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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:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Heubach-Dust-Meter connected to a cascade impactor
Qualifier:
according to
Guideline:
DIN 55992-1 (Determination of a parameter for the dust formation of pigments and extenders - Part 1: Rotation method)
Version / remarks:
2006
Deviations:
yes
Remarks:
Heubach-dust-meter connected to a cascade impactor
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 (2017)
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 polydisperse aerosols in the respiratory tract for particles ranging from ultra-fine (0.01 microns) to coarse (20 microns) sizes. Within each airway, 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
Remarks on result:
other: p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49; p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38
Remarks on result:
not measured/tested
Remarks on result:
not measured/tested

Dustiness (airborne fraction):      total: 47.82 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 bimodal lognormal distribution to the data by standard non-linear regression procedure. The weighting factors p, theMMADsand GSDs were calculated as follows:      

p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49;

p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

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): 43.32 %

Tracheobronchial (TB): 0.07 %

Pulmonary (PU): 0.11 %

Conclusions:
Dustiness (airborne fraction):      total: 47.82 mg/g.

- p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49;
- p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

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

Head (ET): 43.32 %
Tracheobronchial (TB): 0.07 %
Pulmonary (PU): 0.11 %
Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-06-15
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
not performed according to GLP
Qualifier:
according to
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
Deviations:
no
GLP compliance:
no
Type of method:
Laser scattering/diffraction
Type of distribution:
volumetric distribution
Remarks on result:
not measured/tested
Key result
Percentile:
D50
Mean:
118 µm
Remarks on result:
other: no data for St. dev.
Key result
Percentile:
D90
Mean:
581 µm
Remarks on result:
other: no data for St. dev.
Conclusions:
D50 = 118µm
D90 = 581µm

Description of key information

The particle size distribution:

D50 = 118 µm

D90 = 581 µm

Dustiness: 

- total dustiness: 47.82 mg/g.

Mass median aerodynamic diameter:

- p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49;

- p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

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

Head (ET): 43.32 %

Tracheobronchial (TB): 0.07 %

Pulmonary (PU): 0.11 %

Additional information