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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:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Basic data given

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1974
Report Date:
1974

Materials and methods

Test guideline
Qualifier:
no guideline available
Guideline:
other: Continuous dynamic exposure method
Principles of method if other than guideline:
A semi-portable chamber was used for exposure. An exhaust fan was utilized to provide an adjustable air flow. Test material was administered into the incoming airstream just before it entered the circular hood of the chamber.
GLP compliance:
no
Test type:
other: Continuous dynamic exposure method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Sodium borohydride
- Physical state: powder
- Lot/batch No.: 3-97

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: 200 g
- Housing: animals were confined individually in cages constructed entirely of 3/8 inch screen to be placed into the chamber; Following exposure, five of the exposed animals and five of the control animals were placed in screen bottom cages.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: minimum of four weeks


Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: a semi-portable exposure chamber similar to those developed by the Public Health Service in the Taft Laboratories at Cincinnati.
- Exposure chamber volume: not reported
- Method of holding animals in test chamber: confined individually in cages constructed entirely of 3/8 inch screen and placed in a central location in the chamber
- Source and rate of air: an exhaust fan was utilized to provide an adjustable air flow through the chamber. Test material was administered into the incoming airstream just before it entered the circular hood of the chamber. Air flow was maintained at 586 liters/air.
- Method of conditioning air: not reported
- System of generating particulates/aerosols: The material was sprayed into the air stream using a Wright Dust Feeder.
- Method of particle size determination: not reported
- Treatment of exhaust air: no data
- Temperature, humidity, pressure in air chamber: not reported


TEST ATMOSPHERE
Air flow was calculated from the pressure drop across a measured inlet orifice in a steel plate. Because of the quantity of material administered, a certain amount came directly in contact with the inlet pipe and circular hood of the chamber. This material was collected, measued and the amount subtracted from the total material administered when calculating the actual exposure level. The final exposure was calculated in mg per liter by subtracting the amount recovered from upper chamber from the total amount sprayed into the chamber and dividing this difference by the total cubic feet of air circulated through the chamber.


VEHICLE
Not applicable



Analytical verification of test atmosphere concentrations:
not specified
Duration of exposure:
1 h
Concentrations:
5.18 mg/L air
No. of animals per sex per dose:
10
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days; 5 exposed and 5 control animals were sacrificed 30 minutes after completion of the exposure period. The remaining 5 exposed and 5 control animals were observed for 14 days.
- Frequency of observations and weighing: gross observation at necropsy; weighing not reported.
- Necropsy of survivors performed: yes
- Other examinations performed: histopathological: lungs and trachea removed and preserved in fixative. The lungs were inflated with fixative before removal by clamping off the trachea with a hemostat and injecting the fixative into the trachea between the hemostat and the lungs.
Statistics:
Not reported

Results and discussion

Effect levels
Sex:
male
Dose descriptor:
LC50
Effect level:
> 5.18 mg/L air
Exp. duration:
1 h
Mortality:
No deaths
Clinical signs:
other: Not reported
Body weight:
Not reported
Gross pathology:
No effects
Other findings:
- Histopathology: sections of lung and trachea show no tissue pathology. Alterations seen occur in both control and test animals and not considered to be treatment related.

Applicant's summary and conclusion

Interpretation of results:
practically nontoxic
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The acute inhalation LC50 is greater than 5.18 mg/L at 1 hour (converted to > 1.3 mg/l at 4 hours).