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A review of ecological effects and environmental fate of illicit drugs in aquatic ecosystems E.J. Rosi-Marshall a,∗ , D. Snow b , S.L. Bartelt-Hunt b , A. Paspalof b , J.L. Tank c a b c

Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike, Millbrook, NY 12545, USA University of Nebraska-Lincoln, Lincoln, NE 68583-0844, USA University of Notre Dame, Notre Dame, IN 46556, USA

h i g h l i g h t s • • • •

Illicit drugs are detected in surface waters throughout the world. Evidence suggests that illicit drugs may be “pseudo-persistent”. A wide array of aquatic organisms may be sensitive to illicit drugs. Research that focuses on fate and ecological effects of these compounds is needed.

a r t i c l e

i n f o

Article history: Received 15 January 2014 Received in revised form 19 June 2014 Accepted 27 June 2014 Available online xxx Keywords: Cocaine Heroin Methamphetamines Aquatic organisms Freshwater

a b s t r a c t Although illicit drugs are detected in surface waters throughout the world, their environmental fate and ecological effects are not well understood. Many illicit drugs and their breakdown products have been detected in surface waters and temporal and spatial variability in use translates into “hot spots and hot moments” of occurrence. Illicit drug occurrence in regions of production and use and areas with insufficient wastewater treatment are not well studied and should be targeted for further study. Evidence suggests that illicit drugs may not be persistent, as their half-lives are relatively short, but may exhibit “pseudo-persistence” wherein continual use results in persistent occurrence. We reviewed the literature on the ecological effects of these compounds on aquatic organisms and although research is limited, a wide array of aquatic organisms, including bacteria, algae, invertebrates, and fishes, have receptors that make them potentially sensitive to these compounds. In summary, illicit drugs occur in surface waters and aquatic organisms may be affected by these compounds; research is needed that focuses on concentrations of illicit drugs in areas of production and high use, environmental fate of these compounds, and effects of these compounds on aquatic ecosystems at the concentrations that typically occur in the environment. © 2014 Elsevier B.V. All rights reserved.

1. Introduction Throughout the world, humans are conducting an unintended ecological experiment by discharging increasing amounts of an ever-changing mixture of biologically active compounds into aquatic ecosystems. Increasing urbanization and continued human population growth are steadily intensifying this experiment, as wastewater makes up an ever-growing fraction of the flow of lotic ecosystems, especially in urban areas [1]. Pharmaceuticals and personal care products (PPCPs) are biologically-active compounds that are routinely detected in surface waters. The environmental fate and ecosystem consequences of PPCPs represent a crosscutting frontier in aquatic ecology [2] and environmental chemistry [3]. Recent research demonstrates that pharmaceuticals can influence and alter the structure

∗ Corresponding author. Tel.: +1 845 677 5343; fax: +1 845 677 5976. E-mail address: [email protected] (E.J. Rosi-Marshall).

of aquatic communities [4–6] as well as the behavior of aquatic organisms [7,8]. In addition, PPCPs have the potential to influence ecosystem functions such as primary production and microbial respiration [5] and invertebrate secondary production [9]. Illicit drugs and/or illegal use of prescription drugs (e.g., recreational use of opiate painkillers like codeine) are a particularly noteworthy but understudied group of PPCPs. Illicit drugs are designated as those drugs for which non-medical use has been prohibited by international drug control treaties because they are believed to present unacceptable risks of addiction to users [10]. There is a growing global human health risk from the increasing manufacture and use of these chemicals, and there is very likely a global increase in the environmental burden from the continued release of parent compounds, metabolites, and pre-cursor compounds. Hereafter we refer to this group as licit/illicit drugs (LIDs) and they include classes of compounds such as opiates, cocaine, cannabis, amphetamines and other new “designer” drugs [11]. A wide variety of these biologically-active and neurologicallyaddictive substances have been detected in surface waters [11–13]; LIDs likely enter surface waters in similar ways that other PPCPs have been shown to enter surface waters [14–17]. Locations of LID release or ‘hot spots’ include sites downstream

http://dx.doi.org/10.1016/j.jhazmat.2014.06.062 0304-3894/© 2014 Elsevier B.V. All rights reserved.

