Pharmacodynamic activity of drugs and ecotoxicology--can the two be connected?

Occurrence and distribution of steroids, hormones and selected pharmaceuticals in South Florida coastal environments

The common occurrence of human derived contaminants like pharmaceuticals, steroids and hormones in surface waters has raised the awareness of the role played by the release of treated or untreated sewage in the water quality along sensitive coastal ecosystems. South Florida is home of many important protected environments ranging from wetlands to coral reefs which are in close proximity to large metropolitan cities. Because, large portions of South Florida and most of the Florida Keys population are not served by modern sewage treatment plants and rely heavily on the use of septic systems, a comprehensive survey of selected human waste contamination markers was conducted in three areas to assess water quality with respect to non-traditional micro-constituents. This study documents the occurrence and distribution of fifteen hormones and steroids and five commonly detected pharmaceuticals in surface water samples collected from different near shore environments along South Florida between 2004 and 2006. The compounds most frequently detected were: cholesterol, caffeine, estrone, DEET, coprostanol, biphenol-A, beta-estradiol, and triclosan. The concentration detected for estrone and beta-estradiol were up to 5.2 and 1.8 ng/L, respectively. Concentrations of caffeine (5.5-68 ng/L) and DEET (4.8-49 ng/L) were generally higher and more prevalent than were the steroids. Distribution of microconstituents was site specific likely reflecting a diversity of sources. In addition to chemical analysis, the yeast estrogen screen assay was used to screen the samples for estrogen equivalency. Overall, the results show that water collected from inland canals and restricted circulation water bodies adjacent to heavily populated areas had high concentrations of multiple steroids, pharmaceuticals, and personal care products while open bay waters were largely devoid of the target analytes.

Correlations between in situ sensor measurements and trace organic pollutants in urban streams

Quantification of organic and microbial pollutant loading is expensive and labor-intensive because collection and analysis of grab samples are needed. Instruments are available, however, for in situ analysis of basic water quality parameters at high temporal resolution. Throughout the late summer and fall of 2008 a two-node water quality monitoring network was deployed to measure turbidity, specific conductance, pH, depth, temperature, dissolved oxygen, and nitrate at high frequencies in two urban streams in the Minneapolis, MN metropolitan area. Grab samples also were collected at 2 h intervals for 22 h during two dry periods and five rain events and analyzed for organic and microbial pollutants. This study investigated the viability of using in situ near real-time sensors to predict fecal coliforms, prometon (a residential herbicide), atrazine (an agricultural herbicide), and caffeine (a wastewater indicator) concentrations. Such pollutants can be used as indicators of sources that contribute to what is often termed "urban stream syndrome." At one stream, linear correlations were observed between nitrate and caffeine (R(2) = 0.66), turbidity and prometon (R(2) = 0.91), and discharge and prometon (R(2) = 0.92). At another location, caffeine linearly correlated with specific conductance (R(2) = 0.64). A lack of correlation with sensed water quality parameters was also observed with some of the pollutants. When one considers that error is estimated to be as high as 200% when using monthly grab samples to estimate pollutant loading in streams, even moderate correlations, such as the ones found in this study, can provide better loading estimates if frequently sensed parameters can be used for load estimation. Therefore, such site-specific relationships can be used to estimate the loading of specific pollutants in near real-time until robust low-cost technologies to analyze these pollutants in situ become available.

A multi-biomarker assessment of the impact of the antibacterial trimethoprim on the non-target organism Zebra mussel (Dreissena polymorpha)

A battery of eight biomarkers was applied in the freshwater mussel Dreissena polymorpha to evaluate potential sub-lethal effects of the antimicrobial trimethoprim (TMP, 5-[3,4,5-trimethoxybenzyl]pyrimidine-2,4-diamine). Mussels were exposed for 96 h to increasing concentrations (1, 3, 10 nM) of TMP in in vivo experiments. We determined the single cell gel electrophoresis (SCGE) assay, the micronucleus test (MN test), the apoptotic frequency (Halo assay) and the lysosomal membrane stability (Neutral Red Retention Assay) in mussel hemocytes. Moreover, to reveal whether the oxidative status was altered, measurements of the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and the phase II detoxifying enzyme glutathione S-transferase (GST) were performed using the cytosolic fraction extracted from a pool of entire mussels. The biomarker battery pointed out only a moderate cyto- and genotoxicity on Zebra mussel hemocytes since only a slight increase in DNA damage was registered by apoptosis induction and MN frequency, while significant differences of lysosomal membrane stability from baseline levels were measured at 3 and 10 nM at the end of exposures only. Finally, TMP seems to have a very low induction capability or even an inhibitory effect on the activities of antioxidant enzymes, but a clear significant induction on GST.

