Tetrafluoroboric acid

Endpoint summary

Description of key information

A NOAEL of 40 mg/kg bw/day for systemic effects was established in an oral reproduction/developmental toxicity screening test and a NOAEL of 74 mg/m3 for systemic effects was established in a 28-day inhalation study in rats exposed to KBF4, a structural analogue of HBF4.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: oral

Remarks:

other: Reproduction / Developmental Toxicity Screening Test

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany, SPF-bred colony
- Age at study initiation: (P) 8-9 wks
- Weight at study initiation: (P) within 20% of the mean weight for each sex
- Housing: in macrolon cages with wood shavings (Lignocel, Type 3/4) as bedding material and strips of paper (Enviro-dri) as environmental enrichment. During the premating period, the animals were housed in groups of 4/sex. For mating, 1 male and 1 female were housed together. Mated femaleswere housed individually in macrolon cages, which were then placed in another cage rack. After delivery, the cage containing the dam with litter were transferred to another cage rack
- Diet: cereal-based (closed formula) rodent diet (Rat & Mouse No. 3 Breeding Diet, RM3) from a commercial supplier (SDS Special Diets Services, Witham, England), ad libitum
- Water: tap water in polypropylene bottles, cleaned weekly and filled as needed, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30-70
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

1% solution in water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The test substance was suspended in 1% CMC. The dosing solutions were prepared weekly and stored at 2-10 ºC. The miscibility of the test substance in vehicle were checked by visual inspection before the start of the study.

VEHICLE
- Concentration in vehicle: 0, 20, 58.2, 175 and 500 mg/mL
- Amount of vehicle: 2 mL/kg bw
- Lot/batch no.: 101K0185
- Purity: 1% solution in water

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses to determine the stability, homogeneity and content of the test substance in the vehicle was conducted, by quantitative determination of the level of potassium tetrafluoroborate by determination of boron using ICP-AES and determination of fluoride using GC-FID with headspace.

Duration of treatment / exposure:

Males: during 4 weeks premating period and during the mating period for at least 5 weeks until sacrifice. Females: during a 2-week premating period, during the mating, gestation and lactation period until sacrifice. Animals were not dosed on the day of necropsy.

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
40, 116.5 and 350 mg/kg bw/day (adjusted from 116.5, 350 and 1000 mg/kg bw/day due to body weight loss in high-dose animals)
Basis:
actual ingested

No. of animals per sex per dose:

12/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Rationale for animal assignment: computer randomization proportionally to body weight.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily in the morning hours by cage-side observations. On working days, all cages were checked again in the afternoon for dead or moribund animals to minimise loss of animals from the study. On Saturdays and Sundays only one check per day was carried out.

BODY WEIGHT: Yes
- Time schedule for examinations: shortly before the time of dosing (randomization) and on the first day of dosing and weekly thereafter during the premating period. In addition, body weights of the male animals were measured on day 3 and 5 of the study. Males were weighed approximately weekly during the mating period until sacrifice. Females were weighed approximately weekly during mating and mated females were weighed on days 0, 7, 14 and 21 during presumed gestation and on day 1 and 4 of lactation. All animals were weighed on the day of sacrifice.

FOOD CONSUMPTION: Yes
Food consumption of male rats was measured approx. weekly, except during the mating period. In addition, food consumption of the male animals was measured on day 3 and 5 of the study, except for male animals of lowest dose group.
Food consumption of female rats was measured weekly during the premating period and during the gestation period from gestation days 0-7, 7-14 and 14-21, and once during the lacation period from day 1 to 4.

WATER CONSUMPTION: Yes
During daily observations, until day 5 of gestation.

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

SACRIFICE
- Male animals: all male animals of the 1000 mg/kg bw/day group were sacrified on day 7 of the study after 3 daily dosages and 5 days of recovery. Males from other groups were euthanised after approximately 5 weeks of exposure.
- Maternal animals: sperm-positive females that turned out to be non-pregnant were killed 24-26 days after copulation. Females that became pregnant were sacrificed at day 4 of lactation.

