Pharmaceuticals and Personal Care Products in the Environment: Scientific and Regulatory Issues
Daughton, C.G.; Jones-Lepp, T.L. (eds.) Pharmaceuticals
and Personal Care Products in the Environment: Scientific and Regulatory
Issues, Symposium Series 791; American Chemical Society:
Washington, D.C., 2001.
Copyright 2001 American Chemical Society]
The individual and the environment: Often overlooked in our daily lives are the inescapable, intimate, and immediate connections between our personal activities and the environment in which we live. This is especially true with regard to the use and disposal of consumer chemicals. Many of these chemicals are specifically designed to elicit potent pharmacological or toxicological effects. In distinct contrast to nearly all agro/industrial chemicals, which are often used on large, relatively confined scales, the end use for these consumer chemicals is centered around the individual. It is difficult for the individual to perceive their small-scale activities as having any measurable impact on the larger environment -- personal actions are often deemed minuscule or inconsequential in the larger scheme. Yet it is the combined actions and activities of individuals that indeed can significantly impact the environment in a myriad of ways. A factor making it difficult for the individual to perceive the interconnectedness of their lives and the health of the environment is the immediacy of any adverse effects -- as most actions have delayed consequences, obscuring the ultimate causes.
A significant aspect of our global society that illustrates the potential impact of our lives on the environment is the widespread and escalating use of pharmaceuticals and personal care products (simply referred to as "PPCPs"). Together, they comprise a myriad of chemical classes, many of which possess potent biological activity. The personal, individual use of these substances can lead to their direct and indirect discharge to the environment through sewage treatment systems (indirectly from excreta and directly via disposal) and from other sources such as terrestrial runoff from excreta of medicated domestic animals including pets.
The potential importance of this field of research: Chemical pollution represents one of only a few major classes of stressors that can effect ecological change and impair human health. Up to now (over the last 30 years), environmental science has dwelled almost exclusively on what are most conveniently referred to as the "conventional" pollutants -- those that compose various regulatory lists, primarily agrochemicals and large-volume industrial chemicals -- some of the most notorious of which are the persistent organic pollutants ("POPs", such as DDT, PCBs, dioxins). In terms of the vast number of chemicals in commercial use, however, these conventional pollutants comprise only a small percentage of the total numbers of chemicals that could potentially be found in a hypothetical, extensive environmental survey. Do these conventional pollutants represent the major chemical pollution concern, or are we missing major classes of other chemicals?
For society to gain the ability to prioritize risks, and thereby direct a rational allocation of its limited, economic resources to pollution prevention/mitigation, an expanded understanding is needed of the universe of exposure risks. In any process for evaluating additional chemicals for consideration in relative risk, emphasis needs to be given to the likelihood of environmental presence coupled with the potential to elicit biological effects at low exposure levels -- not just in humans, but also in wildlife.
One very large, diverse group of chemicals that has been largely ignored up until the last decade comprises the biologically active ingredients in (and metabolites/transformation products from) pharmaceuticals and personal care products. Ingestion and application of individual, small amounts of these chemicals worldwide has led to their direct and indirect introduction to surface and ground waters via their excretion or washing into domestic sewage systems, and via terrestrial runoff or leaching (from animals and landfill disposal). The direct impact of the individual consumer in adding to the potential pollutant load on the environment is a concept that has not been well appreciated. Recent data on occurrence of PPCPs in the environment has only laid a foundation on which to further explore this topic -- the initial objective of which is to determine if any concern is warranted.
It is important to avoid confusing two separate, and usually unrelated issues -- "endocrine disruptors" and PPCPs. Only a small subset of PPCPs are known or suspected of being direct-acting endocrine disrupting compounds (e.g., synthetic steroids and other hormones or hormone-like compounds); while many xenobiotics can have a wide range of ultimate effects on the endocrine system, few have direct effects (i.e., serve as immediate endocrine agonists/antagonists at the hormone-receptor level). PPCPs and EDCs are NOT synonymous, and the toxicological concerns are usually totally different. Another important point is that the focus of this overview is on the use and disposal of PPCPs as originating from the activities and actions of individuals and hospitals -- not those from the PPCP manufacturing sector, whose waste streams are much better defined and controlled.
