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Particle size distribution (Granulometry)

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Endpoint:
particle size distribution (granulometry)
Remarks:
dustiness
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
DIN 55992-1 (Determination of a parameter for the dust formation of pigments and extenders - Part 1: Rotation method)
Deviations:
yes
Remarks:
a seven stage cascade impactor is connected to a heubach dust meter
Principles of method if other than guideline:
The Heubach dust meter is modified in a way that a seven stage cascade impactor is connected to the system. This involves an additional air fed of 20 L/min via the coarse dust separator needed to supply the cascade impactor with 40 L/min air current as specified in the manufacturer’s specifications.

The calculation report: EBRC (2018)
The Multiple-Path Particle Dosimetry Model (MPPD, v2.1; CIIT, 2009) was used to predict this fractional deposition behaviour for workers.
The model algorithms calculate the deposition (and clearance) of mono-disperse and poly-disperse aerosols in the respiratory tract for particles ranging from ultra-fine (0.01 microns) to coarse (20 microns) sizes. Within each airway, the deposition is calculated using theoretically derived efficiencies for deposition by diffusion, sedimentation and impaction within the airway or airway bifurcation. Filtration of aerosols by the head is determined using empirical efficiency functions.
GLP compliance:
no
Type of method:
rotating drum method
Remarks:
connected to a seven stage cascade impactor
Type of distribution:
volumetric distribution
Test material information:
Composition 1
Mass median aerodynamic diameter:
27.18 µm
Geometric standard deviation:
1.64
Percentile:
D50
Remarks on result:
not measured/tested
Remarks on result:
not measured/tested

Dustiness (airborne fraction):       total: 103.85 mg/g.

In the original study report by DMT, the mass median diameter was not calculated. Since the deposited fractions were provided for each of the cascade impactor stages, it was possible to fit a monomodal lognormal distribution to the data by standard non-linear regression procedure. The MMAD and GSD were calculated as follows:       MMAD = 27.18 µm, GSD = 1.64

As the cascade impactor already takes aerodynamic characteristics of the particles into account, the reported mass median diameter can be interpreted as the mass median aerodynamic diameter.

These data and the corresponding GSD were used as distribution parameters for the MPPD model enabling an estimation of deposited dust fractions in the human respiratory tract: These fractions were estimated as follows:

Head (ET): 50.42 %

Tracheobronchial (TB): 0.09 %

Pulmonary (PU): 0.03 %

Conclusions:
Total Dustiness (airborne fraction): 103.85 mg/g (DMT)

Mass median aerodynamic diameters (monomodal distribution) of airborne fraction: MMAD = 27.18 µm.
Geometric standard deviation: GSD = 1.64

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):
Head (ET): 50.42 %
Tracheobronchial (TB): 0.09 %
Pulmonary (PU): 0.03 %
Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-01-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions - Method A: Particle Size Distribution (effective hydrodynamic radius)
Version / remarks:
1981
Deviations:
no
Qualifier:
according to
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
Version / remarks:
2009
Deviations:
no
Qualifier:
according to
Guideline:
other: CIPAC MT 187
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
signed, 2017-02-28
Type of method:
Laser scattering/diffraction
Type of distribution:
volumetric distribution
Test material information:
Composition 1
Remarks on result:
not measured/tested
Percentile:
D10
Mean:
0.7 µm
St. dev.:
0
Percentile:
D50
Mean:
3.7 µm
St. dev.:
0
Percentile:
D90
Mean:
76.9 µm
St. dev.:
1.27

Two test series of 3 measurements each were performed with the test item.

Test series 1

Test series 2

Average

D10

0.7 µm

0.7 µm

0.7 µm

D50 (Median diameter)

3.7µm

3.7 µm 3.7 µm
D90 77.8 µm 76.0 µm 76.9 µm

The test item zinc fluoride as a median particle size D50 = 4 µm, which was determined by laser diffraction measurement in accordance to inter alia ISO 13320 (2009) and CIPAC MT 187 (2009) method.

Conclusions:
According to OECD 110 (1981), ISO 13320 (2009) and CIPAC MT 187 (2009), strontium fluoride has following particle size distribution:
D10: 0.7 µm
D50: 3.7 µm (Median diameter)
D90: 76.9 µm

Description of key information

Particle size distribution

D10:       0.7 µm

D50:       3.7 µm       (Median diameter)

D90:       76.9 µm

Dustiness

Total Dustiness (airborne fraction): 103.85 mg/g (DMT)

MMAD = 27.18 µm.

GSD = 1.64

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD)

Head (ET): 50.42 %  

Tracheobronchial (TB): 0.09 %

Pulmonary (PU): 0.03 %

Additional information