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Particle size distribution (Granulometry)

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Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-05-04
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
according to guideline
Guideline:
other: SOP 1064L Standard
GLP compliance:
no
Type of method:
Laser scattering/diffraction
Type of distribution:
volumetric distribution
Remarks on result:
not measured/tested
Percentile:
D10
Mean:
1.01 µm
Remarks on result:
other: no St.dev. stated
Percentile:
D50
Mean:
3.96 µm
Remarks on result:
other: no St.dev. stated
Percentile:
D90
Mean:
29.66 µm
Remarks on result:
other: no St.dev. stated

Result:

diameter [µm]  cumulative data [%]
 1.0 9.84
 2.0 30.83
 3.0 43.12 
 4.0 50.20 
 5.0 54.54
 6.0 57.29
 7.0 59.16
 8.0 60.69
 9.0 62.17
 10.0 63.73
 15.0 72.89
 20.0 79.74
 30.0 90.34
 40.0 97.53
 50.0 99.75
 100.0 100.0
 200.0 100.0 
 300.0 100.0 
 400.0 100.0 
 500.0 100.0 
Conclusions:
The particle size distribution of vanadium carbide can be described as follows:

D10 = 1.01 µm
D50 = 3.96 µm
D90 = 29.66 µm
Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-09-13 to 2012-10-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods
Qualifier:
according to guideline
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:
The Heubach dust meter is modified in a way that a seven stage cascade impactor is connected to the system
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 specificcations.

The calculation report: Grewe, T (2012)
The Multiple-Path Particle Dosimetry Model (MPPD, v2.11; ART, 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 (for further information see "attached background material").
GLP compliance:
no
Type of method:
rotating drum method
Remarks:
connected to a cascade impactor
Type of distribution:
volumetric distribution
Percentile:
D50
Remarks on result:
other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Dustiness (airborne fraction): total: 14.54 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 bi- modal lognormal distribution to the data by standard non-linear regression procedure. The MMADs and GSDs were calculated as follows:

p1: 18.1 %, MMAD1 = 4.76 µm, GSD1 = 1.98

p2: 81.9 %, MMAD2 = 27.20 µm, GSD2 = 1.47

As the cascade impactor already takes aerodynamic characteristics of the particles into account, the reported mass median diameter can be interpreted as the mass medianaerodynamicdiameter. 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): 56.40 %

Tracheobronchial (TB): 0.45%

Pulmonary (PU): 1.11%

Conclusions:
Total Dustiness (airborne fraction): 14.54 mg/g (DMT)

Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction: MMAD1 = 4.76 µm (18.1%) , MMAD2 = 27.20 µm (81.9%) (distribution fitted to cascade impactor data, percentale in parentheses indicates weighting factor).

Geometric standard deviation of MMAD: GSD1 = 1.98, GSD 2 = 1.47.

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):
Head (ET): 56.40 %
Tracheobronchial (TB): 0.45%
Pulmonary (PU): 1.11%

Description of key information

Granulometry (Niederbiechler, 2012)

The particle size distribution of vanadium carbide can be described as follows:

D10 = 1.01 µm

D50 = 3.96 µm

D90 = 29.66 µm

Dustiness (Parr & Grewe, 2012)

Total Dustiness (airborne fraction): 14.54 mg/g (DMT)

Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction: MMAD1 = 4.76 µm (18.1%) , MMAD2 = 27.20 µm (81.9%) (distribution fitted to cascade impactor data, percentile in parentheses indicates weighting factor).

Geometric standard deviation of MMAD: GSD1 = 1.98, GSD 2 = 1.47.

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

Head (ET): 56.40 %

Tracheobronchial (TB): 0.45%

Pulmonary (PU): 1.11%

Additional information