Registration Dossier

Administrative data

Endpoint:
nanomaterial dustiness
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2019
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: EN 17199-4
Version / remarks:
2019
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:
no
Type of method:
other: Small rotating drum method
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

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: nanoform

Data gathering

Instruments:
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
Mean:
36 mg/kg
St. dev.:
8 mg/kg
Remarks on result:
other: Respirable dustiness mass fraction

Any other information on results incl. tables

The average respirable mass-based dustiness places the Pigment Brown 23 into the band of low dustiness.

The average number-based dustiness index was found at 1.8 ± 0.29 * 104 mg-1. The size distribution of the aerosol indicates relatively low agglomeration with peak aerodynamic diameters at 0.5μm and at 1.8 μm. 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 is neither extremely low nor extremely high.

Consistently with the average values, the size distribution of the aerosol indicates relatively low agglomeration with two modes .

Applicant's summary and conclusion

Conclusions:
The average respirable mass-based dustiness of 36 ± 8 mg kg-1 places the Pigment Brown 23 into the band of low dustiness.
The average number-based dustiness index was found at 1.8 ± 0.29 * 104 mg-1. The size distribution of the aerosol indicates relatively low agglomeration with peak aerodynamic diameters at 0.5μm and at 1.8 μm.