Addressing the use and end-of-life phase of pharmaceutical products in life cycle assessment

Abstract

Pharmaceutical residues in the environment can pose significant risks to ecosystems and human beings due to adverse pharma-specific effects. Existing life cycle assessment (LCA) studies do not usually consider the use and end-of-life (EoL) phase of pharmaceuticals and thus exclude relevant potentially toxic emissions of an active pharmaceutical ingredient (API). Therefore, a simplified inventory model for the use and EoL phase of pharmaceuticals is provided by estimating API flows and emissions to the environment. Both the qualitative description of the use and EoL phase of pharmaceuticals and the quantification of the flows within each life cycle phase are based on literature and expert knowledge. Existing approaches to determine the API emissions are adjusted to make them applicable in LCA. In addition, different uses and EoL scenarios (e.g. depending on the patients’ disposal behaviour) are specified, and assumptions are highlighted. Finally, the model is exemplarily applied to the oral intake of ibuprofen to test its applicability. Eleven potential flows and emissions of an API are identified and quantified for different application forms (pulmonary, oral, cutaneous). The model is applied to ibuprofen where potential API emissions result from administered and unused products. Referred to the administered amount of ibuprofen (reference flow), the product is mainly metabolized (73.1%). The unmetabolized (parental) compound enters the sewage treatment plant where it is degraded (13.94%), or emitted to surface water (8.35%), air (0%) and sewage sludge (0.36%). The remainder cannot be clearly assigned to one of the flows (4.25%). The results of this example are hardly comparable to existing measured data because they are related to the functional unit. The effect of assumptions, limitations due to data availability and the geographic scope reveal the need for further research. To facilitate the consideration of the use and EoL phase of pharmaceuticals in future pharma-LCAs, a simplified inventory model specified for German conditions, is provided which allows to calculate inventory results with easily and publically accessible data. However, remaining challenges such as the lack of data to model the behaviour of metabolites in the sewage treatment plant, missing approaches to include specific pharmaceuticals (e.g. hormones, anticancer drugs), the consideration of other sewage treatment technologies such as ozonization, the integration of API emissions from sewage sludge (e.g. due to the use as fertilizer) or the scope expansion with regard to the geographic validity of the model shall be further examined.