Please cite this article in press as: E.J. Rosi-Marshall, et al., A review of ecological effects and environmental fate of illicit drugs in aquatic ecosystems, J. Hazard. Mater. (2014), http://dx.doi.org/10.1016/j.jhazmat.2014.06.062

Amphetamine (C9 H13 N)

Structure of primary metabolite

Molecular weight (g/mol)

Aqueous solubility at 25 ◦ C (mg/L)

Log Kow pKa

Log Koc

Elimination half-life

135.21

2800a

1.76c

NA

9–14 h

10.1b

149.23

5 × 105b

2.07c

9.9b

NA

24 h

40–50% unchanged Metabolites: amphetamine, 4-hydroxyamphetmine, norephedrine

Benzoylecgonine (C16 H19 NO4 )

289.33

1605a

−1.32a

2.15

NA

1 h, 6 h (BE)

1–9% unchanged 26–54% as benzoylecgonine Other metabolites: ecgononine methyester

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Methamphetamine (C10 H15 N)

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25–35% unchanged Metabolites: 4-hydroxyamphetamine, norephedrine

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Primary compound(s) excreted

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Table 1 Compound properties.

Structure of primary metabolite

Morphine (C17 H19 NO3 )

Molecular weight (g/mol)

Aqueous solubility at 25 ◦ C (mg/L)

Log Kow

pKa

Log Koc

Elimination half-life

285.34

149 at 20 ◦ Cb

−0.1d

8.0d

2.6–2.7d

2h

11-nor-9-carboxytetrahydrocannibinol (C21 H28 O4 )

344.45

NA

NA

NA

NA

MDA (C10 H13 NO2 )

179.22

2250a

1.64c

NA

NA

MDMA (C11 H15 NO2 )

193.25

5400a

2.28a

NA

NA

mephedrone (C11 H15 NO)

177.24

5211a

2.39a

NA

NA

a

Estimated from US EPA EPI Suite. TOXNET Toxicology Data Network, available at toxnet.nlm.nih.gov. c [72]. d [38]. b

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15–85% as morphine Other metabolites: normorphine

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Primary compound(s) excreted

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Table 1 (Continued)

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of wastewater treatment plants (WWTP), near production/manufacturing facilities, septic fields, and associated with application of municipal biosolids. In addition, leaking pipes, aging infrastructure and combined sewer overflows could contribute to hot spots for LIDs. In fact, aging infrastructure, although not well characterized, may be a significant source of sewage to urban streams [18,19] and likely these areas may contain a cocktail of PPCPs including LIDs. Recent studies confirm that LIDs occur frequently in surface waters [11], but their fate is understudied and these compounds may have ecological consequences even at extremely low concentrations [11]. It will be critical to understand both the fate and the ecological effects of LIDs on aquatic ecosystems in order to determine if these compounds present a unique risk to the structure and function of surface waters. There are clear biological and behavioral effects of LIDs on humans, but these same biochemical regulators and transmitters have yet to be investigated with regard to aquatic organisms and ecological effects. Our goal is to review the current understanding regarding the fate of LIDs and their potential effects on aquatic ecosystems. Although LIDs occurrence and concentrations are not regulated in wastewater, these compounds are discharged to surface waters through their manufacture and subsequent use. First we provide a short review of the occurrence of LIDs, and then we review recent studies that may provide insights into the fate of these compounds. Although LIDs have powerful biological effects on humans, any effects resulting from exposure to aquatic organisms and ecosystems is almost entirely unknown. Because of this gap, we used a wide variety of literature sources to make predictions about how these compounds might affect a range of aquatic organisms (i.e., from bacteria to fish) and ecological functions, and provide a foundation for hypothesis generation and future research directions.

