occupational health - silicosis

7/29/2019 occupational health - silicosis

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Silicosis

Co, Eunice Victoria M. Co, Gregory Allan C.


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Sources and Exposure

Silica common, naturally-

occurring crystal

rock beds

main part of sand

forms dust during mining,quarrying, tunneling, andworking with many metalores

mines, quarries,foundries, and

construction sites, in themanufacture of glass,ceramics, and abrasivepowders, and in masonryworkshops


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Occupations at Risk


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Cases of Silicosis

mining establishment

of Delamar, Nevada

ruined by a dry-

mining process thatproduced a silicosis-

causing dust

the town was

nicknamed The

Widowmaker


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Cases of Silicosis

certain villages in

Northern Thailand

were called "villages

of widows" large number of

pestle-and-mortar-

making workers who

died early fromsilicosis


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Silicosis

potters disease, sand cuttersdisease or grinders rot.

one of the oldest occupationaldiseases

incurable lung disease

disease progresses even whenexposure stops

caused by inhalation of dustcrystalline

silica dust (SiO2)

quartz cristobalite

tridymite


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Formation of Silicosis

Composition Free silica

Higher percentage increased risk

Concentration

5 million particles per cubic foot (mppcf)

Particle size Respirable size reach alveoli: 1-3 microns or less

Time of exposure (duration)

6-7 years of contact Susceptibility of individual

Previous/concurrent lung infection

Age, smoking history


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Phagocytosis Theory

macrophages ingestthe dust particles

tumor necrosisfactors, interleukin-1,

leukotriene B4 andother cytokines

fibroblasts proliferateand produce collagen

around the silicaparticle

fibrosis and theformation of thenodular lesions


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Mechanical Theory

Insoluble

Sharp edged

Tissue irritation


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Chemical Theory

Silanol (SiOH)groups on surface ofparticles may reactwith cell membranes

Negative surfacecharge on SiO-groups may underliedirect toxicity

React with tissue andproduce Salicylic acid
http://upload.wikimedia.org/wikipedia/commons/4/4b/Silica.svg


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Colloidal Reaction Theory

Piezo Electric Theory

Electric discharge emitted when pressure is

applied to one end of crystal


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Immunologic Theory

Silicotics

High gamma globulin

Hyaline matter of

silicotic nodules Beta and gamma

globulin
http://www.osha.gov/SLTC/etools/silica/silicosis/silicosis.html


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Gross Pathology

Fibrotic chages

Milliary nodulations

Silicotic lung

Normal lung


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X-ray

normal x-ray silicosis (upper lobes) silicosis -- diffuse
http://images.google.com/imgres?imgurl=http://a248.e.akamai.net/7/248/430/20040913134745/www.merck.com/mrkshared/mmanual/plates/p75_3.jpg&imgrefurl=http://www.merck.com/mrkshared/mmanual/plates/75pla3.jsp&h=437&w=500&sz=63&tbnid=xj5yAJK0ZvIJ:&tbnh=110&tbnw=127&hl=en&start=13&prev=/images%3Fq%3Dsilicosis%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DNhttp://images.google.com/imgres?imgurl=http://www4.umdnj.edu/cswaweb/rad_teach/images/silic_10.jpg&imgrefurl=http://www4.umdnj.edu/cswaweb/rad_teach/silicosis.html&h=699&w=600&sz=347&tbnid=hddVe1MpbdoJ:&tbnh=138&tbnw=118&hl=en&start=18&prev=/images%3Fq%3Dsilicosis%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DNhttp://images.google.com/imgres?imgurl=http://a248.e.akamai.net/7/248/430/20040913134745/www.merck.com/mrkshared/mmanual/plates/p75_3.jpg&imgrefurl=http://www.merck.com/mrkshared/mmanual/plates/75pla3.jsp&h=437&w=500&sz=63&tbnid=xj5yAJK0ZvIJ:&tbnh=110&tbnw=127&hl=en&start=13&prev=/images%3Fq%3Dsilicosis%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DNhttp://images.google.com/imgres?imgurl=http://a248.e.akamai.net/7/248/430/20040913134745/www.merck.com/mrkshared/mmanual/plates/p75_3.jpg&imgrefurl=http://www.merck.com/mrkshared/mmanual/plates/75pla3.jsp&h=437&w=500&sz=63&tbnid=xj5yAJK0ZvIJ:&tbnh=110&tbnw=127&hl=en&start=13&prev=/images%3Fq%3Dsilicosis%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DN


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Histopathology

Fibrotic nodues

Concentric onion-skin arrangement of collagen fibers Central hyalinization

Cellular peripheral zone

Acute: PAS(+) alveolar exudate (alveolar

lipoproteinosis), cellular infiltrate of alveolar walls


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Occupational Safety and Health Adm inistrat ionis the mainfederal agency charged with the enforcement of safety andhealth legislation for the US Dept. of Labor

The permissible exposure limits refer to a time-weightedaverage (TWA) which shall not be exceeded for an 8-hourworkday within a 40-hour workweek.

