Introduction Persistent organic pollutants (POPs) are potentially dangerous chemical substances which may cross international boundaries, are found often far from their emission sources, persist in the environment, bioaccumulate (ie become concentrated inside the bodies of living things), and consequently pose a threat to human health and the environment. They are poisonous chemical substances that break down slowly and get into food chains. These priority pollutants consist of pesticides, industrial chemical and unintentional by-products of industrial processes. POPs are usually transported across international boundaries by air and water far from their sources, even to regions where they have never been used or produced, affecting ecosystems. For more information on POP emissions, see the data, trackers and indicators on the European Environment Agency website. Efforts to control and ban POPs International At international level there are two major Conventions (international treaties) that are the basis of more focused control measures. Those are: • Protocol to the 1979 Convention on Long-Range Transboundary Air Pollution on POPs (the Protocol) • Stockholm Convention on POPs (the Stockholm Convention) They lay down