Lung cancer in a patient with predominantly short tremolite fibers in his lung.

The carcinogenicity of short tremolite fibers in human has not been cleared and has been argued hitherto. A lung cancer patient had worked at a gabbro quarry. Particles isolated from the excised lung parenchyma of the patient were measured for asbestos bodies (ABs) and asbestos fibers (AFs). The concentrations of ABs were 3964 AB/g dry lung, and AFs were 5.60 × 106 fibers/g dry lung (>5 um in length) and 22.5 × 106 fibers/g dry lung (>1 um in length). AFs were mostly tremolite fibers and under 7 um in length (mean length 4.0 um, standard deviation 2.8 um). Almost all fibers were <10 um in length and an aspect ratio (AR) of <20:1 and ≥3:1. The patient had never smoked. His wife, who had worked with him in the quarry, had died of pleural mesothelioma. This study strongly indicates that such short tremolite fibers will induce lung cancer and possibly mesothelioma in human.