Fish from Nordic fish farms have been criticized for containing "too high" concentrations of persistent organic pollutants (POPs) among others dioxin and PCB. These allegations have caused debate and may have a negative effect on the sale of products from Nordic fish farms in addition to giving a generally bad reputation that affects more or less all Nordic fish farms. It is generally agreed that the relatively high concentrations of POPs detected in fish from Nordic fish farms are caused by the high concentrations of POPs in the fish feed produced and used in the Nordic countries. Beside potential health effects caused by high POP contents in the fish fillet, the surrounding environment may be impacted as well, not only by excreted POPs but also by veterinary medicines used in the fish farms. In Nordic fish farms, veterinary medicines are mainly used therapeutically against different infectious diseases. The amount of veterinary medicines used varies from year to year and in some years, considerable amounts have been used. The major environmental concern in relation to the use of veterinary medicines is the potential occurrence of antibiotic resistance in the naturally occurring micro flora.