Tetraammonium ethylenediaminetetraacetate

Short-term toxicity to fish

Description of key information

With high probability the test substance is acutely not harmful to fish.

Additional information

The toxicity of EDTA on 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 take into account the water hardness and pH. The revealed LC50 -values are in a range of 41 mg/L to 2070 mg/L.

Two consequences 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 in the environment; therefore the results derived by soft water hardness and/or pH <4 are not relevant for the assessment.

The 96-hour LC50 value of (NH4)4EDTA 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 are present as free ammonia, resulting in a NH3 concentration of 2.3 mg/L. Generally a NH3 concentration above 1 mg/L can be considered as toxic alone to fish. Thus, the results of the experiment with (NH4)4 EDTA are also not relevant for the risk assessment.

 

Consequently the LC50 of EDTA is estimated to be higher 1000 mg/L, due to the fact that this predicted value represents the lowest LC50 at acceptable pH which has been performed in natural not synthetic water. The results indicate that for complexed and non complexed EDTA no need for classification as dangerous for the environment. Further on, the results show that the toxicity of complexes with the toxic metals Cu and Zn is in the same concentration range as the uncomplexed EDTA. Chelates with non-toxic metals (Mn, Ca, Mg) are much less toxic. For justification for read-across please refer to IUCLID 5, Chapter 13.