[nitrilotris(methylene)]trisphosphonic acid, sodium salt

Endpoint summary

Description of key information

Short term toxicity to fish

A reliable 96-hour LC₅₀ value of 160 mg active acid/L has been determined for the effects of ATMP-H on mortality of Salmo gairdneri (now known as Oncorhynchus mykiss).

A 96-hour LC₅₀ value of >282 mg/L has been determined for the effects of ATMP-xNa salt on the mortality of the marine fish Cyprinodon variegatus.

Long term toxicity to fish

A 60-day NOEC value of 23 mg active acid/L has been determined for the effects of ATMP-H on growth of the fish O. mykiss. This study represents the only value available for this endpoint.

Short term toxicity to invertebrates

A 48-hour LC₅₀ value of 94 mg active acid/L has been determined for the effects of ATMP-H on mortality of the marine invertebrate Acartia tonsa. This study represents the lowest reliable value available for this endpoint.

A 48-hour EC₅₀ value of 297 mg active acid/L has been determined for the effects of ATMP-H on the immobility of the freshwater flea Daphnia magna.

Long term toxicity to invertebrates

A 28-day NOEC value of ≥ 25 mg active acid/L has been determined for the effects of ATMP-H on adult survival and reproduction of D. magna. The study represents the lowest reliable value available for this endpoint.

A 96-hour NOEC value of 96 mg active acid/L has also been determined for the effects of ATMP-H on the growth of the eastern oyster Crassostrea virginica.

Toxicity to algae and cyanobacteria

72-hour EC₅₀ and NOEC values of 80 and 40 mg active acid/L respectfully, have been determined for the effects on ATMP-H on the growth rate of Skeletonema costatum. This value represents the lowest reliable value available for this endpoint. Another study determined a 96-hour EC₅₀ value 12.39 mg active acid/L based on biomass of Pseudokirchneriella subcapitata, however, this value was not deemed reliable and is not used as the key value for this endpoint.

Additional information

The acid, sodium, potassium and ammonium salts in the ATMP category are freely soluble in water. The ATMP anion can be considered fully dissociated from its sodium, potassium or ammonium cations when in dilute solution. Under any given conditions, the degree of ionisation of the ATMP species is determined by the pH of the solution. At a specific pH, the degree of ionisation is the same regardless of whether the starting material was ATMP-H, ATMP.4Na, ATMP.7K or another salt of ATMP.

 

Therefore, when a salt of ATMP is introduced into test media or the environment, the following is present (separately):

1. ATMP is present as ATMP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the media and not whether ATMP (3-5K) salt, ATMP (3-5Na) salt, ATMP-H (acid form), or another salt was used for dosing.
2. Disassociated potassium, sodium or ammonium cations. The amount of potassium or sodium present depends on which salt was dosed.
3. It should also be noted that divalent and trivalent cations would preferentially replace the sodium or potassium ions. These would include calcium (Ca²⁺), magnesium (Mg²⁺) and iron (Fe³⁺). These cations are more strongly bound by ATMP than potassium, sodium and ammonium. This could result in ATMP-dication (e.g. ATMP-Ca, ATMP-Mg) and ATMP-trication (e.g. ATMP-Fe) complexes being present in solution.