Over the last decade, a successful re-introduction program resulted in the establishment of an otter population in the Wieden-Weerribben area, the Netherlands. The next stage of the reintroduction program intends to create a meta-population by facilitating the establishment of new populations at other locations as well. The current plan is to re-introduce otters in the river-system of the river Rhine and the catchment of the Meuse. These river-systems, however, are known to have elevated concentrations of certain pollutants. Therefore, information is needed on the potential risks of these pollutants for future otter populations. This is a short note summarising the literature on risks of pollutants for otter populations. This note is not exhaustive, but will deliver some insight in their potential impact. Based on this, some recommendations will be formulated.