Abstract
Silica-containing materials (including crystalline, noncrystalline, and silica polymorphs) and related materials may be introduced into the human body by routes of administration other than the traditional routes of inhalation (i.e., into the lungs and respiratory tree by way of the nose or mouth), ingestion (i.e., into the digestive tract, primarily by way of the mouth), or through the skin. This article reviews and summarizes experimental, clinical, and anecdotal data relating to the introduction of silica and related particulates which enter the body by so-called nontraditional routes, including implantation and injection. These nontraditional routes of delivery of silica-containing and related materials into the body, and the subsequent presence of particulates containing silica, can result from a number of causes, mechanisms, and reasons. These include decomposition, degradation, and wear of various implanted medical or dental devices; particulate material present on or in certain devices or equipment which are introduced into the body; or particles contained in certain pharmaceuticals and medications, or illegal substances injected into the body. The presence of silica-containing and related materials in the body might also be the result of various chemical or physical reactions taking place in the body, or of deliberate (e.g., dermal abrasion) or accidental (e.g., falls or explosion) introduction. The forceful introduction of silica-containing materials through the intact skin, into the nail bed, or into the eye is also described. Brief comments are also presented regarding the ways some common silica-containing materials routinely enter the body. For example, even routine brushing with silica-containing toothpastes and denture cleaners (and similar products) can result in the implantation of small quantities of silica into the oral tissue. The chemical, physical, and biological reactions, responses, and long-term effects of the presence of such materials in the body are noted, as are the possible consequences of the migration of such materials within the body. Glaser, Z.R.: Some Health and Safety Aspects Involving In Vivo Particulates Containing Crystalline Silica Which Enter the Body Via Nontraditional Routes. Appl. Occup. Environ. Hyg. 10(12):1107–1111; 1995.