Reference values for elemental concentrations in some human samples of clinical interest: a preliminary evaluation

Over 60 investigators, some of them with an outstanding international reputation as analysts, were requested to identify reliable data from their countries for elemental concentrations in normal adult human samples of clinical interest by contributing their own data as well as screening the literature information. A set of samples consisting of whole blood and its components, urine, milk, liver and hair were chosen and considered for 15 elements of biological significance: Zn, Cu, Fe, Se, Mn, Pb, Cd, Hg, As, Mo, Cr, Co, I, Ni and F. The results partly cover over 40 countries from the global regions of Africa, Asia, Europe, North, South and Central America, Australia and New Zealand. This survey has been useful in demonstrating certain trends of trace element picture around the world, at least qualitatively. Both diet and environment have a strong influence on the distribution pattern of several elements such as As, Cd, Mn, Pb, Se and Zn. A limited comparison of the available information on soil status of different countries revealed interesting associations for elements such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to supply a reasonable amount of data on samples requested here. In particular, for a number of countries, reliable data for even very essential elements such as Cu, Zn and Fe were not available. In view of the nutritional importance of several elements the time is ripe for international organizations to intervene and help produce some reference data for selected global regions which lack data of any kind.