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Administrative data

Endpoint:
nanomaterial dustiness
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16-09-2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: DIN EN 17199-3
Version / remarks:
Workplace exposure - Measurement of dustiness of bulk materials that contain or release respirable NOAA or other respirable particles - Part 3: Continuous drop method
Deviations:
yes
Remarks:
test conditions (humidity) due to laboratory environment; 1 meaurement performed
GLP compliance:
no
Type of method:
continuous drop
Details on methods and data evaluation:
In the continuous drop method, the bulk material falls continuously into a slight vertical counter air flow. The dust released by the falling bulk material is directed by the air stream (53 l/min) into a sampling section where direct reading aerosol measuring devices (SMPS/OPS) measure the time-resolved particle concentrations and the time-resolved particle size distribution of the aerosol.
The number size distribution of particles between 10 and 417 nm is determined using a TSI SMPS (model 3910) equipped with isopropanol based CPC (condensation particle counter). The number size distribution of particles between 0.3 and 10 μm is determined using a TSI OPS (model 3330) integrated in the SMPS.
A special downpipe was used for the detection of possibly released product nanoparticles (including submicron agglomerates) according to the above mentioned method and following the standard DIN EN 15051-3 "Workplace exposure -Measurement of the dustiness of bulk materials - Part 3: Continuous drop method.
In the downpipe described above, the counterflow is provided by cleaned, almost particle-free air (upstream ULPA filter type U15), so that possible background pollution in the room air is eliminated and measured nanoparticles can be clearly assigned to the product.
Sampling:
The test material was used without further treatment (e.g. drying). 70.9 g (519.79 cm3) test material are used for the measurement, dosing rate: 7.09 g/min

Test material

1
Chemical structure
Reference substance name:
4-[(2,5-dichlorophenyl)azo]-N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-hydroxynaphthalene-2-carboxamide
EC Number:
230-258-1
EC Name:
4-[(2,5-dichlorophenyl)azo]-N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-hydroxynaphthalene-2-carboxamide
Cas Number:
6992-11-6
Molecular formula:
C24H15Cl2N5O3
IUPAC Name:
4-[(1E)-2-(2,5-dichlorophenyl)diazen-1-yl]-3-hydroxy-N-(2-oxo-2,3-dihydro-1H-1,3-benzodiazol-5-yl)naphthalene-2-carboxamide
Test material form:
solid: nanoform, no surface treatment

Results and discussion

Dustiness indexopen allclose all
Key result
Mean:
5 992.6 other: 1/mg
Remarks on result:
other: dustiness index as number of airborne particles per mg in the nanoscale (10 nm - 100 nm)
Mean:
801.7 other: N/cm3
Remarks on result:
other: number of airborne nanoparticles per cm3

Any other information on results incl. tables

temperature: 26°C, rel. air humidity 60 %

The cleaned, almost particle-free air had a total particle count of 17 particles/cm3 in the range of 10 nm - 417 nm, the nanoscale fraction (10 - 100 nm) contained 14 particles/cm3.

Table 1: summary SMPS (scanning mobility particle sizer)

Range

[nm]

Mean

[nm]

Concentration

[N/cm3]

ICD[1/mg]

ECD[1/mg·s]

10-100

72.6

801.7

5992.6

10

100-417

176,8

2167,7

16204,4

27

10-417

148.7

2969.4

22197.1

37

ICD: dustiness index as number of airborne particles per mg

ECD: emission rate as number of particles per mg per second

mean: average particle diameter in nm
N: number of airborne particles

Table 2: summary OPS (optical particle sizer)

Range

[nm]

Mean

[nm]

Concentration

[N/cm3]

ICD[1/mg]

ECD[1/mg·s]

0,3 - 10

2.9

21,6

161.5

0.3

Applicant's summary and conclusion

Executive summary:

The dusting behaviour of the test material was investigated using DIN EN 17199 -3: 2019 -12 "workplace exposure - measurement of dustiness of bulk materials that contain or release respirable nano objects and their aggregates and agglomerates or other respirable particles- Part 3: Copntinuous drop method".

The dust released by the falling test material was measured by a scanning mobility particle sizer (SMPS, 10 - 417 nm) and an optical particle sizer (3 - 10 μm). The counterflow was provided by cleaned, almost particle-free air.

The SMPS counted 801.7 particles per cm3 in the nanoscale (10 - 100 m) (2969.4 particles per cm3 in the range of particles 10 -417 nm) corresponding to a dustiness index of 5992.6 particles per mg in the nanoscale (10 - 100 nm) (22197.1 particles per mg in the range of [articles 10 -417 nm).

The mean size of the nanoparticles was 72.6 nm, the mean size of particles in the range 10 - 417 nm was 148.7.

The OPS (0.3 - 10 μm) counted 21.6 particles per cm3 corresponding to a dustiness index of 161.5 particles per mg. The mean size of the particles was 2.9 μm.