Siderosis (Welder's Lung)

What happens in siderosis

When iron is heated, cut or ground, it releases fine iron oxide particles. Inhaled particles are taken up by immune cells (macrophages) in the lungs and stay there. Iron itself causes little scarring or inflammation, so lung function is usually preserved. That is why pure siderosis is called a "benign" pneumoconiosis, in contrast to silicosis and asbestosis, which cause progressive scarring.

However, welders are often exposed to silica, asbestos (in older settings), manganese, chromium, nickel, cadmium and gases, leading to mixed-dust pneumoconiosis, fibrosis, occupational asthma, chronic bronchitis and increased lung cancer risk.

Symptoms

• many people have no symptoms
• cough, sometimes with phlegm
• mild breathlessness
• wheeze or chest tightness, often from coexisting bronchitis or asthma
• symptoms tend to be more significant when other dusts or smoking are involved

Diagnosis

• Occupational history: years of welding or metal work, ventilation, protective equipment, materials used.
• Chest X-ray: small, round, dense spots spread through both lungs, which look striking compared with how well the person feels.
• High-resolution CT: fine nodules and ground-glass changes.
• Lung function tests: usually normal in pure siderosis; abnormal if other conditions are present.
• Bronchoscopy or biopsy in uncertain cases, showing iron-laden macrophages.

Other conditions with similar X-ray findings, such as sarcoidosis, tuberculosis, other pneumoconioses and miliary infections, are ruled out.

Treatment

There is no specific treatment for pure siderosis because it does not usually harm the lungs. Management focuses on:

• reducing exposure: local exhaust ventilation, respirators rated for welding fumes, enclosed welding processes
• stopping smoking, which greatly increases lung damage and cancer risk in welders
• treating associated conditions such as asthma, bronchitis or interstitial lung disease
• regular monitoring for lung changes and symptoms
• vaccinations against flu, COVID-19 and pneumococcus

The X-ray spots may gradually fade after exposure stops, because some iron is cleared over years.

Other types of siderosis

• Superficial siderosis of the central nervous system: iron (hemosiderin) deposits on the surface of the brain and spinal cord from repeated small bleeds, causing hearing loss, unsteadiness and slurred speech. It is unrelated to occupational exposure and is diagnosed on MRI.
• Ocular siderosis: iron deposits in the eye from a retained iron foreign body after a metal fragment injury, which can damage vision. Anyone hammering or grinding metal who feels something hit the eye needs an urgent eye exam.

Prevention

• engineering controls and good ventilation
• appropriate respiratory protection
• safety glasses or face shields to prevent eye injury
• workplace health surveillance
• not smoking

Frequently asked questions

What is siderosis?

Siderosis is a lung condition caused by inhaling iron oxide particles, usually from welding or metal work. The iron collects in the lungs and shows up on chest X-rays. Pure siderosis usually causes few symptoms and little lung damage.

Is welder's lung dangerous?

Pure siderosis is generally not dangerous on its own. However, welders often breathe other harmful fumes and dusts, which can cause scarring, asthma, bronchitis and lung cancer. Reducing exposure and not smoking are important.

Can siderosis be reversed?

Often partly. Once exposure stops, the iron deposits may gradually clear and X-ray changes can improve over years. Scarring from other dusts, if present, does not reverse.

What are the symptoms of welder's lung?

Many people have no symptoms. Some have cough, phlegm, mild breathlessness or wheeze, often due to other exposures or smoking. Severe or worsening symptoms suggest another lung condition and need assessment.