Other Clearly Extrinsic Causes of Diffuse Infiltrative Lung Disease



External radiation in doses in excess of 5000 rads over a 4- to 6-week period frequently pro­duces radiation pneumonitis and the response usually occurs within the first 6 months following exposure and almost always by 13 months. Many drugs cause diffuse lung disease . Some cancer chemotherapeutic agents such as chlorambucil result in dose-related toxicity while others, like methotrexate, produce hypersensitiv­ity reactions. Both phenomena occur with bleo­mycin, an acute syndrome and a chronic illness almost inevitable when greater than 400 to 500 units are used. Synergism with other causes of lung injury such as radiation and high concentra­tions of oxygen is suspected. Antibiotics, espe­cially nitrofurantoin and sulfonamides, may cause hypersensitivity lung disease, while a num­ber of sedatives and hypnotics have been impli­cated in noncardiogenic pulmonary edema, es­pecially with intravenous abuse. Exposure to noxious gases such as chlorine, ammonia, phos­gene, ozone, hydrogen sulfide, and nitrogen diox­ide can cause severe lung injury. The nature of the injury depends upon the reactivity of the gas, its concentration, and the length of exposure and ranges from tracheobronchitis to adult respiratory distress syndrome.