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Short-term toxicity to fish

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Description of key information

The acute toxicity of aspartic acid, N,N'-[methylenebis(2-methyl-4,1-cyclohexanediyl)]bis-, 1,1',4,4'-tetraethyl ester towards fish (Brachydanio rerio) was determined according to the OECD-Guideline 203 yielding a LC0(96 h) ≥ 5 mg/L as no adverse effects were observed at testing concentrations up to the water solubility limit of the test item. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
5 mg/L

Additional information

As the concentration of the test item decreased below 80 % of the nominal concentration, analytical values based on the arithmetic mean of the measured concentrations, were used for the effect evaluation. The losses might be assigned to hydrolytic degradation processes as the stability of the test item in aqueous media at pH 7 and a temperature of 25 °C is characterised by a dissipation half-life of 25.4 h. Therefore, the observed effects cover both, the toxicity of the parent substance as well as the toxicity of the hydrolysis products, although the test media was renewed daily.

To produce the test solutions the test item was weighed daily into water and treated with an ultra-turrax for a selected period. The solution was not filtrated prior to use causing the presence of undissolved particles in the test vessels. Consequently, it cannot be excluded that the observed effects are caused by undissolved particles rather than the dissolved (bioavailable) fraction of the test item. These facts are confirmed by the findings that all of the effective concentrations reported were above the water solubility limit of 5 mg/L.

The investigated concentration range covered concentrations below as well as above the water solubility limit. Even at the first concentration exceeding the water solubility limit, assuming a saturated solution containing the maximal achievable concentration, no adverse effects were observed. Based on these findings it can be concluded that there are no effects up to the water solubility limit of aspartic acid, N,N'-[methylenebis(2-methyl-4,1-cyclohexanediyl)]bis-, 1,1',4,4'-tetraethyl ester and the toxicity toward fish is preferably characterised by a LC0 ≥ 5 mg/L. Therefore, the reported LC50(96 h) of 66 mg/L was not used for the hazard assessment.

Study was performed with aspartic acid, N,N'-[methylenebis(2-methyl-4,1-cyclohexanediyl)]bis-, 1,1',4,4'-tetraethyl ester which is a structural analogue to aspartic acid, N,N'-(methylenedi-4,1-cyclohexanediyl)bis-, 1,1',4,4'-tetraethyl ester. Both substances are diethyl esters of aspartic acid linked to a dicyclohexylmethyldiamine moiety. The difference between these two substances is merely the presence of two methyl groups connected to the cyclohexane rings. This structural analogy was confirmed by the Member State responsible for the notification of both substances under the NONS regulation. The Member State decided that test results obtained for one substance can be transferred to the other substance and that testing of both substances is usually not required. This decision is in accordance with the grouping of substances and read-across approach in Annex XI, 1.5 of the REACH Regulation.