reaction mass of neodymium carbonate and praseodymium carbonate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There was no skin sensitisation study available on the reaction mass of neodymium carbonate and praseodymium carbonate. However, studies were available on the reaction mass constituents and 3 analogous substances showing similar physico-chemical properties (i.e. dineodymium tricarbonate, dipraseodymium tricarbonate, dicerium tricarbonate, neodymium oxide, praseodymium(III,IV) oxide). Thus, data on constituents and analogues were used in a weight-of-evidence approach to conclude on the skin sensitisation potential of the reaction mass of neodymium carbonate and praseodymium carbonate.

 

First, a skin sensitisation study was available on dineodymium tricarbonate, the main constituent of the reaction mass (Sanders A., 2010c). In this study (OECD 429, GLP), scored as Klimisch 2 due to read-across and flagged as weight of evidence, the skin sensitisation potential of the test item was assessed in female CBA/Ca mice (4/dose) observed for up to 6 days following a topical application of the test item (5, 10, 25% w/w in propylene glycol) to the dorsal surface of the ear (25 µl/ear) for 3 consecutive days. The concentration of 25% w/w was selected as the highest dose investigated in the main test of the Local Lymph Node Assay (LLNA) based on a preliminary screening test in which no clinical signs of toxicity were noted at a maximum attainable concentration of 25% w/w. Stimulation indexes were found to be 0.93, 0.88 and 1.10 at tested concentrations of 25, 10 and 5%, respectively. Thus, dineodymium tricarbonate was found not sensitising to murine skin and therefore no classification for skin sensitisation was warranted for this test substance.

 

A second skin sensitisation study was available on dipraseodymium tricarbonate, the minor constituent of the reaction mass (Henzell G., 2012a). This study (OECD 429, GLP), scored as Klimisch 2 due to read-across and flagged as weight of evidence, was performed as described above for dineodymium tricarbonate and used the same concentration levels. In this study, stimulation indexes were found to be 0.77, 0.76 and 0.75 at tested concentrations of 25, 10 and 5%, respectively. Thus, dipraseodymium tricarbonate was found not sensitising to murine skin and therefore no classification for skin sensitisation was warranted for this test substance.

 

These results were further corroborated by 3 studies on analogues of the reaction mass: dicerium tricarbonate, neodymium oxide, praseodymium(III,IV) oxide.

Dicerium tricarbonate was evaluated for its potential as a skin sensitizer in an in vivo study performed according to EU method B.6 and in compliance with GLP (Bertl E., 2006). In this study scored as Klimisch 2 due to read-across and flagged as supporting study, 15 female Dukin/Hartley guinea-pigs were first injected by intradermal route with dicerium tricarbonate (25 % w/w in purified water) ± Freund Complete Adjuvant or with the vehicle (water). In a second step, animals received a 48-h topical occlusive application of dicerium tricarbonate (25 % w/w) or vehicle on day 8. The control and test animals were then topically challenged 2 weeks after the topical induction application with dicerium tricarbonate (25 % w/w) for 24 h. The challenge sites were evaluated for erythema and oedema 24 and 48 h after removal of the patches. No clinical signs and no deaths, related to treatment, were noted during the study. No cutaneous reactions were observed after challenge application. Thus, dicerium tricarbonate was not classified as skin sensitizer according to criteria of Annex VI of the Directive 67/548/EEC, Regulation (EC) No. 1272/2008 and UN GHS.

Two skin sensitisation studies were also available on neodymium oxide and praseodymium(III,IV) oxide, two analogues of the reaction mass (Henzell G., 2012b and 2012c). These in vivo studies (OECD 429, GLP), scored as Klimisch 2 due to read-across and flagged as supporting study, were performed as described above for dineodymium tricarbonate. The tested concentrations were 10, 25 and 50% for neodymium oxide and 5, 10 and 25% for praseodymium(III,IV) oxide in propylene glycol. Stimulation indexes were found to be 1.33, 1.43 and 1.41 at concentrations of 50, 25 and 10% neodymium oxide, respectively, and between 1.43, 1.31 and 1.37 at concentrations of 25, 10 and 5% praseodymium(III,IV) oxide, respectively. Thus, both neodymium oxide and praseodymium(III,IV) oxide were found not sensitising to murine skin and therefore no classification for skin sensitisation was warranted for these analogues.

 

As the reaction mass of neodymium carbonate and praseodymium carbonate showed similar physico-chemical properties compared to the abovementioned constituents and analogues, the reaction mass itself was expected to be non-sensitizer to skin by analogy, therefore warranting no classification for skin sensitisation according to the criteria of Annex VI of Directive 67/548/EEC, Regulation (EC) No. 1272/2008 and UN GHS.

 

	Reaction mass of neodymium carbonate and praseodymium carbonate	Dineodymium tricarbonate	Dipraseodymium tricarbonate	Dicerium tricarbonate	Neodymium oxide	Praseodymium(III,IV) oxide
In vivo skin sensitisation	no data	non-sensitizer to skin (OECD 429, GLP)	non-sensitizer to skin (OECD 429, GLP)	non-sensitizer to skin (EU B.6, GLP)	non-sensitizer to skin (OECD 429, GLP)	non-sensitizer to skin (OECD 429, GLP)

 

Migrated from Short description of key information:
Skin sensitisation (weight-of-evidence approach based on the data on both constituents of the reaction mass and analogues): not sensitising

Justification for selection of skin sensitisation endpoint:
Several studies done on both constituents of the reaction mass and on analogous substances were selected. Performed on both constituents of the reaction mass showing similar physico-chemical properties (dineodymium tricarbonate and dipraseodymium tricarbonate), both skin sensitisation studies were conducted in compliance with GLP and according to the OECD guideline 429. The studies were thus considered in a weight-of-evidence approach to conclude on the skin sensitisation potential of the reaction mass of neodymium carbonate and praseodymium carbonate. Although the report was well described, the data were used as read-across and therefore the maximal reliability score was decreased from 1 to 2 (Klimisch, 1997), according to Practical Guide n°6.
All performed in vivo according to OECD/EU guidelines and in compliance with GLP, 3 other studies on analogues (dicerium tricarbonate, neodymium oxide and praseodymium(III,IV) oxide) showing no skin sensitisation potential were also considered in this weight-of-evidence approach.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

There is no reliable data available for respiratory sensitisation.

Migrated from Short description of key information:
Respiratory sensitisation: no data available

Justification for classification or non-classification

The available data on the constituents of the reaction mass (dineodymium tricarbonate, dipraseodymium tricarbonate) showed that skin sensitisation did not occur in mice after exposure up to the limit doses. Furthermore, no skin sensitisation was observed in vivo after treatment with dicerium tricarbonate, neodymium oxide and praseodymium(III,IV) oxide, 3 analogues of the reaction mass. Thus, the reaction mass of neodymium carbonate and praseodymium carbonate is not classified by analogy as a skin sensitizer according to classification criteria of Annex VI of Directive 67/548/EEC, Regulation (EC) No. 1272/2008 and UN GHS.

 

No reliable data were available for respiratory sensitisation; therefore no conclusion can be drawn on the classification of the reaction mass for this endpoint.