Silicosis Treatment & Management

Updated: Dec 05, 2019
  • Author: Bathmapriya Balakrishnan, MBBS, BMedSc(Melb); Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Treatment

Approach Considerations

Consulting a pulmonologist is appropriate for the evaluation of lung nodules, assessment of pulmonary function, and evaluation of disability, as well as treatment of mycobacterial disease and complications of advanced silicosis.

Treatment for silicosis-associated conditions (eg, mycobacterial infection, chronic obstructive pulmonary disease, lung cancer, autoimmune disorders, and chronic kidney disease) are principally similar to that of patients without silicosis. Please review resources pertinent to each condition.

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Medical Care

Treatment strategies targeting the inflammatory pathway of silicosis have been investigated, however, consistently effective therapies yet to be developed, [5, 9]  and no cure currently exists. [1, 3]

Whole-lung lavage has previously been used for silicoproteinosis. Although the presence of dust particles, macrophages, and cytokines on bronchoalveolar lavage analyses decrease with whole-lung lavage, long-term outcomes, including mortality and pulmonary function parameters, have not demonstrated sustained improvement. [48]

Immunosuppressive therapies have yielded varying results. A study using corticosteroids reported a 300-mL improvement in forced vital capacity (FVC); however, there was no sustained improvement or reduction in mortality. [49]  Improvement in symptoms of dyspnea and cough also occurred, although the benefits were related to longer duration of silica exposure. [49]  Animal model studies using Infliximab have shown a reduction in inflammation and fibrosis histopathologically; however, these findings have yet to be translated into human studies. [50]

Inhaled aluminum citrate powder, which theoretically coats silica particles to reduce its solubility, have been studied. Controlled studies demonstrated symptomatic improvement; however, there was no change in lung function or mortality. [51]  Harmful side effects associated with aluminum powder use potentially outweight the benefits of treatment. 

Polyvinylpyridine-N-oxide (PVPNO) has been shown to decrease the potential for silica toxicity in animal models. It coats the surface of silica particles and decreases their potential for generating reactive oxygen species, thus limiting DNA damage. [52]  However, use of PVPNO is limited by liver and renal toxicity demonstrated in animal studies.

Nintedanib, an antifibrotic therapy used in idiopathic pulmonary fibrosis (IPF), have been studied in animal models, but it has yet to be studied in human trials. [53]  The Nintedanib in Progressive Pneumoconiosis Study (NiPPS), a prospective clinical pilot study evaluating occupational progressive pneumoconiosis (silicosis, coal pneumoconiosis, and asbestosis) with nintedanib 150 mg twice daily for 3 years, has not yet begun recruiting but has an expected start date of February 2020.

Cell-based therapy, including bone marrow-derived mononuclear cells [54] and mesenchymal cell transplantation, [55]  are currently undergoing trials in humans.

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Surgical Care

Lung transplantation remains the only treatment option for end-stage silicosis. However, based on available data, patients with silicosis who underwent lung transplantation (4.9%) showed a nonstatistically significant survival advantage (hazard ratio: 0.6) compared to those undergoing lthe procedure for idiopathic pulmonary fibrosis (IPF). [56]

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Prevention

Primary prevention of silicosis through exposure control is important, because no effective medical treatment exists for this disease, which continues to progress even after a person is removed from further exposure. To achieve this, a sustained effort must be made to increase awareness of silicosis. Deaths from silicosis in younger subjects in the United States have been reported after exposure in the construction and manufacturing sectors, with none from mining. [57] Deaths of young people sandblasting denim are a reminder that there is often a lack of awareness of the hazards of silica outside the traditional occupations associated with silicosis.

Recommendations by the National Institute for Occupational Safety and Health (NIOSH) to reduce exposures to respirable crystalline silica in the workplace and to prevent silicosis and deaths in construction workers are outlined below. [58]

Recognize when silica dust may be generated and plan ahead to eliminate or control the dust at the source. Awareness and planning are keys to prevention of silicosis.

