Particle background levels in human tissues - PABALITH project. Part I: a nanometallic study of metal-based micro- and nanoparticles in liver and kidney in an Italian population group

We used field-emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDS) microanalysis to determine size, shape, and elemental composition of particles in the liver and kidney autopsy of 35 subjects living in Sardinia. Particles were detected in 94% of livers and in 97% of kidney samples as aggregates, ranging between 50 nm and 100 μm. A total of 513 particle aggregates were observed in all tissues (276 in the liver and 237 in the kidney samples). Aggregates consisted of single elements (As, Ba, Cu, F, Fe, Ge, Hg, Ni, P, Pb, S, Si, Ti) or multiple association of elements, up to six. Silicon and Fe were the main element constituents (presence in 61% and 23% of the total Pags) followed by Al, Hg, Ni, Pb, and Ti (< 1%). Calcium, Cl, Co, Cr, Na, K, P, Sc, Sn, W, V, Zn, sometimes Mg, Rh, and Ta, were also detected. Overall, our findings suggest that the ubiquitous presence of metal species as particle aggregates in human tissues would be a condition of normality, although such presence per se is far from being used as a toxicity biomarker. Before being able to clarify the implications of particles in diseases or normal physiological processes, the biological meaning of particles background level we observed in liver and kidney must be elucidated.