Barium fluoride

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-11-06 to 2018-02-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Deviations:

not specified

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Barium fluoride

EC Number:

232-108-0

EC Name:

Barium fluoride

Cas Number:

7787-32-8

Molecular formula:

BaF2

IUPAC Name:

barium fluoride

Test material form:

solid: crystalline

Test animals

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.
- Health inspection: At least prior to exposure. It was ensured that the animals were healthy and without any abnormality that might affect the study integrity.
- Age at study initiation: Young adult animals were selected (approximately 9-10 weeks old).
- Weight at study initiation: Males: 265 to 296 g; Females: 181 to 212 g.
- Fasting period before study: none
- Housing: Group housing of five animals per sex per cage in labelled Makrolon cages (type IV; height 18 cm) containing sterilised sawdust as bedding material (Lignocel S 8-15, JRS - J.Rettenmaier & Söhne GmbH + CO. KG, Rosenberg, Germany).
Animal husbandry on the Day of exposure : The animals were moved to the inhalation area to in order to perform the exposure. During the exposure, there was no access to food and water. After exposure, the animals were returned their cages which were placed in a fume cupboard for a short time period to allow test substance remnants to evaporate. A sheet of filter paper was used to cover the bedding material to prevent suffocation in case of bad health condition and to aid clinical observations. The sheet was removed and before the end of the exposure day, the animals were returned the animal room.
- Diet (e.g. ad libitum): Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany) except during exposure to the test substance.
- Water (e.g. ad libitum): Free access to tap water except during exposure to the test substance.
- Acclimation period: Acclimatisation period was at least 5 days before start of treatment under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Environmental controls for the animal room were set to maintain 18 to 24°C. The actual daily mean temperature during the study was 19 to 20°C.
- Humidity (%): relative target humidity of 40 to 70% (actual daily humidity was 49 to 55%)
- Air changes (per hr): >10 room air changes/hour
- Photoperiod (hrs dark / hrs light): a 12-hour light/12-hour dark cycle

IN-LIFE DATES: From: 16 November 2017 To: 24 January 2018

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber:
The design of the exposure chamber is based on the flow past nose-only inhalation chamber (Am. Ind. Hyg Assoc. J. 44(12): 923-928, 1983). The chamber consisted of animal sections with eight animal ports each. Each animal port had its own atmosphere inlet and exhaust outlet. The animals were placed in restraining tubes and connected to the animal ports. The number of animal sections and number of open inlets were adapted to the air flow in such a way that at each animal port the theoretical air flow was at least 1 L/min, which ensures an adequate oxygen supply to the animals. The main inlet of the test atmosphere was located at the top section and the main outlet was located at the bottom section. The direction of the flow of the test atmosphere guaranteed a freshly generated atmosphere for each individual animal.
All components of the exposure chamber in contact with the test material were made of stainless steel, glass, rubber or plastic. To avoid exposure of the personnel and contamination of the laboratory the exposure chamber was placed in a fume hood, which maintained at a slight negative pressure.

- Test atmosphere generation:
At a target concentration of 1 mg/L, administering the test item to a stream of pressurized air using a combination of a spiral feeder and air mover (AIR-VAC, Milford, CT, USA), with vibrators attached to both the spiral feeder and air mover. The aerosol was passed through a series of one tilted and three vertical cyclones, allowing larger particles to settle, before it entered the exposure chamber.
At a target concentration of 5 mg/L, administering the test item to a stream of pressurized air using a combination of a brush feeder and micronizing jet mill generated an aerosol. The aerosol was passed through a series of one tilted and one vertical cyclone, allowing larger particles to settle, before it entered the exposure chamber.
The mean total airflows were 40 and 17 L/min, for the 1 and 5 mg/L exposure groups respectively. From the exposure chamber the test atmosphere was passed through a filter before it was released to the exhaust of the fume hood.

- Method of particle size determination:
The particle size distribution was characterized twice for the 1 mg/L exposure group and once for the 5 mg/L exposure group during the exposure period. The samples were drawn (2 L/min) from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber. The samples were collected with an 8 stage Marple personal cascade impactor containing fiber glass filters (TE-290-GF. Tisch Environmental, Cleves, Ohio, USA) and a fiber glass back-up filter (SEC-290-F1, Westech, Upper Stondon, Bedfordshire, England). Amounts of test substance collected were measured gravimetrically. Subsequently the Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (GSD) were determined.

- Temperature, humidity, pressure in air chamber:
The temperature and relative humidity were measured with a humidity and temperature indicator (E+E Elektronik, Engerwitzdorf, Austria) and were recorded after the animals were placed in the experimental set-up and at 30 minute intervals after initiation of the exposure. The probe was inserted in a tube mounted in one of the free animal ports of the middle section of the exposure chamber. The temperature of the atmosphere during the exposures was between 20.1 and 22.0°C. The relative humidity was between 22% and 32%. These conditions were considered appropriate for this relatively short 4 hours exposure duration.

