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Acute Toxicity: inhalation

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acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 403 (Acute Inhalation Toxicity)
GLP compliance:
yes (incl. QA statement)
Test type:
standard acute method
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Test material form:
solid: particulate/powder
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Tellurium
- Substance type: inorganic
- Physical state: black powder
- Analytical purity: > 99.5 %
- Lot/batch No.: 1103
- Storage condition of test material: room temperature

Test animals

Details on test animals or test system and environmental conditions:
- Source: Charles River Wiga, Sulzfeld, Germany
- Age at study initiation: 5-6 weeks old upon arrival
- Weight at study initiation: mean body weight 304g males, mean females 192 g
- Fasting period before study: no data
- Housing: five animals per cage stainless steel cages fitted with wire-mesh floor and front.
- Diet (e.g. ad libitum): standard laboratory rodent diet ad libitum
- Water (e.g. ad libitum): Tap water ad libitum.
- Acclimation period: no data

- Temperature (°C): 18.5 - 21.5 °C
- Humidity (%): between 70-85 %
- Air changes (per hr): 10 air changes/hour
- Photoperiod (hrs dark / hrs light): 12 hours Iight/12 hours dark cycle

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Details on inhalation exposure:
- Exposure apparatus: modified nose-only inhalation chamber from ADG Developments LTD.
- Exposure chamber volume: 60 L
- Method of holding animals in test chamber: plastic animal holders (Batelle).
- Source and rate of air: air from compressed air system; average flow 3.1 m³/h
- System of generating particulates/aerosols:
Due to the inhomogeneity of the particles sizes of the test material, the test material was ground during a short period of time using a grinder. In preliminary experiments it turned out that it was not possible to use any moving device for transportation of the particles to the aerosol generation device since the particles coalesced strongly during transport. Therefore, a means of transportation had to be found in which the particles did not move themselves. Hereto, a moving tray was developed with tow grooves filled with test material (effective length 58 cm). A test atmosphere was generated by moving the tray with one filled groove along the suction side of the airmover. (AIR VAC 100) which was operated with pressurized air. When reaching the end of the groove, the second groove was started. In the meantime the first groove was refilled. This procedure was repeated every 15 minutes. The generation system was placed in a hood.
The inhalation equipment was designed to expose tats to a continuous supply of fresh test atmosphere. The generated aerosol was passed to the inlet of the exposure unit. From there it was directed downward through the mixing chambers towards the animal holders. At the bottom of the unit the test atmosphere was exhausted.

- Method of particle size determination: 11 - stage cascade impactor
- Treatment of exhaust air: no data
- Temperature, humidity, pressure in air chamber: 20.3 +/- 0.1 °C; relative humidity was very low (12 +/- 1 %). Air has been used from the compressed air system has a very low relative humidity.

- Brief description of analytical method used: Gravimetrical analysis; once each half hour by passing 10 L test atmosphere at 5 L/min through fiber glass filters.
- Samples taken from breathing zone: yes
- Particle size distribution: 72 % of the particles had an aerodynamic diameter between 1.8 and 4.2 µm.
Analytical verification of test atmosphere concentrations:
Duration of exposure:
4 h
nominal concentration 6.7 g/m³
analytical concentration: 2.42 g/m³
No. of animals per sex per dose:
5 aminals per sex per dose
Control animals:
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The rats were visually inspected just before exposure, for reaction to treatment during the exposure, shortly after exposure, and once daily during the observation period. Body weights were recorded just prior to exposure and at days 7 and 14.
- Necropsy of survivors performed: yes

Results and discussion

Effect levels
Dose descriptor:
Effect level:
> 2 420 mg/m³ air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: None of the rats died during or after exposure.
None of the rats died during or after exposure.
Clinical signs:
Body weight:
Almost all rats showed strongly decreased body weights one week after exposure compared with their pre-exposure weight; all rats had gained weight at the end of the 14-day observation period, although pre-exposure weights was just or nearly reached in female rats.
Gross pathology:
At autopsy, a garlic-like scent was smelled. Greyish, brownish spotted lungs were observed in all male rats. Female rats showed pale and/or grey-black stained lungs. In addition, a grey thymus was observed in 4 females.

Any other information on results incl. tables

The mean actual concentration and standard deviation turned out to be 2.42 (0.19) g/m³. Nominal concentration was 6.7 g/m³.

Particle size measurement showed that ca. 72 % of the particles had an aerodynamic diameter between 1.8 and 4.2 µm.

Applicant's summary and conclusion

Interpretation of results:
Toxicity Category IV
Migrated information Criteria used for interpretation of results: other: EU GHS (Regulation (EC) No 1272/2008)
The 4-hour LC50 value for tellurium was higher than 2.42 g/m³.
Executive summary:

In an acute inhalation toxicity study according to OECD guideline 403, groups of young adult wistar rats (5/sex) were exposed by inhalation route to tellurium powder (99.5 % a.i.) for 4 hours to nose only at an analytical concentration of 2.42 g/m³ corresponding to 6.7 g/m³ nominal, which was the highest attainable concentration.  Animals then were observed for 14 days.

Since none of the rats died, it was concluded that the 4-hour LC50 value was higher than 2.42 g/m³ 

No abnormalities were seen during exposure except for black heads. Black heads, half closed eyes and hunched posture were observed immediately after exposure. Grey dust on the fur was seen in all rats and baldness in female rats during the observation period.

Almost all rats showed strongly decreased body weights one week after exposure; weight gained was observed at the end of the 14-day observation period, although pre-exposure weights was just or nearly reached in female rats.

Greyish, brownish or black stained lungs were seen in all rats at autopsy. A grey thymus was observed in four out of five females.

Particle size measurement showed that ca. 72 % of the particles had an aerodynamic diameter between 1.8 and 4.2 µm.

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