[An experimental quality assurance program for asbestos measurements performed with x-ray diffractometry in bulk samples].

A quality assurance program for the diffractometric determinations of asbestos in bulk samples is presented. The program, developed upon request of the Italian Health Ministry, includes two tests: the qualitative determination of the asbestos forms present in three samples and their quantitative measurements. The samples to be analyzed, the asbestos standards and the criteria for results evaluation are described in detail. The program will start in the year 2000. Compliance with the tests minimum requirements will be considered mandatory for a public or private laboratory be legally allowed to work in the field of asbestos determinations by X-ray diffractometry. The description of the program is preceded by an in-depth discussion on the definition of the terms "quality control" and "quality assurance", which are often confused, and on their operational meaning when they are applied to laboratory measurements. The analytical difficulties involved with the measurement procedures currently used are also discussed. Moreover, the results of a preliminary intercalibration test among fifteen Italian laboratories of proven experience are reported since they provided important information for the arrangement of the present quality assurance program.