation, a pH effect cannot be ruled out when considering the toxicity reported in this study.

Describing the toxicity towards aquatic invertebrates, the study conducted by the National Institute of Technology and Evaluation, Japan

is preferred, despite deficiencies in study documentation concerning pH.