GROSS NECROPSY
Animals were examined grossly for macroscopic changes.

HISTOPATHOLOGY / ORGAN WEIGHTS
Samples of the following organs were preserved: ovaries (after counting of the corpora lutea), uterus (after counting of the implantation sites), testes, epididymides, seminal vehicles, prostate, organs and tissues showing macroscopic abnormalities.

Statistics:

Clinical findings were evaluated by Fisher's probability test. Body weight, body weight gain, organ weights and food consumption data were subjected to one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison tests. Histopathological changes were evaluated by Fisher's exact probability test.

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

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:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Two female animals of the 350 mg/kg bw/day died during lactation period. Daily clinical observations during the study did not reveal any remarkable findings in animal appearance, general condition or behaviour among the dosing and control groups.

BODY WEIGHT (PARENTAL ANIMALS)
Twelve male animals of the 1000 mg/kg bw/day group lost ca. 10% (30 g) of their initial body weight on day 0 after 3 daily dosages. It was decided, after the consultation with the sponsor, to stop dosing these male animals and to keep these animals in the study without treatment up to day 7, to study the reversibility of this effect. Mean body weight of the animals of day 7 was comparable to their body weight on day 0.
Mean body weight and/or body weight change of the male and female animals of 350 mg/kg bw/day group were statistically significantly decreased during several periods of the study. Mean body weight of the male animals of the 350 mg/kg bw/day group was statistically significantly decreased from day 3 until sacrifice. Mean body weight change of the male animals of this group was statistically significantly decreased between days 0-3, 3-5, 7-14 and 21-28. Mean body weight of the male animals of the 116.5 mg/kg bw/day group was statistically significantly decreased from day 28 until sacrifice. Mean body weight change of the male animals of this group was statistically significantly decreased between days 21-28. No decreased in body weight and body weight change was observed in the male animals of the 40 mg/kg bw/day group. During the premating period, no effect on body weight or body weight change was observed in female animals treated with KBF4. Mean body weight of the female animals of the 350 mg/kg bw/day group was statistically significantly decreased from gestation day 7-21. Mean body weight change of the female animals of this group was statistically significantly decreased from gestation days 7-14. Mean body weight of the female animals of this group was statisitcally significantly decreased on lactation day 1. During the lactation period no effect was observed on mean body weight change of the KBF4-treated females.

FOOD CONSUMPTION (PARENTAL ANIMALS)
Food consumption of the male animals of the 1000 mg KBF4/kg body weight group was statistically significantly decreased (5.45 g/animal/day versus 19.65 g/animal in the control group) from day 0-3. Animals of this group were not longer dosed from day 3 to 7; food consumption of the animals was back to normal or even higher from day 5 to 7. Food consumption of the male animals of the 350 mg KBF4/kg body weight group was statistically significantly decreased during the premating period. Food consumption of the animals of the 116.5 mg KBF4/kg body weight group was comparable to the control group except for the statistical significant difference between dat 7 and 14. Food consumption of the female animals of the 350 mg KBF4/kg body weight group was statistically significantly decreased from day 14-21 of the premating period, during GD 0-14 (g/animal/day) and GD 0-7 (g/kg/day) and day 1-4 of lactation (g/animal/day). One animal of this group did not eat any food from lactation day 1-4. Furthermore, no remarkable differences were observed in the KBF4-treated groups.

ORGAN WEIGHTS (PARENTAL ANIMALS)
Absolute and relative testes and epididymides weights were comparable in all groups.

GROSS PATHOLOGY (PARENTAL ANIMALS)
At scheduled necropsy no treatment-related gross changes were observed.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Microscopic examination did not reveal treatment related histopathological changes in any of the sampled organs and tissues (epididymides, testes, uterus and ovaria).

