N-carboxymethyliminobis(ethylenenitrilo)tetra(acetic acid)

Short-term toxicity to aquatic invertebrates

Description of key information

The 48-hour EC50 for Daphnia carinata, a freshwater species, was 245 mg/L DTPA.  The 96-hour LC50 for Crangon crangon, a saltwater species, was 6020 mg/L pentasodium DTPA, which is equivalent to 4751 mg/L DTPA (free acid).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

245 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

4 751 mg/L

Additional information

Four acute toxicity tests with aquatic invertebrates were assessed for this endpoint, and all four studies were found to be of good quality and reliable for use in the risk assessment process. Two studies were conducted with the freshwater cladoceran, Daphnia magna, one study was conducted with the freshwater cladoceran, Daphnia carinata,and one study was conducted with the marine brown shrimp,Crangon crangon. Both the pentapotassium and pentasodium DTPA salts as well as DTPA (free acid) were used as test substances in these exposure studies. Since the pentapotassium and pentasodium salts of DTPA dissociate when in contact with water, these salts are considered equivalent to DTPA (free acid) in aquatic environments. The 48-hour EC50 values forD. magna (after stoichiometric conversion from the pentapotassium and pentasodium salts of DTPA to DTPA free acid) ranged from > 395 to 600 mg/L DTPA (free acid), while the EC50 value for D. carinata was 245 mg/L DTPA (free acid). The 96 -hour LC50 for the brown shrimp was 4751 mg/L DTPA (converting from the reported LC50 of 6020 mg/L for the pentasodium salt of DTPA). The key parameter for the freshwater studies was the EC50 value of 245 mg/L reported for D. carinata, since this is the lowest acute toxicity value reported for a freshwater invertebrate species. The key parameter for the saltwater studies was the 96 -hour LC50 value of 4751 mg/L reported for the brown shrimp.