This geographic-based ecological study, conducted as part of the 2003–2007 Cancer Plan, aims to analyze the relationship between cancer incidence in adults and exposure to air emissions from municipal waste incineration plants. It focuses on cancers diagnosed in the Haut-Rhin, Bas-Rhin, Isère, and Tarn departments between 1990 and 1999. Nearly 135,000 cancer cases were recorded over approximately 25 million person-years. The exposure of statistical units (Iris) during the 1970s and 1980s was quantified using a model of atmospheric dispersion and accumulated surface deposition of dioxins emitted by 16 incinerators. The results are expressed as relative risks that compare the risks of cancer occurrence in highly exposed areas with those observed in low-exposure areas. A statistically significant association was found between exposure to incinerator plumes and the incidence, among women, of all cancers combined, breast cancer, and non-Hodgkin’s lymphomas. A significant association was also found for non-Hodgkin’s lymphomas in both sexes combined and for multiple myeloma in men only. This study does not establish causality for the observed associations, but it provides compelling evidence to the body of epidemiological arguments highlighting the impact of incinerator emissions on health. As the study focuses on a past situation, its results cannot be applied to the present day. They confirm the validity of the regulatory measures to reduce emissions that have been applied to these industrial facilities since the late 1990s.