OSHA class i f ies s i l ica glass dus t as a " nuisance dus t"w ith a TWA fo r total dust o f 15 mg/m3 and respirablefract ion o f 5mg/m3

The OSHA TWA for 100% sil ica quartz is 0.3mg /m3 total

dust and 0.1mg /m3 resp irable fract ion.

Concentration of coal mines respirable dust (avg of 4.9mg/m3)

General Occupational Health Standards, Volume I, State of Washington, Department of Labor and Industries.National Safety Council, Fundamentals of Industrial Hygiene, Second Edition. Chapter 7 , Particulates, pp 171-200. Chicago, Ill, 1979.


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Clinical Presentation: Signs and

Symptoms

Primary complaints:

Chronic dry cough

SOB w/ exercise

Chest tightness Insomnia, pleural pain and hemoptysis

Possible complications:

risk for TB

Progressive massive fibrosis


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Types of Silicosis

Asymp tomat ic s i l icos is Early cases of the disease do not present any symptoms

Chronic si l ico sis

after 1520 years of exposure to moderate to low levels of silicadust.

Patients with this type of silicosis may not have obvioussymptoms

SOB following physical exertion

Severe dry cough

fatigue loss of appetite

chest pains

fever

chest X-ray is necessary to determine if there is lung damage.

http://www.cdc.gov/niosh/silfact1.html


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Accelerated si l icosis

Silicosis that develops 510 years afterhigh exposure

to silica dust. Symptoms include severe shortness of

breath, weakness, and weight loss.

Acute s i l icos is

develops a few months to 2 years after exposure to

very high concentrations of silica dust. severe disabling SOB, pleuritic pain, weakness, and

weight loss, often leading to death.

http://www.cdc.gov/niosh/silfact1.html


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Diagnosis and TestsHistory

Jobs, hobbies, other activities - Exposure to silicadust

Physical Exam

chest expansion breath sounds

Request for:

1. Chest x-ray2. Pulmonary Function Tests (PFT)

3. PPD

http://www.who.int/mediacentre/factsheets/fs238/en/


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Chest X-Ray

Chest X-Ray Differential Diagnosis

Miliary TB

Histoplasmosis

Byssinosis

Bagassosis

Ground glass appearance- frank mottling Bilateral changes


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Chest X-Ray

Stages of disease by x-

ray:

1st Stage discrete

nodular circular shadows; 2mm diameter (present as

emphysema)

2nd Stage nodular

shadows in the whole lung;

some coalesce to form

higher opacities

3rd Stage massive

consolidation

http://emedicine.medscape.com/article/302027-overview


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PFT / PPD

Pulmonary Function Test- Spirometry

lung capacity

Prolonged expiratory phase

PPD

Screening for TB


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Prognosis

Incurable

Develop TB

Heart failure due to increased workload of the

heart to the lungs

Depend on the amount of damage to the

lungs


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Treatment

Silicosis is an irreversible condition with no

cure.

Treatment focus:

Maintain patient comfort

Slow the progression of silicosis


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Treatment

1. Stop further exposure

2. Stop smoking

3. Antibiotics and anti-TB drugs infections4. Cough suppressants

5. Chest physiotherapy

6. Oxygen administration7. Bronchodilators

Breathe easier

http://www.osha.gov/Publications/silicosis.pdf


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Prevention

Identify source

Use local exhaust ventilations

Water spray is often used where dust emanates

Control dust through dry air filtering

Do not eat, drink or smoke near crystalline silica dust.

Wash hands and face before eating, drinking or smokingaway from exposure area.

Use respiration equipment and protective clothing

Undergo medical examination

http://www.osha.gov/Publications/silicosis.pdf


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Extra slides


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Pathology

Fibrotic nodules are most common

usually less than 1 cm. in diameter

Spherical

hard and gray to black. On histologic examination:

Whorled appearance with concentrically arranged

collagen

On the periphery: aggregates of mononuclear cells: Lymphocytes

Fibroblasts


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Pathology

Progressive massive fibrosis Morphological

Central cavitation: related to amount of silica

Disability due to amt of destruction of tissue Radiological

Noduclar masses >2cm in diameter in a

background of silmple silicosis

Larger lesions: coalesce of smaller nodules Nodules: 5-10 cm in diameter

In the upper zones of the lungs= bilateral


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Pathology

Alveolar proteinosisHeavy exposure to finely particulate silica: sand

blasting, boiler scaling

Associated with diffuse fibrosis of the lung

Silicotic nodules not found

Dense eosinophilic material accumulate in alveolar

spaces = produce an appearance that resembles

alveolar lipoproteinsRadiology:

Linear fibrosis and reduced lung volume

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