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JAMA. 1930;94(13):994-995. doi:10.1001/jama.1930.02710390092010.
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The control of the health hazard due to abnormal air conditions causing silicosis is a matter of serious consideration in industry. In a summary of recent investigations, R. R. Sayers1 found that silicosis is a disease of slow evolution, seldom appearing in those under 40 years of age and usually after a period of at least ten years in the industry. Dr. Patrick Heffernan, tuberculosis officer in Derbyshire, England, states that the human body contains normally 1.40 mg. of silica and a silicotic one 123.55 mg. per gram. Silica is not therefore a poisonous substance. It must enter into the intimate structure of the cell. The resulting fibrosis is physicochemical and the process is accelerated by the presence of alkalosis and by the solubility of silica. Observers are agreed that the phagocytes, when overloaded with the dust, lose their motile power, collect in the lymphatic channels and lead to


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