2. Occurrence of LIDs in surface waters There is extensive research demonstrating that PPCPs are present in aquatic ecosystems [e.g. 14,20]. Biologically-active chemicals used illicitly can be classified by their structure, primary metabolites, properties, elimination rates and estimated use (Table 1). Recently several studies have investigated the occurrence of parent compounds, and a few studies have included analysis of expected human metabolites in aquatic environments. Most of this research has focused almost exclusively on urban or moderately-sized rural wastewater treatment plants, often investigating treatment efficacy for specific compounds. Relatively few studies have exclusively reported the occurrence of LIDs in surface waters, though a number have measured low levels (i.e., ng/L) of amphetamine, methamphetamine, morphine, MDMA (ecstasy), tetrahydrocannabinol (THC), and cocaine and cocaine metabolites [12,21–23]. More frequently, investigators have measured the concentrations of LIDs in surface waters receiving wastewater effluent and in general demonstrate that trace concentrations of amphetamine, methamphetamine, morphine, MDMA (ecstasy), tetrahydrocannabinol (THC), and cocaine and cocaine metabolites in occur directly in wastewater effluent, or in rivers receiving effluent [12,13,21,22,24,25]. For example, Bartelt-Hunt et al. [13] detected a range of illicit and other pharmaceutical compounds using passive samplers placed upstream and downstream of WWTP effluent discharges at several Midwestern sites; methamphetamine concentrations downstream of WWTP effluent ranged from ∼2 to 350 ng/L with few detections upstream and no detections of amphetamine. A similar study was conducted in Switzerland and demonstrated that cocaine and benzoylecgonine, amphetamine, methamphetamine, MDMA, morphine, codeine, heroin metabolites 6-acetylmorphine and 6-acetylcodeine, and THC metabolites were present in wastewater treatment plant effluent, as well as several lakes and streams receiving effluent [26]. In the Swiss study, a majority of the river and lake samples contained trace amounts of the cocaine metabolite, as well as methadone at ng/L levels. High concentrations of cocaine and its metabolite, as well as amphetamine-like stimulants (MDMA) were also detected and interpreted to represent event use or “hot moments” of illicit compounds (i.e., parties and raves). Alternatively, in some cases detection of LIDs can be temporally uniform and in a recent study in the United Kingdom, 99% of the monthly samples of influent to

7 WWTPs contained detectable concentrations of the metabolite of cocaine [24]. In addition to measuring residues of drugs downstream of WWTPs, areas upstream of drinking water intake plants have also been surveyed for the occurrence of LIDs. For example, the River Llobregat in Spain supplies raw water for drinking water production to Barcelona, and because the metropolitan area includes >2 million inhabitants, many small to medium-size WWTPs discharge their effluents into the Llobregat. As a result, this area has frequent detections of opiates, cannabinoids and several metabolites in raw and treated wastewater, and in surface water receiving treated effluent, and codeine, morphine, methadone, and a THC metabolite were detected in almost all samples with median concentrations near 60 ng/L [27]. In addition, opiates and cannabinoids in surface waters used for drinking water production showed the presence of the same compounds identified in WWTP effluents at concentrations up to 76 ng/L for codeine; 31 ng/L for EDDP (a metabolite of morphine); 12 ng/L for morphine and 9 ng/L for methadone at drinking water treatment intakes [27]. Leaking infrastructure, combined sewer overflows (CSOs), and septic drainage containing untreated sewage may also contribute LIDs to surface waters. For example, a recent survey in Minnesota found that a third of the residentially-populated lakes studied contained detectable concentrations of the breakdown product of cocaine among other PPCPs [28], though the sources of these compounds were not readily identified. In general, there is less known about the contributions of leaking infrastructure, CSOs, and septic fields as sources of PPCPs to surface waters [29–32], which represents a knowledge gap needing further investigation. Because the occurrence of PPCPs is linked to human use patterns, regional population demographics may influence the concentrations of LIDs detected in surface waters. Human population dynamics associated with LID occurrence in wastewater was investigated in a study of 25 WWTPs throughout France [33]; they found differences in the concentrations of LIDs in rural compared to urban areas and attributed these differences to human use patterns. Other factors may also influence spatial patterns in LID occurrence in the environment. For example, a study of wastewater effluent from an airport in the Netherlands was compared to urban wastewater without airports and methamphetamine was detected only in airport wastewater thought to be primarily from travelers [34]. Both weekly and seasonal dynamics in use, related to weekend activities or cultural events, can influence the occurrence of LIDS in wastewater effluent and surface waters. For example, the highest concentrations of LIDS in a small treatment facility were observed during the weekend and presumed to reflect changing patterns of recreational use [33]. Public gatherings and sporting events will likely change the composition of effluent; the concentrations of cocaine, methamphetamine and MDMA increased in wastewater influent and effluent in conjunction with the 2010 Super Bowl weekend near Miami Gardens, Florida [35]. Weekends, sporting events, large festivals or other gatherings may result in spikes in use and the potential discharge of LIDs to the environment and should be considered in designing sampling associated with research or monitoring programs. Although research describing the occurrence of illicit drugs provides insights into spatial and temporal dynamics of these compounds in surface waters, there are a number of large gaps in our understanding about the presence of these compounds in surface areas. In particular, considering that illicit drugs are often produced in areas of the world where water quality measurements are less frequent (i.e., specifically, regions of central and South America, Afghanistan, and generally, in the developing world), LIDs occurrence in surface waters that drain these areas of production are not well characterized. Based on this short review, most of the available information on occurrence has been focused on

