Respiratory

Question 1

Particle size and deposition

Answer 1

5-30 um - nasopharyngeal region (intertial impaction)

1-5 um - trachea, bronchial, bronchiolar (sedimentation)

1 um - alveolar region (diffusion)

Question 2

interception

Answer 2

trajectory brings particle close to airway surface

interception is dependent on fiber length.

Klaassen, Curtis D.; Watkins, John B.. Casarett & Doull’s Essentials of Toxicology, Third Edition (Lange) . McGraw-Hill Education. Kindle Edition.

Question 3

impaction

Answer 3

inertia, particle continues along original path

Question 4

sedimentation

Answer 4

smaller airways and deep lung

due to gravitational settling

more important for larger sizes

Question 5

diffusion

Answer 5

more important for smaller sizes (submicrometer particles)

Question 6

Asbestos and role of size

Answer 6

2 um - asbestosis (alveolar wall fibrosis)
5 um - mesothelioma
10 um - lung cancer

Question 7

Beryllium

Answer 7

Industry - acute and chronic lung disease

acute - pneumonitis
chronic - immune-mediated granulomatous lung disease; resembles sarcoidosis; found with lower solubility forms
lung cancer - group 1 IARC

Question 8

Ozone

Answer 8

reacts with surfactant - secondary oxidants

Question 9

Metal fume fever

Answer 9

welders of galvanized steel

acute self-limiting flulike illness

most common cause of MFF is the inhalation of zinc oxide (ZnO)

Question 10

Gas solubility and location of toxicity

Answer 10

Highly soluble gases such as SO2 or formaldehyde do not penetrate farther than the nose (during nasal breathing) unless doses are very high, and are therefore relatively nontoxic to the lung of rats (which are obligatory nasal breathers). However, formaldehyde causes cancer in the rat nasal passages (Albert et al., 1982).

Relatively insoluble gases such as ozone and NO2 penetrate deeply into the lung

Very insoluble gases such as CO and H2S efficiently pass through the respiratory tract and are taken up by the pulmonary blood supply to be distributed throughout the body.

Klaassen, Curtis D.. Casarett & Doull’s Toxicology: The Basic Science of Poisons, 9th Edition (p. 803). McGraw-Hill Education. Kindle Edition.

Question 11

Silicosis

Answer 11

Acute silicosis occurs only in subjects exposed to a very high levels of silica, small enough to be respirable (usually <5 μm) over a relatively short period, generally a few months or years. dyspnea, fever, cough, and weight loss that can rapidly progress to respiratory failure, usually ending in death within two years. No known therapeutic strategy

Chronic silicosis has a long latency period, usually >10 years and can be divided into simple and complicated silicosis. simple silicosis may be asymptomatic (i.e., no dyspnea) with little change in pulmonary function - fibrotic nodules. complicated silicosis, which is defined as the presence of conglomerate nodules larger than 1 cm in diameter.

Klaassen, Curtis D.. Casarett & Doull’s Toxicology: The Basic Science of Poisons, 9th Edition (p. 825). McGraw-Hill Education. Kindle Edition.