Niobium dioxide

Endpoint summary

Description of key information

The dermal sensitization potential of the source substance Diniobium pentaoxide (>98.5% purity) was tested in a murine local lymph node assay (LLNA) conducted according to OECD 429. Neither mortality nor any other adverse effects were observed during the study. The maximum SI was 1.3 %.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Positive control results:

Reliability checks with a positive control substance was performed periodically in the performing laboratory. The mean SI-value of the latest reliability check was 13.8 (see table 2 in box "Any other information on results incl. tables).

Parameter:

SI

Value:

0.7

Variability:

SD = 0.3

Test group / Remarks:

12% Diniobium pentaoxide

Parameter:

SI

Value:

1.3

Variability:

SD = 0.4

Test group / Remarks:

25 % Diniobium pentaoxide

Parameter:

SI

Value:

0.9

Variability:

SD = 0.4

Test group / Remarks:

50 % Diniobium pentaoxide

Cellular proliferation data / Observations:

DETAILS ON STIMULATION INDEX CALCULATION
For detailed results please refer to table 3 presented in box "Any other information on results incl. tables".

EC3 CALCULATION
The EC3 value (derived by linear interpolation) could not be calculated as the stimulation indices of all concentrations were below 3.

CLINICAL OBSERVATIONS:
All animals survived throughout the test period without showing any clinical signs.

BODY WEIGHTS
All animals showed the expected weight development, which includes a weight loss of up to 2 g throughout the study.

Results of the preliminary test:

Table 1: Ear Thickness - Preliminary test

Group	Animal No.	Day 1 [mm]	Day 2 [mm]	Day 3 [mm]	Day 4 [mm]
50% Diniobium Pentaoxide	1	0.18	0.17	0.17	0.18
	2	0.17	0.17	0.17	0.18
100 % AOO (3+1) Negative control	3	0.17	0.17	0.18	0.17

Neither signs of systemic toxicity nor signs of irritation at the application site could be detected in the animals.

Results of the Reliability Check (Positive Control)

Table 2: Stimulation indices of the Positive-Control Group of the Recent Study

Test Item	Concentration [%]	Animal Number	Stimulation Index
AOO (3+ I (v/v) Acetone/Olive Oil)	100	16
		17
		18
		19
		20
		MV	1.0
		SD
Phenylenediamine	1	81	10.2
		82	11.0
		83	14.0
		84	17.1
		85	16.8
		MV	13.8
		SD	2.9

Results of the Main Study

Table 3: Stimulation Indices obtained in the main study

Test Item	Concentration [%]	Animal Number	Stimulation Index
AOO (3+ I (v/v) Acetone/Olive Oil)	100	16
		17
		18
		19
		20
		MV	1.0
		SD
Diniobium Pentaoxide	12.5	1	1.0
		2	1.0
		3	0.4
		4	n.d.*
		5	0.5
		MV	0.7
		SD	0.3
Diniobium Pentaoxide	25	6	1.0
		7	1.0
		8	1.7
		9	0.7
		10	1.8
		MV	1.3
		SD	0.4
Diniobium Pentaoxide	50	11	0.3
		12	0.9
		13	1.3
		14	1.0
		15	n.d.*
		MV	0.9
		SD	0.4

* = outlier, failed Grubbs, Nalimov and Dixon; n.d. = not determined

If not noted individually, the results include both lymph nodes of an animal.

SD = standard deviation; MV = mean value

Interpretation of results:

GHS criteria not met

Conclusions:

Diniobium pentaoxide is not sensitizing under the conditions of this LLNA study (OECD 429).

Executive summary:

In a dermal sensitization study conducted according to OECD 429 with Diniobium pentaoxide (> 98.5 % purity) suspended in AOO (3 +1 v/v acetone/olive oil), young adult female CBA/OlaHsd mice (5 per dose group) were tested at concentrations of 12.5% (w/v), 25 % (w/v) and 50 % (w/v) in a local lymph node assay (LLNA). Due to animal welfare reasons a periodically performed positive control (Phenylenediamine in AOO (3 +1 v/v) was used. There was no mortality nor clinical observations nor effects on body weights observed. None of the tested concentrations of the test substance reached the stimulation index threshold of 3. Therefore no EC3 value could be determined. In this study, Diniobium pentaoxide is not a dermal sensitizer.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No data on skin sensitisation is available for the target substance Niobium dioxide. Thus, available data from Niobium pentaoxide (source substance) is used to assess the skin sensitisation potential of Niobium dioxide. For justification of read-across please refer to the read-across report attached to IUCLID section 13.

In a dermal sensitization study according to OECD 429, Diniobium pentaoxide (source substance) was tested at concentrations of 12.5% (w/v), 25 % (w/v) and 50 % (w/v). There was no mortality and no adverse clinical signs of toxicity or adverse effects on body weights were observed. None of the tested concentrations of the test substance reached the stimulation index threshold of 3. Based on the results Diniobium pentaoxide can be considered as not dermal sensitizing.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In a dermal sensitization study according to OECD 429, female mice were tested negative for the source substance Diniobium pentaoxide. Based on the results from the read-across partner, no classification of the target substance Niobium dioxide is warranted.