Respirable fibres: Surfactant coated fibres release more Fe³⁺ than native fibres at both pH 4.5 and 7.2

Exposure to asbestos is associated with several lung diseases. The carcinogenic action of asbestos is not fully understood but oxidative stress is considered to play a role. Iron on the surface can lead to Fenton chemistry and the Haber Weiss reaction producing free radicals such as the hydroxyl radical, which is likely to be important. Little is known of the pathogenic action of man-made fibres. This study involved the use of a panel of man-made fibres, some of which were shown to be pathogenic and others shown to be non-pathogenic in recent animal studies. A short term assay measuring Fe³⁺ release from the fibres over a 20 hour time period, and also a longer study of 12 weeks, found that pathogenic and non-pathogenic fibres could not be differentiated according to Fe³⁺ release only. Iron release from native fibres was compared with that from surfactant-coated fibres, and in all cases surfactant coated fibres released more Fe³⁺ inferring that in vivo lung lining fluid coats native fibres and therefore affects the fibre surface chemistry and hence reactivity.