Barium sulfate

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

no guideline required

Principles of method if other than guideline:

A pre-test was performed to decide if it is possible to generate a stable testing atmosphere.

GLP compliance:

no

Test type:

other: pre-test

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Barium carbonate

EC Number:

208-167-3

EC Name:

Barium carbonate

Cas Number:

513-77-9

Molecular formula:

BaCO3

IUPAC Name:

barium carbonate

Test material form:

solid

Details on test material:

- Name of test material (as cited in study report): Barium carbonate - standard
- Chemical description: Barium carbonate
- Batch No.: HOB L6523
- Molecular formula: BaCO3
- Molecular weight: 197.34 g/mol
- Physical state: Solid, white powder
- Storage condition of test material: Ambient temperature, dark, dry and original containers
- Expiration date of the batch: unlimited if stored in tightly closed original container at room temperature

Results and discussion

Any other information on results incl. tables

The test material as standard powder on the market shows the following MMAD /GSD:

 

 

					deposition fractions
Sample	rel. density	D50 [µm]	MMAD [µm]	GSD	Head [%]	TB [%]	PU [%]
BaCO3(standard)	4.3 at 20°C	2.32	24.22	4.87	45.22	0.95	1.16

*: rounded values                                                                                           Reference: EBRC (2010)

Particle size of the standard powder available on the market:                       

Experimentally determined by laser diffraction:

Particle size

L10                                               0.64 µm

L50                                               2.32 µm

L90                                               7.40 µm

          Reference: Siemens (2010)

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the technical properties of barium carbonate, the performance of an acute inhalation toxicity test is neither technically feasible nor scientifically relevant (see "executive summary") for this type of compound. Due to the MMAD/GSD and the particle size which are much higher than the pestled substance used for the pre-study, the low mobility and the negligible volatility of barium carbonate, the test material can safely be assumed to have a very low potential for human inhalation hazard during handling or application.

Executive summary:

The test substance was used as a powder and used formulated in a vehicle (water or acetone). A wide variety of generation set-ups was performed. Although the test substance were sieved (150µm) and pestled, the highest aerosol concentration that could be maintained for 4 hours was 0.2 mg/L.

The test material as standard powder which is available on the market shows the following MMAD /GSD:

 

 

					deposition fractions
Sample	rel. density	D50 [µm]	MMAD [µm]	GSD	Head [%]	TB [%]	PU [%]
BaCO3(standard)	4.3 at 20°C	2.32	24.22	4.87	45.22	0.95	1.16

*: rounded values                                                                                           Reference: EBRC (2010)

 

The physical particle size has been determined by high-pressure dry dispersion and laser diffraction at a d50 of approx. 2.32 µm.

Furthermore, barium carbonate is an inorganic substance with a melting range between 1380°C at atmospheric pressure, thus rendering it’s vapour pressure negligible, whereas usually inhalation studies are performed with substances of vapour pressures >1 x 10^-2Pa (Legal regulations of the european union for PPP and their a.s., 1997).

Consequently, for acute inhalation toxicity testing in the rat, it is beyond doubt impossible to generate with the supplied test item “barium carbonate standard” an aerosol that has a mass median aerodynamic diameter (MMAD) of < 4 µm as required by the OECD draft proposal for a new guideline: 436 - Acute Inhalation Toxicity: Acute Toxic Class (ATC) Method (08 Dec 2004) with an acceptable test concentration atmosphere (ideally 5.1 mg/L).

 

According to the REACH guidance on information requirements and chemical safety assessment (Chapter R.7a: Endpoint specific guidance), BARIUM CARBONATE STANDARD can be excluded from acute inhalation testing, since if was not technically possible to generate a suitable testing atmosphere, the main study involving animal testing could not be initiated.