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Data on aquatic toxicity are not available for tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate and a read-across approach with the corresponding parent acid 2-phosphonobutane-1,2,4-tricarboxylic acid is proposed.

In aqueous media, tetrasodium hydrogen 2-phosphonatobutane-tricarboxylate and 2-phosphono-butane-1,2,4-tricarboxylic acid dissociate into the corresponding anion (2-phosphonatobutane-tricarboxylate ion) and the sodium ion and hydrogen ion (proton), respectively. Fate, behavior and the ecotoxicological properties of 2-phosphonobutane-1,2,4-tricarboxylic acid and its tetrasodium salt are thought to be an effect of the phosphonato-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 tetrasodium hydrogen 2-phosphonatobutane-tricarboxylate and 2-phosphonobutane-1,2,4-tricarboxylic acid is justified.


A 96h-LC50 of >1042 mg/L was concluded from a 14d-NOEC of >/=1042 mg/L found in a prolonged toxicity study in fish (species: zebra danio), conducted according to the OECD guideline 204, over 14 days. The results refere to measured concentrations, as the test concentrations were confirmed by analytical monitoring using ion chromatography.


A prolonged toxicity study in Daphnia magna (covering to OECD guidelines 202 and 211) was performed over 21 days and the effect on mobility was determined to be 21d-EC 50 (immobilisation) >1071 mg/L. Based on this result, an 48h-EC50 value of > 1071 mg/l was concluded. Other study results refer to effects on reproduction. A 21d-NOEC of 104 mg/l and a 21d-LOEC of 329 mg/l were obtained. The results are expressed in terms of the arithmetic mean of measured concentrations.


In a test, the fresh water alga Desmodesmus subspicatus was exposed to the parent acid 2-phosphonobutane-1,2,4-tricarboxylic acid for 72 hours. The experiment was conducted according to the OECD TG 201. A 72h-ErC50 of > 1081 mg/L; a 72h-NOEC of 17.8 mg/L and an 72h-ErC10 > 33.3 - < 65.5 mg/l, based on measured concentrations was obtained in this test. Analytical monitoring was carried out and stability of the test substance was confirmed during the duration of exposure.