Written Medical Opinion For Employer (Page 5 of 8) in pdf

Federal Register/Vol. 81, No. 58/Friday, March 25, 2016/Rules and Regulations

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and because they are caused by substantial

overexposures to respirable crystalline silica.

Although any case of silicosis indicates a

breakdown in prevention, a case of acute or

accelerated silicosis implies current high

exposure and a very marked breakdown in

prevention.

In addition to silicosis, employees exposed

to respirable crystalline silica, especially

those with accelerated or acute silicosis, are

at increased risks of contracting active TB

and other infections (ATS

1997;

Rees and

Murray

2007).

Exposure to respirable

crystalline silica also increases an employee's

risk of developing lung cancer, and the

higher the cumulative exposure, the higher

the risk (Steenland et al.

2001;

Steenland and

Ward

2014).

Symptoms for these diseases

and other respirable crystalline silica-related

diseases are discussed below.

1.2.

Chronic Silicosis. Chronic silicosis is

the most common presentation of silicosis

and usually occurs after at least

years of

exposure to respirable crystalline silica. The

clinical presentation of chronic silicosis is:

1.2.1.

Symptoms-shortness of breath and

cough, although employees may not notice

any symptoms early in the disease.

Constitutional symptoms, such as fever, loss

of appetite and fatigue, may indicate other

diseases associated with silica exposure,

such as TB infection or lung cancer.

Employees with these symptoms should

immediately receive further evaluation and

treatment.

1.2.2.

Physical Examination-may be

normal or disclose dry rales or rhonchi on

lung auscultation.

1.2.3.

Spirometry-may be normal or may

show only a mild restrictive or obstructive

pattern.

1.2.4.

Chest X-ray-classic findings are

small, rounded opacities in the upper lung

fields bilaterally. However, small irregular

opacities and opacities in other lung areas

can also occur. Rarely, "eggshell

calcifications" in the hilar and mediastinal

lymph nodes are seen.

1.2.5.

Clinical Course-chronic silicosis in

most cases is a slowly progressive disease.

Under the respirable crystalline silica

standard, the PLHCP is to recommend that

employees with a

1/0

category X-ray be

referred to an American Board Certified

Specialist in Pulmonary Disease or

Occupational Medicine. The PLHCP and/or

Specialist should counsel employees

regarding work practices and personal habits

that could affect employees' respiratory

health.

1.3.

Accelerated Silicosis. Accelerated

silicosis generally occurs within

5-10

years

of exposure and results from high levels of

exposure to respirable crystalline silica. The

clinical presentation of accelerated silicosis

is:

1.3.1.

Symptoms-shortness of breath,

cough, and sometimes sputum production.

Employees with exposure to respirable

crystalline silica, and especially those with

accelerated silicosis, are at high risk for

activation of TB infections, atypical

mycobacterial infections, and fungal

superinfections. Constitutional symptoms,

such as fever, weight loss, hemoptysis

(coughing up blood), and fatigue may herald

one of these infections or the onset of lung

cancer.

1.3.2.

Physical Examination-rales,

rhonchi, or other abnormal lung findings in

relation to illnesses present. Clubbing of the

digits, signs of heart failure, and car

pulmonale may be present in severe lung

disease.

1.3.3.

Spirometry-restrictive or mixed

restrictive/obstructive pattern.

1.3.4.

Chest X-ray-small rounded and/or

irregular opacities bilaterally. Large opacities

and lung abscesses may indicate infections,

lung cancer, or progression to complicated

silicosis, also termed progressive massive

fibrosis.

1.3.5.

Clinical Course-accelerated silicosis

has a rapid, severe course. Under the

respirable crystalline silica standard, the

PLHCP can recommend referral to a Board

Certified Specialist in either Pulmonary

Disease or Occupational Medicine, as

deemed appropriate, and referral to a

Specialist is recommended whenever the

diagnosis of accelerated silicosis is being

considered.

1.4.

Acute Silicosis. Acute silicosis is a rare

disease caused by inhalation of extremely

high levels of respirable crystalline silica

particles. The pathology is similar to alveolar

proteinosis with lipoproteinaceous material

accumulating in the alveoli. Acute silicosis

develops rapidly, often, within a few months

to less than

years of exposure, and is almost

always fatal. The clinical presentation of

acute silicosis is as follows:

1.4.1.

