Methodology for case study of asbestos related thoracic diseases, for medico-legal purposes. Critical evaluation of traditional diagnostic tools for assessment of professional exposure

Asbestos related diseases are a topic of actuality, since in 2020 a peak of incidence is expected. Medico legal assessment of the cases is a crucial step to provide adequate bases for forensic decision. At present, no significant study has been published defining a multidisciplinary, standardized protocol for case approach. Furthermore, in theory, multiple diagnostic tools may be useful for exposure assessment: anamnesis; counting of asbestos bodies in slides; body-counting by light microscopy (LM), in digested lungs; fiber counting and characterization by scanning electron microscopy (SEM). In the practical experience, not often they can be performed, due to the scarcity of biological samples and financial resources. In the Literature, quantitative approach for the evaluation of asbestos exposure has been emphasized. Notwithstanding, forensic researchers should critically question its real necessity for medico legal purposes. AIMS Preliminary aim: to develop a protocol evaluating clinical and radiological data; personal history; pathology of disease; mineralogical data. First aim: to assess any relation between anamnestic degree of asbestos exposure and the kind of disease. Second aim: to verify if clinical, morphological, mineralogical parameters are able to discriminate among different lung diseases. Third issue to evaluate the degree of concordance between different diagnostic tools for assessing amiantos exposure, when compared to a careful anamnesis. METHODS Forty-eight exposed individuals and 6 controls, undergoing pneumonectomy or forensic autopsy, were recruited in Padua and Venice. Following data were compiled: A) anamnesis; B) pathology; C) asbestos body counting by LM at histology; D) bodies (by LM) and fiber counting (by SEM) in digested lung specimens, and mineral typization. Statistical analyses evaluated associations between: 1) chest disease/anamnestic categories. 2) different parameters/chest pathology. 3) parameters/anamnestic categories, to evaluate the degree of concordance. RESULTS Database was completed for all subjects and controls. Sixty percent were affected by mesothelioma, 23% by lung cancer, and 17% by pulmonary fibrosis. All the controls and 24 of mesotheliomas resulted non-exposed; 27.59% were borderline, while 48.27% were professionally exposed, according to the Helsinki Criteria. Controls and 33,3% of 12 selected mesotheliomas showed fiber burden at SEM below 1.000.000 fibers/dry gm; 66.7% resulted occupationally exposed. In 100% of lung cancers cigarette smoking was present as main risk factor, and asbestos burden showed low levels of bodies at LM. Association between pleural plaques and RENAM anamnestic categories was significant (P=0.0123). Burden of asbestos bodies (P=0.0028), and of asbestos fibers, revealed a strong relation with the RENAM category. DISCUSSION Deep review of the Literature and personal experience of the Authors allowed to develop an ideal protocol, for maximum morphological detail in the study of subjects exposed to asbestos alleging chest diseases. Pleural plaques confirmed as a marker of asbestos exposure. Cigarette smoking was the main risk factor for all lung cancers, also showing low asbestos burden values at LM. Assessing the causal relation represents a crucial problem for these cases, and asbestos exposure needs to be strictly evaluated by microanalysis. For mesotheliomas, body counting by LM, fiber evaluation by SEM, and pleural plaques, were concordant with the RENAM category attributed to the subject. For this reason, evaluation of all these parameters should be considered redundant. The designed protocol should be promoted in the Veneto Region to standardize the operative approach, establishing premises for reliable expert opinions in the forensic setting.