Coagulation of human plasma by asbestos fibers

Negatively and positively charged asbestos fibers shorten the partial thromboplastin time of human plasma, indicating coagulation of the plasma. A sample containing short (<5 μm in length) chrysotile fibers is ineffective. Only the negatively charged amphiboles (crocidolite and amosite) are able to activate factor XII (Hageman factor). This particular effect of the amphiboles is enhanced by high-molecular-weight kininogen and leads to kinin formation.