[Maximum permissible levels of asbestos and other natural minerals with fibrous structure--necessity of verification].

MACs of asbestos are from 2 to 20 times higher in Poland than in other Western Europe countries. The analysis of occupational diseases reported between 1983 and 1988 among workers of asbestos-cement plants has showed that Polish MAC values do not protect people from work-related asbestosis. Asbestosis was frequently diagnosed in workers employed at mining and processing of nickel ore containing admixtures of fibrous antigorite. The risk of asbestosis in workers of a nickel++ metallurgical plant was 8 times higher that in those employed at an asbestos-cement plant. In an animal study, fibrogenic, carcinogenic and mutagenic activity of antigorite was similar to the biological aggressiveness of crocidolite. Based on own studies and literature data, the following MACs for asbestos and other natural fibrous minerals were established: a) for dusts containing asbestos and other fibrous minerals except crocidolite and fibrous antigorite, total dust concentration equals 1 mg/m3 and concentration of fibres longer than 5 microns = 0.5 fibre/cm3 b) for dusts containing crocidolite and fibrous antigorite total dust concentration = 0.5 mg/m3 and concentration of fibres longer than 5 microns = 0.2 fibre/cm3.