Cardiovascular disease (CVD) is a major public health challenge for the 21st century because of its impact on personal and population health, premature mortality and high societal costs. Identifying novel CVD-risk factors, especially prevalent ones, is therefore important to allow further preventive actions. Polychlorinated (PCBs), other organochlorines and perfluoroalkyl (PFAS) substances, widespread and very persistent environmental pollutants, may be involved in various CVD-related pathophysiological processes. The overall aim is to prospectively assess the association between biomarkers of PCBs and PFAS exposure and first incident myocardial infarction and/or ischemic stroke in two population-based cohorts with biobanks, assuring adequate statistical power and cost-effective handling of expensive chemical analyses. The outcome of this project will fill an important knowledge gap. Because all are exposed to these substances mainly via food – especially fish – a better knowledge of the risks and benefits of fish consumption is important for public health, as the current uncertainty presents a dilemma to consumers and advisory boards.