Lanthanum oxide

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08-2010 to 09.2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guidline study under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Lanthanum oxide

EC Number:

215-200-5

EC Name:

Lanthanum oxide

Cas Number:

1312-81-8

Molecular formula:

La2O3

IUPAC Name:

lanthanum(3+);oxygen(2-)

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland
- Age at study initiation: young adults
- Weight at study initiation: 263 g (males), 181 g (females)
- Fasting period before study: no
- Housing: Marolon cages, 5 animals per cage, sawdust bedding
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +- 3 deg C
- Humidity (%): rel humidity 40 to 70%
- Air changes (per hr): 15
- Photoperiod 12 hrs dark / 12 hrs light):

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Flow past nose only chamber
- Method of holding animals in test chamber: restraining tubes
- Source and rate of air: pressurized air
- System of generating particulates/aerosols:y the substance was fed to a stream of dry pressurize air (mean flow 36.1 L/min) by means of a spiral feeder and a micronizing jet mill. The aerosol was passed through a series of two cyclones an a horizontal elutriator. Large particles settled before entering the exposure chamber.
- Method of particle size determination: Cascade impactor
- Treatment of exhaust air: filtration
- Temperature, humidity: 21-21.8 deg C, humidity: 32-37%

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetry
- Samples taken from breathing zone: yes 10 times sampling during the exposure period

TEST ATMOSPHERE (if not tabulated)
- Particle
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.7 gsd: 1.7

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetry

Duration of exposure:

4 h

Concentrations:

Mean measured concentration: 5.3 +- 1.7 mg/L
Nominal concentraion: 77 mg/L, generation efficiency: 7%. The concentration measurements distributed over time (10 samples during the exposure period) showed that the test substance was sufficiently stable.

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 15 days after exposure
- Frequency of observations and weighing:
Clinical signs
During exposure: 3 times for mortality, behavioural signs of distress and effects on respiration
After exposure on day one 1 and 3 h after exposure, once daily thereafter, symptoms grading on fixed scales.
Body weights
prior to exposure and on days 2, 4, 8 and 15
- Necropsy of survivors performed: yes all internal macroscopic organ changes were recorded with particular emphasis of changes in the respiratory tract.

Statistics:

No statistical analysis was performed.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC0

Effect level:

>= 5.3 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortality occurred

Clinical signs:

other: No expsoure related clinical signs were noted during and after the exposure period

Body weight:

Body weight gains were normal for this strain of rats.

Gross pathology:

No exposure related gross macroscopic findings were reported.

Applicant's summary and conclusion

Interpretation of results:

practically nontoxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

No signs of acute inhalation toxicity were observed in a guideline conform acute inhalation study in male and female Wistar rats with 4 h of exposure to lanthanum oxide dust of a MMAD of 3.5 micro-m (GSD 1.7) at the limit concentration of 5.3 mg/L.

Executive summary:

Male and female Wistar rats were exposed in an acute inhalation study according the OECD guideline No. 403 and conducted under GLP to aerosolised dust of lanthanum oxide particles with a mass medium aerodynamic diameter of 3.5 micro-m (GSD 1.7) at the limit dose of 5.3 mg/L for 4 h. The postexposure observation period was 14 days. No expsoure related mortality, clinical signs or macroscopic organ findings were reported. The LD50 and LD0 as well as the NOEC were equal or greater than 5.3 mg/L under the conditions of this study (van Huygevoort, 2010).