Characterization of lung burden EMPs

The physical characterisation of retained EMPS is extremely important in providing information regarding the aetiology of the disease they may produce. It is now accepted that the biological effects fibres may produce in lung tissue once deposited are closely related to their concentration but more critically to their variation in length and diameter. To assess the disease risk of exposure to EMPs it is necessary to accurately describe their lengths and diameter distribution. Microscopic examination of lung burden and respirable airborne dust samples of EMPs are therefore among the most important investigations necessary to assess the risks of exposure to EMPs and provide an understanding of the manner in which they can produce a disease response. While optical microscopy and electron (SEM and TEM) microscopy are techniques that might be applied in the study of lung burden, in practice the TEM is the only viable procedure suitable for such a purpose as the optical method, for example, cannot resolve the smaller fibres and the SEM may in some instances have similar limitations. It is also necessary to ensure that meaningful samples of EMPs are prepared in order to produce results that can be critically interpreted. Data collection relating to the physical size of fibres is very important and should be collected in a bi-variate form for comparative purposes. Airborne dust samples should relate to respirable sizes and be collected for direct examination. Tissue preparation techniques should be designed to ensure no alteration in the chemical or physical properties of fibre or other particle characteristics. Collection of numerical data by detailed sample analysis enables a better understanding of the most important factors which influence the disease potential of EMP dust clouds.