Lack of a book addressing the topic of PPCPs in the environment: While a select few, heavily used "pharmaceuticals" have been known to occur (and sometimes persist) in the environment for nearly 30 years, only in the last decade has a more concerted effort been made to search for any of the myriad of other PPCPs in the environment. PPCPs enjoy worldwide usage and attendant discharge or inadvertent release to the environment. Their introduction to the environment has no geographic boundaries or climatic-use limitations as do many other synthetic chemicals -- they are discharged to the environment wherever people live or visit, regardless of the time of year.
Until very recently, most of the work on PPCPs had been done in Europe. European municipalities in general are more congested than in the U.S. -- the higher confluence of sewage treatment outfalls coupled with smaller receiving-river capacities has heightened awareness of this issue in Europe. The literature on occurrence, exposure, effects, transport/fate, and engineering treatment is very uneven in its development and is spread over a large and sometimes difficult-to-access literature. Although nearly all the literature is in the form of journals and associated compendia, some of which are reviews, no book or U.S. symposium had ever been dedicated to delineating the overall scope of this potential environmental pollution issue; this book is partly based on the first-ever all-day symposium in North America devoted to this topic: Pharmaceuticals in the Environment, American Chemical Society 219th National Meeting, San Francisco, CA, 27 March 2000 (part of the symposium entitled "Issues in the Analysis of Environmental Endocrine Disruptors"). While a number of PPCPs (representing several therapeutic and consumer classes) have already been identified (esp. antimicrobials and hormonal agents) in surface, ground, and sometimes drinking waters, sparse data exists for many of the most widely prescribed drugs and little data exists for personal care products (e.g., musk fragrances, sunscreen agents, antispetics).
Some relevant questions: The possible significance of PPCPs in the environment triggers a host of questions. This book does not pretend to answer these questions, but rather to promote a focused discussion. Some of these questions include: Are the currently regulated lists of "priority pollutants" the only chemicals that deserve our attention regarding environmental fate and effects? What is the prevalence and occurrence of PPCPs in aquatic environments receiving untreated sewage (overflows/spills and "straight-piping") and liquid effluent from treated sewage? Is there any significance to PPCPs leaching into groundwater from solid waste disposal or sewage sludge application? Is there a concern regarding possible residual PPCPs in treated wastewater intended for groundwater recharge? If PPCPs occur in the environment, are their concentrations sufficient to trigger toxicity concerns for non-target organisms (those species for which these compounds were never intended to expose - PPCPs were designed for human use and consumption, unlike agrochemicals that have designed effects on "pest" species)? Do we know enough about the potential effects of PPCPs on non-target species, many of which may not possess the same suite of receptors as do humans? Even if the concentration of an individual PPCP is sufficiently low, is there perhaps need for concern if other PPCPs sharing the same mode of action can combine to reach a threshold level? Does the aquatic environment present a special exposure case since its biota are exposed continually (through multiple generations) to any pollutant that happens to be present? Are there cellular mechanisms in aquatic biota that confer protection from continual exposure - protection that can be compromised, thereby promoting disease? While acute toxicity, carcinogenesis, and mammalian endocrine disruption are potential concerns for a portion of environmental pollutants, should more attention be paid to other, less overt toxicological endpoints, such as immuno-disruption and neurobehavioral change? Should the direct disposal of excess or expired PPCPs to the domestic sewage system and the over-prescribing of various drugs continue? Can humans receive significant exposures to multiple PPCPs by consuming contaminated drinking water or shell/fin-fish? In short, are there unanticipated consequences of PPCPs in the environment -- where's the evidence -- do sufficient data exist to decide whether PPCPs in the environment warrant a more in-depth look?
These are only some of the questions that this book attempts not necessarily to answer, but rather to highlight, in order to stimulate further discussion and research. A major objective of this book is to foster further research so that the scientific community and the public can reach informed decisions. Future research should focus on establishing sufficient science (especially with regard to extent, magnitude, and diversity of occurrence, exposure, susceptibility/effects, and pollution prevention) so that sound decisions can be made regarding human and ecological health.
Scope of book and intended audience: The scope of knowledge required for understanding the environmental aspects of potential chemical pollution from PPCPs can be compartmentalized into discrete categories of the risk assessment "paradigm", which are subjects of great interest to a very broad spectrum of disciplines. The audience includes analytical and environmental chemists, toxicologists, hydrologists, medical scientists, sanitary engineers, risk assessors, and policy makers. Technical areas of the risk assessment "paradigm" include: chemical analysis (methods for identification and quantitation), identification of source/occurrence, environmental fate, exposure, effects, risk assessment, mitigation, pollution prevention, regulation, and research planning (inter-organization coordination). In addition to professional chemists, anyone with a keen interest in the environment, as well as educators and graduate students, should be able to use some of the materials presented here to gain new insights and reach new perspectives in their fields.
