A rational approach to selecting and ranking some pharmaceuticals of concern for the aquatic environment and their relative importance compared with other chemicals

Aquatic organisms can be exposed to thousands of chemicals discharged by the human population. Many of these chemicals are considered disruptive to aquatic wildlife; the literature on the impacts of these chemicals grows daily. However, since time and resources are not infinite, we must focus on the chemicals which represent the greatest threat. One group of chemicals of increasing concern is the pharmaceuticals, where the struggle is to identify which of them represent the greatest threat. In the present study, we compiled a list of 12 pharmaceuticals based on scoring the prevalence of different compounds from previous prioritization reviews. These included rankings based on prescription data, environmental concentrations, PEC/PNEC ratios, PBT, and fish plasma model approaches. The most frequently cited were diclofenac, paracetamol, ibuprofen, carbamazepine, naproxen, atenolol, ethinylestradiol, aspirin, fluoxetine, propranolol, metoprolol and sulfamethoxazole. For each pharmaceutical, literature on effect concentrations was compiled and compared with river concentrations in the UK. The pharmaceuticals were ranked on the degree of difference between the median effect and median river concentrations. EE2 was ranked as the highest concern, followed by fluoxetine, propranolol and paracetamol. The relative risk of these pharmaceuticals was compared with those of metals and some persistent organic pollutants. Pharmaceuticals appear to be less of a threat to aquatic organisms than some metals (Cu, Al, Zn) and triclosan using this ranking approach