Cobalt sulphate

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:

2009-07-30 till 2009-07-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

The purpose of this study was the determination of the particle size distribution of the test item by laser diffraction according to the consolidated version of Guideline 67/548/EEC (council Directive 92/69/EEC) and under consideration of the following guidelines:
OECD 110 (1981): Particle Size Distribution,
CIPAC MT 187: Particle Size Analysis by Laser Diffraction,
ISO 13320-1: Particle Size Analysis – Laser Diffraction Methods.

GLP compliance:

no

Type of method:

Laser scattering/diffraction

Type of distribution:

volumetric distribution

Remarks on result:

not measured/tested

Percentile:

D10

Mean:

450.34 µm

St. dev.:

16.63

Percentile:

D50

Mean:

917.56 µm

St. dev.:

12.43

Percentile:

D90

Mean:

1 524.13 µm

St. dev.:

12.49

Conclusions:

The median particle size L50 of Cobalt sulfate deduced from the particle size distributions is 917.6 µm.
The particle size L10 of cobalt sulfate deduced from the particle size distributions is 450.3 µm.
The particle size L90 of cobalt sulfate deduced from the particle size distributions is 1524.1 µm.

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-05 to 2010-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

see "Principles of method if other than guideline"

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 (2009)
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:

rotating drum method

Type of distribution:

volumetric distribution

Mass median aerodynamic diameter:

34.24 µm

Geometric standard deviation:

1.56

Percentile:

D50

Remarks on result:

not measured/tested

Dustiness (airborne fraction): total: 32.82 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 mono modal lognormal distribution to the data by standard non-linear regression procedure. As a result, the MMAD and GSD are calculable and reported (MMAD = 34.24µm, GSD = 1.56). 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.

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): 37.9 %

Tracheobronchial (TB): 0.0 %

Pulmonary (PU): 0.0 %

Conclusions:

Cobalt sulfate

Total Dustiness (airborne fraction): 32.82 mg/g (experimental results, DMT Report).

Mass median aerodynamic diamater of airborne fraction: MMAD = 34.24µm (distribution fitted to cascade impactor data).
Geometric standard deviation of MMAD: GSD = 1.56

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):
Head (ET): 37.9 %
Tracheobronchial (TB): 0.0 %
Pulmonary (PU): 0.0 %

Description of key information

Particle size distribution (OECD 110):

d50 = 917.6µm,

d10 = 450.3 µm,

d90 = 1524.1 µm.

Heubach Test:

Mass median aerodynamic diameter of airborne fraction: MMAD = 34.24µm.

Geometric standard deviation of MMAD: GSD = 1.56. Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):

Head (ET): 37.9 %

Tracheobronchial (TB): 0.0 %

Pulmonary (PU): 0.0 %

Additional information

The particle size distribution of cobalt sulfate was determined according to OECD guideline 110 by laser diffraction (light scattering). Before the measurement, the test item was sieved with a sieve of mesh size of 2000µm. For this sample the measuring range was set to 0.02 to 2000µm.

In a second study, examinations were performed to determine the dustiness of a substance sample of cobalt sulfate. The objective of these examinations was to determine the dust fractions of this substance. These are the dust fractions which are defined in DIN EN 481 as the:

• inhalable fraction,

• thoracic fraction and

• respirable fraction.

The modified Heubach procedure was applied.