Disodium adipate

Short-term toxicity to fish

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. In a test of adipic acid with fish (Danio rerio) a LC0 of >=1000 mg/l after 96 hours is obtained. The study was conducted according UBA-Verfahrensvorschlag: "Letale Wirkung beim Zebrabaerbling Brachydanio rerio, LC0, LC50, LC100; 48-96 h" , Mai 1984 (Bayer AG, 1991) in buffered medium. The effect concentrations were confirmed by analytical monitoring.

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.

There are studies on toxicity to fish of lower values for adipic acid available. The studies were discussed in the ICCA OECD/HPV-program as follows.

In a study with adipic acid, conducted according to US-EPA Method 660/3-75-009 a 96 h-LC50 of 97 mg/l for Pimephales promelas was determined. (Mattson, 1976). The authors note that the pH was < 5.9 during the test. In addition, there is no exact information on oxygen content of the test solutions. It is only reported that the oxygen content was not < 4 mg/l. Therefore, it cannot be excluded that the toxicity observed was due to pH effects and possibly oxygen limitations. A reliability score of 3 (invalid) was assigned and the study should not be used for the hazard assessment of adipic acid.

In another acute test performed with Leuciscus idus according to the German national standard method DIN 38412 Part 15 a 96 h-LC50 of 230 mg/l for adipic acid was obtained (BASF, 1980). Also in this study the pH of the test solutions was in the range of 3.8 to 7. For the concentration 215 mg/l that is in the same order of magnitude with the LC50 the pH was between 4.3 and 4.7 and therefore pH related effects cannot be excluded. Additionally, a test at a concentration of 464 mg/l in neutralised test solution was carried out. The exposure duration was not reported. No effects were observed. For this reason also this study should not be used for the hazard assessment.

Further, lower values on toxicity of adipic acid to fish are found for the species Oryzias latipes (MITI, 1997). First, a 96h-LC50 > 100 mg/l conducted according to OECD TG 204 “Fish, Acute Toxicity Test” is reported. Second, a 14d-LC50 of 80 mg/l is obtained following the OECD TG 204 “Fish, Prolonged Toxicity Test: 14-day-Study”. As no information is given on pH, the studies are stated to be reliable, but should not used for the hazard assessment, based on the given reasons resulting from the discussion above.