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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
sub-chronic 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: Comparable to guideline study.

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 413 (Subchronic Inhalation Toxicity: 90-Day Study)
Deviations:
not specified
GLP compliance:
not specified
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 Purina Rat Chow 5001
- Water (e.g. ad libitum): ad libitum
- Acclimation period: for a minimum of 2 weeks

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle); (areosols of BF3 dihydrate)
Details on inhalation exposure:
Exposure Chamber Designs and Operation
Subchronic exposures were conducted in 1000-liter stainless-steel and glass exposure chambers, operated under negative pressure, with filtered, conditioned air.
The total air flow rate was approximately 350 liters/min, providing a t99 equilibration time of 13 min. These exposures were conducted for 6 hr/day, 5 days/week for 13 weeks.
Chamber air temperature and relative humidity were monitored at least twice daily with a YSI Model 47 Scanning Tele-Thermometer (Yellow Springs Instrument, Yellow Springs, Ohio) and an Airguide Model 605 humidity indicator (Airguide Instrument, Chicago, Ill.), respectively.
All animals were left in the chambers for a period of at least 30 min immediately following the exposure to allow for equilibration of the chamber atmosphere with clean air.

Test Atmosphere Generation Procedures
Test atmospheres in the subchronic study were generated with a DeVilbiss No. 40 Glass nebulizer (The DeVilbiss Company, Somerset, Pa.) and Sage Model 355 syringe pump (Sage Instruments, Cambridge, Mass.). The nebulizer was operated with compressed, breathing-grade air under conditions that rapidly aerosolized the liquid BF3 2H20. The rate of delivery, and thus the quantity of aerosol produced, was controlled by regulating the feed rate on the syringe pump.

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 on cellulose nitrate membrane filters, 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 (Carlson and Paul, 1968; Gulens and Lesson, 1980). 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 twice each week during the subchronic exposures. The material collected on each stage was determined gravimetrically.
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
6 h/day, 5 d/week
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 2, 6 and 17 mg/m3
Basis:
analytical conc.
No. of animals per sex per dose:
20 males and 20 females
Control animals:
yes
Details on study design:
Post-exposure period: 2 weeks (5 animals/sex/dose group)

Examinations

Observations and examinations performed and frequency:
CLINICAL OBSERVATIONS AND FREQUENCY:
- Clinical signs: observed twice daily.
- Mortality: daily noted
- Body weight: recorded twice prior to the first exposure and once a week  thereafter.
- Food consumption: no
- Ophthalmoscopic examination: no
- Haematology (complete blood counts), Biochemistry (blood urea nitrogen (BUN), serum glutamic-pyruvic transaminase (SGPT), alkaline phosphatase, glucose, albumin, total protein, globulin by difference, CA, P, Cl, Na and K) and Urinalysis (volume, osmolality, pH and creatinine : measured after one month of exposure in 5 animals/sex/dose, during the final week of the exposure period (15 animals/sex/dose) and at two weeks past the final exposure (retained group of five animals/sexe/dose).
In addition, determination of urinary ionic and total fluoride and serum total fluoride amounts was made at 1 and also 2 months of exposure (for urinary ionic and total fluoride only), during the final week of the exposure period and two weeks following the final exposure with the same animals selected for serum chemistry determinations.


ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Weighted organs: brain, heart, kidneys, liver, lungs (with trachea),  ovaries, spleen and  testes 
- Macroscopic and microscopic examinations: Tissues from 40 major organs  of high-exposure and control groups were examined. In  addition, nasal turbinates, kidneys, lungs and liver were examinated  from all other animals of the study.
Statistics:
The results of measurements of all quantitative continuous variables such  as body weight, hematology, and clinical chemistry data were  intercompared, exposure groups to controls, by the use of the following  tests: Bartlett's homogeneity of variance, analysis of variance, and Duncan's procedure. The latter was  used if F for analysis of variance was significantly high to delineate  which groups differed from the controls.  If Bartlett's test indicated heterogenous variance, the F max test was  used for each group versus the control.  If these individual Fmax tests were not significant or N1 = N2 Student's  t test was used; if significant, the means were compared by the Cochran t  test or the Wilcoxon rank sum test.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
effects observed, treatment-related
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS:
There was an increased incidence of dried material around the mouth and  nose, rales and excessive lacrimation, primarily in the high-exposure  group.

MORTALITY: One rat died in the high-exposure group. This death was attributed to the  test substance. Two accidental deaths occurred.

BODY WEIGHT: No differences were observed between treated and control groups.

HAEMATOLOGY: No differences were observed between treated and control groups.

BLOOD CHEMISTRY: An exposure-related depression of total protein concentrations (up to  16%) accompanied by an exposure-related depression of globulin  concentrations (up to 38%). One male from the high-exposure group had an elevated blood urea nitrogen. Serum fluoride concentration were markedly increased in all exposure  groups (dose-related increase). A recovery was noted after the end of  exposure.

