Titanium dioxide

Nanomaterial dustiness

Administrative data

Endpoint:

nanomaterial dustiness

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: DIN EN 481

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: DIN 55992-1:2006

Version / remarks:

Determination of a parameter for the dust formation of pigments and extenders - Part 1: Rotation method

Deviations:

yes

Remarks:

Heubach dust meter was connected to a seven stage cascade impactor

GLP compliance:

no

Type of method:

rotating cylinder

Remarks:

Heubach dust meter connected to a seven-stage cascade impactor

Details on methods and data evaluation:

The modified Heubach procedure was applied. The substance sample was mechanically stressed in a rotating drum (dust generation device), and both the dust already contained in this sample and the dust generated due to abrasion were removed from the dust generation device by an air current. The proportion of dust separated and considered as dust with the ability to become airborne was fed into a seven-stage cascade impactor connected to the dust generation device. Particle size classification was conducted by subsequent weighing of the respective dust masses deposited on the individual cascade stages reflecting certain particle size ranges.
The “total dustiness” value was determined as the ratio of the mass of removed dust to the total sample mass initially weighed in.
Subsequently, the dustiness values for the inhalable, thoracic and alveolar fractions according to DIN EN 481 were determined

Test material

Test material information

Constituent 1

Reference substance name:

Titanium dioxide

EC Number:

236-675-5

EC Name:

Titanium dioxide

Cas Number:

13463-67-7

Molecular formula:

O2Ti

IUPAC Name:

dioxotitanium

Test material form:

solid: particulate/powder

Details on test material:

Appearance: white odourless powder
Relative density: ~ 3.9

Specific details on test material used for the study:

Product name: Sample G6-3
Appearance: white odourless powder
Substance stability: Stable under normal conditions
Substance humidity (by DMT): 0.4

Data gathering

Instruments:

Heubach dust meter:
- Volume: 2.2 L
- Rotation: 30 rpm
- Air flow: 20 L/min

Cascade impactor:
- Number of cascades: 7 between approx. 0.3 µm and 30 µm
- Air flow: 40 L/min

The rotating drum requires an air flow rate of approx. 20 L/min in accordance with the manufacturer’s specifications, the cascade impactor requires an air flow rate of 40 L/min in order to work properly. Therefore, 20 L/min of additional air is fed into the system via the coarse dust separator.
By introducing a glass tubing, the dust generated in the rotating drum is now directly conveyed into the cascade impactor. The vessel used as the coarse dust seperator in the original set-up now only serves as a tool to introduce additional air and for the purpose of visual inspection.
The 20 L/min additional air required for the functioning of the cascade impactor are channelled off the exhaust air current of the cascade impactor via a three-way valve on the pressure side of the vacuum pump. For the detailed experimental setup please refer to the attached Illustration.

Results and discussion

Dustiness index

Dustiness index 1

Key result

Mean:

662 210 mg/kg

Remarks on result:

other: Total dustiness

Dustiness index 2

Mean:

474 750 mg/kg

Remarks on result:

other: Inhalable fraction

Dustiness index 3

Mean:

325 980 mg/kg

Remarks on result:

other: Thoracic fraction

Dustiness index 4

Mean:

161 350 mg/kg

Remarks on result:

other: Respirable fraction

Any other information on results incl. tables

Dust masses and calculated relations (Pass/Residue) on the impactor stages

Impactor stage	Average aerodyn. diameter	Calculated particles size	Separated dust mass	Pass	Residue
	dae [μm]	dg [μm]	[mg]	D [%]	[%]
Limit inhalable fraction^*1)	100	-	-	100
A	32.40	16.41	226.53	65.83	34.17
B	15.80	8.00	80.90	53.63	46.37
C	8.13	4.12	58.15	44.86	55.14
D	4.06	2.06	149.24	22.35	77.65
E	2.04	1.03	100.36	7.21	92.79
F	0.99	0.50	37.2	11.60	98.40
G	0.47	0.24	8.16	0.37	99.63
<G^*2)	<0.47	<0.24	2.42
Extrapolated total dust quantity^*3)			659.84 mg
Total dust mass, including impactor correction^*4)			662.96 mg
Total dustiness of the examined sample (incl. correction)			662.2078 mg/g

 

¹⁾According EN 481 for the inhalable fraction exists an upper limit which is defined for the aerodynamic particle size of 100 μm. This corresponds with a mass limit of 100 % for the total dust which can be inhaled (EN 481 chap. 5 “agreement of conventions”).

²⁾The dust mass is taken into account with the impactor stage "< G" (which was validated independently of the substance in earlier investigations) which is removed from the impactor with the exhaust air (mass extrapolation).

³⁾The "extrapolated total dust quantity" takes into account the dust masses separated at the individual impactor stages (without mass of stage "< G"). The dust masses separated at the individual impactor stages are evaluated with experimentally determined correction factors, taking into account the various separating strengths of the impactor stages (manufacturer’s specifications).

⁴⁾The "total dust mass including impactor correction" is the total mass from impactor stage A to G plus the extrapolated mass from stage "< G".

 

This cumulated particle size distribution (CPSD) was then differentiated for particle size d_ae, to calculate the frequency distribution data.

 

Characteristics data of the frequency distribution of the inhalable fine dust

Particle size	Residue	Average particle size	Slope of CPSD
dae [μm]	[%]	dae av. [μm]	D'
0.47	99.63	0.73	2.37
0.99	98.40	1.52	5.35
2.04	92.79	3.05	7.49
4.06	77.65	6.10	5.53
8.13	55.14	11.97	1.14
15.80	46.37	24.10	0.74
32.40	34.17	49.20	0.59
66.00	14.29	83.00
100.00	0.00

 

Applicant's summary and conclusion

Conclusions:

The dustiness values for the Sample G6-3 were determined and calculated according to DIN EN 481:
- Total dustiness: 662.21 [mg/g]
- Inhalable fraction: 474.75 [mg/g]
- Thoracic fraction: 325.98 [mg/g]
- Respirable fraction: 161.35 [mg/g]