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Toxicological information

Acute Toxicity: inhalation

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Administrative data

acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
from 2010-05-19 till 2010-08-05
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study reliable without restrictions
Reason / purpose for cross-reference:
reference to same study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
GLP compliance:
yes (incl. QA statement)
signed 2009-11-12
Test type:
acute toxic class method
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
Zinc selenite
EC Number:
EC Name:
Zinc selenite
Cas Number:
Molecular formula:
zinc selenite
Details on test material:
- Name of test material (as cited in study report): Zinc selenite
- Substance type: technical product
- Physical state: solid
- Storage condition of test material: At room temperature, in tightly closed original container, well-ventilated, kept away from water and metals which are attacked by an alkaline medium.

Test animals

other: CD / Crl: CD(SD)
Details on test animals or test system and environmental conditions:
- Source: Charles River Laboratories, Research Models and Services, Germany GmbH, Sandhofer Weg 7, 97633 Sulzfeld, Germany
- Age at study initiation: males: approx. 7 weeks; females: approx. 9 weeks
- Weight at study initiation: males: 242 - 270 g; females: 218 - 247 g
- Fasting period before study: feeding was discontinued approx. 16 hours before exposure.
- Housing: Granulated textured wood (Granulat A2, J. Brandenburg, 49424 Goldenstedt, Germany) was used as bedding material for the cages. During the 14-day observation period the animals are kept by sex in groups of 2 - 3 animals in MAKROLON cages (type III plus).
- Diet: Commercial diet, ssniff® R/M-H V1534 (ssniff Spezialdiäten GmbH, 59494 Soest, Germany) - discontinued before exposure
- Water: tap water in bottles (ad libitum)
- Acclimation period: at least 5 adaptation days

- Temperature (°C): 22°C±3°C (maximum range)
- Humidity (%): 55%±15% (maximum range)
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12/12


Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Details on inhalation exposure:
- Exposure apparatus: The study was carried out using a dynamic inhalation apparatus (air changes/h (≥ 12 times)) with a nose-only exposure of the animals according to KIMMERLE & EBEN. The apparatus consists of a cylindrical exposure chamber which holds the animals in pyrex tubes at the edge of the chamber in a radial position.
- Exposure chamber volume: 40 L
- Source and rate of air: Air was taken from the surrounding atmosphere of the laboratory room and filtered using an in-line disposable gas-filter. At the bottom of the exposure chamber, the air was sucked off at a lower flow rate than it was created by the dust generator in order to produce a homogenous distribution and a positive pressure in the exposure chamber (inflow 900 L/h, outflow 800 L/h, 22.5 air changes per hour).
- System of generating particulates/aerosols: The dust of the test material was generated with a rotating brush dust generator. The generator was fed with compressed air (5.0 bar) from a compressor.
- Treatment of exhaust air: The exhaust air was drawn through gas wash-bottles.
- Temperature, humidity, pressure in air chamber: Temperature (22°C ± 3°C) and humidity (30 % - 70 %) were measured every hour with a climate control monitor.

- Before initiating the study with the animals, a pre-test was carried out with the exposure system in order to verify that under the experimental settings chosen, the limit concentration of 5 mg/L air could be achieved by gravimetric analysis.
- Brief description of analytical method used: The actual dust concentration in the inhalation chamber was measured gravimetrically with an air sample filter and pump, controlled by a rotameter. Dust samples were taken once every hour during the exposure. - Samples taken from breathing zone: yes; a probe was placed close to the animals' noses and air was drawn through the air sample filter at a constant flow of air of 5 L/min for 1 minute. The filters were weighed before and after sampling (accuracy 0.1 mg).
- Particle size distribution: An analysis of the particulate size distribution was carried out twice during the exposure period using a cascade impactor. The dust from the exposure chamber was drawn through the cascade impactor for 5 or 10 minutes at a constant flow rate of 5 L/min. The slides were removed from the impactor and weighed on an analytical balance. Delta of slides’ weight were determined.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The mass median aerodynamic diameter (MMAD) was estimated by means of non-linear regression analysis to be 2.595 µm (for 5.16±0.06 mg/L) and 2.719 µm (for 1.07±0.08 mg/L). The Geometric Standard Deviation (GSD) of the MMAD was calculated to be 2.855 (5.16±0.06 mg/L) and 3.130 (1.07±0.08 mg/L). Both obtained from a non-linear regression analysis. In addition, a sample of approx. 10 g test material was taken from the exposure chamber to determine the median physical particulate size with a Malvern Sizer by Malvern, 71083 Herrenberg, Germany.