URINALYSIS: An exposure-related depression in calcium amounts and an exposure-related  increase in urinary fluoride were noted. The decrease in calcium values was found to be reversible at the end of  exposure.

NECROPSY:
- Organ weight: No differences were observed between treated and control groups.
- Macroscopic findings: No specific changes were observed in treated groups when compared to  control group.
- Microscopic findings: In the high-exposed dead male, necrosis of the renal tubular epithelium  was seen. Another high-exposed rat also exhibited such a necrosis (this is the rat  which had an elevated blood urea nitrogen).

Effect levels

open allclose all
Dose descriptor:
NOAEC
Effect level:
6 mg/m³ air
Sex:
male/female
Basis for effect level:
other: kidney effects
Dose descriptor:
LOAEC
Effect level:
17 mg/m³ air
Sex:
male/female
Basis for effect level:
other: Tubular necrosis in 2 male rats
Dose descriptor:
LOEC
Effect level:
2 mg/m³ air
Sex:
male/female
Basis for effect level:
other: Increase of fluorine in urine and in blood samples
Dose descriptor:
LOEC
Effect level:
6 mg/m³ air
Sex:
male/female
Basis for effect level:
other: Minimal findings of respiratory irritation

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

MEAN URINARY CALCIUM CONCENTRATIONS (mg/dl)
Exposure (mg/m3) Males Females
Week 5 Week 9 Week 13 Week 15 Week 5 Week 9 Week 13 Week 15
0 7.70 a 12.22 15.12 25.00 10.34 18.44 14.17 40.0
2.49 5.31 11.29 8.99 4.02 5.71 7.57 12.7
3 5 20 5 5 5 20 3
2 8.67 8.36 11.45 25.50 7.24 12.42 9.63 31.8
4.46 3.17 8.90 6.36 2.15 4.99 5.19 14.0
4 5 20 5 5 5 20 5
6 11.18 5.82* 8.01* 19.76 4.22** 6.22** 6.63** 29.5
5.99 1.58 3.68 7.89 1.30 2.52 4.47 18.8
5 5 20 5 5 5 19 4
17 3.38 3.72** 5.95** 19.26 6.75 6.78** 11.67 51.9
2.06 1.10 4.70 12.15 1.98 3.62 7.36 21.7
5 5 19 5 4 5 20 5
a Mean, standard deviation, number of animals evaluated.
* Significantly different from control p< 0.05.
** Significantly different from control p< 0.01.

URINARY FLUORIDE AND TOTAL FLUORINE AMOUNTS
Exposure (mg/m3) Males Females
Week 5 Week 9 Week 13 Week 15 Week 5 Week 9 Week 13 Week 15
Urinary ionic fluoride amounts (µg)                
0 14 a 7 11 5 11 6 ll 7
2 5 8 1 2 1 6 6
3 5 20 5 5 4 20 5
2 121 160** 257** 86* 192** 187** 251** 57**
57 62 98 30 59 37 79 19
4 5 20 5 5 5 20 5
6 175* 211** 228** 114** 340** 240** 382** 68**
67 85 104 50 39 83 103 35
5 5 20 5 5 5 20 5
17 418** 430** 412** 140** 409** 346** 453** 64**
82 61 212 79 72 78 144 16
5 5 19 5 4 5 20 5
Total urinary fluorine amounts (µg)                
0 21 17 59 7 10 6 12 8
3 11 56 2 4 1 6 6
5 4 20 5 5 4 20 5
2 166 192 392 111 323 338 360* 64
60 36 155 40 169 80 153 22
4 5 20 5 5 5 20 5
6 506 465 506- 213 805** 595* 811** 119**
188 115 252 80 314 264** 248 70
5 5 20 5 5 5 20 5
17 2201** 2546* 2021** 476** 1766** 1592** 1694** 184**
574 2221 1418 258 435 438 796 47
5 5 19 5 4 5 20 5
a Mean, standard deviation, number of animals evaluated.
*Significantly different from control p< 0.05.
**Significantly different from control p< 0.01.

Exposure (mg/m3) Males Females
Week5 Week13 Week15 Week5 Week13 Week15
Total serum protein (g/dl)            
0 6.24 a 7.29 6.92 6.80 7.15 7.03
0.31 0.27 0.42 0.35 0.17 0.15
5 15 5 5 15 4
2 5.90 6.91 7.18 5.94** 6.79** 7.00
0.26 0.46 0.26 0.50 0.25 0.34
5 15 5 5 15 5
6 6.16 6.89 6.98 6.06 6.74** 6.88
0.29 0.45 0.26 0.34 0.16 0.27
5 15 5 5 15 5
17 6.14 6.56** 6.90 5.74** 6.67** 6.94
0.30 0.65 0.27 0.23 0.20 0.15
5 15 5 5 15 5
Globulin (g/dl)            
0 1.60 2.59 2.06 2.62 2.63 2.93
0.31 0.30 0.21 0.63 0.17 0.28
5 15 5 5 15 4
2 1.56 2.36 2.40 1.88 2.35** 2.94
0.33 0.39 0.14 0.51 0.20 0.42
5 15 5 5 15 5
6 1.78 2.31 2.20 1.86 2.31** 2.78
0.23 0.43 0.26 0.31 0.15 0.15
5 15 5 5 15 5
17 1.86 2.09** 2.30 1.66* 2.27** 2.70
0.25 0.54 0.63 0.49 0.15 0.12
5 14 5 5 15 5
a Mean, standard deviation, number of animals evaluated.
* Significantly different from control p< 0.05.
** Significantly different from control p< 0.01.