OTHER FINDINGS (PARENTAL ANIMALS):
Effects on water consumption were observed (not exactly measured) in the male and female animals of the 350 mg/kg bw/day group from week 3 onwards. In consultation with the study director it was decided to stop registration of water consumption after day 5 of gestation.

Dose descriptor:

NOAEL

Effect level:

40 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on the effects on mortality in the 350 mg/kg bw/day group and body weight and food consumption in the 116.5 and 350 mg/kg bw/day group.

Critical effects observed:

not specified

Conclusions:

A NOAEL of 40 mg/kg bw/day was established in a reproduction/developmental toxicity screening test.

Executive summary:

In a GLP compliant reproduction/developmental toxicity screening test, performed according to OECD Guideline 421, Wistar rats of both sexes were orally exposed to potassium tetrafluoroborate. 1% carboxymethylcellulose solution in water (CMC) was used as vehicle. Groups of 12 rats per sex were dosed daily with 0, 40, 116.5 and 350 mg KBF4/kg body weight for up to approx. 35 days (males) or during 4 weeks premating, mating, gestation and up to day 4 of lactation (females). Initially a group of male rats was dosed with 1000 mg KBF4/kg body weight. These animals showed a weight loss of approx. 10% after 3 daily dosages. For that reason this group was replaced by the 40 mg KBF4/kg body weight. Two female animals of the 350 mg KBF4/kg body weight died during the lactation period. Daily clinical observations during the study did not reveal any remarkable findings in animals' appearance, general condition or behavior among the dosing and control groups. Effects on water consumption were observed (not exactly measured) in the male and female animals of the 350 mg KBF4/kg body weight group from week 3 onwards. Mean body weight and or body weight change of the male and female animals of the 350 mg KBF4/kg body weight were statistically significantly decreased during several periods of the study. Mean bodyweight or bodyweight change of the 116.5 mg KBF4/kg body weight group was only statistically significantly decreased in the male animals from day 21 onwards. Food consumption of the 350 mg KBF4/kg body weight group was statistically significantly decreased in male and female animals during several periods of the study. Food consumption of the male animals of the 116.5 mg KBF4/kg body weight group was statistically significantly decreased from day 7 to 14. Terminal body weight of the male animals of the 40 and 116.5 mg KBF4/kg body weight groups was statistically significantly decreased. At scheduled necropsy no treatment related gross changes were observed. Microscopic examination did not reveal treatment related histopathological changes in any of the sampled organs and tissues (epididymides, testes, uterus and ovaries). Based on the effects on mortality in the 350 mg KBF4 group/ kg body weight group, (terminal) body weight and food consumption in the 116.5 and 350 mg KBF4/kg body weight groups, the NOAEL for parental toxicity is 40 mg KBF4/kg body weight/day.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

