Trace elements were determined by TXRF in whole blood samples in a randomly non-occupational exposed population living in
the Metropolitan Zone of the Mexico Valley (MZMV). Arithmetic and geometric means of S, Ca, Cu, Zn, Rb and Pb concentrations,
were on the reported range values for non-occupational population in other countries, while those of K and Br were higher,
possibly due to dietary habits and geographical or environmental factors. The noticeable decline in blood lead level (91%)
should be positively perceived. As a part of the Quality Control Program, a certified IAEA-A13 was tested.