Comparison of Prospective and Retrospective Environmental Risk Assessments of Human Pharmaceuticals

Prospective risk assessment is performed in the context of market authorization of a compound, whereas the retrospective risk assessment is generally aimed to identify the causes of adverse effects that have already occurred (Calow and Forbes 2003). For a large number of existing substances, an environmental risk assessment (ERA) was not required at the time of their introduction; rather it was based on data sets, which nowadays are not considered to be state-of-the-art. For such substances, a retrospective ERA may serve to define quality standards which mark levels of environmental safety. Ideally, the prospective and retrospective risk assessment should have the same outcome if the conceptual approach and the data used for both the proand retrospective risk assessment are likewise suitable. However, in several cases it appeared that the prospective exposure assessment underestimated the actual occurrence of a substance in the environment after a few years of use, or adverse effects were identified, which previously had not been anticipated (e.g., endocrine disrupting effects). In this paper we will compare the prospective and retrospective environmental risk assessment approaches for human pharmaceuticals (proand re-ERA) which have been established within the European Union (EU) in recent years. We have chosen three existing pharmaceuticals for which sufficient data have been generated to compare pro-ERA and re-ERA for the aquatic compartment. Based on these examples, we will highlight and explain the differences between the proand re-ERA for human pharmaceuticals.