アスベスト繊維試料の長さによる分級 動物実験に使用するための繊維長さ分離回収法

Abstract

A size-selective procedure has been developed in order to obtain samples of asbestos fibers of different lengths for use in biological experiments. Short Chrysotile fibers less than 5μm in length are widely suspected to be less carcinogenic than longer fibers. The bulk sample of U. I. C. C. standard asbestos (Chrysotile B) was aerosolized using -component fluidized bed. It was then separated in the dry state by wire ens (200 mesh and 635 mesh) and a virtual impactor with a cut-off point of 2μm.0.1g (sufficient weght for in-vitro tests) of a short-fiber fraction that passed through the wire screens and then onto the fine side of the virtual impactor, and 1.5g of a medium fraction that passed through the 200 mesh screen but did not pass through the 635 mesh screen, were obtained from about 20g of raw material. The length distribution of the short fiber fraction was 81% of fibers less than 5μm long and 96 percent of fibers less than 10μm long. X-ray diffraction analysis revealed that the crystallinity of the separated chrysotile was not markedly changed. The present dry and mild separation process that was developed thus successfully avoids any artificial change in the physicochemical properties of asbestos fibers.