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Particle size distribution (Granulometry)

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Inhalable fraction

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Granulometry is of considerable importance for the toxic properties of a substance as it influences aspects such as the route of exposure of humans and toxicity by inhalation; the choice of route of administration for animal testing; the efficiency of uptake in an organism and the distribution in the environment.

For this purpose fractions can be divided in:

Inhalable fraction(the mass fraction of particles that can be inhaled by nose and mouth. Particles >100 μm are not included in the inhalable convention;

Thoracic fraction(the mass fraction of the inhaled particles that passes the larynx). The convention for thoracic fraction sets that 50% of the particles in air with an aerodynamic diameter of 10 μm belong to the thoracic fraction;

Respirable fraction(the mass fraction of the inhaled particles that reaches the alveoli) The convention for respirable fraction sets that 50% of particles with an aerodynamic diameter of 4 μm belong to the respirable fraction.

 

The tested substance presented a granulometry of 17.533 µm (D50 after 2 minutes of ultrasonic treatement) that can be considered as inhalable