Welder Pneumoconiosis

Welder pneumoconiosis is the lung disease caused by chronic inhalation of welding fume, a mixed aerosol of iron oxide, manganese, chromium (including hexavalent chromium), nickel, zinc, aluminium and fluoride compounds, together with gases such as ozone and nitrogen oxides. Particle size is below 1 micrometre, so deposition reaches the alveoli. Shipbuilding, construction, vehicle repair and informal roadside metal workshops are the main settings, and the risk is highest with stainless steel and in confined or poorly ventilated spaces.

The disease is a spectrum: pure iron deposition producing radiographic change with little impairment, mixed dust pneumoconiosis with fibrosis when silica or other dusts coexist, chronic bronchitis and airway obstruction, and occasional occupational asthma. Welders have excess pneumonia mortality, and a 30 to 40 percent excess lung cancer risk, mainly with stainless steel fume. Latency is commonly 10 years or more.

• Often asymptomatic with an abnormal film.
• Chronic cough and sputum, exertional dyspnoea, wheeze.
• Metal fume fever (chills, fever, myalgia, metallic taste 4 to 12 hours after exposure) in the same worker.
• Eye (arc eye, siderosis bulbi), skin and nasal mucosal irritation.
• Bibasal crackles, expiratory wheeze; clubbing is uncommon and suggests another diagnosis.
• Manganese exposure can produce parkinsonism, tremor and mood change.
• Red flags: haemoptysis, weight loss, unilateral signs (cancer), rapid decline in lung function.

• History: type of metal and process, years of welding, location, ventilation, respirator use.
• Chest radiograph: diffuse small rounded or irregular opacities (ILO profusion 1/0 to 2/1) in a mid to lower zone distribution.
• High resolution CT: centrilobular nodules and ground glass change; emphysema; fibrosis in mixed disease.
• Spirometry: normal, obstructive, or mixed; DLCO reduced when fibrosis is present.
• Blood or urine manganese and chromium in appropriate exposure settings.
• Bronchoalveolar lavage or biopsy with iron laden macrophages (Perls stain) and particle analysis when the diagnosis is uncertain.
• Exclude silicosis, sarcoidosis, hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, tuberculosis, and lung cancer. Radiological nodules in a Kenyan welder warrant sputum for acid fast bacilli and GeneXpert.

• Reduce exposure: local exhaust ventilation, respirators with P3 filters, flux and electrode substitution, avoid welding galvanised or cadmium plated metals, rotate tasks.
• No specific therapy removes retained particles. Smoking cessation is the most effective intervention.
• Airflow obstruction: salbutamol 200 micrograms inhaled up to 4 times daily as needed; tiotropium 18 micrograms inhaled once daily or 2.5 micrograms by Respimat 2 puffs once daily for persistent breathlessness; add budesonide formoterol 200/6 micrograms 1 to 2 puffs twice daily if eosinophils exceed 300 per microlitre or asthma features are present.
• Symptomatic fibrosis or occupational asthma: reassign work, prednisolone 0.5 mg/kg orally daily for 2 to 4 weeks may be tried in the inflammatory form, then tapered.
• Annual influenza vaccine, pneumococcal conjugate vaccine once.
• Surveillance: chest radiograph and spirometry every 3 years for the exposed, annually if abnormal; lung cancer screening low dose CT annually for heavy smokers aged 50 to 80 years.
• Manganese neurotoxicity: remove from exposure; levodopa response is poor.
• Counselling: advise on compensation reporting and exposure control.