Niobium oxide

Endpoint summary

Description of key information

In an acute oral toxicity study (OECD 423) with niobium oxide (target substance) no mortality has been reported at the limit dose of 2000 mg/kg bw. Thus, the oral LD50 can be considered to be greater than 2000 mg/kg bw. In an acute inhalation toxicity study according to OECD Guideline 403, groups of young adult Sprague-Dawley rats (5/sex) were exposed via the inhalation route to niobium pentoxide (source substance) as aerosol in air for 4 hours nose only at a concentration of 5.45 mg/L. Animals then were observed for 14 days. No death occurred. Based on the results a LC50 of greater than 5.45 mg/L can be considered for both sexes.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2003-01-02 to 2003-03-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Specific details on test material used for the study:

- Treatment of test material prior to testing: The test item was suspended in dimethylsulfoxide prior to use after crushing with a pestle and mortar to a fine dust, because there is no other suitable solvent. The suspension was carefully mixed immediately before administration. The homogeneity was proved visually.

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles RIver Wiga GmbH, 9730 Sulzfeld, Germany
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: approx. 7 weeks
- Weight at study initiation: 214.0 ± 13.3 g
- Fasting period before study: over night before oral administration
- Housing: groups of up to 3 per cage (Makrolon type 3)
- Bedding: ALTROMIN Type S8/15, granulated soft wood bedding
- Diet (e.g. ad libitum): ad libitum, ALTROMIN 1324, pelleted standard diet
- Water (e.g. ad libitum): ad libitum, tap water
- Acclimation period: 6 days before randomisation

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 - 21.5
- Humidity (%): 30 - 40 %, with a shortly falling below 25 %
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

other: 0.5 % (m/v) solution of Tylose MH 1000 in deionised water

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 3 g test item filled up to 15 mL using 0.5 % (m/v) solution of Tylose MH 100 in deionised water
- Amount of vehicle (if gavage):

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg bw

CLASS METHOD (if applicable)
- Rationale for the selection of the starting dose: according to the mentioned regulatory guideline the limit test should be done at one dose level of 2000 mg/kg bw

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

6 female rats

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
- Clinical signs and mortality: continuously on administration day, once daily thereafter
- Weighing: On the day of administration and on days 7 and 14.
- Necropsy of survivors performed: yes, all animals were examined externally. The cranial, thoracic and abdominal cavities were then opened and examined macroscopically.

Statistics:

Group mean values and standard deviations for body weights and body weight gain.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Sex:

female

Dose descriptor:

LD0

Effect level:

2 000 mg/kg bw

Based on:

test mat.

Mortality:

None

Clinical signs:

No signs observed

Gross pathology:

No findings observed

Interpretation of results:

GHS criteria not met

Conclusions:

In conclusion, the oral LD50 in rats after treatment with niobium oxide is considered to be greater than 2000 mg/kg bw.

Executive summary:

In an acute oral toxicity study according to OECD guideline 423, six fasted female Wistar rats were given a single oral dose of niobium oxide (>99% purity), suspended in a 0.5% (m/v) solution of Tylose MH 1000 in deionised water, at a dose of 2000 mg/kg bw (limit test) and were observed for 14 days. Neither mortality nor adverse clinical signs were recorded during the observation period. Based on the results from this study, the oral LD50 in rats is considered to be greater than 2000 mg/kg bw.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Guideline study

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

key 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

Preliminary study:

not applicable

Key result

Sex:

male/female

Dose descriptor:

LC0

Effect level:

> 5 450 mg/m³ air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

There were no unscheduled deaths.

Clinical signs:

other: During exposure: Exaggerated breathing was observed in most test rats from 1 hour, and all test rats from 2 hours into exposure. Observation period: Exaggerated breathing was observed in all test rats immediately post exposure, persisting to day 4 of the

Body weight:

A slightly reduced mean bodyweight gain was evident for male test rats during the first week following exposure. Thereafter, the mean bodyweight gain was similar to that of the control values. Bodyweight gain values of the female test rats were similar to that of the control values.

Gross pathology:

There were no treatment-related findings noted at necropsy

Other findings:

- Organ weights: no effects seen on lung weights
- Water consumption: no treatment-related effects were observed

Interpretation of results:

GHS criteria not met

Conclusions:

The LC0 (4-hour) for diniobium pentoxide is greater than 5.45 mg/L and therefore no classification is required according to CLP.

Executive summary:

In an acute inhalation toxicity study according to OECD Guideline 403, groups of young adult Sprague-Dawley rats (5/sex) were exposed via the inhalation route to niobium pentoxide (99.99 % purity) as aerosol in air for 4 hours nose only at a concentration of 5.45 mg/L. Animals then were observed for 14 days. No death occurred. Exaggerated breathing was observed in most test animals from the 1st hour and in all test rats from the 2nd hour of exposure. Exaggerated breath persisted until day 4 post exposure. Based on the results a LC50 of greater than 5.45 mg/L can be considered for both sexes. Niobium pentoxide is not classified according to CLP.

 

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

Dose descriptor:

LC50

Value:

5 450 mg/m³

Quality of whole database:

Guideline study

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

In an acute oral toxicity study (OECD 423) with Niobium oxide (target substance) no mortality has been reported at the limit dose of 2000 mg/kg bw. Thus, the oral LD₅₀ can be considered to be greater than 2000 mg/kg bw. No data is available for the inhalation route for the target substance. Thus, available data from Niobium pentoxide (source substance) is used to assess the acute inhalation potential of niobium oxide. For justification of read-across please refer to the read-across report attached to IUCLID section 13.

In an acute inhalation toxicity study according to OECD Guideline 403, groups of young adult Sprague-Dawley rats (5/sex) were exposed via the inhalation route to niobium pentoxide as aerosol in air for 4 hours nose only at a concentration of 5.45 mg/L. Animals then were observed for 14 days. No death occurred. Based on the results a LC₅₀ of greater than 5.45 mg/L can be considered for both sexes.

Justification for classification or non-classification

Based on the available data, Niobium oxide does not warrant classification for acute toxicity in accordance to regulation (EC) No 1272/2008.