Silver nanoparticles are increasingly being used in consumer products, such as clothing and personal care products, in the medical and pharmaceutical industry, and in the food industry. That is why their presence is expected to increase in the environment where they can exert harmful effects on organisms. The UPV/EHU’s Cell Biology in Environmental Toxicology research group has analysed adult zebrafish to find the effects that can be caused in the long term by silver particles present in fresh water.