Silicic acid, aluminum sodium salt

Nanomaterial dustiness

Administrative data

Endpoint:

nanomaterial dustiness

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

appearance / physical state / colour

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: visual examination in a guideline study

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

visual inspection

GLP compliance:

no

Physical state at 20°C and 1013 hPa:

solid

Key result

Form:

solid: particulate/powder

Remarks:

fine powder

Colour:

white

Substance type:

inorganic

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Principles of method if other than guideline:

The determination of the dustiness based on a laser diffraction analysis of the test substance according to
- Dustiness equivalent of synthetic amorphous silica (CAS-No:7631-86-9) for the purpose of substance registration and evaluation within REACH (2018) by Prof. Dr.- Ing. Habil. Michael Stintz

Weak dry dispersion method GRADIS/L and determination of particle size distribution by laser diffraction measurement according to OECD Test Guideline 110 (1981) and ISO 13320 (2009).
The health relevant volume-weighted fractions according to EN481:1993 with an aerodynamic cut-off diameter of 100 µm and 37 µm were calculated based on these measured values and the tamped density. The tamped density was assumed to be the effective particle density at weak dry dispersion intensity.

GLP compliance:

no

Type of method:

other: weak dry dispersion combined with laser diffraction

Test material

Test material information

Constituent 1

Reference substance name:

Silicic acid, aluminum sodium salt

EC Number:

215-684-8

EC Name:

Silicic acid, aluminum sodium salt

Cas Number:

1344-00-9

Molecular formula:

nSiO2*mAl2O3*zNa2O n = 2-4; m = 0.12-3.20; z = 0.11-4.5

IUPAC Name:

aluminium(3+) sodium bis(oxosilanebis(olate))

Test material form:

solid: nanoform, no surface treatment

Remarks:

crystalline-free

Data gathering

Instruments:

HELOS/KR
A laser diffraction spectrometer (Modell HELOS/KR, Sympatec GmbH, Clausthal-Zellerfeld, Germany) according to ISO 13320:2009 with a He-Ne-laser (laser wavelength of 632.8 nm). Four different size ranges (R1: 0.1 µm- 35 µm, R3: 0.5 µm-175 µm; R5: 0.5 µm- 875 µm; R7: 0.5 µm – 3500 µm) could be used to determine volume-weighted particle size distributions. The FRAUNHOFER theory was used for the evaluation of the detected signals. From the diffraction pattern the particle size distribution according to the Fraunhofer evaluation (no refractive index is necessary) was calculated.
Particle Analyzer: HELOS KR of company Sympatec
Observed range: 0.1 µm to 3500 µm
Software: PAQXOS 3.0.4

GRADIS/L (weak dispersion)
The sedimentation shaft GRADIS/L (Sympatec GmbH, Clausthal-Zellerfeld, Germany) was a dry dispersion unit that was developed for the operation in combination with the laser diffraction spectrometer HELOS KR. The powder material feeding into the head of the sedimentation shaft could be realized by different dosing systems (e.g. vibrating chute called VIBIR/L).
During the fall from a drop height of 500 mm, the material impinged onto two sloping planes (inclination of 45°) within the GRADIS. Next to the weak dispersion, which results from the fall-induced drag force, the powder dispersion was thus additionally affected by particle-wall impaction.

Calibration:

Verification and calibration
Every measuring cell was checked with the corresponding reference substance.
As different ranges (Range 5 and Range 7) could be used, the different ranges were also checked with the corresponding reference substance.
The reference substances were certified standards of the company Sympatec for testing the device.
Following ranges were used for following test methods:
Range 5 and 7: reference substance SiC-P80'11

Results and discussion

Dustiness index

Dustiness index 1

Mean:

21 531 mg/kg

St. dev.:

1 782 mg/kg

Remarks on result:

other: inhalable fraction, calculated until cut-off 100 µm

Dustiness index 2

Mean:

4 mg/kg

St. dev.:

1 mg/kg

Remarks on result:

other: thoracic fraction

Dustiness index 3

Mean:

0 mg/kg

St. dev.:

0 mg/kg

Remarks on result:

other: alveolar fraction

Any other information on results incl. tables

The determination of the dustiness was performed based on laser diffraction analyses by the weak dry dispersion GRADIS/L and the tamped density. With these measured values the health relevant volume-weighted fractions according to EN 481:1993 were determined with an aerodynamic cut-off diameter off 100 µm.
For comparison with results of the standardised dustiness methods according to EN 15051-1:2013, the inhalable fraction of the substitute method was calculated additionally until the corresponding technological-limited aerodynamic cut-off diameters of 37 µm (in the case of the method EN 15051-3:2013) and not until the aerodynamic cut-off diameter of 100 µm based on EN 481:1993.
With the test method GRADIS/L and the tamped density the dust behaviour or the dust formation of the sample after a single drop, i.e. after normal handling, is shown.

Mean value of the singular fractions until selected aerodynamic cut-off 100 µm (calculated from laser diffraction analysis, measurements 1 – 3):

	Inhalable [mg/kg]	Thoracic [mg/kg]	Alveolar [mg/kg]
Mean value	21531	4	0
Standard deviation	1782	1	0
RSD	8.28 %	17.78 %	18.85 %

 

Mean value of the singular fractions until selected aerodynamic cut-off 37 µm (calculated from laser diffraction analysis, measurements 1 – 3):

	Inhalable [mg/kg]	Thoracic [mg/kg]	Alveolar [mg/kg]
Mean value	436	2	0
Standard deviation	87	0	0
RSD	19.92 %	19.92 %	19.92 %

 

As the relative standard deviation of the singular measurements with the weak dry dispersion GRADIS did not exceed 5 % the study can be considered valid. The relative standard deviation of the determination of the health fractions was high due to the fact that the agglomeration behaviour of the sample can vary.

 

 

Average volume weighted particle size distribution (of measurements 1 – 3) of test method GRADIS/L:

	D10 [µm]	D50 [µm]	D90 [µm]
Mean value	232.9	449.18	706.81
Standard deviation	4.92	11.23	34.45
Width	227.45 – 237.02	440.00 – 461.70	685.64 – 746.56