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Toxicological information

Acute Toxicity: inhalation

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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.
Test type:
other: pre-test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Identification Barium carbonate standard
Molecular formula BaCO3
Molecular weight 197.37
Description Solid, white powder
Test substance storage At room temperature in the dark, in original container
Stability under storage conditions Stable

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:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
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.