Aluminium vanadium tetraoxide

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Reference 1

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

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:

a seven stage cascade impactor is connected to a heubach dust meter

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:

not specified

Type of method:

rotating drum method

Remarks:

connected to a seven stage cascade impactor

Type of distribution:

volumetric distribution

Specific details on test material used for the study:

Substance stability: Stable under normal conditions

Remarks on result:

other: p1: 9.2 %, MMAD1 = 4.70 µm, GSD1 = 2.28 / p2: 90.8 %, MMAD2 = 28.60 µm, GSD2 = 1.78

Remarks on result:

not measured/tested

Remarks on result:

not measured/tested

Dustiness (airborne fraction): total: 235.31 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: 9.2 %, MMAD1 = 4.7 µm, GSD1 = 2.28

p2: 90.8 %, MMAD2 = 28.6 µm, GSD2 = 1.78

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): 50.84 %

Tracheobronchial (TB): 0.30 %

Pulmonary (PU): 0.59 %

Conclusions:

Total Dustiness (airborne fraction): 235.31 mg/g (DMT)

Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction: MMAD1 = 4.7 µm (9.2 %), MMAD2 = 28.60 µm (90.8 %) (distribution fitted to cascade impactor data, percentile in parentheses indicates weighting factor).

Geometric standard deviation: GSD1 = 2.28, GSD2 = 1.78.

Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD):
Head (ET): 50.84 %
Tracheobronchial (TB): 0.30 %
Pulmonary (PU): 0.59 %

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-04-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

no detailed documentation of the test procedure

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions - Method A: Particle Size Distribution (effective hydrodynamic radius)

Deviations:

not specified

GLP compliance:

no

Type of method:

Laser scattering/diffraction

Type of distribution:

volumetric distribution

Remarks on result:

not measured/tested

Percentile:

D10

Mean:

4.524 µm

Remarks on result:

other: no St. dev. was stated

Percentile:

D50

Mean:

66.77 µm

Remarks on result:

other: no St. dev. was stated

Percentile:

D90

Mean:

228.3 µm

Remarks on result:

other: no St. dev. was stated

No.:

#1

Size:

4.524 µm

Distribution:

10 %

No.:

#2

Size:

18.08 µm

Distribution:

20 %

No.:

#3

Size:

31.97 µm

Distribution:

30 %

No.:

#4

Size:

48.07 µm

Distribution:

40 %

No.:

#5

Size:

66.77 µm

Distribution:

50 %

No.:

#6

Size:

92.16 µm

Distribution:

60 %

No.:

#7

Size:

129.5 µm

Distribution:

70 %

No.:

#8

Size:

174.4 µm

Distribution:

80 %

No.:

#9

Size:

228.3 µm

Distribution:

90 %

No.:

#10

Size:

271.3 µm

Distribution:

95 %

Conclusions:

The test item has following particle size distribution:
D10: 4.524 µm
D50: 66.77 µm
D90: 228.3 µm

Description of key information

As “physical” particle size distributions do not necessarily reflect the particle size of aerosols that may be formed under practically relevant workplace conditions (e.g., during manual operations, including bag filling and emptying, or under mechanical agitation during mixing and weighing), the particle size distribution of the airborne fraction generated during mechanical agitation in the rotating drum according to the method by Heubach was determined.

Based on MPPD modelling, the following conclusions can be drawn for potential risk characterisation purposes:

(i) aluminium vanadium tetraoxide has a limited deposition ability in the human respiratory tract: 51.73 % of airborne material is estimated to deposit. The rest of the airborne material is not inhaled due to physical phenomena related to air streams and turbulences close to the mouth or simply exhaled (i.e. not deposited).

(ii) about 0.59 % of the inhaled material are predicted to deposit in the pulmonary region (PU), whereas the material deposited in the tracheobronchial (TB = 0.30%) and the extrathoracic region (Head=50.84%) may be assumed to be cleared to the GI tract (i.e., by mucociliary escalation and subsequent swallowing).

Refinements of measured inhalation monitoring data for the tested substances would therefore be justified. The extent of such refinements does however depend on (i) the nature of the involved toxicological effects (e.g. systemic or local) and (ii) a further consideration of differences in species (e.g., toxicological testing in rats compared with measured human exposures, different lung parameters of the two species should be considered). Corrections for systemic bioavailability may be applied if toxicokinetic data are available that allow a definitive assessment of the degree of oral absorption for each compound.

DUSTINESS

- Total Dustiness (airborne fraction): 235.31 mg/g (DMT)

- Mass median aerodynamic diameters (bi-modal distribution) of airborne fraction:

MMAD1 = 4.7 µm (9.2 %),

MMAD2 = 28.60 µm (90.8 %) (distribution fitted to cascade impactor data, percentile indicates weighing factor).

- Geometric standard deviation: GSD1 = 2.28, GSD2 = 1.78.

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

- Head (ET): 50.84 %  

- Tracheobronchial (TB): 0.30 %

- Pulmonary (PU): 0.59 %

PSD

The test item has following particle size distribution:

D10: 4.524 µm

D50: 66.77 µm

D90: 228.3 µm