Cytotoxic and genotoxic effects of in vitro exposure to triclosan and trimethoprim on zebra mussel (Dreissena polymorpha) hemocytes

Pharmaceuticals and personal care products (PPCPs) have been detected in several aquatic ecosystems for a number of years, but the potential for biological effects in exposed non-target organisms is only now being reported. In this study the potential cellular damage due to two of the main PPCPs found in aquatic environments was investigated by in vitro exposures. Hemolymph samples of the freshwater bivalve Dreissena polymorpha were collected and treated with increasing concentrations of the antibacterial agent Triclosan (TCS) and the antibiotic Trimethoprim (TMP). Doses selected for TCS were 0.1, 0.15, 0.2, and 0.3 microM, while 0.2, 1, and 5 microM for TMP exposures, respectively. We evaluated the potential genotoxicity on hemocytes by the SCGE (single cell gel electrophoresis) assay and apoptosis frequency evaluation, while the cytotoxicity was measured by the lysosomal membranes stability test (NRRA, neutral red retention assay). TCS genotoxicity increased in a dose-dependent manner and this pharmaceutical significantly affects hemocyte functionality due to severe DNA injuries at very low doses. In contrast, TMP seems to be less dangerous than TCS for D. polymorpha because the cytotoxic and the moderate genotoxic effects noticed were obtained only at very high concentration levels.

Environmental risk and toxicology of human and veterinary waste pharmaceutical exposure to wild aquatic host-parasite relationships

Pollution of the aquatic environment by human and veterinary waste pharmaceuticals is an increasing area of concern but little is known about their ecotoxicological effects on wildlife. In particular the interactions between pharmaceuticals and natural stressors of aquatic communities remains to be elucidated. A common natural stressor of freshwater and marine organisms are protozoan and metazoan parasites, which can have significant effects on host physiology and population structure, especially under the influence of many traditional kinds of toxic pollutants. However, little is known about the effects of waste pharmaceuticals to host-parasite dynamics. In order to assess the risk waste pharmaceuticals pose to aquatic wildlife it has been suggested the use of toxicological data derived from mammals during the product development of pharmaceuticals may be useful for predicting toxic effects. An additional similar source of information is the extensive clinical studies undertaken with numerous classes of drugs against parasites of human and veterinary importance. These studies may form the basis of preliminary risk assessments to aquatic populations and their interactions with parasitic diseases in pharmaceutical-exposed habitats. The present article reviews the effects of the most common classes of pharmaceutical medicines to host-parasite relationships and assesses the risk they may pose to wild aquatic organisms. In addition the effects of pharmaceutical mixtures, the importance of sewage treatment, and the risk of developing resistant strains of parasites are also assessed.

Assessing the effects of fluoxetine on Physa acuta (Gastropoda, Pulmonata) and Chironomus riparius (Insecta, Diptera) using a two-species water-sediment test

Fluoxetine has been tested in a two-species water-sediment system, which allowed a two-generation study with Chironomus riparius and a partial life-cycle with the freshwater snail Physa acuta to be performed at the same time. The design considered the continuous application of fluoxetine to overlaying water for nominal concentrations of 31.25, 62.5, 125 and 250 microg/L. A fifth treatment (87.5 microg/L) level consisted of pulse applications once a week. Measures of water and sediment concentrations were determined once a week and at the end of experiment (day 44), respectively. The fate study demonstrated that water dissipation can be explained by partitioning of fluoxetine to sediment. At the end of experiment, the percentage of detected fluoxetine was up to 10-fold higher in sediment than in overlaying water. The employed two-species test allowed distinguishing, in the same exposure conditions, effects due to waterborne exposure together ingestion at the sediment surface (freshwater grazing snail P. acuta) and exposure by burrowing activities (sediment-dwelling insect larvae C. riparius). The effect assessment showed a stimulation of P. acuta reproduction at lower concentrations (31.25 and 62.5 microg/L), while the opposite effect was observed at the highest treatment (250 microg/L). Additional studies should be conducted to establish if the statistically significant differences observed in F0 sex ratio at the 62.5 microg/L and F1 adult emergence at 31.25 microg/L of C. riparius have a toxicological significance. This study showed that fluoxetine can affect reproduction of freshwater molluscs. The results of the present study may contribute to knowledge on ecotoxicology of pharmaceuticals, about which little data is available. The possible consequences and implications for targeting the environmental risk assessment of fluoxetine are discussed.

