Cerium gadolinium oxide

Nanomaterial dustiness

Administrative data

Endpoint:

nanomaterial dustiness

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 2021 to 13 October 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Mathiak (2021).

Reference

Endpoint:

appearance / physical state / colour

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Remarks:

The description of the substance comes from study reports on other physico-chemical endpoints determined in accordance with internationally-recognized standard guidelines. In these reports, the substance is adequately defined and a certificate of analysis is available.

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Demangel (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Demangel (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Demangel (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Demangel (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Demangel (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Mathiak (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Mathiak (2021).

Qualifier:

no guideline required

Principles of method if other than guideline:

Visual inspection.

GLP compliance:

yes

Remarks:

The test substance is described in the context of GLP-compliant physico-chemical studies in the study report of Demangel (2021). The description is confirmed in the study report of Mathiak (2021) which concerns a non-GLP compliant physico-chemical study.

Physical state at 20°C and 1013 hPa:

solid

Key result

Form:

solid: particulate/powder

Colour:

White to beige

Substance type:

inorganic

Conclusions:

Cerium gadolinium oxide is an inorganic solid appearing under the form of a white to beige powder.

Executive summary:

The test substance was described as a white powder in the context of GLP-compliant physico-chemical studies (Demangel, 2021). A similar description as a white to beige powder was reported in the study report of Mathiak (2021) which concerns a non-GLP compliant physico-chemical study.

Cross-reference 2

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Mathiak (2021).

Reference

Endpoint:

density, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From June 2021 to 13 October 2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

The density was part of the information measured in the context of the study from Mathiak (2021) dedicated to assess the dustiness of the test substance. Therefore, determination of density was not the ultimate aim of this study, and no guideline was followed. However, the method used (i.e. air comparison pycnometry) was the same as the one used in the key study of Demangel (2021) and the results are pretty similar.

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Mathiak (2021).

Reason / purpose for cross-reference:

reference to same study

Remarks:

Other physico-chemical endpoints are covered in the study report of Mathiak (2021).

Qualifier:

no guideline followed

Principles of method if other than guideline:

Air comparison pycnometry.

GLP compliance:

no

Type of method:

air comparison pycnometer (for solids)

Type:

density

Density:

6.909 g/cm³

Temp.:

26.33 °C

Remarks on result:

other: ± 0.0057 g/cm3

Cycles of measurement	Volume (cm3)	Density (g/cm3)
#1	1.1845	6.9064
#2	1.1855	6.9009
#3	1.1830	6.9152
#4	1.1847	6.9053
#5	1.1825	6.9182
#6	1.1855	6.9005
#7	1.1833	6.9134
#8	1.1846	6.9059
#9	1.1834	6.9127
#10	1.1844	6.9070
Mean	1.1842 ± 0.0010	6.9085 ± 0.0057

Conclusions:

The density of cerium gadolinium oxide is equal to 6.9085 ± 0.0057 g/cm3.

Executive summary:

The density of cerium gadolinium oxide was determined as part of a non-GLP compliant study dealing with another endpoint. The gas comparison pycnometer (DSC) method was used, but no guideline was followed. The density was determined to be equal to 6.9085 ± 0.0057 g/cm3.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: DIN 55992-1:2006 "Determination of a parameter for the dust formation of pigments and extenders - Part 1: Rotation method"

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: DIN EN 481

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: DIN EN 15051-2

GLP compliance:

no

Other quality assurance:

other: DIN EN ISO 9001 and DIN EN ISO 14001 certification

Type of method:

rotating cylinder

Details on methods and data evaluation:

The dust fractions of cerium gadolinium oxide was determined according to the DIN 55992-1:2006 method. The different dust fractions are defined in DIN EN 481 as the inhalable fraction, thoracic fraction and respirable fraction.
The modified Heubach procedure was applied. ln the process, 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 (respirable) fractions according to DIN EN 481 were determined.

Test material

Test material information

Constituent 1

Reference substance name:

Cerium gadolinium oxide

EC Number:

953-470-2

Molecular formula:

Gd2CeO5

IUPAC Name:

Cerium gadolinium oxide

Test material form:

solid: nanoform

Data gathering

Instruments:

Heubach dust meter with a rotating drum (dust generation device) applying the modified Heubach procedure.