40 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

GLP-compliant guideline study, klimisch 1

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories
- Age at study initiation: 8 weeks
- Weight at study initiation: 243 g (males); and 171 g (females)
- Fasting period before study: none
- Housing: macrolon cages with a bedding of wood shavings (Lignocel, Type ¾) and a wooden block and strips of paper (Enviro-dri) as environmental enrichment, 5 animals to a cage
- Diet: cereal-based (closed formula) rodent diet (Rat & Mouse No. 3 Breeding Diet, RM3) from a commercial supplier (SDS Special Diet Services, Whitham, England), ad libitum
- Water: domestic mains tap-water, ad libitum
- Acclimation period: 8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 45-65
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: The average particle size (Mass Median Aerodynamic Diameter; MMAD) was 1.68 μm (with a geometric standard deviation (gsd) of 2.31), 2.57 μm (gsd of 2.57) and 2.52 μm (gsd of 2.54) for the low, mid and high concentration test atmospheres, respectively.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: cylindrical polypropylene (group 1) or aluminium (groups 2-4) column, surrounded by a transparent cylinder. The column had a volume of approximately 50 litres and consisted of a top assembly with the entrance of the unit, a mixing chamber, a rodent tube section and at the bottom the base assembly with the exhaust port.
- Method of holding animals in test chamber: secured in plastic animal holders (Battelle), positioned radially through the outer cylinder around the central column. The remaining ports were closed. Only the nose of the rats protruded into the interior of the column.
- Source of air: fresh test atmosphere.
- System of generating particulates/aerosols: Since the aerodynamic particle size of the original test material (as delivered by the sponsor) was above the range of 1-3 μm recommended by OECD guideline 412, the test material was milled using a ball mill fitted with a agate beaker and 5 agate balls with a diameter of 20 mm. Among a few alternative scenarios, milling of batches of 5 gram of test material for a period of 30 minutes resulted in a powder that could be aerosolized with a MMAD (mass median aerodynamic particle size) below 3 μm. The test atmospheres for groups 3 and 4 were generated by aerosolization of the test material using a turntable dust feeder, an eductor and a jetmill. The eductor was supplied with humidified compressed air and operated at a pressure of 1.0 bar; the jetmill was supplied with dry compressed air and operated at 5.0 bar. The test atmosphere, exhausted from the jetmill at the top inlet of the exposure unit, was directed downward and led to the noses of the animals. At the bottom of the unit the test atmosphere was exhausted. To generate the test atmosphere for group 2, part of the atmosphere of group 3 was extracted using an eductor. The eductor was mounted in the rodent tube section of the exposure chamber of group 3 and was supplied with humidified compressed air to dilute the test atmosphere. The resulting aerosol was directed towards the top inlet of the exposure chamber of group 2.
- Temperature and humidity in air chamber: controlled at a temperature of 22 ± 2°C and 30-70% relative humidity.
- Air flow rate: ≥1 litre/min for each rat.
- Method of particle size determination: carried out using a 10-stage cascade impactor (2110k, Sierra instruments, Carmel Valley, California, USA). The Mass Median Aerodynamic Diameter (MMAD) and the geometric standard deviation (gsd) were calculated.

TEST ATMOSPHERE
- Brief description of analytical method used: by means of gravimetric analysis.
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Representative test atmosphere samples were obtained from the animals’ breathing zone during the main study by passing 138, 46 and 18.4 Ln2 test atmosphere at 4.6 Ln/min through fiber glass filters. Filters were weighed before sampling, loaded with a sample of test atmosphere, and weighed again. The actual concentration was calculated by dividing the amount of test material present on the filter by the volume of the sample taken.

Duration of treatment / exposure:

A total of 20 exposure days over a 28-day period.

Frequency of treatment:

6 hours/day, 5 days/week.

Remarks:

Doses / Concentrations:
25, 75, 225 mg/m3
Basis:
other: target concentration

Remarks:

Doses / Concentrations:
20.5 (± 1.8), 74.0 (± 5.1) and 224.2 (± 10.1) mg/m3
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
38.4 (± 2.7), 107.3 (± 11.3) and 264.4 (± 12.9) mg/m3
Basis:
nominal conc.

No. of animals per sex per dose:

5

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: based on a 7-day range finding study in which no exposure-related changes were found up to a concentration of 104.4 mg/m3, the highest concentration tested.

Positive control:

None.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily in the morning hours by cage-side observations and, if necessary, handled to detect signs of toxicity. A group-wise observation was made halfway through each exposure day. On working days, all cages were checked again in the afternoon, especially for dead or moribund animals. In weekends and on public holidays only one check per day was carried out.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: see cage side observations.

BODY WEIGHT: Yes
- Time schedule for examinations: The body weight of each animal was recorded two days before the start of exposure and prior to exposure on the first day (day 0). Subsequently, animals were weighed twice weekly for the first two weeks (on days 4, 7, 11 and 14). Thereafter, the frequency was reduced to once weekly (i.e. on days 21 and 27), because there were no statistically significant effects on body weight in the first two weeks. All animals were also weighed on their scheduled sacrifice date in order to calculate the correct organ to body weight ratios.

