[[(phosphonomethyl)imino]bis[ethylenenitrilobis(methylene)]]tetrakisphosphonic acid, potassium salt

Endpoint summary

Description of key information

There are no data on the skin and eye irritation of potassium salts of DTPMP. Therefore data on the sodium salts of DTPMP have been read across. 
In a skin irritation study conducted to OECD 404 and GLP (Springborn Laboratories, 2000) Dequest 2066A (sodium salt of DTPMP) was very mildly irritating to the skin of rabbits. 
In an eye irritation study conducted to OECD 405 and GLP (Springborn Laboratories, 2000b) Dequest 2066A (sodium salt of DTPMP) was not irritating to the eyes of rabbits. 

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

In in vivo toxicity studies the local pH and ionic conditions within the stomach, GI tract etc. dominate the speciation of the phosphonate, irrespective of the form originally dosed. At a defined pH, a salt will behave no differently to the parent acid, at identical concentration of the particular speciated form present, and will be fully dissociatedto yield DTPMP acid and potassium.Hence some properties for a salt (in contact with water or in aqueous media) can be directly read across (with suitable mass correction) to the parent acid and vice versa (see CSR for mass correction values). In the present context the effect of the alkaline metal counter-ion (sodium/potassium) will not be significant and has been extensively discussed in the public literature. In biological systems and the environment, polyvalent metal ions will be present, and the phosphonate ions show very strong affinity to them.

The most reliable studies were selected as the key studies.

The active salt content of DTPMP sodium was 58.3%, (0.5 ml; equivalent to 300 mg active acid, 0.1 ml; equivalent to 100 mg active acid, for skin and eye irritation respectively).

The supporting studies also show the sodium salts of DTPMP are, at most, mildly irritating to the skin and eyes of rabbits although these have not been included as read across in the data set.

Effects on skin irritation/corrosion: slightly irritating

Justification for classification or non-classification

The irritation potential of DTPMP salts is dependent on the ionisation state and affects classification as follows for skin irritation, where x ≤.1 Cat 2 H-314, x = 2,9 NC; x=10 Cat 1 H-314. For eye irritation the same principle applies and the classification of the salts is based on the following; x ≤ Cat 1 H-318; x=2,9 NC; x=10 Cat 1 H-318.