Pneumoconiosis Caused by Wooden Dust Among Workers of Lumber and Wood Products

Pneumoconiosis has been defined as a diagnosable disease of the lungs produced by the inhalation of dust. In Yumaguchi prefecture, workes who are employed to lumber and wood products, furniture and fixture-markers, are exposed to dense wooden dust. In order to comfirm the possibility of the development of pneumoconiosis, mass survey of these workers were performed by means of direct chest roentgenography. The chest roentgenogram showed small oparacities of puncti-form and liner ones in some cases. This examination revealed 9 cases of category L1 and 2 cases of L2 out of 121 workers, and on the other hand, 4 cases of of category p1 and one case of p2 out of 121 workers. Statistical significance was found in subjects over forty of age. Fundamental experiments were performed using rats in order to prove that pneumoconiosis was caused by wooden dust of pailownia. Intra-tracheal infusions of 0.3 ml saline solution suspending dust were carried out. It caused dust foci and most of foci occupied one alveolar region. Acute bronchitis as well as chronic lymph-adenitis occurred. The results of animal experiments suggest that wooden dust causes dust foci of alveolar type in human lungs. Radiological finding of workers exposed to wooden dust and pathological findings of animal experiments also suggest that wooden dust causes pneumoconiosis as inorganic dust does.