Elsevier

Environment International

Volume 34, Issue 8, November 2008, Pages 1157-1169
Environment International

Beyond the medicine cabinet: An analysis of where and why medications accumulate

https://doi.org/10.1016/j.envint.2008.05.002Get rights and content

Abstract

Active pharmaceutical ingredients (APIs) from medications can enter the environment as trace contaminants, at individual concentrations generally below a part per billion (μg/L). APIs enter the environment primarily via the discharge of raw and treated sewage. Residues of unmetabolized APIs from parenteral and enteral drugs are excreted in feces and urine, and topically applied medications are washed from skin during bathing. These trace residues may pose risks for aquatic life and cause concern with regard to subsequent human exposure.

APIs also enter the environment from the disposal of unwanted medications directly to sewers and trash. The relative significance of this route compared with excretion and bathing is poorly understood and has been subject to much speculation. Two major aspects of uncertainty exist: the percentage of any particular API in the environment originating from disposal is unknown, and disposal undoubtedly occurs from a variety of dispersed sources. Sources of disposal, along with the types and quantities of APIs resulting from each source, are important to understand so that effective pollution prevention approaches can be designed and implemented.

Accumulation of leftover, unwanted drugs poses three major concerns: (i) APIs disposed to sewage or trash compose a diverse source of potential chemical stressors in the environment. (ii) Accumulated drugs represent increased potential for drug diversion, with its attendant risks of unintentional poisonings and abuse. (iii) Leftover drugs represent wasted healthcare resources and lost opportunities for medical treatment.

This paper has four major purposes: (1) Define the processes, actions, and behaviors that control and drive the consumption, accumulation, and need for disposal of pharmaceuticals. (2) Provide an overview of the diverse locations where drugs are used and accumulate. (3) Present a summary of the first cataloging of APIs disposed by a defined subpopulation. (4) Identify opportunities for pollution prevention and source reduction.

Introduction

Pharmaceuticals have myriads of uses for both humans and animals, including therapy, disease prevention, diagnosis, cosmetics, and lifestyle. Residues from hundreds of widely used active pharmaceutical ingredients (APIs) can gain entry to the environment via a complex network of sources and pathways, interspersed through numerous parts of society. These potential contaminants make their way into the environment primarily as a result of their intended use — as caused by excretion or bathing. Disposal of unwanted, leftover medications to sewage and trash is another source of entry, but its relative significance is unknown with respect to the overall levels of APIs in the environment. Wildlife and humans can then experience long-term or intermittent exposure to APIs as trace pollutants, primarily via contaminated water and foods.

Of the research accomplished to date regarding sources, fate and transport, exposure, biological effects, waste treatment, and pollution prevention, very little has been directed at the role played by the APIs in the environment originating from disposal of leftover medications compared with APIs introduced into the environment through excretion and bathing. Leftover, unwanted pharmaceuticals (both human and veterinary) tend to accumulate after being set aside, stored, or forgotten — and this occurs at just about any location where people live, work, or visit. Accumulated or stockpiled leftover medications are eventually disposed either through formal collection programs (with disposal generally at hazardous waste landfills or by incineration) or simply by the end-user discarding directly into sewerage or trash. During storage and imprudent disposal (e.g., leaving leftover drugs visible and accessible to others), a leftover drug can be inadvertently diverted to those for whom the medication was never intended. This can lead to poisoning of humans and pets, or can increase abuse and addiction. Well-designed, efficient disposal programs hold the potential for preventing unnecessary human (and animal) exposure and poisonings, as well as for reducing environmental pollution.

Many factors cause medications to remain unused, creating leftover drugs that can accumulate. A wide spectrum of forces underlies the generation of leftover drugs, ranging from inefficiencies and certain practices of manufacturers, distributors, prescribers, dispensers, and patients themselves. Although design of environmentally prudent and safe disposal programs is currently being pursued (Reid, 2007), much of the need for drug disposal in the first place could be eliminated by focusing corrective actions on these major causes of accumulation with the design and implementation of pollution prevention measures. Such practices would be part of a larger program that oversees all the aspects of unintended, adverse consequences of medications. Such a program has been termed pharmEcovigilance (Daughton and Ruhoy, in press).

Leftover medications pose an acute exposure hazard for both humans and the environment. Opportunities are lost for optimal delivery of healthcare, and valuable healthcare resources are squandered. The likelihood also greatly increases for drug diversion and environmentally unsound disposal. These latter two liabilities can pose acute and chronic poisoning risks for humans and wildlife alike (Daughton, 2007).

This paper focuses on two major aspects of the larger topic of pharmaceuticals as environmental pollutants: (i) the processes, actions, activities, events, and behaviors that cause drug wastage (leading to accumulation and disposal), and (ii) the many and diverse physical sources from which stored and accumulated drugs can enter the environment as a result of disposal. Such information should prove useful for the design of pollution prevention measures that encompass a significant portion of the life cycle of medications. This paper presents the first comprehensive examination of why medications accumulate and the many potential sources or locations from where leftover drugs are disposed. Better understanding of the many and varied origins and sources of leftover drugs will allow for the design of pollution prevention actions best tailored to minimize or eliminate these accumulations, and therefore eliminate or reduce the need for disposal. This paper also presents a summary of the first comprehensive cataloging of the types and quantities of APIs disposed by a defined subpopulation into known sewage treatment plants; these first-ever data provide insights regarding what classes of drugs most commonly accumulate and require eventual disposal.

Section snippets

Background

The use of human and veterinary pharmaceuticals for their intended purposes is accompanied by a very complex network of routes by which APIs eventually gain entry to the environment or result in unintended direct exposures to humans and wildlife (Fig. 1; also Daughton, in press, Fig. 1). A holistic, integrated view of the life cycle of pharmaceuticals includes not just the intended uses of drugs, but also their unintended consequences. A broad spectrum of unanswered questions surrounds the

Discussion

The origin of all pharmaceuticals is probably the simplest part of the puzzle. Pharmaceuticals are manufactured and produced within facilities owned or contracted by the individual pharmaceutical company. Following their manufacture and production, the drugs are transported to those entities that are then charged with distribution of the drugs. These entities include both traditional brick-and-mortar pharmacies and online e-commerce pharmacies (some of which operate illegally as “rogue”

Acknowledgments

We acknowledge P. Michael Murphy and the Clark County Coroner Office staff for granting access to all CCCO case files and for the information they provided. ISR thanks David Hassenzahl, University of Nevada, Las Vegas for continued guidance, and the U.S. Environmental Protection Agency for granting an appointment as a U.S. EPA Student Volunteer.

U.S. EPA Notice: The United States Environmental Protection Agency through its Office of Research and Development funded and managed the research

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