Siderosis is the deposition of excess iron in body tissue. When used without qualification, it usually refers to an environmental disease of the lung, also known more specifically as pulmonary siderosis or Welder's disease, which is a form of pneumoconiosis. Pulmonary siderosis was first described in 1936 from X-ray images of the lungs of arc welders. The name siderosis comes from Ancient Greek word for iron, sídēr(os), and has an -osis suffix..