Various studies show an increase in the number of cases of early puberty in girls with breast development with a variable clinical presentation and evolution. This increasing phenomenon concerns girls between 6 and 8 years old. In a large number of cases, from 70 to 95% depending on the series, no medical cause is found and environmental factors are suspected to be involved. Descriptive studies of these patients are scarce and not always provide an overview of all the parameters in line with the concept of the exposome. The PENELOPE clinical trial will allow to analyze a large number of parameters, including the adipose tissue, its metabolism, the endocrine disruptors, and the epigenetic modifications, and to study the impact of environmental health measures in the evolution of these parameters. The data from the analyses of the endocrine disruptors of the patients will be explored in parallel in experimental models (amphibians, murine, cellular) in order to test potential mechanistic hypotheses.