title: Evaluation of hazardousness of refractory fibers by cell magnetometry.
abstract: This study was carried out to assess the cytotoxicity of three kinds of refractory fibers (RFs), RF1, RF2, and RF3, by cell magnetometry, lactate dehydrogenase (LDH) assay and morphological observation by scanning electron microscopy, using a mouse-derived cultured cell line, RAW264.7. As an indicator for cell magnetometry, Fe(3)O(4) was added to RAW264.7 cells. RF1, RF2 and RF3 were each added to an aliquot of this solution to make final concentrations of 250, 500 and 1,000 µg/ml in the experimental group. Phosphate buffered solution was added to make the control solution (n = 6). After culturing for 48 hr, the solution was magnetized from outside using a cell magnetometric apparatus, and the remnant magnetic field was measured for 20 min postmagnetization. In cell magnetometry, a significant delay of relaxation compared to that of the control was observed. In the LDH assay, LDH release into the culture medium was observed by addition of RFs. Furthermore, a quantity-dependent relationship was found between the quantity of RF added and the cytotoxicity in cell magnetometry and LDH assay. Morphological examination revealed incomplete phagocytosis of fibers and a decrease of microvilli in the experimental groups. These results suggest that RFs are cytotoxic to RAW264.7 cells, showing concentration-dependent cytotoxicity, and have a possible risk of cytotoxicity similar to that of asbestos. Further studies by pulmonary magnetometry are necessary to assess the hazardousness of RFs.
authors.affiliation: Department of Preventive Medicine and Public Health, Kitasato University School of Medicine, Japan. yuichiro@med.kitasato-u.ac.jp
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kudo
authors.forename: Makoto
authors.initials: M
authors.lastname: Kotani
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Aizawa
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004867:Equipment Design; D052203:Ferrosoferric Oxide / Q000494:pharmacology; D045022:Lactate Dehydrogenases / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D008280:Magnetics / Q000295:instrumentation / Q000379:methods; D051379:Mice; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D019016:Mineral Fibers / Q000633:toxicity*; D010587:Phagocytosis / Q000187:drug effects; D018675:Toxicity Tests
chemical_list: D019016:Mineral Fibers; D045022:Lactate Dehydrogenases; D052203:Ferrosoferric Oxide