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: according to guideline
Analytical verification of test atmosphere concentrations:
gravimetrically determined
Duration of exposure:
4 h
Remarks on duration:
per animal and concentration
(i) 5.16±0.06 mg/L air (gravimetric concentration)
(ii) 1.07±0.08 mg/L air (gravimetric concentration)
No. of animals per sex per dose:
two concentrations of 3 males and 3 females, each
Control animals:
Details on study design:
- The animals were acclimatised to the test apparatus for approx. 1 hour on 2 days prior to testing.
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: clinical examination at least twice daily until all symptoms subsided, thereafter each working day; observations on mortality were made at least once daily (in the morning starting on test day 2) to minimize loss of animals to the study.
Individual weights of animals were determined once during the acclimatisation period, before and after the exposure on test day 1, on test days 3, 8 and 15. Changes in weight were calculated and recorded when survival exceeded one day. At the end of the test, all surviving animals were weighed and sacrificed.
- Necropsy of survivors performed: yes, necropsy of all animals was carried out and all gross pathological changes were recorded (with particular attention to any changes in the respiratory tract). Autopsy and macroscopic inspections of rats which died prematurely were carried out as soon as possible after death. No microscopic examination was carried out as no pathological findings were noted at necropsy.
- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other: Cageside observations included, but were not limited to: changes in the skin and fur, eyes, mucous membranes, respiratory, circulatory, autonomic and central nervous system, as well as somatomotor activity and behaviour pattern. Particular attention was directed to observation of tremor, convulsions, salivation, diarrhoea, lethargy, sleep and coma. The animals were also observed for possible indications of respiratory irritation such as dyspnoea, rhinitis etc.
no data

Results and discussion

Effect levelsopen allclose all
Dose descriptor:
Effect level:
> 1 - <= 5 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: LC50 was assigned to a level between the second dosing (1.07 mg/L air) and the first dosing (5.16 mg/L air) since no mortality occurred with the second dose and 3/6 animals died from the first dose (acc. to class method).
Dose descriptor:
other: cut-off value
Effect level:
5 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: with a concentration of 5.16 mg/l air
(i) at 5.16 mg/L air: 1 of 3 male and 2 of 3 female animals died prematurely (on test day 2)
Clinical signs:
other: (i) at 5.16 mg/L air: slight ataxia, slight to moderate tremor and slight dyspnoea on test day 1 immediately after end of exposure until 3 hours post exposure in all 3 male and 3 female animals (ii) at 1.07 mg/L air: slight ataxia, slight tremor and slig
Body weight:
(i) at 5.16 mg/L air: All 3 surviving male or female rats appeared to be reduced in body weight gain.
(ii) at 1.07 mg/L air: Body weight changes of all animals revealed throughout the study period normal gains.
Gross pathology:
(i) at 5.16 mg/L air: No abnormalities were detected at necropsy.
(ii) at 1.07 mg/L air: No abnormalities were detected at necropsy.
Other findings:
- Organ weights:
- Histopathology:
- Potential target organs:
- Other observations:

Any other information on results incl. tables

The mean actual exposure concentrations, MMAD and GSD of zinc selenite were as follows


nominal concentration


gravimetric concentration


mass median aerodynamic diameter



geometric standard deviation



[mg/L air]


[mg/L air]













Applicant's summary and conclusion

Interpretation of results:
Migrated information Criteria used for interpretation of results: EU
Under the conditions of this study, the 4-hour inhalation LC50 of zinc selenite was determined at > 1 - 5 mg/L air. According to the EC Regulation No. 1272/2008 and subsequent regulations, the test item is assigned to the hazard category 4 (LC50: > 1 - 5 mg/L air) for acute toxicity hazard, inhalation route.