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municipal treatment plant effluent in urban areas of developed countries and, for a variety of reasons, few studies have examined occurrence in underdeveloped counties near manufacturing centers, or areas of high use with little wastewater treatment infrastructure. Although the number of hectares in cultivation of illicit drugs including marijuana, coca, and heroin has declined in recent years [36], it is currently not known how this cultivation intensity translates into detectable concentrations of these compounds in surface waters. In developing countries the use of drugs including cocaine and heroin has declined, but the use of amphetamine-type stimulants has been on the rise [36]. This shifting mosaic of production and use in the developing world is likely to result in shifts in the concentrations of these substances entering surface waters but this has not been investigated. For example, there will be a net increase in the concentrations of illicit drugs entering surface waters if use of illicit drugs in regions of the world where human waste is typically treated by WWTPs shifts to regions lacking wastewater treatment infrastructure. More research is needed to characterize the occurrence of LIDs in many areas of the world, especially in regions where high production or use and limited wastewater treatment occur. The presence of LIDs in surface waters may occur in the developing world and developed urban areas where drug use is high and aging infrastructure or CSOs contribute untreated sewage to surface waters. Generally, the suite of LIDs present in surface waters is likely to be linked with production and/or human population use in the watershed [21,22,37].

3. Fate of LIDs in streams To date only a few studies have examined the fate and transformation of illicit drugs in surface water, soils, and sediments. For example, the partitioning of illicit drugs in soils and wastewater solids has been investigated for some illicit drugs including morphine [38] and cocaine and cocaine metabolites [39]. Using kinetic experiments, Stein et al. [38] evaluated sorption of morphine to two sediments and found significant dissipation of morphine, even in the presence of sodium azide, which complicates interpretation of morphine sorption kinetics. Using a 24 h equilibration period, log Koc values for morphine ranged from 2.6 to 2.7 and were in good agreement for the two sediments evaluated. Plósz et al. [39] evaluated sorption of cocaine and cocaine metabolites to wastewater biomass at near neutral pH, and they determined linear partition coefficients (Kd ) equal to 8400; 200; and 300 L/kg for cocaine, benzoylecgonine, and ecgonine methyl ester, respectively. Sorption of illicit drugs is likely to be pH dependent, as several illicit drugs will be charged at pH ≥ 8 (Table 1) and many illicit drugs are highly polar and may exhibit hydrogen bonding [38]. In addition, LIDs may have positively charged functional groups at environmentally-relevant pH levels, which can interact with negatively charged soil or mineral surfaces. Although there is minimal published literature on the sorption of LIDs to soils, parallels may be drawn from the behavior of other cationic pharmaceuticals in the environment. For example, based on Kd values measured in the laboratory, Stein et al. [38] determined the solid-associated fraction of psychoactive drugs to be less than

A review of ecological effects and environmental fate of illicit drugs in aquatic ecosystems.

Although illicit drugs are detected in surface waters throughout the world, their environmental fate and ecological effects are not well understood. M...
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