New
Jersey Department of Health and Senior Services
Division of Environmental and Occupational Health
This document should be filed in the medical records
of:
Patient's name and social security number_________________________________________
Patient's occupation and union affiliation _________________________________________
Construction,
Demolition, and Renovation Workers Are At Risk of Developing Silicosis
Crystalline silica is found in materials, such as those listed in
the box to the right, which are often present during construction,
demolition, and renovation projects. When these materials are made
into a fine dust by tasks such as those listed in the box on page
2, the inhalation and deposition of these fine particles can produce
silicosis over time.
Silica dust exposure to construction worker sawing
masonry brick without dust control or a respirator.
Construction
Materials Containing Crystalline Silica
- Many
abrasives used for blasting
- Brick,
refractory brick
- Concrete,
concrete block, cement, mortar
- Granite,
sandstone, quartzite, slate
- Gunite
- Mineral
deposits
- Rock
and stone
- Sand,
fill dirt, top soil
- Asphalt
containing rock or stone
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Tasks
Associated With Silica Exposure
- Abrasive
blasting using sand or other abrasive containing crystalline
silica
- Abrasive
blasting of concrete
- Demolition
of concrete and masonry structures
- Chipping,
cutting, sawing, grinding, drilling, jack hammering concrete,
masonry, or mortar
- Crushing,
loading, hauling, dumping rock, stone, sand
- Gunite
spraying
- Chipping,
hammering, drilling rock
- Dry
sweeping or pressurized air blowing of concrete, rock, or
sand dust
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Many construction, demolition, and renovation occupations are at risk,
including:
- abrasive
blasters
- masonry
workers -- bricklayers, stone masons
- laborers
- operating
engineers
- painters
and plasterers
- plumbers
- truck drivers
Other occupations
that do not work directly with construction materials or tasks involving
silica may be exposed as bystanders if they are in the construction,
demolition, or renovation area when crystalline silica containing
materials are being used.
Construction worker exposure to silica dust while drilling
concrete pavement during interstate highway repair.
Definition and Clinical Features
Silicosis is a diffuse, nodular, interstitial pulmonary fibrosis caused
by a tissue reaction to inhaled crystalline silica dust. It can take
the acute form under conditions of intense exposure but usually
takes the chronic form, requiring several to many years to
develop. People who have silicosis have increased susceptibility to
infections such as tuberculosis, complicating the patient's prognosis.
There is also increasing evidence that crystalline silica causes cancer
and that individuals with silicosis are at increased risk of developing
lung cancer.
Except in its acute form, silicosis begins with few, if any, symptoms.
When clinical symptoms of silicosis are present, they could include
cough and shortness of breath of increasing severity. On physical
examination, breath sounds may be normal or distant and, with increased
severity, there may be signs of right heart failure. Evidence of pathological
response to silica exposure exists well before symptoms occur.
Chronic reactions, occurring after 10 or more years from first
exposure, involve nodular lesions, (bilateral, multiple, rounded opacities)
often more prominent in the upper lobes. In this simple
stage of silicosis, nodules are usually small (1 cm or less). There
may be little effect on pulmonary function at this stage.
Complicated silicosis or progressive massive fibrosis
(PMF) also usually develops in the upper lobes but the nodules go
on to consolidate and exceed 1 cm and encompass blood vessels and
airways. Lung function may be severely compromised, often with a mixed
restrictive/obstructive pattern, but either pure restriction or obstruction
may be seen.
Acute reactions may appear within a few weeks to two years
after the onset of massive exposure. The distinguishing feature of
acute silicosis is intraalveolar deposits, similar to those seen with
alveolar proteinosis. In contrast to the nodular fibrosis seen in
the chronic form, diffuse interstitial fibrosis is not found. Silicosis
developing in less than 10 years, the accelerated form, has
been described most often in sandblasters. In these cases, diffuse
fibrosis is likely to develop and may be located throughout all lobes
of the lung.
Progression of disease and radiographic findings can continue
even after exposure has ended.
Clinical
Signs of Silicosis
Simple
- mild
restrictive and/or obstructive defects
- small,
rounded opacities on x-ray
Accelerated
- diffuse,
small rounded opacities on x-ray
- more
severe restrictive and/or obstructive defects
Advanced
- increased
profusion of small opacities and development of large opacities
on x-ray
- more
severe restrictive and/or obstructive defects
- cor
pulmonale
Acute
- diffuse
perihilar alveolar filling process with ground glass opacities
on x-ray
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Recommended Medical Surveillance
The following are recommended by the New Jersey Department of Health
and Senior Services as a baseline before exposure, then periodically
as noted:
1. Occupational history to determine years of exposure -- update
annually. Inquire about the materials used and tasks performed listed
in the boxes on pages 1 and 2. In addition, inquire about employment
in nonconstruction industries with silica exposure -- foundries, quarries,
mining, tile, clay, pottery, glass, and cement manufacture.
