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Acute Toxicity: inhalation

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acute toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2010-07-05 to 2010-07-26
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study reliable without restrictions

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 403 (Acute Inhalation Toxicity)
Version / remarks:
GLP compliance:
Test type:
standard acute method
Limit test:

Test material

Details on test material:
- Name of test material (as cited in study report): Barium chloride di-hydrate
- EC No.: 233-788-1
- Molecular formula: BaCl2 * 2H2O
- Molecular weight: 244.26
- Physical state: White crystalline powder (determined at NOTOX)
- Stability under storage conditions: Stable
- Storage condition of test material: At room temperature in the dark
- pH: 5.5 - 7.5 (100 g/L at 20 °C)
No further information on the test material was stated.

Test animals

Details on test animals and environmental conditions:
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: Approximately 9 weeks old
- Weight at study initiation: Males (mean weight): 253 g +/- 6 g; Females (mean weight): 165 g +/- 5 g
- Housing: Before exposure: Group housing of five animals per sex per cage in labelled Macrolon cages (type IV; height 18 cm) containing sterilised sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France) and paper as cage-enrichment (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom). After exposure: Group housing as decribed for before expsoure, except that a paper sheet was introduced into the cage covering the bedding and cage enrichment to prevent suffocation in case of bad health condition. At the end of the Day of exposure the paper sheet was removed.
- Diet (ad libitum except during exposure to the test substance): Pelleted rodent diet (SM R/M from SSNIFF® Spezialdiäten GmbH, Soest, Germany)
- Water (ad libitum except during exposure to the test substance): Tap water
- Acclimation period: At least 5 daysbefore start otf treatment under laboratory conditions.

Animals were housed in a controlled environment.
- Temperature: 21.0 +/- 3.0 °C (actual range: 19.7 - 21.6 °C)
- Relative humidity: 40 - 70 % (actual range: 43 - 79 %)
- Air changes: Approx. 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12
No further information on the test animals was stated.

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
clean air
Details on inhalation exposure:
Before use the test substance was grounded with an automatic grinder (ZM-100, Retsch, Ochten, The Netherlands) and passed through a 150 µm steel mesh sieve.

- Exposure apparatus: 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 three animal sections with eight animal ports each. Each animal port had its own atmosphere inlet and exhaust outlet. The animals were placed in ploycarbonate 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. The exposure chamber was placed in a fume hood, which maintained at a slight negative pressure.
Fifteen minutes after the last animal was pplaced the generation of the test atmosphere was started.

- System of generating particulates/aerosols: The test substance was fed to a stream of pressurized air (mean air flow 28.4 L/min) by means of a spiral feeder (Randcastle Extrusion Systems, Cedar Grove, NJ, USA) and an air mover (type 611210-060, Foxvalve, Dover NJ, USA). The aerosol was passed through a cyclone, allowing larger particles to settle, before it entered the exposure chamber. The rotation speed of the feeder was varied to obtain the desired exposure concentration. Due to the unexpected high usage of test substance, part of the test substance was retrieved from the exposure system, grounded, sieved and used for the continuation of the exposure.
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 during the exposure period. The samples were drawn (2L/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 (SKC 225-713, fiber glass, SKC Omega Specialty Division, Chelmsford, MA, 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 MMAD and the 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 was between 22.0 and 22.6 °C and relative humidity was between 49 and 58 %.

- Nominal concentration: The nominal concentration has to be 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. Since part of the test substance was retrieved from the exposure system but not weighed before use, the exact nominal concentration could not be calculated.
- Brief description of analytical method used: The actual concentration was determined fourteen times during the exposure period. 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 of 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).
The mean concentration with standard deviation was calculated.

- MMAD / GSD : The MMAD and GSD were determined tiwce. The MMAD was 4.2 µm (GSD 1.6) and 4.2 µm (GSD 1.4) respectively.

- STABILITY MONITORING: The opacity of the test atmosphere exceeded the maximum which could be monitored by means of an aerosol monitoring system. An indication of the stability of the test atmosphere was obtained from the concentration measurements, which were equally distributed over time.
No further information on the inhalation exposure was stated.
Analytical verification of test atmosphere concentrations:
see "details on inhalation exposure" above
Duration of exposure:
240 min
Mean actual concentration: 1.1 +/- 0.4 mg/L
The nominal concentration was between 44.9 and 89.8 mg/L resulting in a generation efficiency (ratio of actual and nominal concentration) between 1.2 and 2.4 %. Due to the unexpected high usage of test substance, test substance was retrieved from the exposure system and re-used. Since the weight of the retrieved amount was inadvertently not documented, the nominal concentration and efficiency could not be calculated precisely. This did not invalidate the outcome of the study.
No. of animals per sex per dose:
5 males / 5 females
Control animals:
Details on study design:
- 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.
- Clinical signs: During exposure: Three times during exposure for mortality, behavioural signs of distress and effects on respiration; 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).
- Body weights: Days 1 (pre-administration, 2, 4, 8 and 15
- Necropsy of survivors performed: Yes
The animals surviving to the end of the observation period were sacrificed by an intraperitoneal injection with Euthasol® (AST FArma BV, Oudewater, The Netherlands). All animals assigned to the study were subjected to necropsy and descriptions of all internal macroscopic abnormalities were recorded. Particular attention was given to any changes in the respiratory tract.
No further information on the study design was stated.
No statistical analysis was performed.

Results and discussion

Effect levels
Dose descriptor:
Effect level:
> 1.1 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
243 min
Remarks on result:
other: This value is the mean actual concentration. The standard deviation is 0.4 mg/L.
One male was found dead within three hours after exposure. No further mortality occurred.
Clinical signs:
other: No clinical signs were noted during exposure. After exposure, slow breathing, shallow or laboured respiration, flat or hunched posture, lethargy, hypothermia, piloerection and/or ptosis were noted among the animals on Days 1 and/or 2. One female showed ab
Body weight:
Overall mean body weight gain in surviving males and females was within the range expected for rats of this strain and age used in this type of study.
Gross pathology:
No abnormalities were found at macroscopic post mortem examination of the animals.
Other findings:
No data

Any other information on results incl. tables

Exposure to 1.1 mg/L of barium chloride di-hydrate resulted in significant signs of toxicity (mortality of one male, severe and persisting clinical signs) indicating that significant mortality could be expected at the next higher exposure level of 5 mg/L. In consultation with the sponsor, it was therefore decided not to expose animals to a higher concentration.

Applicant's summary and conclusion

Interpretation of results:
Migrated information Criteria used for interpretation of results: EU
Based on the results, the inhalatory LC50 (4h) value of barium chloride di-hydrate in Wistar rats was considered to exceed 1 mg/L.
According to the Regualtion (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures, barium chloride di-hydrate should be classified as Category 4 and should be labelled as H332: Harmful if inhaled.
Also, according to 67/548/EC and subsequent regulations, barium chloride di-hydrate is classified as harmful by inhalation.