Quality control of data produced in biological population surveillance studies on the risk of environmental lead poisoning

: The biological surveys of the general population against the risk of lead intoxication carried out in Italy--in accomplishment both of the EEC directive EEC 77/312 and the Presidential Decree 496/1982--have been always conceived as multicentric activities. Therefore, starting from the first campaign carried out in 1979, strict quality control procedures have been adopted. In brief, each participant laboratory used internal quality control samples and took part in external quality assessment exercises. In addition, ten percent of the blood samples collected during the campaign were analyzed as blind duplicate by both participating laboratories and a reference laboratory. In this paper the quality control procedures adopted will be presented and discussed in detail together with the quality of results obtained in each campaign.