动物体内青石棉纤维变化特征的显微研究

石棉纤维粉尘注入动物体内后，一部分形成石棉小体或石棉斑，一部分仍为裸露纤维。石棉小体内的纤维表面基团和组织内的某些蛋白反应可形成新的表面介体。粉尘在动物体内引起的动物病变主要是纤维化组织包裹和间皮瘤，机体以吞噬、包裹、缠绕，或以生化溶解方式排解粉尘。纤维自身则出现变短、尖部圆化、折断、分叉现象，也可以出现溶解、迁移、表面化学反应等。肺泡内纤维的碳酸盐化现象是体内纤维溶解和反应的新方式。动物体内间皮瘤可生长在注入部位也可在非注入部位，某种毒性衍生物质的生成和迁移是引起病变的主要原因。体内纤维粉尘的溶解是一个非常缓慢的过程，细小粉尘易于溶解和迁移。体内粉尘的膜阻滞现象在腹膜、胸膜上较为常见，在膜部位不易生成间皮瘤，肿瘤多引发在膜的内侧。但膜可以弱纤维化包裹。     

Restrictive definition of asbestos and the assessment of potential health hazards: insights from Northern Chile

When asbestos fibres become airborne, they can be inhaled into the lungs, where they may cause significant health problems. The latter includes progressive pulmonary fibrosis (asbestosis), pleural disease (effusion and pleural plaques) and malignancies such as bronchogenic carcinoma and malignant mesothelioma. The term asbestos applies to a group of hydrated fibrous mineral silicates including those belonging to the serpentine group of phyllosilicates (chrysotile) and amphiboles. However, only the ‘asbestiform varieties’ of amphiboles such as grunerite (amosite), riebeckite (crocidolite), anthophyllite, tremolite and actinolite are regarded as asbestos (s.s.). This implies that ‘non-asbestiform varieties’ of such minerals, that nevertheless generate acicular cleavage fragments, cannot be regarded as asbestos s.s. We argue that a discussion on the term asbestos goes beyond mere semantics, because for environmental regulatory bodies, the definition of a term can make the difference between classifying a mineral as harmful or non-harmful. A case of mesothelioma in the small mining town of La Higuera, northern Chile, may shed some light into this matter, because this form of cancer is almost always caused by exposure to asbestos. The town hosts about 20,000 t of fine-grained tailings left behind after flotation of Cu sulphides during 1950–1979. The ore was extracted from actinolite-rich, copper-iron vein deposits. We show that, if a ‘non-asbestiform variety’ of amphibole (e.g. La Higuera actinolite) is finely ground, it will cleave to asbestos-like acicular crystals and as such has the potential to induce similar health hazards to those posed by asbestos (s.s.).