Substances of concern have intrinsic properties which are harmful to human health and/or the environment. Examples are Endocrine Disruptors (ED), Persistent, Bioaccumulative and Toxic (PBT), very Persistent and very Bioaccumulative (vPvB) and Per and polyfluorinated alkyl substances (PFAS) as well as Mineral Oils (MOSH and MOAH). Whereas the impact of Microplastics is still under investigation, various exclusion lists and policies were introduced on a global level to exclude the use of materials, which under normal established and foreseeable conditions of use would cause a risk. In this chapter you will find detailed information about all of the mentioned substance classes and the relevance of the EuPIA Exclusion Policy for Siegwerk as printing ink manufacturer.