Pharmacoemissions: contribution of an ageing population to emissions arising from utilisation of pharmaceutical products

Abstract

Emissions of pharmaceuticals into the environment are growing proportionately to the level of consumption of medicinal products. Likewise, the general upward trends in consumption of pharmaceuticals across the European Union (EU) are influenced by epidemiological changes, demographic changes and lifestyle expectations experienced in many Member States. Research on pharmaceuticals in the environment is expanding at a significant rate, elucidating more aspects of this emerging environmental issue. Despite that, the knowledge base on pharmaceuticals in the environment is still markedly limited, primarily because of challenges posed by the sheer number of substances available on the market, exceeding 3,000 pharmaceutical ingredients worldwide. This research focused on explaining two aspects of the emission of pharmaceuticals into the environment. The principal investigation of the research consisted of addressing the novel question of the contribution to the emissions levels exerted by one aspect of demographic change: population ageing. This multidisciplinary research question framed the overall scope of the study, leading to the investigation of consumption of medicinal products. Availing of a five and half year prescribing data sample for Ireland covering the period from 2008 to 2013, the study progressed into the statistical analysis of consumption patterns, which evolved into a systematic methodology, developed in R statistical software, for the rapid assessment of historical and forecast trends of consumption of medicinal products. In addition to assisting in measuring the contribution of population ageing to the consumption of pharmaceutical products in Ireland, the software developed in R also provided empirical evidence on trends of consumption, potentially warranting research of substances currently belonging to the knowledge gaps on the occurrence of pharmaceuticals in the environment. For instance the antineoplastic mercaptopurine was identified because, along with the intrinsic toxicity of the substance, outpatient consumption increased by 13.2 % per annum during the data sample period. The research showed that, while population ageing caused an increase in contribution to the consumption of 66.7 % of the substances assessed (n = 84), a general increase in consumption, irrespective of demographic changes, was measured for 77.5 % of the formulary of pharmaceutical products evaluated (n = 89). A six month survey measuring environmental concentrations in the treated effluent of a major urban sewage treatment plant of the antiepileptic pregabalin, one of the substances showing the highest annual change in consumption (28.5 %), was conducted to validate the statistical analyses of consumption patterns. Pregabalin was detected in 100 % of the samples analysed (n = 10) at an average monthly concentration of 1.11 ± 0.22 μg/L. The modelling conducted in this research demonstrated the erratic pattern of consumption for most pharmaceutical substances suggesting that measured environmental concentrations of pharmaceutical products reported in the body of literature are likely to be transient. Since October 2005 holders of patents of new molecules seeking to enter the EU market have had to provide an environmental risk assessment before the medicinal product could be marketed. In light of the erratic consumption trends identified by this research, the long-term validity of such environmental risk assessments may be disputed.