Overview 

Pleurisy is irritation of the lining of the lungs, causing sharp chest pain. 

Asbestos is a term used to describe a class of minerals.They are divided into two bunches: serpentine asbestos and amphibole asbestos. Asbestos has been mined and utilised commercially in North America and other countries since the late 19th century.

In the late 1970s, the United States Item Security Commission (SEC) prohibited the utilisation of asbestos in divider tiles and gas chimneys since asbestos filaments in these items might be discharged into the environment amid utilisation. All types of asbestos have been banned in the UK since 1999.

Asbestos exposure: causes and effects

What is asbestos?

Workers in various industries have reported to be exposed to asbestos, including: 

• Shipbuilding 
• Asbestos mining and milling 
• Production of asbestos textiles (and other types of Asbestos fibres) 
• Construction and building insulation work 
• Demolition workers 
• Plasterers 
• Asbestos removers 
• Firefighters 
• Auto workers 

There exists limited research regarding the cancer risk associated with auto mechanics being exposed to asbestos while performing brake repair, however, the evidence suggests that there is no safe exposure level.

What are the common sources of asbestos exposure?

The primary cause of asbestosis is inhalation of small asbestos fibres or dust. The longer you have been exposed to asbestos and the greater the exposure, the greater your chance of developing asbestosis. 

People who work in industries mentioned above and regularly inhale asbestos particles are at greatest risk of developing asbestosis. The inhalation of airborne asbestos particles causes asbestosis.

What other products contain asbestos? Materials and products that may potentially contain asbestos include: 

• Car pads and brakes 
• Many household products and substances also contain asbestos, such as the ash and coal used in gas fireplaces³

Are there any health risks associated with asbestos exposure?

Pharyngeal cancer risk

A combination of asbestos exposure and smoking is a well-established risk factor for lung cancer, but only one study considered asbestos exposure as a cofactor with smoking for pharyngeal (throat) cancer. 

Although several cohort studies and larger, better-designed studies have suggested a correlation between asbestos exposure and pharyngeal cancer and asbestosis, the epidemiologic evidence is generally limited and the biological plausibility at this site is uncertain.

Laryngeal cancer risk

The evidence for laryngeal cancer included more studies than were available for other cancer targets considered by the committee, and the cohort populations were similar to those for gastric or colorectal cancer.

Many studies have investigated the association between asbestos exposure and laryngeal cancer and have reported tobacco use, which may influence or modify asbestos exposure and laryngeal cancer risk. Some studies have found a link between asbestos exposure and esophageal cancer, but the overall results of epidemiological studies are inconsistent. 

Colon cancer risk

Six lifetime asbestos feeding studies in rodents have not provided evidence that asbestos fibres act as direct or indirect carcinogens in the stomach. A case-control study with the most detailed assessment and analysis of asbestos exposure found no association between asbestos exposure and colon cancer risk in a study.⁴

Understanding pleurisy

The symptom of pleurisy is characterised by localised chest pain that is caused by inflammation of the pleura, which is the cause of the disease. Pleurisy may arise from either primary pleural disease or secondary systemic disease. 

The most recent definition of pleurisy was made by Giambattista Morgagni in 1961, who conducted postmortem examinations of patients suffering from pleurisy. Laennec, who invented the stethoscope, added egophony to the definition of pleurisy.⁵

Causes of pleurisy

• Viral infection
• Bacterial infection
• Pneumonia (an infection of the lungs)
• Tuberculosis
• Trauma to the chest wall
• Connective tissue disorders such as rheumatoid arthritis and lupus erythematosus
• Pulmonary embolism (blood clot)
• Cancer⁶

Diagnosis and treatment options

   To establish the diagnosis need history of onset symptoms and confirm by imaging include: 

• Chest X -ray 
• Ultrasound 
• CT scan 
• MRI 
• Pleural fluid analysis to reach to the type and cause
• Medical thoracoscopy 

For the treatment it depended on the cause 

1. Thoracocentesis is an Aspiration of the fluid either blood or pus from pleural cavity  
2. Needle aspiration and /or chest tube
3. Endobronchial⁷

Asbestos and pleurisy: connection and mechanism

How asbestos exposure leads to pleurisy

Asbestos tends to cause pleural damage, although the exact pathogenic mechanisms by which fibres accumulate in the pleura and cause pleural changes are unclear. Asbestos causes the following damage to the lungs: 

• Benign pleural effusion: There is an unspecified pleural effusion due to asbestos, which may later precede asbestos-related pleural disease
• Plaques 
• Diffuse pleural fibrosis: Diffuse pleural fibrosis, in contrast to pleural plaques, is a manifestation of parietal and/or visceral pleural connective tissue, frequently accompanied by dense pleural adhesions. Histologically, diffuse pleural fibrosis consists of collagen bundles with a basket-like pattern of droplets and focal calcification, similar to the histology of pleural plaques 
• Circular atelectasis: An associated lesion is circular atelectasis, often seen in the lung beneath diffuse pleural fibrosis or adherent pleural plaques. The pathogenesis of circular atelectasis is believed to be due to pleural infolding with pleural or pleural effusion

Pathophysiology of pleurisy in asbestos-exposed individuals

These results suggest that pulmonary pleural thickening prevented normal lung expansion, despite abnormally high distension pressures. Our patients may have experienced pleural thickening due to a condition described as benign asbestos pleuritis, rather than asbestosis interstitial fibrosis. 

