m-toluic acid

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

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)

Version / remarks:

2006

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 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:

no

Type of method:

rotating drum method

Remarks:

connected to a seven stage cascade impactor

Type of distribution:

volumetric distribution

Remarks on result:

other: p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49; p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

Remarks on result:

not measured/tested

Remarks on result:

not measured/tested

Dustiness (airborne fraction):      total: 47.82 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 bimodal lognormal distribution to the data by standard non-linear regression procedure. The weighting factors p, theMMADsand GSDs were calculated as follows:      

p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49;

p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

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): 43.32 %

Tracheobronchial (TB): 0.07 %

Pulmonary (PU): 0.11 %

Conclusions:

Dustiness (airborne fraction):      total: 47.82 mg/g.

- p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49;
- p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

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

Head (ET): 43.32 %
Tracheobronchial (TB): 0.07 %
Pulmonary (PU): 0.11 %

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-06-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

not performed according to GLP

Qualifier:

according to guideline

Guideline:

ISO 13320 (Particle size analysis - Laser diffraction methods)

Deviations:

no

GLP compliance:

no

Type of method:

Laser scattering/diffraction

Type of distribution:

volumetric distribution

Remarks on result:

not measured/tested

Key result

Percentile:

D50

Mean:

118 µm

Remarks on result:

other: no data for St. dev.

Key result

Percentile:

D90

Mean:

581 µm

Remarks on result:

other: no data for St. dev.

Conclusions:

D50 = 118µm
D90 = 581µm

Description of key information

The particle size distribution:

D50 = 118 µm

D90 = 581 µm

Dustiness: 

- total dustiness: 47.82 mg/g.

Mass median aerodynamic diameter:

- p1 (82.73 %): MMAD1 = 29.14 µm, GSD1 = 1.49;

- p2 (17.27 %): MMAD2 = 100 µm, GSD2 = 6.38

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

Head (ET): 43.32 %

Tracheobronchial (TB): 0.07 %

Pulmonary (PU): 0.11 %