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Particle size distribution (Granulometry)

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Reference
Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 July 2008 to 17 November 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
cascade impaction
Type of distribution:
mass based distribution
Test material information:
Composition 1
Percentile:
D50
Remarks on result:
other: No source field for Standard deviation.

Calculation

Table 1: Calculation of the cumulative mass and cumulative % using the values obtained from the cascade impactor

Collection Site

Mass at Stage (g)

Cumulative Mass (g)

Cumulative (%)

Entry Port

0

m0

M0

100

10.0 µm stage

1

m1

M1

100 x M1 / M0

5.5 µm stage

2

m2

M2

100 x M2 / M0

2.4 µm stage

3

m3

M3

100 x M3 / M0

1.61 µm stage

4

m4

M4

100 x M4 / M0

0.307 µm stage

5

m5

M5

100 x M5 / M0

Filter

6

m6

M6

100 x M6 / M0

where:

m = mass of material found at indicated site (g)

M = cumulative mass (g) at indicated site (e.g. M3 = m3 + m4 + m5 + m6)

 

Results

Screening Test (sieve method)

Table 2: Results of Screening Test

Sieve aperture (µm)

100

Mass of test material transferred to sieve (g)

19.66

Mass of test material passed through sieve (g)

4.67

Test material less than sieve aperture size (%)

23.8

 

Determination 1:

- Amount of test material found in artificial throat: 0.06 g

- Total amount of test material recovered from impactor cups, filter and artificial throat: 2.8543 g

 

Determination 2:

- Amount of test material found in artificial throat: 0.05 g

- Total amount of test material recovered from impactor cups, filter and artificial throat: 2.9645 g

 

Determination 3:

- Amount of test material found in artificial throat: 0.06 g

- Total amount of test material recovered from impactor cups, filter and artificial throat: 2.9031 g

 

Table 3: Overall cumulative amounts of test material with a particle size less than 10.0 gm (%) from Determinations 1 to 3

Determination

Cumulative Amount of Test Material

Less Than 10.0 gm (%)

Mean Cumulative Amount of Test Material

Less Than 10.0 gm (%)

1

1.68

2.77

2

2.39

3

4.24

 

Table 4: Overall cumulative amounts of test material with a particle size less than 5.5 µm (%) from Determinations 1 to 3

Determination

Cumulative Amount of Test Material

Less Than 5.5 gm (%)

Mean Cumulative Amount of Test Material

Less Than 5.5 gm (%)

1

0.238

0.357

2

0.290

3

0.544

 

Table 5: Overall Test Results

Measurement

Method

Result

Proportion of test material having an inhalable particle size less than 100 µm

Sieve

23.8 %

Proportion of test material having a thoracic particle size less than 10.0 µm

Cascade Impactor

2.77 %

Proportion of test material having a respirable particle size less than 5.5 µm

Cascade Impactor

0.357 %

 

Discussion

Too few particles were of a size less than 10.0 µm to allow accurate assessment of mass median aerodynamic diameter.

Representative sampling was ensured by rolling the sample container for approximately 10 minutes and sampling from the top, middle and bottom prior to definitive testing.

The inhalable fraction is defined as the mass fraction of particles which can be inhaled by nose or mouth, the thoracic fraction is defined as the mass fraction of particles that passes the larynx and the respirable fraction is defined as the mass fraction of particles that reaches the alveoli.

For some measurements, negative weight differences have been reported. These differences were considered to be within the anticipated accuracy of the balance. In these instances zero has been used for the cumulative calculated data.

Conclusions:
Under the conditions of the study, 23.8 % of the test material is the proportion of test material having an inhalable particle size less than 100 µm; 2.77 % is the proportion of test material having a thoracic particle size less than 10.0 µm, and 0.357 % is the proportion of test material having a respirable particle size less than 5.5 µm.
Executive summary:

A determination of the particle size distribution of the test material was investigated in a study which was performed under GLP conditions and in accordance with the standardised guideline OECD 110. The sieve method was used for the screening test, followed by three determinations using the cascade impactor.

Under the conditions of the study, 23.8 % of the test material is the proportion of test material having an inhalable particle size less than 100µm; 2.77 % is the proportion of test material having a thoracic particle size less than 10.0 µm, and 0.357 % is the proportion of test material having a respirable particle size less than 5.5 µm.

Description of key information

PSD = proportion of test material having an inhalable particle size less than 100µm = 23.8 %, proportion of test material having a thoracic particle size less than 10.0 µm = 2.77 %, proportion of test material having a respirable particle size less than 5.5 µm = 0.357 %, sieve method (screening), cascade impactor (main test, three determinations), OECD 110, Butler & O'Connor (2008)

Additional information

A determination of the particle size distribution of the test material was investigated in a study which was performed under GLP conditions and in accordance with the standardised guideline OECD 110. The study was assigned a reliability score of 1 in line with the principles for assessing data quality as defined by Klimisch (1997).

The sieve method was used for the screening test, followed by three determinations using the cascade impactor. Under the conditions of the study, 23.8 % of the test material is the proportion of test material having an inhalable particle size less than 100µm; 2.77 % is the proportion of test material having a thoracic particle size less than 10.0 µm, and 0.357 % is the proportion of test material having a respirable particle size less than 5.5 µm.