[First SIVR list of reference values: definitions, methodologic criteria and analytical strategies]

In this paper, a list of reference values for trace elements and some of the main organic xenobiotics and/or their metabolites in biological matrices (urine, serum or blood) is presented. This list has been made out taking into account several variables, such as sex, diet, alcohol and drugs consumption, smoking habits, living area, etc. and it is referred to as the 1st SIVR list 2001. In addition, the SIVR research activity is reassessed on the basis of the availability of multielement techniques and new analytical approaches. In particular, to define the reference values for PCB, selection criteria and analytical methodologies are discussed with a view to choosing the more significant congeners and the most suitable technique. In the end, the results from two SIVR projects concerning the determination of haematic Pb and urinary Hg are synthesized.