Niobium hydride

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 June 2018 to 24 July 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Version / remarks:

2001

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

Version / remarks:

2008

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

2002

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: Appendix to Director General Notification, No. 12-Nousan-8147. Agricultural Production Bureau, Ministry of Agriculture, Forestry and Fisheries of Japan (JMAFF)

Version / remarks:

November 2000, including the most recent revisions.

Deviations:

no

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Niobium hydride

EC Number:

237-769-9

EC Name:

Niobium hydride

Cas Number:

13981-86-7

Molecular formula:

HNb

IUPAC Name:

niobium(1+) hydride

Test material form:

solid

Details on test material:

- Appearance: Silver grey solid
- Storage: At room temperature

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Crl: WI(Han)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: approximately 8-9 weeks old
- Weight at study initiation: 140 to 164 g
- Fasting period before study: Animals were deprived of food overnight (for a maximum of 20 hours) prior to dosing and until 3-4 hours after administration of the test material. Water was available.
- Housing: On arrival and following assignment to the study, animals were group housed (up to 3 animals of the same sex and same dosing group together) in polycarbonate cages (height 18 cm) containing sterilised sawdust as bedding material equipped with water bottles. The room in which the animals were kept was documented in the study records. Animals were separated during designated procedures/activities. Each cage was clearly labelled.
- Animal Enrichment: For psychological/environmental enrichment, animals were provided with paper, except when interrupted by study procedures/activities.
- Diet: Pelleted rodent diet was provided ad libitum throughout the study, except during designated procedures. The feed was analysed by the supplier for nutritional components and environmental contaminants. Results of the analysis were provided by the supplier and are on file at the Test Facility. It is considered that there were no known contaminants in the feed that would interfere with the objectives of the study.
- Water: Municipal tap-water was freely available to each animal via water bottles. Periodic analysis of the water was performed, and results of these analyses are on file at the Test Facility. It is considered that there were no known contaminants in the water that would interfere with the objectives of the study.
- Acclimation period: The animals were allowed to acclimate to the Test Facility toxicology accommodation for at least 5 days before the commencement of dosing.

ENVIRONMENTAL CONDITIONS
- Temperature: 21 - 22 °C
- Humidity: 32 - 72 %
- Air changes: Ten or greater air changes per hour with 100 % fresh air (no air recirculation).
- Photoperiod: 12-hour light/12-hour dark cycle

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Details on oral exposure:

VEHICLE
- Polyethylene glycol 400
- Specific gravity: 1.125
- Justification for choice of vehicle: Trial preparations were performed at the Test Facility to select the suitable vehicle and to establish a suitable formulation procedure. Trial preparation formulations were not used for dosing and were discarded after the assessment is complete. These trial preparations have a
non-GLP status and were carried out in the quality assured environment of the Test Facility.

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg body weight

DOSAGE PREPARATION:
- Test material dosing formulations (w/w) were homogenised to visually acceptable levels at appropriate concentrations to meet dose level requirements.
The dosing formulations were kept at room temperature until dosing. The dosing formulations were stirred until and during dosing. Adjustment was made for specific gravity of the vehicle. No correction was made for the purity/composition of the test material. For the second dosing group, the test material was grinded with a mortar and pestle prior to formulation. Any residual volumes were discarded.

CLASS METHOD
- Rationale for the selection of the starting dose: The dose levels were based on the OECD test guidelines and were selected from the series 5 (lowest dose level), 50, 300 and 2 000 (highest dose level) mg/kg body weight. The starting dose level should be the one that is likely to produce mortality in at least some of the animals and was selected based on available toxicity data of the test material.
- The toxicity of the test material was assessed by stepwise treatment of groups of 3 females. The absence or presence of mortality of animals dosed at one step determined the next step, based on the test procedure defined in the guidelines. The onset, duration and severity of the signs of toxicity were taken into account for determination of the time interval between the dose groups. The first group was treated at a dose level of 2 000 mg/kg. Based on the results, one
additional group was dosed at 2 000 mg/kg.

Doses:

2 000 mg/kg

No. of animals per sex per dose:

6 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Throughout the study, animals were observed for general health/mortality and moribundity twice daily, in the morning and at the end of the working day. Animals were not removed from cage during observation, unless necessary for identification or confirmation of possible findings. Post-dose observations were performed at intervals on the day of dosing (at least three times) and once daily thereafter. The observation period was 14 days. All the animals were examined for reaction to dosing. The onset, intensity and duration of these signs was recorded (if appropriate). Signs were graded for severity and the maximum grade was predefined at 3 or 4. Grades were coded as slight (grade 1), moderate (grade 2), severe (grade 3) and very severe (grade 4). For certain signs, only its presence (grade 1) or absence (grade 0) was scored. Animals were weighed individually on Day 1 (pre-dose), 8 and 15. A fasted weight was recorded on the day of dosing.
- Necropsy of survivors performed: Yes, all animals were sacrificed by oxygen/carbon dioxide procedure at the end of the observation period. All animals assigned to the study were subjected to necropsy and descriptions of all internal macroscopic abnormalities were recorded.

Statistics:

All results presented in the tables of the report are calculated using values as per the raw data rounding procedure and may not be exactly reproduced from the individual data presented.
The oral LD50 value of the test material was ranked within the following ranges: 0-5, 5-50, 50-300 or 300-2 000 mg/kg b.w. or as exceeding 2 000 mg/kg b.w. The LD50 cut-off value was established based on OECD guideline 423. No statistical analysis was performed. The method used is not intended to allow the calculation of a precise LD50 value.

Results and discussion

Effect levels

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortality occurred.

Clinical signs:

other: Hunched posture, abnormal gait and/or piloerection were noted for the animals on Day 1.

Gross pathology:

No abnormalities were found at macroscopic post mortem examination of the animals.

Applicant's summary and conclusion

Interpretation of results:

other: Not classified in accordance with EU criteria

Conclusions:

Under the conditions of this study, the oral LD50 value of the test material in Wistar rats was established to exceed 2 000 mg/kg body weight.

Executive summary:

The acute oral toxicity of the test material was investigated in accordance with the standardised guidelines OECD 423, EU Method B.1.tris and OPPTS 870.1100 and JMAFF guidelines, under GLP conditions.

The test material was administered by oral gavage to two consecutive groups of three female Wistar rats at 2 000 mg/kg body weight. Animals were subjected to daily observations and weekly determination of body weight. Macroscopic examination was performed after terminal sacrifice (Day 15).

No mortality occurred. Hunched posture, abnormal gait and/or piloerection were noted for the animals on Day 1. The body weight gain shown by the animals over the study period was considered to be similar to that expected for normal untreated animals of the same age and strain. No abnormalities were found at macroscopic post mortem examination of the animals.

Under the conditions of this study, the oral LD50 value of the test material in Wistar rats was established to exceed 2 000 mg/kg body weight.