TRACE-ELEMENT REFERENCE VALUES IN TISSUES FROM INHABITANTS OF THE EUROPEAN-UNION .9. HARMONIZATION OF STATISTICAL TREATMENT - BLOOD CADMIUMIN ITALIAN SUBJECTS

Obtaining reliable trace element reference values in tissues and fluid s from inhabitants of the European Union [3] relies on the availabilit y of standardized and harmonized protocols for the statistical treatme nt of the data on trace element levels in general European populations . In this context, cadmium was measured in the blood (BCd) of 514 Ital ian inhabitants from the Lombardy region and the results statistically treated and presented according to a procedure which includes: simple descriptive statistics and graphical analysis such as stem and leaf a nd box-plot representations (average BCd levels were 0.62 mu g/l; geom etric mean, 0.51 mu g/l; median, 0.50 mu g/l; mode, 0.30 mu g/l; 95th percentile, 1.48 mu g/l; 5th percentile, 0.20 mu g/l); p-p plot, Shapi ro-Wilk and Lilliefors tests for normality (the distribution of the da ta is closer to the log-normal distribution and inconsistent with the hypothesis of normality); analysis of variance (BCd increases from 20 to about 60 years and then decreases; it is influenced by smoking but not by body mass and alcohol consumption and it is higher in men than in women); and step wise multiple regression analysis (BCd is influenc ed by the number of cigarettes/day and the total dose of exposure, cig arettes/day multiplied by smoking years). Tentative reference interval s for BCd based on the log transformation of the data are 0.14-1.82 mu g Cd/l (whole population); 0.16-1.94 mu g Cd/l (male) and 0.13-1.66 m u g Cd/l (female); 0.24-2.68 mu g Cd/l (smokers); and 0.14-1.27 mu g C d/l (non-smokers).