**4. Conclusion**

Risks associated with exposure to fibers, such as asbestos, and particulates, such as silica, were discussed based on our experimental findings and analyzed using cell lines, freshly isolated peripheral immune cells from HD, as well as patients exposed to silica particles, exposed to asbestos fibers, and patients with silicosis, PP, and MM. The immunological risks manifested in different directions, in that silica caused dysregulation of autoimmunity, whereas asbestos induced a reduction of antitumor immunity. Both cellular and molecular alterations contrib‐ uted to the complications of silica exposure, the occurrence of autoimmune diseases and asbestos exposure, and the development of malignant tumors.

These risks may be detected using findings described in this chapter, and early detection of these risks may assist workers, as well as other exposed populations, in avoiding further exposure and therefore prevent the onset of various pathological states caused by exposure to fibrous and particulate substances. Recently, although exposure to silica and asbestos has been reduced through the improvement of work-related environments as well as banning the use of asbestos, new substances, such as nanomaterials, which are widely used in the industrial fields, are now feared to cause health risks. It should be reiterated that risks, and particularly immunological ones which hitherto have not received a great deal of attention, caused by classical types of particulate and fibrous substances, such as silica and asbestos, require continued and greater consideration in an effort to further prevent the health impairment caused by environmental substances.
