Registration Dossier

Administrative data

Description of key information

The results for irritation were read across from the stucturally analogous DTPMP-H (CAS 15827-60-8). 
The results for skin and eye irritation are mixed and range from no/mild irritation to corrosion.
In the key skin irritation study conducted to GLP and OECD 404 (Safepharm Laboratories, 1982) Briquest 543-50A (DTPMP acid) was mildly irritating to the skin of two rabbits and not irritating to the skin of one rabbit. The mild irritation was not sufficient to trigger classification. It was noted that the irritation might have been underestimated due to the fact that a 50% aqueous solution of DTPMP was tested. However, the presence of HCl in the test formulations of DTPMP acid would be expected to over predict the skin irritation potential of the phosphonic acid. Although these investigations have used formulations, and therefore the limit dose for the active acid or its salt was not achieved, the results appear to be reliable. Therefore it is considered likely that the acid would be slightly irritating only.
In a supporting study (Huntingdon, 1983), which was similar to OECD 404, DTPMP (Dequest 2060s no further details on the formulation) caused corrosion of the skin in two animals. Additional animals were not tested due to the severity of the reaction in the first two animals.
In an eye irritation study (Huntingdon 1983) which was similar to OECD 405, DTPMP (Dequest 2060s - no further details on the formulation) caused severe damage to the eye of a single rabbit, which had to be euthanised as a result of the severity of the reaction. Additional animals were not tested due to the severity of the reaction in the tested rabbit. A supporting study, conducted prior to the adoption of OECD test guidelines and GLP (Younger Laboratories, 1971), diethylenetriamine penta(methylene phosphonic acid was mildly irritating to rabbit eyes. It was noted that the irritation might have been underestimated due to the fact that a 50% aqueous solution of DTPMP was tested.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The results for irritation were read across from the stucturally analogous DTPMP-H (CAS 15827-60-8).

The studies most comparable with OECD test guidelines were selected as the key studies. However, the supporting studies described above, were of similar reliability to the key study, and conducted more recently.

Justification for selection of skin irritation / corrosion endpoint:
Study conducted in accordance with appropriate OECD guideline and in compliance with GLP.

Justification for selection of eye irritation endpoint:
Study conducted in accordance with appropriate OECD guideline and in compliance with GLP.

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: highly irritating

Justification for classification or non-classification

The classification decision is based on read-across from the stucturally analogous DTPMP-H (CAS 15827-60-8). Several studies on DTPMP acid indicate low skin irritation potential. The presence of HCl in the test formulations of DTPMP acid would be expected to over predict the skin irritation potential of the phosphonic acid. Although these investigations have used formulations, and therefore the limit dose for the active acid or its salt was not achieved, the results appear to be reliable. Therefore it is considered likely that the acid would be slightly irritating only. There is evidence from reliable eye irritation studies that DTPMP can cause irreversible damage to the eyes of rabbits. These results together with the knowledge that the pH of DTPMP is less than 2, lead to the proposal that this substance should be labelled according to Regulation (EC) No 1272/2008 as 'Skin Irr. 2' whereas the serious damage to eye necessitates the classification of the substance as 'Eye Damage Cat 1'. This reasoning is extrapolated to BHMT-H (CAS 34690-00-1) the pH of which is equal to that of DTPMP-H and which is structurally analogous and therefore expected to behave in the same way as the read across substance.