Calcium 3-hydroxy-4-[(1-sulphonato-2-naphthyl)azo]-2-naphthoate

Nanomaterial dustiness

Administrative data

Endpoint:

nanomaterial dustiness

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April - May 2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: EN 17199-4:2019-03 Workplace exposure — Measurement of dustiness of bulk materials that contain or release nano-objects or submicrometer particles — Part 4: Small rotating drum method

Principles of method if other than guideline:

CEN standard method

GLP compliance:

no

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

Test material information

Constituent 1

Reference substance name:

Calcium 3-hydroxy-4-[(1-sulphonato-2-naphthyl)azo]-2-naphthoate

EC Number:

229-142-3

EC Name:

Calcium 3-hydroxy-4-[(1-sulphonato-2-naphthyl)azo]-2-naphthoate

Cas Number:

6417-83-0

Molecular formula:

C21H12N2O6S.Ca

IUPAC Name:

calcium 3-hydroxy-4-[(1-sulfonato-2-naphthyl)diazenyl]-2-naphthoate

Test material form:

solid: nanoform

Data gathering

Instruments:

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:

ca. 23 mg/kg

St. dev.:

8.1 mg/kg

Applicant's summary and conclusion

Conclusions:

The average respirable mass-based dustiness of 23.0 ± 8.1 mg kg-1 places the Pigment Red 63:1 into the band of low dustiness.

Executive summary:

The average respirable mass-based dustiness of 23.0 ± 8.1 mg kg-1 places the Pigment Red 63:1 into the band of low dustiness.
The average number-based dustiness index was found at 0.30 ± 0.03 * 104 mg-1. The size distribution of the aerosol indicates significant agglomeration with a peak aerodynamic diameter around 3 to 5 μm.