Diniobium pentaoxide

Endpoint summary

Description of key information

LLNA (OECD 429): Not sensitizing

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-08-31 to 2009-10-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmann, Borchen, Germany
- Age at study initiation: 8-9 weeks
- Weight at study initiation: 15-22 g
- Housing: in groups of 5 in IVC cagews, type II L, polysulphone cages on Altromin saw fibre bedding
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 55 +/- 10
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light):12/12

IN-LIFE DATES: From: 2009-09-11 To: 2009-10-01

Vehicle:

other: AOO (3+1 (v/v) acetone/olive oil

Concentration:

12.5 %, 25 % and 50 % (w/v) [Based on the results of the preliminary test]

No. of animals per dose:

5

Details on study design:

PRELIMINARY TEST
To determine the highest tolerated and non-irritant test concentration a preliminary test was performed.
For this purpose, two animals were treated by topical application with the test item on three consecutive days at a concentration of 50% (suspended in AOO) to the entire dorsal surface of each ear.
One further animal was treated with 100% AOO and served as negative control.
From day 1 to day 4 the ear thickness of each animal was measured.
During this period also all clinical signs were recorded.
Cage side observations included spontaneous activity, lethargy, recumbent position, convulsions, tremors, apnoea, asphyxia, vocalisation, diarrhoea, changes in the skin and fur, eyes and mucous membranes (salivation, discharge).
Neither signs of systemic toxicity nor signs of irritation at the application site could be detected in the animal.

MAIN TEST
- Topical Application
Each mouse was treated by topical application of 25 μL of the selected solution to the entire dorsal surface of each ear.
Topical applications were performed once daily over three consecutive days.
- Administration of 3H-methyl thymidine
Five days after the first topical application all mice were dosed with 20 μCi 3H-methyl thymidine by intravenous injection (tail vein) of 250μL of 3H-methyl thymidine, diluted to a working concentration of 80μCi/mL.
- Preparation of cell suspension
Approximately 5 hours after 3H-methyl thymidine-injection all mice were sacrificed by cervical dislocation. The draining “auricular lymph nodes” were excised, individually pooled for each animal (2 lymph nodes per animal) and collected in phosphate buffered saline (PBS). A single cell suspension of pooled lymph node cells was prepared by gentle mechanical disaggregation through polyamide gauze (200 mesh size). After washing the gauze with PBS the cell suspension was pelleted in a centrifuge. The supernatant was discarded and the pellets were resuspended with PBS. This washing procedure was repeated.
After the final wash each pellet was resuspended in approx. 1 mL 5% TCA at approx. 4 °C for approximately 18 hours for precipitation of macromolecules. Each precipitate was once washed again, resuspended in 1 mL 5% TCA and 7 mL scintillation fluid was added. Then this solution was transferred into scintillation vials and stored at room temperature overnight.
- Determination of incorporated 3H-methyl thymidine
The 3H-methyl thymidine – incorporation was measured in a ß-counter and expressed as the number of disintegrations per minute (DPM). Similarly, background 3H-methyl thymidine levels were also measured (5% TCA). Determination of radioactivity was performed individually for each animal.

OTHER:
Reliability checks with a positive control substance was performed periodically in the performing laboratory.

Positive control substance(s):

other: P-Phenylenediamine (CAS 106-50-3)

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

Key result

Parameter:

SI

Value:

0.7

Test group / Remarks:

12.5

Key result

Parameter:

SI

Value:

1.3

Test group / Remarks:

25%

Key result

Parameter:

SI

Value:

0.9

Test group / Remarks:

50%

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: DPM (mean values) DPM for negative control: 1251.5 DPM at an extract concentration of 12.5%: 870.3 DPM at an extract concentration of 25%: 1562.2 DPM at an extract concentration of 50%: 1107.5

Cellular proliferation data / Observations:

The stimulation index at an extract concentration of 12.5% was 0.7 The stimulation index at an extract concentration of 25% was 1.3 The stimulation index at an extract concentration of 50% was 0.9.
DPM (mean values) DPM for negative control: 1251.5 DPM at an extract concentration of 12.5%: 870.3 DPM at an extract concentration of 25%: 1562.2 DPM at an extract concentration of 50%: 1107.5.

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

All animals gained weight as expected.

Interpretation of results:

other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008

Conclusions:

According to OECD guideline 429 and EU criteria the tested substance should not be classified for dermal sensitization.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Diniobium pentaoxide did not stimulate lymphocyte proliferation in a murine LLNA.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Undiluted diniobium pentaoxide caused a maximum SI of 1.3 in the murine LLNA. No classification as skin sensitizer is warranted.