BLOOD LEAD MONITORING IN ITALY - ASSESSMENT OF THE QUALITY OF RESULTSOBTAINED BETWEEN 1992 AND 1994

Between 1992 and 1994, a new screening campaign for blood Pb monitorin g in the Italian general population was carried out. Since the first c ampaign (started in 1978, in accomplishment of the European Community Directive 77/312/EEC) a working group of the Laboratory of Clinical Bi ochemistry at the Italian National Institute of Health (Istituto Super iore di Sanita), as the Reference Centre (RC), has coordinated the act ivity of various laboratories spread over the national territory. Appr opriate quality assurance procedures, including an external quality as sessment scheme (EQAS), were elaborated. Within the EQAS, three or fou r trials were carried out every year. Each laboratory participating in the trial analyzed eight control samples prepared from cow blood at d ifferent Pb concentrations. The results obtained by each peripheral la boratory and the RC between 1992 and 1994 have been compared by regres sion analysis. The same statistical method was adopted to compare the results obtained by each peripheral laboratory and the RC in the dupli cate analysis of about 10 per cent of the human samples collected duri ng the 1992-1994 monitoring campaign. There was no evidence of systema tic differences between the regression lines obtained on control and h uman samples. In spite of the lower Pb concentration in the control sa mples analyzed during the 1992-1994 campaign, the analytical performan ce of the laboratories was better than that obtained in the previous s creening campaign (1985-1986). Blood Pb levels observed in human sampl es collected between 1992 and 1994, confirm the downward time trend ob served in the campaigns carried out in 1978-1979, 1980-1981 and 1985-1 986. This study confirms that the results obtained in an EQAS are repr esentative of the actual performance in the analysis of real (human) s amples.