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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:
supporting study
Study period:
2010-01-11
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
significant methodological deficiencies
Remarks:
Detailed description of the measurement, sample preparation method, temperature and pH of the suspending medium and concentration were missing
Qualifier:
according to guideline
Guideline:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)
Deviations:
not specified
GLP compliance:
no
Type of method:
other: no data
Type of distribution:
mass based distribution
Remarks on result:
not measured/tested
Percentile:
D10
Mean:
7.1 µm
Percentile:
D50
Mean:
21.8 µm
Percentile:
D90
Mean:
56.2 µm
Conclusions:
The particle size distributen of the test item is:
d 10 = 7.1 μm
d 50 = 21.8 μm
d 90 = 56.2 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:
guideline study
Remarks:
Heubach dust meter connected to a cascade impactor
Qualifier:
according to guideline
Guideline:
DIN 55992-1 (Determination of a parameter for the dust formation of pigments and extenders - Part 1: Rotation method)
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 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
Type of distribution:
volumetric distribution
Remarks on result:
other: p1: 35.6 %, MMAD1 = 13.56 µm, GSD1 = 2.85 / p2: 64.4 %, MMAD2 = 38.09 µm, GSD2 = 1.85
Remarks on result:
not measured/tested

Dustiness (airborne fraction): total: 71.49 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: 35.6 %, MMAD1 = 13.56 µm, GSD1 = 2.85

p2: 64.4 %, MMAD2 = 38.09 µm, GSD2 = 1.85

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): 43.92 %

Tracheobronchial (TB): 0.38%

Pulmonary (PU): 0.67%

Conclusions:
Total Dustiness (airborne fraction): 71.49 mg/g (DMT)

Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction: MMAD1 = 13.56 µm (35.6 %) , MMAD2 = 38.09 µm (64.4 %) (distribution fitted to cascade impactor data, percentale in parentheses indicates weighting factor).

Geometric standard deviation of MMAD: GSD1 = 2.85, GSD 2 = 1.58.

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):
Head (ET): 43.92 %
Tracheobronchial (TB): 0.38 %
Pulmonary (PU): 0.67 %

Description of key information

PSD

D10 = 7.1 μm

D50 = 21.8 μm

D90 = 56.2 μm

Dustiness

Total Dustiness: 71.49 mg/g

MMAD1 = 13.56 µm (35.6 %), GSD1 = 2.85; MMAD2 = 38.09 µm (64.4 %), GSD 2 = 1.58.

Fractional deposition in human respiratory tract: Head (ET): 43.92 %, Tracheobronchial (TB): 0.38 %, Pulmonary (PU): 0.67 %

Additional information

Granulometry (GfE, 2010)

Sodium metavanadate has following particle size distribution:

D10 = 7.1 μm

D50 = 21.8 μm

D90 = 56.2 μm

Dustiness (Parr & Grewe, 2012)

Total Dustiness (airborne fraction): 71.49 mg/g (DMT)

Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction: MMAD1 = 13.56 µm (35.6 %) , MMAD2 = 38.09 µm (64.4 %) (distribution fitted to cascade impactor data, percentage in parentheses indicates weighting factor).

Geometric standard deviation of MMAD: GSD1 = 2.85, GSD 2 = 1.58.

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

Head (ET): 43.92 %

Tracheobronchial (TB): 0.38 %

Pulmonary (PU): 0.67 %