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Organization of an International Database on Micronucleus Frequency in Humans Project Objectives The first objective of the HUMN project is the comparison of results accumulated for base-line MN frequencies from laboratories that have performed human population studies using the cytokinesis-block MN assay. This comparison will provide the information on the extent of variation of "normal" range values for different laboratories and countries. Furthermore, it will provide information on the role played by the laboratory protocol, as well as on the extent to which there is agreement on some variables potentially affecting the base-line micronucleus frequency in lymphocytes, e.g., sex, age, cigarette smoking, diet, etc. The use of a database which consists of data gathered from different laboratories provides many advantages, such as the availability of a very large study group and the ability to compare the results of this dataset with the smaller, independent datasets that make it up. Such a large study group allows more complex analyses on subsets of individual characteristics, than can be obtained from the individual component datasets. Another advantage is the possibility of studying a biological effect under different experimental conditions. If a homogeneous effect is observed in many laboratories, the validity of that finding is clearly more substantiated. Moreover, this approach groups populations that are heterogeneous by origin, age, occupational exposure, life-style, etc., ensuring a representative view of the occurrence of MN in the human species. The main focus of the project is on the cytokinesis-block technique in human lymphocytes, but data on uncultured lymphocytes, will be also be collected. This may give a more comprehensive picture of the in vivo MN occurrence, and the factors that affect MN frequencies. A similar project concerning MN in exfoliated cells is at an evaluation stage. To ensure the high quality of the data on which the analyses will be performed, as well as to reduce the variability inherent to the multi-centers design of the study, some restriction criteria have been defined for laboratories and individual records: (1) use of the cytokinesis-block technique (for cultured lymphocytes); (2) data published in peer reviewed journals, or in case of unpublished data, positive evaluation of the laboratory protocol from the steering committee; (3) a database of at least 50 subjects and for each subject MN frequency evaluated on a minimum of 1000 cells. However, all databases submitted were re-evaluated before their inclusion in the HUMN database. Dr. Stefano Bonassi has conducted analysis of the initial dataset. One paper is already published (EMM 2001), and one more is in preparation (#2: smoking). The organization of a large international database on the MN frequency in human population will make a significant contribution to the understanding of the endogenous and exogenous determinants of this type of chromosomal damage. Furthermore, the availability of data from different laboratory protocols will offer a valuable tool for the purpose of the assay interpretation and standardization. Data Collection and Organization of the database The duty of putting together data from heterogeneous sources and exploiting all the available information without discouraging participants with a huge list of requests, is really challenging. Therefore, for the sake of simplicity, we choose some straightforward rules to collect data. A list of variables which are frequently reported in biomonitoring studies and that are relevant to the aims of the project represent the basic information collected. This information addressed two major aspects, i.e. laboratory methods and subject information. On the contrary, if much more information than requested was available, we appreciated receiving details about what was actually available. Each laboratory, after having verified that all inclusion criteria are met, have prepared three files to be sent to the center collecting data (i.e. method-file, information-file, database-file). Data have been thoroughly analyzed and described in EMM 2001. More papers are in preparation. Should you have any questions about database, please contact Dr. Stefano Bonassi at bonassi@hp380.ist.unige.it. |
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| The HUman MicroNucleus Project | |