Validated reference standards to support the identification of asbestos fibers

Abstract

National Institute for Occupational Health and Safety stated: "all levels of asbestos exposure demonstrated asbestos-related diseases and there is no level of exposure below which clinical effects do not occur". New legislation in European Community and the United Nations Environment Program states that all forms of asbestos should be banned and added to an international list of chemicals submitted to trade controls. The asbestos reference standards have been prepared and validated by Institute of Occupational Medicine under contact to the Health and Safety Executive, UK. The identification of commonly encountered asbestos fibers is performed with a dispersion staining objective using well matched high dispersion liquids. The certainty of the method is analyst dependent, since the subjective nature of asbestos analysis is involved. Appropriate training is of fundamental importance to both sampling and analysts. Microscopic determination of asbestos requires the analyst to make repeated assessments of a number of physical properties and maintain consistent diligence in the search for fibers. Analysts should be thoroughly familiar with the appearance and characteristic of asbestos. Misidentification occurs not only when other kinds of fibrous material are incorporated into a bulk material, but also when more than one kind of asbestos are present in such a material. For routine purposes the examinations by means of polarized light microscopy (PLM) are usually sufficient to identify positively whether asbestos is present and its type.