Encyclopedia of Health and Medicine

S
silicosis An obstructive condition of the LUNGS
that develops with repeated and usually long-term
exposure to crystalline silica (silica dust). Silicosis
is a disease of occupational exposure. The silica
dust causes irritation and INFLAMMATION of the airways
and lung tissue. SCAR tissue forms when the
inflammation heals, resulting in fibrosis that gradually
overtakes healthy lung tissue. The fibrosis
continues extending through the lungs even after
exposure ends.
Health experts identify three forms of silicosis:
• chronic silicosis, the most common form,
results from long-term exposure (10 to 20 years
or longer) and generally is present as a disease
entity in the lungs for 5 to 10 years before
symptoms lead to its diagnosis
• accelerated silicosis, which shows rapidly progressive
symptoms after 5 to 10 years of exposure
• acute silicosis, which occurs with exposure to
high concentrations of silica dust and shows
symptoms within weeks to months of exposure
A secondary complication, progressive massive
fibrosis, may occur with accelerated or chronic silicosis.
In progressive massive fibrosis the scarring
is severe and results in extensive destruction of
lung tissue and loss of lung function.
The US Occupational Safety and Health Administration
(OSHA) began regulating silica exposure
in the 1990s and currently monitors silica levels as
well as cases of silicosis. Employees who work in
occupations with silica exposure should wear
appropriate protective equipment including filtered
respirators to limit as much as possible the
amount of silica dust they breathe. About 200
people die each year in the United States as a consequence
of silicosis.
Symptoms and Diagnostic Path
The primary symptoms of silicosis are chronic
COUGH and DYSPNEA (shortness of breath) that
worsens with exertion. People who have acute silicosis
may also have FEVER and experience rapid,
unintended weight loss. The diagnostic path
includes chest X-RAY, imaging procedures such as
COMPUTED TOMOGRAPHY (CT) SCAN, and pulmonary
function tests. Characteristic findings with these
diagnostic procedures in combination with a history
of silica exposure allow the doctor to make a
conclusive diagnosis.
People who have silicosis have high risk for
developing TUBERCULOSIS, and many have latent
(asymptomatic) tuberculosis when tested at the
time of the silicosis diagnosis. Health experts recommend
routine testing for tuberculosis as part of
the diagnostic process for silicosis.
Treatment Options and Outlook
Treatment can only help manage symptoms such
as cough. There are no specific treatments for the
silicosis, and there is no known method of intervention
to prevent the condition’s progression. It
is crucial to end the silica exposure to end further
damage to the lungs, and for those who smoke
cigarettes to stop. Treatment may also be necessary
for tuberculosis in people who test positive,
even if there are no symptoms of the INFECTION.
The course of progression often extends over
decades, though does result in persistent decline
of pulmonary function. Prevention remains the
most effective therapeutic approach.
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