Silver carbonate

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 November 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Company data. Laser diffraction measurements of one representative commercial sample. Non-GLP

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)

Deviations:

yes

Remarks:

Please refer to the assessment of reliability indicated above.

Principles of method if other than guideline:

No guideline specified, but comparable to OECD 110. A laser diffraction analysis has been carried out using the instrument Malvern Mastersizer 2000.

GLP compliance:

no

Type of method:

Laser scattering/diffraction

Type of distribution:

volumetric distribution

Percentile:

D10

Mean:

ca. 2.5 µm

St. dev.:

0

Percentile:

D50

Mean:

ca. 7.5 µm

St. dev.:

0

Percentile:

D90

Mean:

ca. 25.5 µm

St. dev.:

0

Conclusions:

The particle size distribution of a typical commercial sample of silver carbonate is characterised by the following parameters: D10= ca. 2.5µm, D50=ca. 7.5 µm and D90 = ca. 25.5µm.

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Remarks:

Test procedure in accordance with national standards DIN 55992-1:2006 ("Determination of a parameter for the dust formation of pigments and extenders - Part 1: Rotation method"), modified Heubach method

Qualifier:

according to guideline

Guideline:

other: DIN 55992-1:2006 (Determination of a parameter for the dust formation of pigments and extenders – Part 1: Rotation method)

Deviations:

yes

Remarks:

Please refer to rationale for reliability mentioned above.

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: (Klipsch, 2011)
The Multiple-Path Particle Dosimetry Model (MPPD, v2.0; CIIT, 2006) 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:

cascade impaction

Type of distribution:

volumetric distribution

Percentile:

other: MMAD 1 and GSD 1

Mean:

0.52 µm

St. dev.:

1.1

Percentile:

other: MMAD 2 and GSD 2

Mean:

25.91 µm

St. dev.:

2.93

Remarks on result:

not determinable

Dustiness (airborne fraction): total: 59.45 mg/g.

In the original study report by DMT, a calculation of the mass median diameter was not conducted. 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. As a result, the MMAD and GSD are calculable and reported: p1: 1%, MMAD1 = 0.52 µm, GSD1 = 1.10 / p2: 99%, MMAD 2 = 25.91 µm, GSD2 = 2.93

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.

This figure 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): 49.31%

Tracheobronchial (TB): 0.48%

Pulmonary (PU): 0.73%

Conclusions:

Total Dustiness (airborne fraction): 59.45 mg/g (experimental results, DMT Report).

Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction: MMAD1 = 0.52µm (1%) , MMAD2 = 25.91 µm (99%) (distribution fitted to Cascade impactor data, percentage in parentheses indicates weighting factor).

Geometric standard deviation of MMAD: GSD1 = 1.10, GSD 2 = 2.93.

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):
Head (ET): 49.31%
Tracheobronchial (TB): 0.48%
Pulmonary (PU): 0.73%

Description of key information

The particle size distribution of a representative commercial sample of silver(I)carbonate is characterised by the following parameters (mass/volume-based distribution): D10 = ca. 2.5 µm, D50 = ca. 7.5 µm, D90 = ca. 25.5 µm. 
In a laboratory test for dustiness (rotating drum), simulating conditions of physical agitation of the material, approx. 60 mg/g (i.e. ca. 6% of the mass of the material) became airborne. The mass median diameter (MMAD) of the airborne material was determined at ca. 26 µm. Using a multiple path particle dosimetry model (MPPD), the fractional deposition of inhaled material in the human lung was estimated as follows: head-region: 49.31%, tracheobronchial-region: 0.48%, pulmonary-region: 0.73%. The balance to 100%, i.e. 49.48% of airborne material are considered not to be inhalable.