Trace elements in forensic human lung: a new approach to the diagnosis of seawater drowning. A preliminary study

Abstract: The diagnosing of drowning remains one of the most challenging activities for the forensic pathologist. There is little information on the impact on the lung as a target organ in death by drowning. We aimed to investigate the concentration of trace elements in the lungs of people who had suffered different types of death to evaluate the discriminating ability of trace elements to identify seawater drowning (SWD). A total of 11 trace elements were analyzed by Inductively Coupled Plasma-Mass Spectrometry in 74 forensic cases. Sampler scanning electron microscopy and Energy Dispersive X-ray spectroscopy (EDX) were used to identify ultrastructural lung alterations. A Principal Component Analysis (PCA) of trace elements was carried out. The trace elements in SWD lungs were detected in the following order of concentration: Br˃Zn˃Sr˃Cr˃Cu˃As˃Pb˃Se˃Mn˃Ni˃Cd. Our results showed significantly higher concentrations of Br and Sr (P=0.010 and P=0.000) and significantly lower concentrations of Zn, Pb, Cu, Cd, and Se in SWD compared with other causes of death. After adjusting by confounder factors, Sr and Br remained as predictive independent factors for diagnosis of drowning (p=0.042, in both cases). These results were confirmed by PCA, which revealed a wide separation between SWD and the rest of the causes of death. Our SWD cohort was characterized by high concentrations of the trace elements Br and Sr and low concentrations of Zn, Pb, Cu, Cd, and Se in lung tissue, while PCA showed its discriminatory capacity to identify death by seawater drowning. These findings, together with those obtained using other techniques, can be of great importance in the diagnosis of SWD. Keywords: trace elements; seawater drowning; asphyxia; forensic; human lung; ICP-MS

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