Comparative analysis of pharmaceuticals versus industrial chemicals acute aquatic toxicity classification according to the United Nations classification system for chemicals. Assessment of the (Q)SAR predictability of pharmaceuticals acute aquatic toxicity and their predominant acute toxic mode-of-action

Pharmaceuticals have been reported to be ubiquitously present in surface waters prompting concerns of effects of these bioactive substances. Meanwhile, there is a general scarcity of publicly available ecotoxicological data concerning pharmaceuticals. The aim of this paper was to compile a comprehensive database based on OECD's standardized measured ecotoxicological data and to evaluate if there is generally cause of greater concern with regards to pharmaceutical aquatic toxicological profiles relative to industrial chemicals. Comparisons were based upon aquatic ecotoxicity classification under the United Nations Global Harmonized System for classification and labeling of chemicals (GHS). Moreover, we statistically explored whether the predominant mode-of-action (MOA) for pharmaceuticals is narcosis. We found 275 pharmaceuticals with 569 acute aquatic effect data; 23 pharmaceuticals had chronic data. Pharmaceuticals were found to be more frequent than industrial chemicals in GHS category III. Acute toxicity was predictable (>92%) using a generic (Q)SAR ((Quantitative) Structure Activity Relationship) suggesting a narcotic MOA. Analysis of model prediction error suggests that 68% of the pharmaceuticals have a non-specific MOA. Additionally, the acute-to-chronic ratio (ACR) for 70% of the analyzed pharmaceuticals was below 25 further suggesting a non-specific MOA. Sub-lethal receptor-mediated effects may however have a more specific MOA.

Norfluoxetine induces spawning and parturition in estuarine and freshwater bivalves

Fluoxetine, a commonly prescribed antidepressant (Prozac), has been detected in sewage effluent. Its active metabolite norfluoxetine is more potent and has been detected in sewage influent and in fish tissues. We tested the effects of norfluoxetine on spawning and parturition in bivalves. Norfluoxetine induced significant spawning in zebra mussels and dark false mussels at concentrations as low as 5 microM. Norfluoxetine induced significant parturition in fingernail clams at 10 microM. Fluoxetine also induced spawning in dark false mussels at concentrations as low as 100 nM. Implications for environmental impacts of norfluoxetine and fluoxetine on native and exotic bivalves are discussed.

Acute effects of diclofenac and DMSO to Daphnia magna: immobilisation and hsp70-induction

To determine the toxicity of the anti-rheumatic drug diclofenac to Daphnia magna, acute toxicity tests according to the OECD guideline 202 were combined with biochemical investigations of the hsp70 level as a biomarker for proteotoxicity. Particular attention was paid to the impact of the solvent DMSO as a confounding factor to diclofenac toxicity by means of testing different variations of producing stock solutions. In the acute immobilisation tests, diclofenac was most toxic as a singular test substance, with indication of a slight antagonistic interaction between the two substances. The highest EC50 values were obtained in those approaches using diclofenac pre-dissolved in DMSO. Thus, the observed antagonism seems to be intensified by pre-dissolution. Hsp70 levels of 12- to 19-days-old D. magna were determined after 48h exposure using a highly reproducible immunological protocol. Hsp70 induction occurred at a LOEC of 30mgl(-1) diclofenac plus 0.6mll(-1) DMSO, and at a LOEC of 40mgl(-1) for diclofenac alone. In summary, DMSO showed only slight confounding effects on diclofenac action in the applied range of concentrations.

Evolutionary conservation of human drug targets in organisms used for environmental risk assessments

Pharmaceuticals are typically found in very low concentrations in the aquatic environment. Accordingly, environmental effects clearly assigned to residual drugs are consistent with high affinity interactions with conserved targets in affected wildlife species rather than with a general toxic effect. Thus, evolutionarily well-conserved targets in a given species are associated with an increased risk. In this study orthologs for 1318 human drug targets were predicted in 16 species of which several are relevant for ecotoxicity testing. The conservation of different functional categories of targets was also analyzed. Zebrafish had orthologs to 86% of the drug targets while only 61% were conserved in Daphnia and 35% in green alga. The predicted presence and absence of orthologs agrees well with published experimental data on the potential for specific drug target interaction in various species. Based on the conservation of targets we propose that aquatic environmental risk assessments for human drugs should always include comprehensive studies on aquatic vertebrates. Furthermore, individual targets, especially enzymes, are well conserved suggesting that tests on evolutionarily distant organisms would be highly relevant for certain drugs. We propose that the results can guide environmental risk assessments by improving the possibilities to identify species sensitive to certain types of pharmaceuticals or to other contaminants that act through well defined mechanisms of action. Moreover, we suggest that the results can be used to interpret the relevance of existing ecotoxicity data.