TEST ATMOSPHERE
- Brief description of analytical method used:
A total of 29 and 27 representative samples were taken for determination of the actual concentration during exposure at target concentrations of 1 and 5 mg/L, respectively. Samples were drawn from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber. Samples were drawn through a glass fiber filter (type APFC04700, Millipore, Billerica, MA, USA). The collected amount the test substance in the air sample was measured gravimetrically. Sample volumes were measured by means of a dry gas meter (type G 1.6, Actaris Meterfabriek B.V., Dordrecht, The Netherlands). Subsequently the time-weighted mean concentrations with the standard deviations were calculated. It was considered that the opacity of the test atmosphere could not be reliably monitored by means of an aerosol monitoring system. An indication of stability of the test atmosphere was obtained from the concentration measurements equally distributed over time.
- Samples taken from breathing zone: yes

VEHICLE
No vehicle used except air.

TEST ATMOSPHERE (if not tabulated)
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): At 1.1 mg/L, the MMAD was 2.5 μm (gsd 1.8) and 2.8 μm (gsd 1.6). At 2.3 mg/L, the MMAD was 2.7 μm (gsd 1.9).

CLASS METHOD
- Rationale for the selection of the starting concentration: Target concentrations were based on the cut off concentration values specified in the UN and EC classification guidelines. Five animals of each sex were exposed in a limit test for 4 hours to a target concentration of the test substance of 1 mg/L. Based on the results, five additional animals of each sex were exposed to 5 mg/L.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetrically measurement

Duration of exposure:

4 h

Concentrations:

nominal concentrations of 1 and 5 mg/L corresponding to 1.1 and 2.3 mg/L.
The nominal concentration was calculated by dividing the amount of test substance used by the volume of pressurized air (average air flow times exposure time) entering the exposure chamber used for exposure of the animals. Due to the small volume of the exposure chamber the equilibrium time was negligible. The volume of air was calculated from the average air flow (measured by means of thermal mass flow meters and was recorded regularly, preferably in 30 minute intervals) and the exposure time.

No. of animals per sex per dose:

5 males and 5 females (females were nulliparous and non-pregnant) per exposure level.

Control animals:

no

Details on study design:

- Treatment: Prior to each exposure, the eyes of the animals were treated with protective crème in order to protect the eyes from possible adverse effects for the eyes before they are placed in the tubes. Prior to exposure the animals were placed in polycarbonate restraining tubes; these tubes were connected to the exposure chamber. Animals were allowed to acclimatize for at least fifteen minutes after the last animal has been placed. The exposure time was 4 hours.

- Duration of observation period following administration: 14 days

- Frequency of observations and weighing:
Mortality/Viability: Twice daily. The time of death was recorded as precisely as possible.
Body weights: Days 1 (pre-administration), 2, 4, 8 and 15 and at death (if found dead or sacrificed after Day 1).

- Necropsy of survivors performed: yes
The moribund animals and animals surviving to the end of the observation period were sacrificed by an intraperitoneal injection with Euthasol ®. All animals assigned to the study were subjected to necropsy and descriptions of all internal macroscopic abnormalities were recorded.

- Other examinations performed:
clinical signs during exposure: three times during exposure for mortality, behavioural signs of distress and effects on respiration.
clinical signs after exposure : On Day 1, one and three hours after exposure and once daily thereafter until Day 15. The symptoms were graded according to fixed scales and the time of onset, degree and duration were recorded:
Maximum grade 4: grading slight (1) to very severe (4)
Maximum grade 3: grading slight (1) to severe (3)
Maximum grade 1: presence is scored (1).

- Electronic capture data :
Observations/measurements in the study were recorded electronically using the following programs:
REES Centron Environmental Monitoring system version SQL 2.0 (REES Scientific, Trenton, NJ, USA): Environmental monitoring.
TOXDATA version 8.0 (WIL Research Europe B.V., ‘s-Hertogenbosch, The Netherlands): Mortality / Clinical signs / Body weights.

Statistics:

No statistical analysis was performed.

Results and discussion

Preliminary study:

No preliminary study has been performed.

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 1 - < 5 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

At 1.1 mg/L, no mortality occurred.
At 2.3 mg/L, two females and one male were found dead or sacrificed in moribund condition between Days 1 and 4. No further mortality occurred.

