Evaluation of exposure to man-made vitreous fibers by nasal lavage.

The objectives of this study were to develop a biomonitoring method for the assessment of exposure to man-made vitreous fibers (MMVF), to examine the level of exposure to MMVF ill the prefabricated house industry. and to study nasal inflammatory reactions and respiratory symptoms associated with MMVF among workers. Nasal lavage was performed oil workers from two factories, and concentrations of MMVF were measured by electron microscopy. Cytokines (IL-6, IL-8, TNF-alpha, and IFN-gamma) were also assayed and inflammatory cells (lymphocytes, eosinophils, neutrophils, and macrophages) were counted microscopically. Concentrations of airborne fibers (longer than 5 mum) were measured for comparison. Moreover, the exposure to MMVF and the related symptoms were studied with a structured questionnaire. In nasal lavage samples, the mean concentration of MMVF (length > 1.5 mum) was 3260 f/mL in Factory 1, 1680 f/mL in Factory 2, and below 500 f/mL in the control group. About 52% of the retained fibers were longer than 100 mum. The group-specific mean concentrations of MMVF in nasal lavage samples correlated with production rates and airborne fiber levels in both plants. The airborne concentrations of MMVF both in the breathing zone and fixed point samples were low (below 0.1 f/cm(3)). No significant differences in the biological response (inflammatory cells, cytokines) were found between the groups exposed and the control group. The workers complained of some irritation of the skin, eyes, and upper respiratory tract, which could be reduced by appropriate protective equipment. It is concluded that nasal lavage call be used as a biomonitoring method in the assessment of MMVF exposure.