Ethylenediamine-N,N'-di(acetic acid)

Short-term toxicity to fish

Description of key information

For H2 ED2A, no acute fish toxicity data is available. The available data for H4 EDTA is therefore read across to H2 ED2A. Justification of this read across is presented in the read across document included in Chapter 13 of IUCLID.

For H4 EDTA the following results were found for the acute toxicity to fish: with high probability the test substance is not acutely harmful to fish.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 000 mg/L

Additional information

No data on the short term toxicity to fish is available for H2 ED2A. Consistent with the other ecotoxicity endpoints, the available data from H4 EDTA are read-across to fill the datagap. All ecotox, fate and phys-chem data from H4 EDTA, Na2H2 EDTA, Na4 EDTA, HEDTA, H2 ED2A etc have been collated in a document which is compiled to justify the read across. This document is included in IUCLID 6, Chapter 13.

The toxicity of EDTA to fish highly depends on water hardness, pH and metal speciation [EU Risk Assessment, 2004]. The toxicity of EDTA complexes to bluegill was determined in a key study performed by Batchelder et al. (1980), which takes into account the water hardness and pH. The revealed LC50 -values are in a range of 41 mg/L to 2070 mg/L.

Two conclusions can be drawn. First, the tests performed with the acid form lead to very low pH values under test conditions. A pH of 4 alone leads to toxicity in bluegill. The low LC50 value in very soft water can be explained by a surplus of uncomplexed EDTA which was present in the test media. This is not expected to occur in the environment where EDTA may be emitted; the results from this study where conditions of soft water hardness and/or pH <4 are considered to be not representative and therefore not relevant for the assessment.

The 96-hour LC50 value of (NH4)4 EDTA was determined to be 705 mg/L. at pH 8. The toxicity is driven by ammonia. At pH 8 ca. 5.3 % of the total ammonia is present as free ammonia, resulting in a NH3 concentration of 2.3 mg/L. Generally an NH3 concentration above 1 mg/L can be considered as toxic to fish. The results of the experiment with (NH4)4 EDTA are also not relevant for the risk assessment of other EDTA complexes..

Based on the available data and taking the specific fate of EDTA into account the LC50 of EDTA is estimated to be higher than 1000 mg/L, due to the fact that this predicted value represents the lowest LC50 at environmentally relevant pH which has been performed in natural not synthetic water. The results indicate that for complexed and non complexed EDTA there is no need for classification as dangerous for the environment. In addition, the results show that the toxicity of toxic metal ions like Cu2 + and Zn2 + is significantly reduced when complexed with EDTA.