With regard to the published environmental PPCP research, the coverage among these categories is very uneven and within some categories is partial/non-existent (such as for aquatic effects). For example, while the sources for PPCPs are well-defined (sewage and runoff from confined animal feeding operations, and medicated pet excreta), and while it appears that direct aquatic exposure may be more significant than human exposure (i.e., via drinking water), major advances are needed: (i) in chemical analysis (with respect to non-volatile, polar, poorly extracted chemicals and ultra-trace analysis), (ii) for a generalized understanding of the distribution of PPCPs across multiple municipal watersheds (to assess magnitude and scope), and (iii) for assessing potential aquatic effects (little is known for these chemicals, which were designed expressly for human and domestic animal usage). Finally, although a number of measures could be instituted to greatly reduce the burden of PPCPs in the environment (from "green drug" design, to controlling dispensing/use/disposal, to implementing new waste treatment technologies) or to screen for risks, few actions can be warranted at this time without a better overall understanding of the issue.
New perspectives in environmental science: Perhaps the most revealing aspect of this book is its attempt to wrest some of the perhaps long overwrought attention that has been devoted to a small subset of conventional pollutants (i.e., POPs) and in posing a bigger question as to whether true environmental risk assessments can be performed without a more encompassing understanding of the universe of chemical stressors to which wildlife is exposed.
Some interesting and potentially important issues relevant to environmental chemistry and ecotoxicology but which are not frequently discussed include the notions that chemical stability is not a prerequisite for environmental "persistence", that subtle toxicological effects could yield major outcomes, and that toxic outcomes could result from non-toxic chemical "potentiators."
Coupled with ecotoxicology's traditional preoccupation with conventional pollutants has been an emphasis on easily measured acute/overt toxicity endpoints. PPCPs serve to illustrate the potential importance of other, more subtle biotic effects (for example, see Fong's chapter on the effect of antidepressants on aquatic life) and less-known cellular processes (for example, see Epel and Smital's review of multi-drug transport and the consequences of its inhibition in aquatic biota) -- two aspects of environmental toxicology that have received little attention, and the latter of which has some profound implications for aquatic health. The question can be asked as to whether subtle effects can accumulate so slowly that major outward change is not detectable until their cumulative level finally cascades to irreversible change. Perhaps another underappreciated issue is that of combined, cumulative exposures to multiple pollutants (perhaps each at a sub-toxicity concentrations) but whose combined doses prove significant. Also to consider is the significance of stressors that do not follow the monotonic sigmoid dose-response curve (e.g., U- and inverted-U-shaped curves). While these concerns are not necessarily unique to PPCPs, their biochemically active nature serves to illustrate these possibilities more so than other pollutants.
The book's final chapter breaks new ground in applying the current body of knowledge (on the occurrence of therapeutic drugs in the environment) by opening a window onto what has long been an aspect of society that has proved difficult to accurately assess -- the magnitude and extent of the use of illicit drugs. The use of sewage-influent monitoring is proposed as a non-intrusive means of calculating illicit drug usage on a community-wide scale. A variety of public and governmental organizations will have to decide whether (and how) they want to implement this newly proposed tool, which is merely the next step in the natural extension of current scientific knowledge.
Acknowledgments: The editors sincerely thank the efforts of the authors in completing their high-quality contributions in a timely manner, and in collaborating with each other to minimize overlap. We thank the numerous reviewers who donated their time and insights to peer review. We also thank the Managers from the U.S. EPA's National Exposure Research Laboratory (especially Dr. John G. Lyon, Dr. Rick Linthurst, and J. Gareth Pearson) without whose active support and encouragement this effort simply would not have been possible, and we thank Marilyn Janunas for her help with some of the details involved in preparing this book.
NOTE: This preface is reprinted with permission from the American Chemical Society. It can be cited as follows:
Daughton, C.G.; Jones-Lepp, T. "Preface," in Pharmaceuticals and Personal Care Products in the Environment: Scientific and Regulatory Issues, Daughton, C.G. and Jones-Lepp, T. (eds.), Symposium Series 791; American Chemical Society: Washington, D.C., 2001.