Impact of Pharmaceuticals on the Environment: Risk Assessment Using QSAR Modeling Approach

Abstract

An extensive use of pharmaceuticals and the widespread practices of their erroneous disposal measures have made these products contaminants of emerging concern (CEC). Especially, active pharmaceutical ingredients (APIs) are ubiquitously detected in surface water and soil, mainly in the aquatic compartment, where they do affect the living systems. Unfortunately, there is a huge gap in the availability of ecotoxicological data on pharmaceuticals' environmental behavior and ecotoxicity which force EMEA (European Medicines Agency) to release guidelines for their risk assessment. In silico modeling approaches are vital tools to exploit the existing information to rapidly emphasize the potentially most hazardous and toxic pharmaceuticals and prioritize the most environmentally hazardous ones for focusing further on their experimental studies. The quantitative structure-activity relationship (QSAR) models are capable of predicting missing properties for toxic end-points required to prioritize existing, or newly synthesized chemicals for their potential hazard. This chapter reviews the information regarding occurrence and impact of pharmaceuticals and their metabolites in the environment along with their persistence, environmental fate, risk assessment, and risk management. A bird's eye view about the necessity of in silico methods for fate prediction of pharmaceuticals in the environment as well as existing successful models regarding ecotoxicity of pharmaceuticals are discussed. Available toxicity endpoints, ecotoxicity databases, and expert systems frequently used for ecotoxicity predictions of pharmaceuticals are also reported. The overall discussion justifies the requirement to build up additional in silico models for quick prediction of ecotoxicity of pharmaceuticals economically, without or involving only limited animal testing.

Keywords: APIs; CEC; Ecotoxicity; In silico; Pharmaceuticals; QSAR; Risk assessment; Risk management; Waste management.

Fig. 1

Sources, routes and fate of pharmaceuticals in different compartments of environment

Fig. 2

Types of pharmaceutical hazardous wastes with few examples [Color of the boxes for the medical waste represents the color of the waste container]

Fig. 3

Different ways of treatment for medical wastes to avoid high risk of ecotoxicity

Fig. 4

Reasons for ecotoxicity study along with steps for risk assessment and risk management due to pharmaceuticals hazards

Fig. 5

Areas of risk assessment and modeling for ecotoxicity prediction as stated to the OECD

Fig. 6

Category of information included in predicting health and environmental effects according to the OECD guidelines

Fig. 7

Most common in silico tools for the prediction of pharmaceuticals ecotoxicity

Fig. 8

The need of in silico modeling assessing the impact of pharmaceuticals ecotoxicity