FOOD CONSUMPTION: Yes
- Food consumption was measured per cage by weighing the feeders. The results were expressed in g per animal per day. Consumption was measured over three 7-day periods, starting on the day of the first exposure, followed by a 6-day period.

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the treatment period
- Anaesthetic used for blood collection: Yes (pentobarbital)
- Animals fasted: Yes (overnight)
- How many animals: 3 males and 5 females of each group (due to an error in handling of the blood samples, clotting occurred in 2 of 5 samples of the male animals of each group, preventing haematological analysis)
- Parameters examined: haemoglobin (Hb), packed cell volume (PCV), red blood cell count (RBC), reticulocytes, total white blood cell count (WBC), differential white blood cell count, prothrombin time, thrombocyte count. Mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were calculated.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the treatment period
- Animals fasted: Yes (overnight)
- How many animals: all
- Parameters examined: alkaline phosphatase activity (ALP), aspartate aminotransferase activity (ASAT), alanine aminotransferase activity (ALAT), gamma glutamyl transferase activity (GGT), total protein, albumin, ratio albumin to globulin, urea, creatinine, fasting glucose, bilirubin total, cholesterol, triglycerides, phospholipids, calcium, sodium, potassium, chloride, inorganic phosphate.

URINALYSIS: No (Samples of urine were stored for one year for possible future analysis)

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

SACRIFICE: The animals were sacrificed on the day after the last exposure in such a sequence that the average time of killing was approximately the same for each group. Animals were sacrificed by exsanguination from the abdominal aorta under pentobarbital anaesthesia.

GROSS PATHOLOGY: Yes.
HISTOPATHOLOGY: Yes

Other examinations:

None data.

Statistics:

- Body weight data: ‘Ancova & Dunnett’s Test’ (abbreviation ANCDUN) with ‘Automatic’ as data transformation method (abbreviation AUTO).
- Haematology, clinical chemistry and organ weight data: ‘Generalised Anova/Ancova Test’ (abbreviation GEN AN) with ‘Automatic’ as data transformation method (abbreviation AUTO).
- Food consumption: no statistics were applied.
- Incidences of histopathological changes: Fisher’s exact probability test.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

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:

no effects observed

Urinalysis findings:

not examined

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:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
The only clinical abnormalities observed during the study were sparsely haired areas and encrustations of the skin on the back of a few females in the last 1-2 weeks of the study. These findings, probably the results of some irritation due to the restraint in restraining tubes during exposure, were observed throughout the groups – including the control group – and were not related to exposure to the test material.

BODY WEIGHT AND WEIGHT GAIN
Male animals of the high concentration group showed a decreased body weight gain when compared to control animals, which reached statistical significance by day 21. On day 4 of the study, an increased body weight was observed in male animals of the low concentration group. Since this was an isolated finding, it was not considered to be treatment-related. No effects on growth were observed in female animals.

FOOD CONSUMPTION:
Slightly decreased consumption of food was observed in male animals of the high concentration group, which was most evident in the last week of the study. In female animals, food consumption was similar among the groups throughout the study period.

HAEMATOLOGY
Although in male animals only 3 out of 5 samples per group could be analyzed, it was clear that exposure-related changes in haematology parameters did not occur in male or in female animals.

CLINICAL CHEMISTRY
Clinical chemistry results indicated a dose-dependent increase in plasma activity of alkaline phosphatase (ALP) in male animals, which reached statistical significance at the mid and high concentration level. No such increase was observed in female animals. Decreased plasma concentrations of cholesterol and phospholipids were found in male animals of the mid concentration group. In the absence of a dose-response relationship and any corroborative changes in females, this was considered to be a change finding.

ORGAN WEIGHTS
Absolute weights of almost all organs were decreased in males of the high concentration group, when compared to unexposed controls. The decrease in brain and liver weight reached statistical significance. Although brain weight is usually relatively unaffected by body weight changes, it is highly likely that all absolute organ weight changes were a secondary effect associated with the growth retardation, since the changes occurred in almost all organs and relative organ weights were unaffected. No organ weight changes were observed in females.

