Baritosis

Baritosis is the benign pneumoconiosis caused by inhalation of barium sulfate (barite) dust. Exposure occurs in barite mining and milling, in the manufacture of paints, paper, rubber, glass and drilling mud, and in oil exploration. Barium sulfate is insoluble and chemically inert. Particles are retained by macrophages around bronchioles and vessels with no fibrotic response, no inflammation and no functional loss.

The condition is detected only radiologically, and the opacities fade after exposure stops, usually within 1 to 2 years and sometimes over several more years. It is not caused by barium meal contrast. Soluble barium salts (carbonate, chloride) are toxic when ingested or inhaled in large quantity and cause hypokalaemia, which is a separate clinical problem. Tuberculosis risk is not raised by barium sulfate alone.

• Asymptomatic in almost all patients.
• Rarely mild cough or sputum from coincident bronchitis.
• Normal lung examination, normal oxygen saturation, no clubbing.
• Red flags that should lead to another diagnosis: dyspnoea, crackles, haemoptysis, weight loss, fever.
• Mixed dust exposure to silica can result in silicosis in barite miners.
• Soluble barium inhalation or ingestion: vomiting, diarrhoea, muscle weakness, paralysis, arrhythmia from hypokalaemia.

• Occupational history of barite dust exposure.
• Chest radiograph: diffuse discrete dense nodular opacities of 1 to 3 mm, extremely radio opaque, distributed evenly in both lungs, with no hilar enlargement or pleural disease.
• High resolution CT: dense, small, well defined centrilobular and subpleural nodules without fibrosis.
• Spirometry and DLCO: normal.
• Confirmation: electron microscopy and X-ray spectroscopy of lavage or tissue shows barium and sulfur. Biopsy is rarely justified.
• Serum potassium and ECG if soluble barium salt exposure is suspected.
• Exclude silicosis, miliary tuberculosis, sarcoidosis, stannosis, siderosis, pulmonary alveolar microlithiasis and metastatic disease.

• No medication treats baritosis. Management is reassurance and exposure control.
• Reduce further exposure by wet milling, enclosed handling, local exhaust ventilation and half face P2 respirators.
• Workers with radiographic change but normal function may continue work with dust control; remove from exposure when mixed dust fibrosis is shown.
• Screening: chest radiograph and spirometry at appointment, then every 3 years.
• Stop smoking: nicotine patch 21 mg per 24 hours for 6 weeks, 14 mg for 2 weeks, then 7 mg for 2 weeks.
• If soluble barium poisoning occurs: potassium chloride 10 to 20 mmol/hour intravenously (maximum 40 mmol/hour under continuous ECG monitoring) targeting potassium 4.0 to 4.5 mmol/L; magnesium sulfate 2 g intravenously over 20 minutes; oral magnesium sulfate 30 g once to precipitate barium sulfate in the gut after recent ingestion; haemodialysis in severe cases.
• Follow up: radiograph at 1 and 2 years after leaving exposure to confirm regression.
• Counselling: the disease is benign; workers should understand the importance of exposure reduction because of mixed dust.