title: Criteria for the definition of reference values for toxic metals.
abstract: Two types of selection are used to identify subjects who make up reference groups: 'a posteriori' selection starting from a large number of subjects who are then subsequently selected and 'a priori' selection wherein the group to be examined is defined on the basis of preestablished criteria. The main variability factors are biological and those depending on the modalities of selection of groups and determination of the analysis. The nature of the element is also particularly important, i.e. whether an essential element must be considered only a micropollutant or whether it should be considered essential and at the same time a micropollutant. In addition two other factors which play an important role are the temporo-spatial modifications induced by natural or anthropogenic phenomena which influence the modality and degree of exposure in man. Two criteria are generally used in the production of reference groups: exclusion/inclusion and partitioning criteria. While in clinical chemistry the health status represents an important exclusion factor, in the case of metals, the environmental conditions and the function of organs and apparatuses involved in the toxicokinetics of metals can be considered as main criteria. All the other variables such as sex, age, life-style are partitioning criteria and enable us to obtain reference values for more and more homogeneous subgroups.
authors.affiliation: Occupational Health Institute, University of Brescia, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Apostoli
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001782:Blood Donors; D004391:Dust; D004785:Environmental Pollutants / Q000032:analysis / Q000633:toxicity*; D006304:Health Status; D006801:Humans; D007558:Italy; D008670:Metals / Q000032:analysis / Q000097:blood / Q000633:toxicity*; D008962:Models, Theoretical; D012016:Reference Values; D012424:Rural Population; D012907:Smoking; D014505:Urban Population
chemical_list: D004391:Dust; D004785:Environmental Pollutants; D008670:Metals