2. Medical exam emphasizing the respiratory system -- annually.
3. Chest x-ray to look for evidence of abnormality. Posteroanterior
14" x 17" or 14" x 14", classified according to
the 1980 Guidelines for the Use of ILO International Classification
of Radiographs of Pneumoconiosis by a certified class .B. reader,
is recommended. The ILO system has the distinct advantage of a standardized
set of comparison x-ray films. Names of B-readers are available from
NIOSH. Information on how to contact NIOSH is given at the bottom
of the last page. The above box gives recommendations for the frequency
of x-rays. NOTE the potential for excessive x-rays given the multiemployer
nature of construction and other possible construction exposures like
asbestos for which OSHA may require employers to provide x-rays.
4. Pulmonary Function Tests (PFT) to look for evidence of respiratory
impairment. Should include FEV1 (forced expiratory volume in 1 second),
FVC (forced vital capacity), and DLCO (diffusion capacity of the lungs)
-- annually. All PFT should use equipment and follow recommendations
issued by the ATS (American Thoracic Society) and be administered
by a technician who has successfully completed NIOSH-certified training.
5. A baseline PPD skin test for tuberculosis because people
who have silicosis have increased susceptibility. Repeat annually
if there is x-ray evidence of silicosis (1/0 or greater profusion
category using the ILO classification) or 25 years or longer exposure.
Frequency
of Chest X-rays for Silicosis
- Every
3-5 years with normal x-ray, low exposure, and less than
20 years exposure.
- Every
1-3 years with normal x-ray, high exposure, or greater than
20 years exposure.
- Annually
with x-ray evidence of silicosis (ILO 1/0 or greater or
ILO results A, B, or C large opacities), massive exposure,
or positive PPD test.
- See
NOTE in item 3.
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Reporting Guidelines
Physicians, radiologists, pathologists and other health care professionals
should report cases of silicosis to the health department in their
state so that it can be determined whether silica exposures are being
controlled at the workplaces where the patient has been employed.
Such reporting is mandatory in many states, including New Jersey.
(In NJ, call 800-772-0062 to report cases or for reporting forms.)
If the state has no occupational health program, cases of concern
should be discussed with NIOSH (National Institute for Occupational
Safety and Health) or the local OSHA (Occupational Safety and Health
Administration) office. Information on how to contact NIOSH and OSHA
is given at the end of this bulletin.
The following elements define a case of silicosis for reporting
purposes:
- A physician.s
provisional or working diagnosis of silicosis, OR
- Chest x-ray
or other imaging technique interpreted as consistent with silicosis,
OR
- Pathologic
findings consistent with silicosis.
Because
silicosis is sometimes confused with sarcoidosis, asbestosis, coal
miner's pneumoconiosis, or other pneumoconiosis it is important that
all chest x-rays be reviewed by a B-reader.
Medical Management of Silicosis
There is no known medical treatment to reverse silicosis, therefore
prevention is critically important. Removal from exposure may decrease
the rate of disease progression. Corticosteroids are not useful to
reduce the progression of the disease. Appropriate treatment for heart
failure and tuberculosis should be begun if these complications exist.
All individuals should be strongly advised to stop smoking and offered
smoking cessation information and support. Regular follow-up exams
to assess progression and possibly to screen for lung cancer should
be scheduled. Individuals who develop silicosis should be given the
option of transfer to silica-free jobs. In order for this to be a
realistic alternative, the individual should be able to maintain the
same rate of pay and benefits without loss of seniority.
For Additional Information
NIOSH: e-mail -- pubstaft@niosdt1.em.cdc.gov
1-800-35-NIOSH (1-800-356-4674) or 513-533-8328, fax 513-533-8573,
Internet site -- http://www.cdc.gov/niosh/topics/silica/
- CDC/NIOSH
Alert, Request for Assistance in Preventing Silicosis and Deaths
in Construction Workers, DHHS (NIOSH) Publication No. 96-112,
May 1996. Contains details on case definition, case reports, control
measures, and 26 references.
- Lists of
certified B-readers by state, approved pulmonary function technician
courses, state health department contacts for reporting purposes.
OSHA: Local
offices are listed in the government section of the telephone directory,
usually under United States Department of Labor or the state Department
of Labor. Internet site -- http://www.osha.gov
has a directory of all offices. Or, call the national office for the
number of your local office: 202-219-8151.
ATS (American Thoracic Society): Adverse Effects of Crystalline
Silica Exposure. American Journal Respiratory and Critical Care
Medicine, 1997; 155:761-765. Standardization of Spirometry - 1994
update. American Journal Respiratory and Critical Care Medicine,
1995; 152: 1107-1136.
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