Dioxins (PCDD) and furans (PCDF), collectively referred to as "dioxins," belong to the chemical family of chlorinated polycyclic aromatic hydrocarbons (CPACs). They are highly stable, ubiquitous pollutants. The carcinogenic potential and bioaccumulation of these substances in living organisms, as well as accidents such as Seveso, have led to growing public, political, and scientific interest in this chemical family. At the request of the Ministry of Health and the French Environment and Energy Management Agency (ADEME), this study was commissioned to the Institute for Public Health Surveillance (InVS) and the Rhône-Alpes Center for Epidemiology and Public Health Prevention (CAREPS) to clarify the situation regarding "dioxins" in France within the European context and to identify the factors explaining variations in levels within the population. This study was conducted in 1988 and 1999 in collaboration with French milk banks. Indeed, due to the lack of acceptability of blood or adipose tissue samples, most studies on population exposure have been based on the analysis of milk samples. Thus, it focuses on 244 breastfeeding mothers who provided a milk sample for dioxin measurement and completed a questionnaire regarding various factors that could influence the measured levels. This study provides the first results in France on PAH concentrations, allowing for a comparison with those of our European neighbors. It also serves as a solid baseline for levels in France to consider the possibility of establishing monitoring of exposure via breast milk.