Clinical signs:

other: At 1.1 mg/L, no clinical signs were seen during exposure (not presented in the table). After exposure, hunched posture and piloerection were seen for all animals on Day 1. In addition, lethargy was noted for all females on Day 1. At 2.3 mg/L, slow breathi

Body weight:

At 1.1 mg/L, overall body weight gain in males and females was within the range expected for rats of this strain and age used in this type of study and were therefore considered not indicative of toxicity.
At 2.3 mg/L, body weight loss compared to body weights on Day 1 was noted for all surviving animals up to Day 8 (except for one female for which body weight loss was noted up to Day 4); these animals regained weight during the second week.

Gross pathology:

Black discoloration of the liver was noted for the male at 2.3 mg/L found dead on Day 1. For the remaining animals no abnormalities were found at macroscopic post mortem examination of the animals.

Any other information on results incl. tables

Test atmosphere characterization: Concentration

At a target concentration of 1 mg/L, the time-weighted mean actual concentration was 1.08 ± 0.03 mg/L. The nominal concentration (amount of test item used divided by the volume of pressurized air used) was 34.2 mg/L. The generation efficiency (ratio of actual and nominal concentration) was 3.2%.

At a target concentration of 5 mg/L, the time-weighted mean actual concentration was the technical maximum feasible concentration of 2.33 ± 0.06 mg/L. The nominal concentration was 43.5 mg/L. The generation efficiency was 5.3%. Variations in concentration were observed caused by clogging and subsequent adjustments to the generation equipment. The generation was interrupted on respectively three and seven occasions in order to remove test item deposits from the system. To compensate for these interruptions, the generation time was elongated in order to achieve an actual exposure time of 240 minutes. By calculating the time-weighted mean concentrations, effects of interruptions and variations were taken into account.

Applicant's summary and conclusion

Interpretation of results:

harmful

Conclusions:

The inhalatory LC50, 4h value of barium fluoride in Wistar rats was established to be within the range of 1 – 5 mg/L.

Executive summary:

The acute inhalation toxicity of barium fluoride in the rat was assessed according to the OECD Testing Guideline 403 and under GLP. Barium fluoride was administered as an aerosol by inhalation for 4 hours to one group of five male and five female Wistar rats at 1 mg/L.Based on the results, five additional animals of each sex were exposed to a nominal concentration of 5 mg/L. Animals were subjected to daily observations and determination of body weights on Days 1, 2, 4, 8 and 15 and at death. Macroscopic examination was performed on the day of death or after terminal sacrifice (Day 15).

For the exposure to 5 mg/L, the time-weighted mean actual concentration was the technical maximum feasible concentration of 2.33 ± 0.06 mg/L. For the exposure to 1 mg/L, the time-weighted mean actual concentration was 1.08 ± 0.03 mg/L

The Mass Median Aerodynamic Diameter (MMAD) and geometric standard deviation (gsd) was determined twice for the 1 mg/L exposure group and once for the 5 mg/L group. At 1.1 mg/L, the MMAD was 2.5 μm (gsd 1.8) and 2.8 μm (gsd 1.6). At 2.3 mg/L, the MMAD was 2.7 μm (gsd 1.9).

At 1.1 mg/L, no mortality occurred. At 2.3 mg/L, two females and one male were found dead or sacrificed in moribund condition between Days 1 and 4. No further mortality occurred. At 1.1 mg/L, no clinical signs were seen during exposure. After exposure, hunched posture and piloerection were seen for all animals on Day 1. In addition, lethargy was noted for all females on Day 1. At 2.3 mg/L, slow breathing was seen for the majority of the animals and fast breathing was noted for one male and one female during exposure. After exposure, lethargy, flat and/or hunched posture, uncoordinated movements, labored respiration, piloerection, lean appearance and ptosis, were seen for the animals. The surviving animals had recovered from the clinical signs by Day 6. At 1.1 mg/L, overall body weight gain in males and females was within the range expected for rats of this strain and age used in this type of study and were therefore considered not indicative of toxicity. At 2.3 mg/L, body weight loss compared to body weights on Day 1 was noted for all surviving animals up to Day 8 (except for one female for which body weight loss was noted up to Day 4); these animals regained weight during the second week. Black discoloration of the liver was noted for the male at 2.3 mg/L found dead on Day 1. For the remaining animals no abnormalities were found at macroscopic post mortem examination of the animals.

The inhalation LC50, 4h value of Barium fluoride in Wistar rats was established to exceed the technical maximum feasible concentration of 2.3 mg/L. Given the nature and severity of the observed exposure-related effects, it is considered highly unlikely that the inhalation LC50, 4h value of Barium fluoride in Wistar rats will be exceeding 5 mg/L. Based on these considerations, the inhalatory LC50, 4h value of barium fluoride in Wistar rats was established to be within the range of 1 – 5 mg/L. Based on these results the test substance needs to be classified as Category 4 H332 'Harmful if inhaled' according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.