Kennedy J, Fountain M, Comber S, and Watts C D
There are over 3,000 pharmaceuticals on the UK market but most have never been subject to an environmental risk assessment. In 2003, the Environment Agency published a Position Statement on the impacts of human pharmaceuticals on the aquatic environment  which called for reassurance that low levels of pharmaceuticals being measured in rivers are unlikely to cause significant harm to the aquatic environment. With so many possible candidates it became clear that we needed to prioritise substances so we can focus attention on those with the greatest potential to cause chronic impacts on aquatic life.
We revisited an original ranking exercise conducted in 2002/3 , to generate an up-to-date list of priority substances for investigation, based on present usage patterns in the UK. The top 300 or so substances used in the UK (in terms of tonnage) are included in the exercise. We ranked substances according to their relative risk to the aquatic environment, using a Risk Characterisation Ratio (Predicted Environmental Concentration/Predicted No Effect Concentration). This approach is an initial screening tool based on worst-case assumptions, e.g. no metabolism prior to excretion in the human body.
The PECs were derived using the approach detailed in the EMEA Guideline on the Environmental Risk Assessment of Medicinal Products for Human Use  and were refined using estimates of removal of pharmaceuticals during passage through sewage treatment plants. The PNECs were derived using a number of approaches, and a number of assumptions were necessary due to the lack of experimental ecotoxicity data.
The exercise identified a number of priority substances (RCR>1). We are now in dialogue with the ABPI (Association of British Pharmaceutical Industry) to undertake more detailed reviews, to establish whether or not they pose a chronic risk to aquatic life.
1. Environment Agency (2003) Human Pharmaceuticals: Position Statement. EA, Bristol, UK.
2. Environment Agency (2003) Targeted Monitoring Programme for Pharmaceuticals in the Aquatic Environment (R&D report P6-012/06/TR).
3. EMEA (2005) Guideline on the Environmental Risk Assessment of Medicinal Products for Human Use. Committee for Medicinal Products for Human Use (CHMP), EMEA, London, report no. CHMP/SWP/4447/00.
Poster presented at:
International Conference on Analysis of Emerging Contaminants in the EnvironmentWebsite link:http://www.environment-agency.gov.uk/business/444304/1290036/1290100/1290353/1294402/1314699/