There is a great concern in the Basque Country regarding emissions from waste incineration, in particular that of organochlorines (OCs), including dioxins, furans and polychlorinated biphenyls (PCBs), and their potential effect on human health. In 2005, a municipal solid waste plant (MSWP) started to operate in Bilbao, representing an opportunity to assess the exposure to the aforementioned pollutants among people living at various distances from the plant. In 2006 and 2008, we carried out two cross-sectional studies to quantify and assess changes in levels of these pollutants. The objective of this study was to describe the levels of OCs in the blood serum in 2013 of 127 adults of this prospective cohort, in four centres of population, near to and further away from the MSWP, and to study trends over time since it started to operate. This study shows the levels of OCs have decreased significantly, from 37.2% to 80.1%. Further, levels of OCs in areas near to the MSWP were not found to be higher than those in areas further afield.