Cerium dioxide

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

from 03 NOV 2005 to 09 MAR 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: European Commission, Directorate general XII- JRC, Science Research and Development-Joint Research centre. "Particle size distribution, fibre length and diameter distribution". Guidance document, ECB/TM/February 1996.

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: European Commission, Directorate general JRC, Joint Research Centre. "Particle size distribution, fibre length and diameter distribution". Draft guidance document, EUR 20268 EN (2002), Part 5.2 "Laser scattering / diffract".

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of distribution:

counted distribution

Mass median aerodynamic diameter:

2.4 µm

Percentile:

other: D5

Mean:

< 0.6 µm

St. dev.:

0.014

Percentile:

D10

Mean:

< 1 µm

St. dev.:

0.042

Percentile:

D50

Mean:

< 2.4 µm

St. dev.:

0.116

Percentile:

D90

Mean:

< 4.4 µm

St. dev.:

0.225

Cerium dioxide is a very fine powder of lightly beige appearance. Under the microscope (with a magnification of 400) very small, dark, rounded crystalline structures were observed.

 

A solubility test showed, that the test item is both: sparingly soluble and well dispersible in silicon oil.

 

The particle size distribution was found to range from approximately 0.3 µm to 9 µm.

 

Particle size distribution of cerium dioxide

[%]	1st Run Particle Size [μm]	2nd Run Particle Size [μm]	3rd Run Particle Size [μm]	4th Run Particle Size [μm]	Mean Particle Size [μm]	Stand. Dev. [±]
5	< 0.56	< 0.53	< 0.56	< 0.55	< 0.6	0.014
10	< 0.93	< 0.92	< 1.01	< 0.98	< 1.0	0.042
50	< 2.36	< 2.26	< 2.52	< 2.47	< 2.4 *	0.116
90	< 4.53	< 4.04	< 4.47	< 4.46	< 4.4	0.225

*) The MMD of the test item indicates that 50 % (by mass) of the particles are smaller than 2.4 μm.

 

The results obtained during the measurements showed no relevant difference (standard deviation was found to be below 10%). Therefore the study is considered to be valid and no further testing is necessary.

Conclusions:

The mass median diameter of cerium dioxide was determined to be 2.4 µm.
The particle size distribution was found to range from approximately 0.3 µm to 9 µm.

Executive summary:

Using the laser diffraction method under GLP compliance to study the particle size of cerium dioxide ranging between 0.3 µm and 300 µm, the mass median diameter (MMD) was determined to be 2.4 µm. The particle size distribution was found to range from approximately 0.3 µm to 9 µm.

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

This entry corresponds to a compilation of internal company data that were obtained using methods highly adapted to the in-house products. Furthermore, the sedimentation / gravitational settling method here applied is recommended in internationally recognized guidelines.

Qualifier:

equivalent or similar to guideline

Guideline:

other: EUROPEAN COMMISSION, DIRECTORATE GENERAL JRC, JOINT RESEARCH CENTRE. PARTICLE SIZE DISTRIBUTION FIBRE LENGTH AND DIAMETER DISTRIBUTION. DRAFT guidance document EUR 20268 EN (2002), Part 4.3 "Sedimentation (Gravitational Settling)"

Qualifier:

equivalent or similar to guideline

Guideline:

other: EUROPEAN COMMISSION, DIRECTORATE GENERAL XII-JRC SCIENCE, RESEARCH AND DEVELOPMENT - JOINT RESEARCH CENTRE. PARTICLE SIZE DISTRIBUTION FIBRE LENGTH AND DIAMETER DISTRIBUTION, GUIDANCE DOCUMENT ECBITM/ February 1996

Principles of method if other than guideline:

The used apparatus (Sedigraph 5100) measured the settling rate of particles in suspension. Settling of the particles in fluid depends on the difference in specific gravity between that of the liquid and the particle material, the specific gravity of the particle material being greater than that of the liquid. The results were automatically provided and expressed as a distribution of the cumulated percentages in function of the spherical equivalent diameters (based on Stokes Law).

