Human placenta as a ‘dual’ biomarker for monitoring fetal and maternal environment with special reference to potentially toxic trace elements. Part 2: Essential minor, trace and other ž non-essential/ elements in human placenta

A survey of elemental composition of the human placenta was undertaken to evaluate reference values for minor and trace elements Žessential and non-essential.. The new data collection was narrowed down to results generated between the period of 1975 2000, since analytical methodology was becoming increasingly reliable with time for many elements. The search revealed the following results Ž g g, based on wet weight.: Ca 770; Cl 1900; K 1685; Mg 100; Na 360; P 1700; and S 350. However, Na, P and S need further confirmation. For a group of essential trace elements following average values were evaluated Ž g g, based on wet weight.: Co 0.007; Cr 0.03; Cu 0.9; Fe 69; I 0.005; Mn 0.08; Mo 0.02; Se 0.2; and Zn 10. However, the iodine value needs further confirmation. In addition, information values have been identified for a number of so-called non-essential elements such as Ag, Au, B, Ba, Br, Cs, F, La, Rb, Sb, Sc, Si, Sn, Sr, Ti, V and W. The survey results for toxic trace elements As, Cd, Hg, Ni and Pb are discussed in part 3 of this paper along with placenta as a biomonitor for toxic trace elements.