Symptoms-sudden, progressive,

and severe shortness of breath. Constitutional

symptoms are frequently present and include

fever, weight loss, fatigue, productive cough,

hemoptysis (coughing up blood), and

pleuritic chest pain.

1.4.2.

Physical Examination-dyspnea at

rest, cyanosis, decreased breath sounds,

inspiratory rales, clubbing of the digits, and

fever.

1.4.3.

Spirometry-restrictive or mixed

restrictive/obstructive pattern.

1.4.4.

Chest X-ray-diffuse haziness of the

lungs bilaterally early in the disease. As the

disease progresses, the "ground glass"

appearance of interstitial fibrosis will appear.

1.4.5.

Clinical Course-employees with

acute silicosis are at especially high risk of

TB activation, nontuberculous mycobacterial

infections, and fungal superinfections. Acute

silicosis is immediately life-threatening. The

employee should be urgently referred to a

Board Certified Specialist in Pulmonary

Disease or Occupational Medicine for

evaluation and treatment. Although any case

of silicosis indicates a breakdown in

prevention, a case of acute or accelerated

silicosis implies a profoundly high level of

silica exposure and may mean that other

employees are currently exposed to

dangerous levels of silica.

1.5.

COPD. COPD, including chronic

bronchitis and emphysema, has been

documented in silica-exposed employees,

including those who do not develop silicosis.

Periodic spirometry tests are performed to

evaluate each employee for progressive

changes consistent with the development of

COPD. In addition to evaluating spirometry

results of individual employees over time,

PLHCPs may want to be aware of general

trends in spirometry results for groups of

employees from the same workplace to

identify possible problems that might exist at

that workplace. (See Section 2 of this

Appendix on Medical Surveillance for

further discussion.) Heart disease may

develop secondary to lung diseases such as

COPD. A recent study by Liu et al.

2014

noted a significant exposure-response trend

between cumulative silica exposure and

heart disease deaths, primarily due to

pulmonary heart disease, such as car

pulmonale.

1.6. Renal and Immune System. Silica

exposure has been associated with several

types of kidney disease, including

glomerulonephritis, nephrotic syndrome, and

end stage renal disease requiring dialysis.

Silica exposure has also been associated with

other autoimmune conditions, including

progressive systemic sclerosis, systemic

lupus erythematosus, and rheumatoid

arthritis. Studies note an association between

employees with silicosis and serologic

markers for autoimmune diseases, including

antinuclear antibodies, rheumatoid factor,

and immune complexes Ualloul and Banks

2007;

Shtraichman et al.

2015).

1.7. TB

and Other Infections. Silica-

exposed employees with latent TB are

times more likely to develop active

pulmonary TB infection (ATS

1997;

Rees and

Murray

2007).

Although respirable

crystalline silica exposure does not cause TB

infection, individuals with latent TB

infection are at increased risk for activation

of disease if they have higher levels of

respirable crystalline silica exposure, greater

profusion of radiographic abnormalities, or a

diagnosis of silicosis. Demographic

characteristics, such as immigration from

some countries, are associated with increased

rates of latent TB infection. PLHCPs can

review the latest Centers for Disease Control

and Prevention (CDC) information on TB

incidence rates and high risk populations

online (See Section

of this Appendix).

Additionally, silica-exposed employees are at

increased risk for contracting nontuberculous

mycobacterial infections, including

Mycobacterium avium-intracellulare and

Mycobacterium kansaii.

1.8.

Lung Cancer. The National Toxicology

Program has listed respirable crystalline

silica as a known human carcinogen since

2000

(NTP

2014).

The International Agency

for Research on Cancer

(2012)

has also

classified silica as Group

(carcinogenic to

humans). Several studies have indicated that

the risk of lung cancer from exposure to

respirable crystalline silica and smoking is

greater than additive (Brown

2009;

Liu et al.

2013).

Employees should be counseled on

smoking cessation.

2. Medical Surveillance

PLHCPs who manage silica medical

surveillance programs should have a

thorough understanding of the many silica-

related diseases and health effects outlined in

Section

of this Appendix. At each clinical

encounter, the PLHCP should consider silica-

related health outcomes, with particular

vigilance for acute and accelerated silicosis.

In this Section, the required components of

Written Medical Opinion For Employer Page 5

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