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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:
22 December 2008 to 20 February 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to current guideline and GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)
Deviations:
yes
Remarks:
(The study is only applicable to materials less than 100 µm. The sieve method was used to satisfy the guideline as the result obtained determines whether or not the material is suitable for the full study.)
GLP compliance:
yes (incl. QA statement)
Type of method:
other: sieve
Type of distribution:
volumetric distribution
Percentile:
D50
Remarks on result:
other: No source field for Standard deviation.
No.:
#1
Size:
< 100 µm
Distribution:
3.3 %

The results of the sieving procedure are shown in the following table:

Sieve aperture size (µm)

100

Mass of test material transferred to sieve (g)

14.41

Mass of test material passed through sieve (g)

0.48

Test material less than sieve aperture size (%)

3.3

Conclusions:
From a sub-sample of the test material the percentage of material with a particle size less than 100 µm was determined to be 3.3% by sieve analysis. This indicated that the test material was of a particle size that was essentially non-inhalable. It must be noted that this value is a significant overestimate of the true fine particle fraction of the test material due to the sampling procedure.
Executive summary:

The particle size of the test material was determined following the screening study as outlined in the standardised guideline OECD 110.

On visual assessment the test material was observed to be composed of rocks of various sizes from approximately 10 cm to <1 cm plus some dust. To represent a worst case scenario for potential inhalation risk the larger particles were removed and only smaller particles and dust were sub-sampled. From this sub-sample the percentage of test material with a particle size of <100 µm was calculated by sieve analysis. A representative portion of this sub-sample (14.41 g) was sieved for approximately 30 minutes on an Inclyno sieve shaker using a 100 µm sieve. The mass of the test material passing through the sieve was measured.

From a sub-sample of the test material the percentage of material with a particle size less than 100 µm was determined to be 3.3%. This indicated that the test material was of a particle size that was essentially non-inhalable. It must be noted that this value is a significant overestimate of the true fine particle fraction of the test material due to the sampling procedure.

Description of key information

The proportion of test material having an inhalable particle size less than 100 µm was below 3.3 % w/w, OECD 110 sieve method, Butler & O'Connor (2009)

Additional information

The particle size of the test material was determined following the screening study as outlined in the standardised guideline OECD 110.

On visual assessment the test material was observed to be composed of rocks of various sizes from approximately 10 cm to <1 cm plus some dust. To represent a worst case scenario for potential inhalation risk the larger particles were removed and only smaller particles and dust were sub-sampled. From this sub-sample the percentage of test material with a particle size of <100 µm was calculated by sieve analysis. A representative portion of this sub-sample (14.41 g) was sieved for approximately 30 minutes on an Inclyno sieve shaker using a 100 µm sieve. The mass of the test material passing through the sieve was measured.

From a sub-sample of the test material the percentage of material with a particle size less than 100 µm was determined to be 3.3%. This indicated that the test material was of a particle size that was essentially non-inhalable. It must be noted that this value is a significant overestimate of the true fine particle fraction of the test material due to the sampling procedure.