GLP compliance:

no

Percentile:

D50

Mean:

>= 0.4 - <= 1 µm

Remarks on result:

other: Range for different products of a same grade of cerium dioxide

Conclusions:

This grade of cerium dioxide showed D50 ranging from 0.4 to 1 µm.

Executive summary:

The particle size distribution of cerium dioxide was measured in accordance with the sedimentation / gravitational settling method using Sedigraph 5100. While the study was not GLP-compliant, the method used is referenced in internationally recognized guidelines. D50 ranging from 0.4 to 1 µm were obtained for this grade of cerium dioxide.

Reference 3

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

This entry corresponds to a compilation of internal company data that were obtained using methods highly adapted to the in-house products. Furthermore, the laser diffraction method here applied is recommended in internationally recognized guidelines.

Qualifier:

equivalent or similar to guideline

Guideline:

other: EUROPEAN COMMISSION, DIRECTORATE GENERAL JRC, JOINT RESEARCH CENTRE. PARTICLE SIZE DISTRIBUTION FIBRE LENGTH AND DIAMETER DISTRIBUTION. DRAFT guidance document EUR 20268 EN (2002), Part 5.2 "Laser scattering / diffraction"

Qualifier:

equivalent or similar to guideline

Guideline:

other: EUROPEAN COMMISSION, DIRECTORATE GENERAL XII-JRC SCIENCE, RESEARCH AND DEVELOPMENT - JOINT RESEARCH CENTRE. PARTICLE SIZE DISTRIBUTION FIBRE LENGTH AND DIAMETER DISTRIBUTION, GUIDANCE DOCUMENT ECBITM/ February 1996

GLP compliance:

no

Percentile:

D50

Mean:

>= 5 - <= 20 µm

Remarks on result:

other: Range for different products of a same grade of cerium dioxide

Conclusions:

This grade of cerium dioxide showed D50 ranging from 5 to 20 µm.

Executive summary:

The particle size distribution of cerium dioxide was measured in accordance with the laser diffraction method using the granulometer Coulter LS-13320. While the study was not GLP-compliant, the method used is referenced in internationally recognized guidelines. D50 ranging from 5 to 20 µm were obtained for this grade of cerium dioxide.

Reference 4

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: :

Remarks:

This entry corresponds to an internal company data for which the experimental results are available, but not the associated methodological procedure. Only the name of the method was orally communicated by the owner company. Therefore, it is not possible to assign a reliability score to this data.

Principles of method if other than guideline:

No data

GLP compliance:

not specified

Percentile:

D10

Mean:

3.51 µm

Remarks on result:

other: No further data on results

Percentile:

D50

Mean:

16.56 µm

Remarks on result:

other: No further data on results

Percentile:

D90

Mean:

49.62 µm

Remarks on result:

other: No further data on results

Conclusions:

This grade of cerium dioxide showed D10, D50 and D90 of 3.51, 16.56 and 49.62 µm, respectively.

Executive summary:

The particle size distribution of cerium dioxide was measured in accordance with the current particle method using a Microtrac instrument with no reference to a particular guideline or to GLP compliance. Except the name of the method, no details were provided concerning the experimental procedure. D10, D50 and D90 of 3.51, 16.56 and 49.62 µm were obtained for this grade of cerium dioxide, respectively.

Description of key information

Different tests conducted on several representative samples of bulk cerium dioxide show a variety of particle size distributions. Indeed, the reported D50 ranges from 0.4 to 20 µm. Nevertheless, materials with higher particle size distributions can also exist. As such products should show a lesser risk in terms of inhalation toxicity, they can be considered as covered by this registration dossier.

Additional information

One experimental study is scored as Klimisch 1 and conducted in compliance with GLP. The other available data, scored as Klimisch 2 or 4, are internal company information. Tests were performed using methods highly adapted to the in-house products. The whole information were used in a weight-of-evidence approach intended to cover all the cerium dioxide size distributions.