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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The CRO at which this study was performed was discredited for falsifying study reports and generating fake data. Therefore, the reliability of this study is questionable and it is rated with Klimisch 4. However, since two other routes (oral and dermal) are addressed adequately, data for this route is not required and the study is disregarded.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1972
Report Date:
1972

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
no
GLP compliance:
no
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
- Source: ARS/Sprague-Dawley, Madison, Wisconsin.
- Weight at study initiation: 191 g (average)
- Acclimatisation period: at least 5 days
- Housing: single housing in stock cages
- Diet: Purina Rat Chow, Ralston Purina Co., St, Louis, Missouri, ad libitum
- Water: ad libitum

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Plexiglas inhalation chamber. The chamber was designed so that the animals could be introduced to the test atmosphere after the maximum dust concentration was established. Each animal was caged separately during exposure to minimize filtration of inspired air by animal fur.
- Exposure chamber volume: capacity of 70 L
- System of generating particulates/aerosols: Dust was suspended with a specially designed dust feeder capable of producing high concentrations over a long period of time. The test material powder was passed through a high-velocity stream of clean dry air (-40°C dewpoint). The resulting air and dust mixture was then introduced into the exposure chamber at the top center, dispersed by a baffle plate and exhausted at the bottom of the chamber. Air flow rate through the system (8.2 L/min at 29.92 inches Hg and 25 °C) was measured with a rotameter connected upstream of the dust feeder. The rotameter was calibrated with a wet-test meter after the exposure was completed.
- Method of particle size determination: A sample of airborne dust was collected from the test atmosphere for the purpose of conducting a microscopic determination of particle size distribution. Particles were counted with respect to three size ranges, five microns or smaller, which is considered to be respirable, six to twenty-five microns and larger than twenty-five microns. The smallest particle which can be detected by the light-field technique employed is approximately one micron. The largest particle observed was also recorded.
- Temperature, humidity, pressure in air chamber: The temperature of the test atmosphere was 26°C and the pressure was 30.04 inches Hg.

TEST ATMOSPHERE
- Brief description of analytical method used:
The concentration of test material dust present in the exposure chamber was determined by sampling the test atmosphere in the breathing zone of the animals being exposed. The total weight of dust collected on a glass fiber filter was divided by the total volume of air drawn through the filter during the sampling period. Air flow rate for sampling was regulated by a calibrated limiting orifice. The average concentration of airborne dust, obtained by repeated air sampling, was 0.4 mg/L air at 29.92 inches Hg and 25° C.
- Samples taken from breathing zone: yes
- Particle size distribution: a total of 601 particles was counted microscopically
1-5 microns: 82% of total particles counted
6-25 microns: 17%
25-38 microns: 1%
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
0.4 mg/L air
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of weighing: before the study and after 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs and mortality were observed during the exposure

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 0.4 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: No mortality and no clinical signs were observed.
Mortality:
No mortality was observed.
Clinical signs:
No clinical findings were observed.
Body weight:
A mean body weight gain of 54 gram was observed within 14 days, which was within the normal limits.
Gross pathology:
Necropsy did not reveal any gross pathologic alterations in any of the tissues and organs examined.

Applicant's summary and conclusion