  • Use the dust collection systems available for many types of dust-generating equipment. When purchasing equipment, look for dust controls. Use local exhaust ventilation to prevent dust from being released into the air. Always use the dust control system, and keep it well maintained. Do not use equipment if the dust control system is not working properly.
  • During rock drilling, use water through the drill stem to reduce the amount of dust in the air, or use a drill with a dust collection system. Use drills that have a positive-pressure cab with air conditioning and filtered air supply to isolate the driller from the dust.
  • When sawing concrete or masonry, use saws that provide water to the blade.
  • Use good work practices to minimize exposures and to prevent nearby workers from being exposed. Eg, Remove dust from equipment with a water hose rather than with compressed air. Use vacuums with high-efficiency particulate air (HEPA) filters, or use wet sweeping instead of dry sweeping.
  • Use containment methods such as blast-cleaning machines and cabinets to prevent dust from being released into the air.

Do not use silica sand or other substances containing more than 1% crystalline silica as abrasive blasting materials. Substitute with less hazardous materials.

Practice good personal hygiene to avoid unnecessary exposure to other worksite contaminants, such as lead.

Take the following steps to assure that dusty clothes do not contaminate cars, homes, or worksites outside the dusty area:

  • Change into disposable or washable work clothes at the worksite.
  • Shower and change into clean clothes before leaving the worksite. 
  • Do not eat, drink, or use tobacco products in dusty areas.
  • Wash hands and face before eating, drinking, or smoking outside dusty areas.
  • Park cars where they will not be contaminated with silica and other substances such as lead.

Conduct air monitoring to measure worker exposures and ensure that controls are providing adequate protection for workers.

Use adequate respiratory protection when source controls cannot keep silica exposures below the NIOSH recommended exposure limitis (REL).

Do not use respirators as the primary means of preventing or minimizing exposures to airborne contaminants. Instead, use effective source controls such as substitution, automation, enclosed systems, local exhaust ventilation, wet methods, and good work practices. Such measures should be the primary means of protecting workers.

Respirators and respiratory protection program

The Occupational Safety & Health Administration (OSHA) and NIOSH offer general guidance on respiratory protection as well as provide information on standards for respiratory protection. [59]  Specific respiratory protection recommendations are summarized below.

When respirators are used, the employer must establish a comprehensive respiratory protection program, as outlined in the NIOSH Guide to Industrial Respiratory Protection [NIOSH 1987a] [60]  and as required in the OSHA respiratory protection standard [29 CFR 1910.134 and 1926.103]. [59]  Important elements of this standard are: 

  • Periodic environmental monitoring
  • Regular training of personnel
  • Selection of proper NIOSH-approved respirators
  • Evaluation of the worker’s ability to perform the work while wearing a respirator
  • Respirator fit testing
  • Maintenance, inspection, cleaning, and storage of respiratory protection equipment

The respiratory protection program should be evaluated regularly by the employer.

  • Provide periodic medical examinations for all workers who may be exposed to respirable crystalline silica.
  • Post warning signs to mark the boundaries of work areas contaminated with respirable crystalline silica.
  • Provide workers with training that includes information about health effects, work practices, and protective equipment for respirable crystalline silica.
  • Report all cases of silicosis to State health departments and OSHA.
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Long-Term Monitoring

Medical monitoring

The National Institute for Occupational Safety and Health (NIOSH) indicates medical examinations should be available to all workers who may be exposed to respirable crystalline silica. [58] However, examinations should always supplement effective dust monitoring and controls—never substitute for them. Such examinations should occur before job placement or upon entering a trade, and at least every 3 years thereafter. Examinations should include at least the following items [58] :

  • A medical and occupational history to collect data on crystalline silica exposure and signs and symptoms of respiratory disease
  • A chest radiograph classified according to the 2011 International Labour Organization (ILO) International Classification of Radiographs of Pneumoconioses [47]
  • Spirometry
  • An annual evaluation for tuberculosis

Training

Workers should receive safety training and education that includes the following [58] :

  • Information about the potential health effects of exposure to respirable crystalline silica.
  • Material safety data sheets for silica, masonry products, alternative abrasives, and other hazardous materials.
  • Instruction about the purpose and set-up of regulated areas marking the boundaries of work areas containing crystalline silica.
  • Information about safe handling, labeling, and storage of toxic materials.
  • Discussion about the importance of substitution, engineering controls, work practices, and personal hygiene in reducing crystalline silica exposure.
  • Instruction about the use and care of appropriate protective equipment (including protective clothing and respiratory protection).
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