The likelihood of relapse 

Most exacerbations are unilateral, but the pleural fluid lacks diagnostic features. The subpleural lung typically comprises alveoli . Asbestos fibres are found in the subpleural lung. 

In many early cases, subjects were more likely to develop asbestosis and mesothelioma than primary workers, and clear visceral pleura was recorded in the surgical notes. 

The distinction between cases of pleural restriction and cases of asbestosis with solely interstitial fibrosis is of clinical significance as surgery has the potential to alleviate pleural narrowing. 

During making this distinction, radiographic changes associated with marked pleural thickening usually suggest the diagnosis, although pleural calcification is usually not seen on a conventional PA film.⁹ 

Case studies and statistics

Benign asbestos effusion was defined as exposure to asbestos, confirmation by roentgenograms or thoracenteses, and no other disease related to pleural effusion within three years. There were 34 benign effusions among 1,135 exposed workers, compared to none among 717 control subjects. Incidence studies indicated that there were 9.2 effusions per 1,000 person-years for level III exposure, 3.9 for level II, and 0.7 for level I. Most effusions were small; 28.6% recurred, and 66% were asymptomatic. Patients with 'Idiopathic' pleural effusion should be carefully searched for asbestos exposure in patients with 'Idiopathic' pleural effusion.

Asbestos is responsible for the following lung diseases: asbestosis, pleural plaques, diffuse pleural thickening, benign asbestos pleural effusion, rounded atelectasis, lung cancer, and MM. 

World Health Organization (WHO) officials estimate that 125 million people worldwide are yearly exposed to asbestos in occupational settings. Moreover, more than 107 000 people die yearly from diseases associated with asbestos exposure. Either occupational or taken home asbestos exposure has been recognised for over 50 years and can be described as exposure to asbestos that occurs in the worker's home because of dust that has accumulated on the worker's clothing and/ or hair.

The primary cause of ARDs remains the direct occupational exposure to raw asbestos or asbestos products. The development of asbestosis necessitates relatively high levels of asbestos inhalation, despite the existence of reports indicating asbestosis following lower levels of asbestos exposure. Although cases of environmental and para-occupational asbestos exposure have been described, most MMs are occupational in origin.¹¹

Legal and social implications

Eight to fifteen percent of lung cancer cases and almost all mesothelioma cases are caused by asbestos. The latter pertains to the unscientific requirement for a predetermined number of asbestos bodies or fibres to be detected in lung tissue in order to "prove" disease causation, provided that lung specimens are available. Similar misleading arguments are currently being employed in newly industrialised nations, where white asbestos, which is carcinogenic and fibrogenic like other asbestos types, is effectively promoted as being less harmful. 

Although asbestos is a known carcinogen to humans, it is still a popular raw material in the construction industry, particularly in industrialised countries. From 1920 to 2003, the global consumption of asbestos has been estimated at 180 million metric tons.

The elimination of ARDs holds significant significance in determining the correlation between the historical utilisation of asbestos, the implementation of asbestos prohibitions, and the prevalence of ARDs.

Future concerns regarding asbestos usage in Asian countries are evident. While asbestos usage has decreased in the industrialised world, it has experienced a significant increase in many developing countries, particularly in Asian countries, resulting in a high-risk incubator for ARDs. Although there is sufficient evidence that asbestos has human carcinogenic effects, there is no safe level of exposure to asbestos fibres.^12,13

Summary 

Asbestos minerals are classified into two significant categories, namely serpentine asbestos and amphibole asbestos. Workers exposed to asbestos have reported health risks in various industries, including shipbuilding, asbestos mining and milling, the production of asbestos textiles, and construction and building insulation work. The combination of asbestos exposure and smoking is a well established risk factor for lung cancer, but only one case control study considered asbestos exposure as a cofactor with smoking.

Asbestos is responsible for the development of the following lung disorders: asbestosis, pleural plaques, diffuse pleural thickening, benign asbestos pleural effusion, rounded atelectasis, lung cancer, and MM. The World Health Organization estimates that 125 million individuals worldwide are annually exposed to asbestos in occupational settings, and more than 107 000 individuals die annually from diseases resulting from asbestos exposure.

From the above facts, one needs to distinguish between previous occupations with exposure to amphibole asbestos or to white asbestos in the interpretation of asbestos body numbers and asbestos fibre numbers in the human lung.

In practice, diagnostically appropriate fibre analytics, for example, ARTEM analysis does not apply to the partially possible documentation of asbestos bodies or asbestos fibres in the lung of the patient previously exposed to asbestos.

Asbestos continues to circulate despite the existence of ample evidence regarding its human carcinogenic effects. Evidence suggests that the controlled use of asbestos is impracticable, and there are no safe levels for exposure to asbestos fibres.