Once a popular substance utilised for its fire-resistant qualities, asbestos exposure has been linked to severe health conditions such as asbestosis and lung cancer. Long-term inhalation of asbestos fibres can cause the development of asbestosis, a chronic lung disease that impairs breathing and causes scarring of the lung tissue. Asbestos exposure can also cause lung cancer (including mesothelioma), which is one of the most common causes of global cancer-related fatalities. There is a connection between asbestos and lung cancer since asbestos fibres can damage cells and increase the risk of cancer. It is crucial to understand this relationship for the prevention and treatment of asbestos-related diseases. This underscores the need for workplace safety and public health initiatives.

Introduction

Asbestosis is a type of restrictive lung disorder, meaning that there is a decreased forced vital capacity (the maximum volume of air which can be forcefully exhaled after a maximum forced inhalation) compared to healthy individuals. Reduced lung volume is also present. 

This condition is caused by long-term exposure and inhalation of asbestos fibres. Asbestos comprises six different minerals that interact with each other and become fibrous. This gives them heat and fire-resistant properties, making it ideal for building infrastructure. However, research has found that long-term exposure to fine asbestos dust is dangerous and the use of this material was discontinued in the 1990s. According to the US Department of Health, asbestos is classified as a human carcinogen (a substance that causes cancer).¹ The International Agency for Research on Cancer determined that there is sufficient evidence of asbestos causing asbestosis, mesothelioma (cancer of mesothelial tissue found lining the internal organs), lung cancer, and cancer in the larynx and ovary.

Background information on asbestosis

Homes built before the 1990s could contain asbestos in materials like pipes, ceilings, and floor tiles. Asbestos in its solid state is harmless, but when turned to dust, usually during house or building demolition, it can be harmful when inhaled. The risk of asbestos exposure for people living in these homes would not be particularly high. However, individuals who demolish or construct buildings are at a higher risk of developing asbestosis due to their long-term exposure and direct contact with the material. 

These occupations include heating and ventilation engineers, demolition workers, plumbers, construction workers, and electricians. People who were first-line responders for the 9/11 World Trade Center twin tower collapse also experienced asbestosis because of the heavy exposure to asbestos-containing materials they encountered. The toxic dust contained relatively low levels of asbestos, glass, and paper, but many other construction materials were known as irritants and carcinogens. This study, done in 2011 on frontline firefighters present at the World Trade Center, showed that they were 19% more likely to develop cancer versus the general population.³

The precise mechanism of lung damage due to asbestos exposure is not fully understood but it appears that the immune system plays a role. 

Our bodies have immune defence mechanisms – innate (present from birth) and adaptive (developed through exposure). When foreign substances like asbestos are deposited in our respiratory tract, the ciliated (hairy) epithelial cells that line the upper respiratory tract move to sweep and transport those substances out of the respiratory tract along with mucous. We then cough it up or it gets digested in our stomach and is cleared from the body. Specialised macrophages (a type of white blood cell) perform phagocytosis (“eat” the foreign particles) and are then transported out of the lungs. However, smaller-sized particles of asbestos may be unable to be dislodged from the tract, and stay embedded for a long period of time, potentially causing accumulation, scarring (pulmonary fibrosis), and inflammation. 

According to the NHS, the common symptoms of asbestosis include:

• Shortness of breath 
• Persistent cough 
• Wheezing 
• Fatigue 
• Chest or shoulder pain
• Clubbed (swollen) fingertips in the more severe cases 

To diagnose asbestosis, medical history, including an exposure history, would be carefully obtained Then a chest computed tomography (CT) scan or X-ray could be performed to identify the presence of scarred lung tissue. Breathing tests can be done with a spirometer to measure the forced vital capacity and forced expiratory volume (amount of air that can be forcibly exhaled) in one second. This provides insight as to whether the lung disease is restrictive or obstructive. 

Background information on lung cancer

There are two types of lung cancer: small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC is common in smokers and is considered the most aggressive form of lung cancer due to its rapid growth and spread. NSCLC includes these three types: 

• Adenocarcinoma (present in the mucus-making gland cells lining the airways)
• Squamous cell carcinoma (present in the flat cells that cover the surface of your airways)
• Large cell carcinoma (the origin is not well-defined but is probably epithelial)

Cause

Smoking is the most common cause of lung cancer⁴ and cigarettes and e-cigarettes contain carcinogenic chemical substances. Asbestos is the second main contributor. It is important to know that health issues occur with long-term exposure, and there is not an immediate effect. It is easy for individuals to dismiss the risks of smoking that create long-term health conditions which worsen over time. 

Lung cancer and asbestosis share similar symptoms. These common symptoms include:

• A cough with or without mucus
• A cough with blood (also known as hemoptysis) 
• Chest pain 
• Pain when breathing or coughing 
• Fatigue 
• Loss of appetite 
• Weight loss 

Diagnosing lung cancer is more extensive than asbestosis because both imaging studies and biopsies are done. CT scans can provide insight into specific medical conditions like co-existing lung disease, intrathoracic (in the chest) or extrathoracic (outside of the chest) metastatic disease, post obstructive pneumonitis (inflammation in the lung caused by an obstructive infection), and tumour-related atelectasis (collapse of part of the lung). Then a positron emission tomography (PET) scan can be done to determine the tumour’s activity and if it has spread. Then after imaging scans, invasive testing is used to obtain biopsies to confirm the stage and type of cancer based on the specific cell’s appearance. Such procedures include mediastinoscopy, video-assisted thoracoscopy (VATS), and bronchoscopic endobronchial ultrasound-transbronchial needle aspiration (TBNA).⁵

Clinical management and treatment

Unfortunately there is no cure for asbestosis. However, there are some treatments to mitigate further development of the disease. These treatments include pulmonary rehabilitation (where exercises are used to help manage your symptoms), oxygen, and inhalers with medicine to relieve bronchoconstriction (narrowing of the respiratory tubes). By monitoring the progression of asbestosis after diagnosis, flares can be prevented, and symptoms can be treated more effectively. 

As for lung cancer, there are different treatment options depending on the type present. Treatment for NSCLC differs according to the stage. Surgery is the primary treatment in Stage I; individuals with more damaged lungs may benefit from less invasive treatments, but lobectomy (removing one lung lobe) or pneumonectomy (removing an entire lung) yield the best results. Tumours that invade the chest wall or sit on top of the lung (Pancoast tumour) also require radiation therapy. These tumours are classified as stage II; treatment also consists of surgery followed by chemotherapy. Stage III treatment is complex and includes surgery, and chemo-radiotherapy customised to lymph node involvement. Stage IV focuses on symptom relief and extending survival through chemotherapy, targeted treatments, and immunotherapies.

Chemotherapy and radiation are the main treatments for small-cell lung cancer (SCLC). Surgery may be beneficial for limited-stage SCLC, while chemotherapy and preventive brain radiation are the main methods for managing metastases in extensive-stage SCLC; however, the overall survival rate is still low. For more detailed information on lung cancer treatment, follow this link.⁵  

Summary

Once widely utilised for its ability to withstand fire, asbestos is now recognised to have significant health hazards, such as the development of lung cancer and asbestosis. Chronic lung disease known as asbestosis, which causes lung tissue scarring and breathing difficulties, can be brought on by long-term inhalation of asbestos fibres. In addition, lung cancer, the world's largest cause of cancer-related mortality, is greatly elevated by asbestos exposure. It is imperative to understand this connection to prevent and treat diseases associated with asbestos use. Improved outcomes depend on early diagnosis and treatment recognition of the symptoms. Research continues to pave the way for new lung cancer therapies and potential future cures. This will open up new ways to tackle this disease.