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nanomaterial dustiness
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
other: EN 17199-4
Version / remarks:
Principles of method if other than guideline:
EN 17199-4:2019-03
Workplace exposure — Measurement of dustiness of bulk materials that contain or release respirable nano-objects or submicrometer particles — Part 4: Small rotating drum method.
GLP compliance:
Type of method:
other: Small Rotating Drum
Details on methods and data evaluation:
3.4 Detection methods
3.4.1 Mass-based dustiness index
The mass-based dustiness index is determined gravimetrically. The filter in the cyclone is measured before and after the rotation of the drum. The results are given as average of the triplicate, and its standard deviation.

3.4.2 Number-based dustiness index
The number-based dustiness index is determined by the Condensatino Particle Counter (CPC). The filter in the cyclone is measured before and after the rotation of the drum. The results are given as average of the triplicate, and its standard deviation.

3.4.3 Size distribution of the aerosol
The size distribution is determined by weighing the impactor stages (MOUDI) before and after the complete set of triplicate rotations, because a single rotation of many materials does not deposit enough dust on each individual impactor stage. The results thus reflect the average of the triplicate.

3.4.4 Morphology of the aerosol
Non-mandatory, the aerosol can be collected on porous Gold filters for analysis of the identity and morphology of the airborne particles by Scanning Electron Microscopy (SEM). This option was not performed in the present case, because the test item is a pure substance with no uncertainty on the identity of aerosols.

Test material

Constituent 1
Chemical structure
Reference substance name:
Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate
EC Number:
EC Name:
Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate
Cas Number:
Molecular formula:
calcium 3-hydroxy-4-[(1E)-2-(4-methyl-2-sulfonatophenyl)diazen-1-yl]naphthalene-2-carboxylate
Test material form:
solid: nanoform

Data gathering

Small Rotating Drum (SRD)
The powder is loaded into the drum and is evenly spread on one of the lamellae that lift the powder during rotation. One “conditioning” run coats the inner surface of the drum, and is not used for data acquisition (Schneider and Jensen 2008).
Then, the three replicate measurements are each performed with fresh powder. Particle-free air is flushed through the drum at standstill, and the aerosol concentration is monitored by the CPC until the background (here: 13 particles /mL, indicating a very airtight setup) is reached. Then, the drum is rotated for 60 seconds. This rotation event results in a peak aerosol concentration in the CPC, and deposits dust onto the filter after the cyclone, and onto the MOUDI impactor stages. When the concentration has fallen after stopping the drum, the drum is removed, powder exchanged, and the next replicate taken.
The speed of rotation is 11 rpm as given for the SRD in the revised CEN standard.

Results and discussion

Dustiness index
Key result
51 mg/kg
St. dev.:
10 mg/kg
Remarks on result:
other: respirable dustiness mass fraction

Any other information on results incl. tables

The average respirable mass-based dustiness of 51±10 mg/kg places the Pigment Red 57:1 into the band of low dustiness (borderline to low dustiness).

As far as we know, no fixed bands have been established for the number-based dustiness index. Comparing to academic data on other fillers and pigments, the average number-based dustiness index of 3.6±0.26 * 104mg-1is neither extremely low nor extremely high.

Consistently with the average values, the size distribution of the aerosol indicates relatively low agglomeration with aerosol aerodynamic sizes of 0.18 to 1.8 µm, without a clearly identified mode. 


Considering that the measurements were performed at 45 % relative humidity, which is the lower end of the permitted humidity range, considering further that low humidity tends to increase dustiness, the present values can be regarded as upper limit of the dustiness of Pigment Red 57:1.

Applicant's summary and conclusion

The average respirable mass-based dustiness of 51 ± 10 mg/kg places the Pigment Red 57:1 into the band of moderate dustiness (borderline to low dustiness).
The average number-based dustiness index was found at 3.6 ± 0.26 * 104 mg-1. The size distribution of the aerosol indicates low agglomeration without clearly identifiable modal diameter.