Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Test procedure in accordance with normal standard methods.

Data source

Reference
Reference Type:
publication
Title:
Inhalation toxicity Studies with Boron Trifluoride
Author:
Rusch GM et al.
Year:
1986
Bibliographic source:
Toxicol. and Appl. Pharmacol., 83, 67-78

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
not specified
GLP compliance:
not specified
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of the test substance: Boron trifluoride dihydrate
- Source: Allied Corporation
- Batch number: no data
- Purity: The substance was tested in a dihydrate form which contained 63.87% of BF3.

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Labs (Portage, Mich.)
- Age at study initiation: approximately 7 weeks old
- Weight at study initiation: no data
- Fasting period before study: no
- Housing: individually in suspended stainless-steel mesh cages
- Diet (e.g. ad libitum): ad libitum Purin Rat Chow 5001
- Water (e.g. ad libitum): ad libitum
- Acclimation period: for a minimum of 2 weeks

ENVIRONMENTAL CONDITIONS: no data

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
whole body
Vehicle:
other: air
Details on inhalation exposure:
Exposure Chamber Designs and Operation
The acute exposure was conducted in 225-liter stainless-steel and glass exposure chambers, operated under negative pressure with filtered, conditioned air.
The total flow rate during the acute study was approximately 50 liters/min, providing a t99 equilibration time of 21 min.

Test Atmosphere Generation Procedures
Test atmospheres in the acute study were generated with a Solo-Sphere nebulizer (McGraw Respiratory Therapy, Irvine, CA.) operated with compressed, breathing-grade air. Exposure concentrations were controlled by regulating the airflow through the nebulizer, and thus the rate of aerosol generation.

Analysis of Chamber Concentrations
Nominal aerosol concentrations were determined daily by measuring the amount of test material consumed during the exposure and dividing this by the total airflow through the chamber. At hourly intervals, actual air concentration measurements were made by trapping aerosol samples of known volume in I5-ml impingers, using a flow-Gmiting orifice (Millipore XX50000014) with a pump (Gast DOA-122) and dry test meter (Singer DTM-115-3) for volume measurement. The aerosol was then dissolved in distilled water and analyzed for BF3 content by an ion-selective electrode technique. Sample volumes were varied to permit collection of roughly equal quantities of BF3.
Particle size measurements were made with an Anderson I ACFM particle sizing sampler (Anderson 2000, Inc., Atlanta, Ga.). Measurements were performed hourly during the acute exposures; three times/week during the subacute exposures; and twice each week during the subchronic exposures. The material collected on each stage was determined gravimetrically.
Mass median aerodynamic diameter: 1.8 µm
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
1.01, 1.22, 1.32 and 1.54 mg/l
No. of animals per sex per dose:
5 males + 5 females
Control animals:
no
Details on study design:
EXAMINATIONS: 
Duration of observation: 14 days
- Clinical signs: examined just before exposure, at 15-minute intervals  during the first hour then hourly for the remaining of exposure and daily until the completion of the study.
- Mortality: idem
- Body weight: measured on days 1, 2, 4, 7 and 14
- Necropsy:
. macroscopic examination of the main organs: yes
. microscopic examination: no

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
1 210 mg/m³ air
Exp. duration:
4 h
Mortality:
Deaths occurred in all exposure groups: nine (out of 10) at 1.54 mg/l,  eight at 1.32 mg/l, two at 1.22 mg/l, and three at 1.01 mg/l, ranging  from the day of the exposure to 6 days post-exposure. 
Clinical signs:
Clinical signs elicited by the exposures included dry and moist rales,  gasping, excessive oral and nasal discharge, and lacrimation, indicative  of respiratory distress and irritation. Recovery was apparent for the  rats surviving beyond 6 days post-exposure. 
Body weight:
A body weight decrease was recorded.
Gross pathology:
A decrease in liver and kidney decrease was noted.

Applicant's summary and conclusion

Conclusions:
An LC50 of 1.21 mg/l or 1210 mg/m3 was calculated for a 4-hr exposure to boron trifluoride. The animals exhibited clinical signs of oral and nasal discharge, gasping, lacrimation, indicative of irritation and respiratory distress. Recovery was apparent for the rats surviving beyond 6 days post-exposure.