TOTAL SERUM FLUORINE AND BONE FLUORIDE
Exposure (mg/m3) Males Females
  Week 5 Week 13 Week 15 Week 5 Week 13 Week 15
Serum total fluorine (µg/ml)            
0 0.21 a 0.27 0.19 0.46 0.28 0.10
0.17 0.16 0.06 0.12 0.09 0.03
5 15 5 5 15 4
2 0.36 0.98 0.38 0.81 2.26 0.29
0.05 0.35 0.10 0.27 0.32 0.14
5 15 5 5 15 5
6 1.04 2.17 1.15* 2.82* 3.46* 0.77
0.23 0.6 0.42 1.33 1.00 0.56
5 15 5 5 15 5
17 3.32* 8.94* 1.65* 5.06* 7.25* 2.97*
1.11 0.69 0.65 0.88 2.97 0.51
5 14 5 5 15 5
Bone fluoride (µg/g)            
0   167 145   157 155
  16 27   56 27
  8 5   14 4
2   758* 905*   1159* 1178*
  180 161   262 179
  12 5   15 4
6   1119* 1430*   1564* 1709*
  165 204   197 63
  15 5   15 5
17   1554* 2109*   2289* 2763*
  183 536   422 364
  14 5   15 5
a Mean, standard deviation, number of animals evaluated.
* Significantly different from control p< 0.01.

Applicant's summary and conclusion

Conclusions:
The No Observed Adverse Effect Level (NOAEL) is 6 mg/m3 and the LOAEL is 17 mg/m3 for effects on kidney. The increase of fluorine amounts in serum and in urine are not considered as adverse since no signs of toxicity was associated and since it was reversible or partially reversible (as the recovery period was only 2 week, a full reversibility was not observed for urinary fluorine); nevertheless they are related to treatment.
Executive summary:

The potential toxicity of Boron Trifluoride (BF3) was evaluated following repeated inhalation administration for 13 weeks, according to OECD Guideline 413. The substance was tested in a dihydrate form which contained 63.87% of BF3. Aerosols of BF3 dihydrate were administered daily by inhalation to Fischer 344 rats (20 Males and 20 Females), 6 hrs/day, 5 days a week, at the dose-levels of 0, 2, 6, 17 mg/m3 during 90 days.

Body weights were recorded pre-test, weekly and at death or prior necropsy. Animals were observed daily for toxicity and pharmacological effects, and twice daily for morbidity and mortality.

Whole blood, serum and plasma, and urine were sampled after one month of exposure in 5 animals/sex/dose, during the final week of the exposure period (15 animals/sex/dose) and in the retained animals (5/sex/dose) at the end of the post-exposure period. In addition, fluoride was measured in urine and in blood after 1 and 2 months of exposure and 2 weeks after the final exposure. All animals were examined for gross pathology, and organs were weighted and submitted to histopathology. Tissues from 40 major organs of high-exposure and control groups were examined. In addition, nasal turbinates, kidneys, lungs and liver were examinated from all other animals of the study.

At 17 mg/m3, one death was attributed to the test substance.

No differences were observed between treated and control groups for body weight and haematology. Urine analysis and blood chemistry were affected by treatment.

Clinical signs of respiratory irritation were seen, but without abnormal histological findings.

An exposure - related depression of total protein concentrations accompanied by an exposure-related depression of globulin concentrations was observed.

In urines, an exposure-related depression in calcium amounts and an exposure-related increase in urinary fluoride were noted. The decrease in calcium values was found to be reversible at the end of exposure, contrary to the decrease of urinary fluoride which was partially reversible.

Serum fluoride concentration were markedly increased in all exposure groups (dose-related increase). A recovery was noted after the end of exposure.

At necropsy, no differences for organ weight and macroscopic appearance were observed between treated and control groups. At microscopy examination, necrosis of the renal tubular epithelium was seen in the highest dose group and was the apparent cause of a death in one of the animals.

Consequently, under the experimental conditions, the No Observed Adverse Effect Level (NOAEL) is 6 mg/m3 and the LOAEL is 17 mg/m3 for effects on kidney. The increase of fluorine amounts in serum and in urine are not considered as adverse since no signs of toxicity was associated and since it was reversible or partially reversible (as the recovery period was only 2 week, a full reversibility was not observed for urinary fluorine); nevertheless they are related to treatment.