This document discusses silicosis, a lung disease caused by inhalation of crystalline silica dust. It provides background on OSHA's silica emphasis program and why silica exposures need to be targeted. A key case study describes the silicosis deaths of 500-750 workers during tunnel construction in the 1930s. The document outlines the health effects of silicosis and means of diagnosis. It emphasizes that silicosis is non-curable and prevention through controlling dust exposures is critical. Components of an effective silicosis prevention program are identified.

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Silicosis Prevention
By
Drx.Jayesh rajput

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Silica
Special Emphasis Program
 Began in 1997
 Part of OSHA current Strategic Plan
(through 2008)
 Compliance Enforcement
 Consultation
 Training and Outreach
– OSHA Web-site
 Standard Development and Stakeholders
Meetings Currently in Progress

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Why Target Crystalline Silica
Exposure?
1. Toxicity is well documented
2. Widespread worker overexposure
3. Exposures can be controlled

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Case Study, 1930’s: Hawk’s
Nest Tunnel
 Gauley Mt., W. VA.
 1930 – 1935
 Estimated Deaths
from Silicosis:
– 500 to 750

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Progress made: Exposures
in the 21st Century

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What is Silica?
Composes 15% of Earth’s Crust
1. Crystalline Silica (regulated)
– has a diagnostic X-ray diffraction
pattern
2. Amorphous Silica (not regulated)
– “without form”
– cannot distinguish by X-ray diffraction
– Glass is common example

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Crystalline Silica
Examples:
– Sand, Granite, other “Hard” rocks
Quartz, most common
Cristobalite, Tridymite
Much less common, but more toxic than
quartz

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Potential Silica
Exposures
 Foundries
 Ceramics Industry
 Abrasive Blasting
 Construction
 Manufacturing of
cleaning agents
 Mining Operations
 Use of Coal (e.g.,
electric power
generation)

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Silica and Mortality
 250 Worker deaths per year from Silica
– (Compare to 175 deaths/yr from trenching accidents)
 Silicosis
 Tuberculosis
 Heart Disease
 Lung Cancer?
– Suspect Hum. Carcinogen –A2 (ACGIH)

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Health Effects
Chronic-Obstructive Pulmonary
(Lung) Disease--COPD
Affects Aveolar Surface
–Decreases Elasticity
–Prevents Oxygen/CO2 Exchange

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Silicosis Diagnosis
Requires Chest X-ray
X-ray must be read by qualified “B-
Reader”
Silica Nodules are Non-Reversible

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Disease Classes of Silicosis
1. Acute Silicosis (Highest Exp.)
– Latency of weeks to 5 years
2. Accelerated Silicosis (High Exp.)
– Latency of 5 to 15 years
3. Chronic Silicosis (Moderate Exp.)
– Latency >15 years

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Silicosis:
Non-Curable Disease
Prevention through Safe
Workpractice is critical

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Silicosis Prevention Program
Engineering Control of Dust
Training on crystalline silica
Respiratory protection program
Work clothes, change and wash area

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Silicosis Prevention Program
Air monitoring program
Medical surveillance
Housekeeping and Regulated Areas
Recordkeeping

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