GROSS PATHOLOGY
Macroscopic examination at the end of the exposure period revealed no treatment-related gross lesions. The abnormalities observed, mostly representing background pathology, were considered to be chance findings because they occurred only incidentally or at random incidences between the groups. As already mentioned, the sparsely haired areas and encrustions of the skin in a few females were probable the result of some irritation due to the restraint during exposure, and were not related to exposure to the test material.

HISTOPATHOLOGY: NON-NEOPLASTIC
The histopathological changes in the respiratory tract were slight and focal, observed at similar incidences in exposed animals and controls, and were considered part of common background pathology. No visible test material residues were detected in the airways of animals exposed to the high concentration Potassium tetrafluoroborate. No microscopic abnormalities were observed in the thyroid, a possible target organ of the test material. Microscopic examination of the other organs and tissues did not reveal any treatment-related changes either; the histopathological changes observed occurred only incidentally and/or at similar incidences between the control and the high concentration group.

Dose descriptor:

NOAEL

Effect level:

74 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Impaired growth and reduced food intake in male animals of the high concentration group.

Critical effects observed:

not specified

Conclusions:

A NOAEC of 74 mg/m3 was established in a 28-day inhalation study in rats.

Executive summary:

In a GLP compliant inhalation toxicity study performed according to OECD Guideline 412, potassium tetrafluoroborate was administered to Wistar rats. Four groups of 5 male and 5 female rats were exposed nose-only to target concentrations of 0 (control), 25, 75 or 225 mg/m3 potassium tetrafluoroborate for 6 hours/day, 5 days/week over a 28 -day period, with a total of 20 exposure days. The concentration levels were chosen based on the results of a 7 -day range finding study in which no exposure related changes were found up to a concentration of 104.4 mg/m3, the highest concentration tested. The mean actual concentrations (± standard deviation) of potassium tetrafluoroborate in the various test atmospheres – based on gravimetric analysis – were 20.5 (± 1.8), 74.0 (± 5.1) and 224.2 (± 10.1) mg/m3 for the low, mid and high concentration levels, respectively. The average particle size (Mass Median Aerodynamic Diameter; MMAD) was 1.68μm (with a geometric standard deviation (gsd) of 2.31), 2.57μm (gsd of 2.57) and 2.52μm (gsd of 2.54) for the low, mid and high concentration test atmospheres, respectively. No treatment-related clinical abnormalities or mortality were observed in response to the exposure to potassium tetrafluoroborate. Decreased body weight gain was observed in males of the high concentration group. A concomitant reduction in food consumption was observed in males of this group. No other changes in body weight or food consumption were observed during the study. Hematology, conducted in all rats at necropsy, did not reveal any treatment-related abnormalities. Clinical chemistry, conducted in plasma obtained from all rats at necropsy, did not show any treatment-related changes. An elevated – although within the historical control range – alkaline phosphatase (ALP) activity in males of the mid and high concentration group was not corroborated by changes in other parameters and was therefore considered to be of no toxicological relevance. There were no treatment-related changes in absolute organ weights or in organ to body weight ratios. The slightly decreased absolute weights of almost all organs in males of the high concentration group – of which brain and liver weight reached statistical significance – were considered secondary to the growth impairment, as relative organ weight remained unaffected. Macroscopic examination at necropsy and histopathological examination of organs and tissues – including the complete respiratory tract – did not reveal any treatment-related changes. No visible residues of test material were detected in the airways during histopathological examination. No indications of impaired thyroid function – as judged by possible organ weight or microscopic changes – were observed. In conclusion, exposure to potassium tetrafluoroborate resulted in impaired growth and reduced food intake in male animals of the high concentration group. Therefore, the NOAEC in rats was placed at the mid concentration level of 74.0 mg/m3 potassium tetrafluoroborate.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

