Occupational exposure assessment for crystalline silica dust: approach in Poland and worldwide.

Crystalline silica is a health hazard commonly encountered in work environment. Occupational exposure to crystalline silica dust concerns workers employed in such industries as mineral, fuel-energy, metal, chemical and construction industry. It is estimated that over 2 million workers in the European Union are exposed to crystalline silica. In Poland, over 50 thousand people work under conditions of silica dust exposure exceeding the occupational exposure limit. The assessment of occupational exposure to crystalline silica is a multi-phase process, primarily dependent on workplace measurements, quantitative analyses of samples, and comparison of results with respective standards. The present article summarizes the approaches to and methods used for assessment of exposure to crystalline silica as adopted in different countries in the EU and worldwide. It also compares the occupational limit values in force in almost 40 countries. Further, it points out the consequences resulting from the fact that IARC has regarded the two most common forms of crystalline silica: quartz and cristobalite as human carcinogens. The article includes an inter-country review of the methods used for air sample collection, dust concentration measurements, and determination of crystalline silica. The selection was based on the GESTIS database which lists the methods approved by the European Union for the measurements and tests regarding hazardous agents. Special attention has been paid to the methods of determining crystalline silica. The author attempts to analyze the influence of analytical techniques, sample preparation and the reference materials on determination results. Also the operating parameters of the method, including limit of detection, limit of quantification, and precision, have been compared.