Environmental risk analysis and prioritization of pharmaceuticals in a developing world context

The impact of residual pharmaceuticals on the aquatic environment has gained widespread attention over the past years. Various studies have established the occurrence of pharmaceutical compounds in different water bodies throughout the world. In view of the absence of occurrence data in a number of developing world countries, and given the limited availability of analytical resources in these countries, it is prudent to devise methodologies to prioritize pharmaceuticals for environmental monitoring purposes that are site specific. In this work, several prioritization approaches are used to rank the 88 most commonly consumed pharmaceuticals in Lebanon. A simultaneous multi-criteria decision analysis method utilizing the exposure, persistence, bioaccumulation, and toxicity (EPBT) approach is applied to a smaller subset of the original list (69 pharmaceuticals). Several base cases are investigated and sensitivity analysis is applied to one of these base case runs. The similarities and differences in the overall ranking of individual, and classes of, pharmaceuticals for the base cases and the sensitivity runs are elucidated. An environmental risk assessment (ERA), where predicted environmental concentrations (PEC) and risk quotients (RQ) are determined at different dilution factors, is performed as an alternative method of prioritization for a total of 84 pharmaceuticals. The ERA results indicate that metformin and amoxicillin have the highest PECs while 17β-estradiol, naftidrofuryl and dimenhydrinate have the highest RQs. The two approaches, EPBT prioritization and ERA, are compared and a priority list consisting of 26 pharmaceuticals of various classes is developed. Nervous system and alimentary tract and metabolism pharmaceuticals (9/26 and 5/26 respectively) constitute more than half of the numbers on the priority list with the balance consisting of anti-infective (4/26), musculo-skeletal (3/26), genito-urinary (2/26), respiratory (2/26) and cardiovascular (1/26) pharmaceuticals. This list will serve as a basis for the selection of candidate compounds to focus on for future monitoring campaigns.