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Active Pharmaceutical Ingredients and Aquatic Organisms
Citation:
DAUGHTON, C. G. AND B. W. Brooks. Active Pharmaceutical Ingredients and Aquatic Organisms. Edition 2, Chapter 8, N. Beyer and J. Meador (ed.), Environmental Contaminants in biota: Interpreting Tissue Concentrations, Invited Chapter. Taylor and Francis, Philadelphia, PA, , 287-347, (2011).
Impact/Purpose:
The published literature on APIs as environmental contaminants is dominated with data on the analysis, occurrence, and fate of these chemicals in the environment, together with evaluation of waste and water treatment technologies. Surprisingly, comparatively little has been published regarding the aquatic toxicology of APIs, especially data relevant to exposure. Little information is available, for example, on the occurrence of APIs in aquatic organisms. This in itself is surprising given that predictive models for bioconcentration in fish are not yet up to the task, and empirical data are needed at least to validate computational approaches. The complexities and limitations of modeling bioconcentration of conventional pollutants (especially the legacy pollutants) in fish are discussed in detail by a number of authors (e.g., Nichols et al. 2007; Geyer et al. 2000; Gobas and Morrison 2000; van der Oost et al. 2003).
Description:
The presence of active pharmaceuticals ingredients (APIs) in aquatic systems in recent years has led to a burgeoning literature examining environmental occurrence, fate, effects, risk assessment, and treatability of these compounds. Although APIs have received much attention as “emerging” contaminants of concern from the scientific and public sectors, it is important to understand how traditional approaches to understand and predict exposure and effects of other environmental organic contaminant classes may or may not be appropriate for APIs. For example, traditional approaches for understanding aquatic effects may not be as useful for some APIs (Brooks et al. 2003), but lessons learned from the study of compounds active at the hypothalamic-pituitary-gonadal axis (endocrine disruptors/modulators) may reduce uncertainties associated with environmental assessments of APIs (Ankley et al. 2007). Whereas APIs are often considered as a combined class of environmental contaminants, APIs include diverse groups of chemicals with different physiochemical properties ranging in pharmacological potencies, environmental fate profiles, and patient usage patterns. Due to the relatively rudimentary state of knowledge for aquatic exposures to these substances, an understanding of critical body residues necessary to elicit pharmacologically and ecologically relevant responses is not available at this time. Because exposure does not necessarily evoke effects or risk, current challenges include understanding the relationship between exposure and effects within an ecological risk assessment framework. It appears particularly critical to understand whether internal pharmacological doses of APIs in target tissues result from environmentally relevant exposures. Such information can inform ecological risk assessments examining the potential effects of APIs based on their specific mechanism/mode of action (MOA). Tissue residues of contaminants are commonly used in retrospective ecological risk assessments to support an understanding of environmental exposure (Suter et al. 2000). Bioconcentration factors (BCFs) are useful in both retrospective and prospective assessments of traditional contaminants. APIs are conceptually no different from these conventional contaminants because tissue residues can provide important information in exposure analysis, particularly when used as indicators of exposure in the field. In this chapter we examine relevant information on residues in aquatic organisms, select factors influencing exposure, and available methods to understand relationships between exposure scenarios and effect thresholds. Though APIs are often combined with personal care products (PCPs) in a rapidly developing literature following publication of Daughton and Ternes (1999), we specifically focus on APIs for the purposes of this chapter. A broad literature on PCPs in aquatic organisms continues to develop (e.g., Mottaleb et al. 2009) and was recently summarized elsewhere (Ramirez 2007).