74 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

GLP-compliant guideline study, klimisch 1

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No repeated dose studies on tetrafluoroboric acid (HBF4) were available. Furthermore, since HBF4 is corrosive, testing of this substance at dose levels causing corrosivity will cause unnecessary animal suffering, which should be avoided. Although non-corrosive concentrations of HBF4 could be tested, article 13 of the REACH legislation states that, in case no appropriate animal studies are available for assessment, information should be generated whenever possible by means other than vertebrate animal tests, i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. Therefore, information from the structural analogue potassium tetrafluoroborate (KBF4) was used to determine the possible effects of HBF4 after repeated exposure.

Oral studies:

In a GLP compliant reproduction/developmental toxicity screening test, performed according to OECD Guideline 421, Wistar rats of both sexes were orally exposed to potassium tetrafluoroborate (TNO Quality of Life, 2007). 1% carboxymethylcellulose solution in water (CMC) was used as vehicle. Groups of 12 rats per sex were dosed daily with 0, 40, 116.5 and 350 mg KBF4/kg body weight for up to approx. 35 days (males) or during 2 weeks premating, mating, gestation and up to day 4 of lactation (females). Initially a group of male rats was dosed with 1000 mg KBF4/kg body weight. These animals showed a weight loss of approx. 10% after 3 daily dosages. For that reason this group was replaced by the 40 mg KBF4/kg body weight. Two female animals of the 350 mg KBF4/kg body weight died during the lactation period. Daily clinical observations during the study did not reveal any remarkable findings in animals' appearance, general condition or behaviour among the dosing and control groups. Effects on water consumption were observed (not exactly measured) in the male and female animals of the 350 mg KBF4/kg body weight group from week 3 onwards. Mean body weight and or body weight change of the male and female animals of the 350 mg KBF4/kg body weight were statistically significantly decreased during several periods of the study. Mean bodyweight or bodyweight change of the 116.5 mg KBF4/kg body weight group was only statistically significantly decreased in the male animals from day 21 onwards. Food consumption of the 350 mg KBF4/kg body weight group was statistically significantly decreased in male and female animals during several periods of the study. Food consumption of the male animals of the 116.5 mg KBF4/kg body weight group was statistically significantly decreased from day 7 to 14. Terminal body weight of the male animals of the 40 and 116.5 mg KBF4/kg body weight groups was statistically significantly decreased. At scheduled necropsy no treatment related gross changes were observed. Microscopic examination did not reveal treatment related histopathological changes in any of the sampled organs and tissues (epididymides, testes, uterus and ovaries). Based on the effects on mortality in the 350 mg KBF4 group/ kg body weight group, (terminal) body weight and food consumption in the 116.5 and 350 mg KBF4/kg body weight groups, the NOAEL for parental toxicity is 40 mg KBF4/kg body weight/day.

In a GLP-compliant OECD Guideline 407 study, groups of 10 male and female Wistar rats were administered the test substance in aqueous solution by gavage at dose levels of 0, 20, 80 or 320 mg/kg bw/day for 28 days, 7 days per week (Hoechst AG, 1997). In addition 5 male and 5 female animals from the control and high dose group were placed in the recovery groups for a recovery period of 14 days. Animals were observed for clinical signs, body weight, food and water consumption. Hematological and clinical chemistry examinations were performed at the termination of the study and after the recovery period on all animals. Urinalysis was performed on all animals a few days before termination of the study. After 8 days, at the termination of the study and after the recovery period, biochemical examination was performed on all animals, including examination of total thyroxine, triiodothyronine and thyroid-stimulation hormone levels. All animals were subjected to necropsy, including macroscopic examination of the skin, orifices, eyes, teeth, oral mucosa and internal organs. Animals of the control and high dose groups were subjected to histopathological examinations. No mortalities or clinical signs were observed in the study. There were no effects on food and water consumption, body weight and body weight gain. No macroscopically visible changes were seen, which were considered to be compound-related. Organ weights were unaffected by treatment. Histopathological examination did not reveal any compound-related effect. Hematological examinations revealed slight but statistically significant decreases in erythrocytes counts and hematocrit value in female animals of the intermediate and high dose group. Females of the high dose group also showed slightly decreased hemoglobin values. The MCV values were not affected. All findings on hematological parameters were completely reversible after a 14-day recovery period. No treatment-related changes were detected by examination of the thyroid hormone levels in all dose groups. Clinical chemistry examinations revealed no compound-related changes in any dose group. No treatment-related changes were detected by urinalysis. Based on the slight decrease in erythrocytes counts and hematocrit and hemoglobin values in intermediate and high-dose females, which were fully reversible after 14 days recovery period, the lowest dose level of 20 mg/kg bw/day is considered to be a NOEL for females. Based on the lack of adverse changes the highest dose level of 320 mg/kg bw/day is considered to be a NOAEL for males and females.

