Comparison of Fiber Counting by Monitor Screen and Eyepieces of Phase Contrast Microscopy

Background: These minerals have been extensively used in industrial products such as cement-asbestos sheet and pipe, brake shoe, clutch, insulation materials, etc. Occupational and non - occupational exposures to this carcinogenic material have caused to develop several methods to evaluate airborne asbestos fibers.

Materials and Methods: In this study, multiple microscopic method of determining the type and concentration of asbestos fibers has been used in an industry. The forty five personal samples on membrane filters (MCE) were collected of different processes of a manufacturing factory of cement-asbestos sheet. The half of each filter was prepared and then fibers counting were accomplished by ocular PCM and LCD images methods. Another part of filters was used for identification of asbestos fibers elements and types by scanning electron microscope method.

Results: Fibers concentration range were determined 0.009-0.243 fibers/cc by direct counting method (Ocular PCM), while by indirect method (LCD Images), results were 0.00-0.117 fibers/cc and statistical tests showed significant difference (p<0.02). Study of elemental composition of fibers by scanning electron microscope confirmed that, the majority of fibers were chrysotile. Study of elemental composition of fibers by scanning electron microscope confirmed that majority of fibers are chrysotile.

Conclusion: Due to limitation of study, use of 1.3 megapixels in indirect method, PCM direct method remains one the best methods of Asbestos fibers counting in Iran.