An intravenous drug abuser presents to the clinic with shortness of breath. He admits to abusing heroin; however, he has no signs of intoxication at this time. He says that his shortness of breath has...

An intravenous drug abuser presents to the clinic with shortness of breath. He admits to abusing heroin; however, he has no signs of intoxication at this time. He says that his shortness of breath has been going on for a long time. He denies being a cigarette smoker. The physicians are concerned about a chronic lung disease. A lung biopsy is performed which shows inflammation and scarring in the lung tissue, with refractile angulated material trapped in small blood vessels. A polarizing filter placed on the microscope shows that fragments of the material are polarizable. What is the likely source and nature of material, and why is it found in the lungs?