N-carboxymethyliminobis(ethylenenitrilo)tetra(acetic acid)

Short-term toxicity to fish

Description of key information

When rainbow trout (O. mykiss) were exposed to pentapotassium salt of DTPA, the 96-hour LC50 was > 1,000 mg/L. Stoichiometric conversion from  the pentapotassium salt to the free acid resulted in a 96-hour LC50 value of 674 mg/L for DTPA (free acid). However the supporting study provides a measured media effect value (although nominal)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

674 mg/L

Additional information

Two acute freshwater fish studies were assessed for this endpoint. One study was conducted with rainbow trout (Oncorhynchus mykiss) exposed to the pentapotassium salt of DTPA, while the other study was conducted with bluegill sunfish (Lepomis machrochirus) exposed to the pentasodium salt of DTPA. Upon contact with water, these DTPA salts are expected to dissociate, thus, these test chemicals are considered essentially equivalent to the free acid form of DTPA. Both studies were found to be of good quality and were comparable to or equivalent to guideline studies. The acute test with the rainbow trout was a limit test that concluded that the 96 hour LC50 for DTPA (pentapotassium salt) was >1,000 mg/L, which was equivalent to 674 mg/L DTPA (free acid). The acute test with the bluegill sunfish concluded that the 96 -hour LC50 for DTPA (pentasodium salt) was 1115 mg/L, equivelent to 880 mg/L DTPA (free acid). Since these toxicity results were conducted with two different fish species, the lower of the two values (674 mg/L) was selected as the key parameter for this endpoint.