7-Isopropyl-2H,4H-1,5-benzodioxepin-3-one

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was conducted according to EU guideline, with minor deviations. Test substance is adequately characterised with its purity. However, as a single measurement was performed, intra and inter batch variation were not assessed. Therefore validity applies with restrictions.

Qualifier:

according to guideline

Guideline:

other: EUR 20268 EN: Guidance Document on the Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of chemical substances (European Commission, 2002)

Deviations:

yes

Remarks:

observation with binocular; no preliminary screening test at 100 µm

Principles of method if other than guideline:

Laser diffraction

GLP compliance:

no

Type of method:

Laser scattering/diffraction

Type of particle tested:

primary particle

Type of distribution:

volumetric distribution

Percentile:

D10

Mean:

9.3 µm

Remarks on result:

other: no data on SD

Percentile:

D50

Mean:

34 µm

Remarks on result:

other: no data on SD

Percentile:

D90

Mean:

88 µm

Remarks on result:

other: no data on SD

Size:

< 515 µm

Distribution:

100 %

Remarks on result:

other: sample as supplied

Size:

< 105 µm

Distribution:

94 %

Remarks on result:

other: sample as supplied

Size:

< 11 µm

Distribution:

12 %

Remarks on result:

other: sample as supplied

Size:

< 4.5 µm

Distribution:

4.8 %

Remarks on result:

other: sample as supplied

Particle size distribution

The results of the sample show a Gaussian-type distribution, with a median size (D50) of 34 µm.

For the thresholds relevant to inhalation potential, results below were not corrected (no pre-sieving therefore total sample distribution), and assuming %v and %w are similar:
Inhalable fraction (< 105 µm):    94 %
Thoracic fraction (< 11 µm):       12 %
Respirable fraction (< 4.5 µm):     4.8 %

A threshold of 500 µm is generally assumed to be of concern for dust explosion potential; the corresponding fraction (< 515 µm) accounts for 100%.

Conclusions:

The test substance contains a fraction of particles fine enough to be inhaled and reach the thoracic fraction.
Dust explosion potential should be considered.

Executive summary:

Following guidance EUR 20268 EN, the test substance was first examined under microscope, and described as crystalline needles, without clusters.

The particle size was measured with a laser diffraction granulometer, in air. For the single sample tested, the distribution was Gaussian, with a median diameter of 34 µm.

With regard to inhalation potential, about 94% of total particles are smaller than 105 µm, and about 12% could reach the thoracic fraction (<11 µm).

Fine particles relevant to dust explosion hazard (<515 µm) account for 100%.

Description of key information

Median diameter = 34 µm

Thoracic fraction (<11µm) = 12%.

Dust particles (<515µm) = 100% (dust explosion potential)

Additional information

A reliable experimental study, conducted according to a recognized EU guideline, is available. Despite restrictions due to single measurement, it is considered as a key study.