Pharmaceuticals are designed to have biological effects and these effects have also bern observed in organisms exposed to these pollutants in the environment. A myriad of effects have been reported and range from the feminisation of fish to the bacterial selection of resistance to antibiotic medicines, potentially affecting human populations. The potency and concentration of chemicals in the environment is key with some effects observed at extremely-low concentrations down to the nanograms per litre scale (think of a few grains of salt in an olympic-sized swimming pool). 

​

​