The inflammation results from concentrations far below those needed to cause corrosion. A primary irritant exerts no systemic toxic action, either because the products formed on the tissue of the respiratory tract are non-toxic or because the irritant action is more severe than a systemic toxic action. A secondary irritant's effect on mucous membranes is overshadowed by a systemic effect resulting from absorption. Simple Asphyxiants deprive the tissue of oxygen. Simple asphyxiants are inert gases that displace oxygen.
Some toxic agents act on the blood or hematopoietic system.
The blood cells can be directly affected or the bone marrow can be damaged. Fibrotic changes can be caused by free silica and asbestos. Other dusts can cause a restrictive disease called pneumoconiosis. A carcinogen commonly describes any agent that can initiate or speed the development of malignant or potentially malignant tumors, malignant neoplastic proliferation of cells, or cells that possess such material. See listing of some carcinogenic materials .