Inhalation study:

In a GLP compliant inhalation toxicity study performed according to OECD Guideline 412, potassium tetrafluoroborate was administered to Wistar rats (TNO Triskelion BV, 2012). Four groups of 5 male and 5 female rats were exposed nose-only to target concentrations of 0 (control), 25, 75 or 225 mg/m3 potassium tetrafluoroborate for 6 hours/day, 5 days/week over a 28 -day period, with a total of 20 exposure days. The concentration levels were chosen based on the results of a 7 -day range finding study in which no exposure related changes were found up to a concentration of 104.4 mg/m3, the highest concentration tested. The mean actual concentrations (± standard deviation) of potassium tetrafluoroborate in the various test atmospheres – based on gravimetric analysis – were 20.5 (± 1.8), 74.0 (± 5.1) and 224.2 (± 10.1) mg/m3 for the low, mid and high concentration levels, respectively. The average particle size (Mass Median Aerodynamic Diameter; MMAD) was 1.68μm (with a geometric standard deviation (gsd) of 2.31), 2.57μm (gsd of 2.57) and 2.52μm (gsd of 2.54) for the low, mid and high concentration test atmospheres, respectively. No treatment-related clinical abnormalities or mortality were observed in response to the exposure to potassium tetrafluoroborate. Decreased body weight gain was observed in males of the high concentration group. A concomitant reduction in food consumption was observed in males of this group. No other changes in body weight or food consumption were observed during the study. Hematology, conducted in all rats at necropsy, did not reveal any treatment-related abnormalities. Clinical chemistry, conducted in plasma obtained from all rats at necropsy, did not show any treatment-related changes. An elevated – although within the historical control range – alkaline phosphatase (ALP) activity in males of the mid and high concentration group was not corroborated by changes in other parameters and was therefore considered to be of no toxicological relevance. There were no treatment-related changes in absolute organ weights or in organ to body weight ratios. The slightly decreased absolute weights of almost all organs in males of the high concentration group – of which brain and liver weight reached statistical significance – were considered secondary to the growth impairment, as relative organ weight remained unaffected. Macroscopic examination at necropsy and histopathological examination of organs and tissues – including the complete respiratory tract – did not reveal any treatment-related changes. No visible residues of test material were detected in the airways during histopathological examination. No indications of impaired thyroid function – as judged by possible organ weight or microscopic changes – were observed. In conclusion, exposure to potassium tetrafluoroborate resulted in impaired growth and reduced food intake in male animals of the high concentration group. Therefore, the NOAEL in rats was placed at the mid concentration level of 74.0 mg/m3 potassium tetrafluoroborate.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Read across with KBF4, a structural analogue of HBF4.

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Read across with KBF4, a structural analogue of HBF4.

Justification for classification or non-classification

Based on the findings of the repeated dose toxicity studies of KBF4, the structural analogue of HBF4, the test substance does not meet the criteria of the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 and therefore no classification is needed.