For each piece of research mentioned in 1° or 2° of Article L. 1121-1, the dossier submitted to the Committee for the Protection of Individuals and, where applicable, to the competent authority, shall determine whether it is necessary for the person not to be able to participate simultaneously in another piece of research and, where applicable, shall set a period of exclusion during which the person taking part in the research may not participate in another piece of research. The length of this period varies according to the nature of the research.