Calibration:

Not specified

Reproducibility:

Not specified

Results and discussion

Dustiness index

Key result

Mean:

75 643 mg/kg

Remarks on result:

other: Total dustiness is given here (ratio of the mass of removed dust to the total sample mass initially weighed in). Standard deviation is not available in the study report.

Any other information on results incl. tables

Table 1 - Dust masses and calculated relations (Pass/Residue) on the impactor stages

Impactor stage	Average aerodynamic diameter dae [µm]	Calculated particle size Dg [µm]	Separated dust mass [mg]	Pass D [%]	Residue [%]
Limit inhalable fraction^1)	100	-	-	100
A	32.40	12.33	32.67	56.84	43.16
B	15.80	6.01	15.82	35.94	64.06
C	8.13	3.10	10.93	21.50	78.50
D	4.06	1.55	9.76	8.61	91.39
E	2.04	0.78	4.73	2.35	97.65
F	0.99	0.38	1.34	0.59	99.41
G	0.47	0.18	0.34	0.13	99.87
<G^2)	<0.47	<0.18	0.10
Extrapolated total dust quantity^3)	75.32 mg
Total dust mass, incl. impactor correction^4)	75.69 mg
Total dustiness of the examined sample (incl. correction)	75.6430 mg/g

¹⁾ According to 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".

 

Table 2 – Characteristics data of the frequency distribution of the inhalable fine dust

Particle size dae [µm]	Residue [%]	Average particle size daeav. [µm]	Slope of CPSD D’
0.47	99.87	0.73	0.87
0.99	99.41	1.52	1.68
2.04	97.65	3.05	3.10
4.06	91.39	6.10	3.17
8.13	78.50	11.97	1.88
15.80	64.06	24.10	1.26
32.40	43.16	49.20	0.72
66.00	18.80	83.00
100.00	0.00

 

Table 3 – Summary of results of the examined dust sample

Quantity of substance used	1.00059		Relative amounts of used quantity	Relative amounts of the whole fraction
Total dust mass in impactor	75.69 mg
Mass Median Aerodynamic Diamter (MMAD)^5)	26.5 µm
Geometric Standard Deviation (GSD)^5)	2.9 µm
Total dustiness, whole fraction	75.6430 mg/g
Dustiness, inhalable fraction	49.3708 mg/m		4.94 %	65.27 %
Dustiness, thoracic fraction	22.2586 mg/g		2.23 %	29.43 %
Dustiness, alveolar fraction	7.7114 mg/g		0.77 %	10.19 %

⁵⁾ Median of the distribution of airborne particle mass with respect to the aerodynamic diameter. MMAD is one of the metrics most widely adopted as a single number descriptor of aerodynamic particle-size distribution. MMADs are usually accompanied by the geometric standard deviation (GSD) which characterizes the variability of the particle size distribution. The diameter that divides the mass distribution of an aerosol in half [P.A. Baron, K. Willecke; Aerosol Measurement, 2005].

Applicant's summary and conclusion

Conclusions:

The most important information resulting from the determination of the dustiness is that the respirable fraction represents 0.77 % of used quantity of cerium gadolinium oxide under the modified Heubach procedure. According to EN 15051-2, the dustiness is allocated to category "low".

Executive summary:

The dustiness of cerium gadolinium oxide and also the different dust fractions were determined in a non-GLP compliant study in accordance with DIN 55992 -1:2006 method using the Heubach procedure modified by the laboratory DMT. ln the process, 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:

Total dustiness [mg/g]	75.6430
Inhalable fraction [mg/g]	49.3708 (4.94 %)
Thoracic fraction [mg/g]	22.2586 (2.23 %)
Respirable fraction [mg/g]	7.7114 (0.77 %)
Mass Median Aerodynamic Diameter (MMAD) [µm]	26.5
Geometric Standard Deviation (GSD) [µm]	2.9

As a conclusion, the most important information resulting from the determination of the dustiness is that the respirable fraction represents 0.77 % of used quantity of cerium gadolinium oxide under the modified Heubach procedure. According to EN 15051-2, the dustiness is allocated to category "low".