Physiological endpoints for potential SSRI interactions in fish

Selective serotonin reuptake inhibitors (SSRIs) are among the pharmaceutical compounds frequently detected in sewage treatment plant effluents and surface waters, albeit at very low concentrations, and have therefore become a focus of interest as environmental pollutants. These neuroactive drugs are primarily used in the treatment of depression but have also found broader use as medication for other neurological dysfunctions, consequently resulting in a steady increase of prescriptions worldwide. SSRIs, via inhibition of the serotonin (5-hydroxytryptamine, 5-HT) reuptake mechanism, induce an increase in extracellular 5-HT concentration within the central nervous system of mammals. The phylogenetically ancient and highly conserved neurotransmitter and neurohormone 5-HT has been found in invertebrates and vertebrates, although its specific physiological role and mode of action is unknown for many species. Consequently, it is difficult to assess the impact of chronic SSRI exposure in the environment, especially in the aquatic ecosystem. In view of this, the current knowledge of the functions of 5-HT in fish physiology is reviewed and, via comparison to the physiological role and function of 5-HT in mammals, a characterization of the potential impact of chronic SSRI exposure on fish is provided. Moreover, the insight on the physiological function of 5-HT strongly suggests that the experimental approaches currently used are inadequate if not entirely improper for routine environmental risk assessment of pharmaceuticals (e.g., SSRIs), as relevant endpoints are not assessed or impossible to determine.

Occurrence and fate of antibiotics in the Seine River in various hydrological conditions

Occurrence and fate of 17 antibiotics were investigated in the aqueous phase of river water under different hydrological conditions at 5 sampling locations in the Seine River inner estuary. The target analytes belonged to 4 groups: quinolones, sulfonamides, nitro-imidazoles and diaminopyrimidines. This six-month survey (from January to June 2006) showed that different compounds were occurring at individual concentrations reaching 544 ng L(-)(1) (sulfamethoxazole). All 17 compounds were detected at least once in the survey. Sulfamethoxazole was detected in every sample, and showed the highest concentrations. Norfloxacin and flumequine were found to be the most ubiquitous quinolones, with detection frequencies of 33 and 75% respectively at the most contaminated site (Poses). Investigations concerning the origins of this contamination were made by means of a longitudinal profile along the Seine River between Paris and Poses. It showed large inputs of norfloxacin, ofloxacin, trimethoprim and sulfamethoxazole from wastewater treatment plants, with an increase in norfloxacin and sulfamethoxazole concentrations of 84% and 70% respectively, both reaching 155 ng L(-)(1) in the river, downstream from a wastewater outlet. The detected compounds showed different dissipation patterns and behaviours under different hydrological conditions. Higher inputs of norfloxacin were found in low flow conditions, which were rapidly attenuated along the stream. In contrast, sulfamethoxazole inputs were increasing in high flow conditions, and dissipation of this compound was found to be slow. Similar behaviour was observed for the synergist trimethoprim. Flumequine was also frequently detected and its input increased during flood events.

Risks to aquatic organisms posed by human pharmaceutical use

In order to help prioritize future research efforts within the US, risks associated with exposure to human prescription pharmaceutical residues in wastewater were estimated from marketing and pharmacological data. Masses of 371 active pharmaceutical ingredients (APIs) dispensed in the US in 2004 were estimated from marketing data, and then divided by therapeutic dose rate to normalize for potency. Metabolic inactivation of the 50 most dispensed APIs was estimated from published data, and active metabolites were tabulated. Comparing maximum likely average wastewater concentrations of API-associated activity to exposure rates that produce therapeutic effects in humans suggests that the threat to healthy human adults from aquatic exposure is low, even when likely mixture effects are considered. Comparing predicted wastewater concentrations to human therapeutic plasma concentrations suggests that some APIs may be present at sufficient concentrations to affect organisms which eliminate them inefficiently. Comparing predicted antimicrobial concentrations to published minimum inhibitory concentrations suggests that antibacterial APIs in wastewater, but probably not antifungal APIs, may select for low-level antimicrobial resistance. The taxonomic distribution of molecular targets of the 50 most dispensed APIs suggests that potential effects of some APIs are likely restricted to vertebrates, while other APIs can probably affect many eukaryotic and prokaryotic clades.

Aquatic plants exposed to pharmaceuticals: effects and risks

Pharmaceuticals are biologically active, ubiquitous, low-level contaminants that are continuously introduced into the environment from both human and veterinary applications at volumes comparable to total pesticide loadings. Recent analytical advances have made possible the detection of a number of these compounds in environmental samples, raising concerns over potential nontarget effects to aquatic organisms, especially given the highly specific biologically active nature of these compounds. These concerns become paramount when the evolutionary conservation of metabolic pathways and receptors is taken into consideration, particularly in the case of aquatic plants, where a great deal of homology is displayed between the chloroplast and bacteria, as well as between other metabolic pathways across multiple phyla of biological organization. Common receptors have been identified in plants for a number of antibiotics affecting chloroplast replication (fluoroquinolones) transcription and translation (tetracyclines macrolides, lincosamides, P-aminoglycosides, and pleuromutilins), metabolic pathways such as folate biosynthesis (sulfonamides) and fatty acid biosynthesis (triclosan), as well as other classes of pharmaceuticals that affect sterol biosynthesis (statin-type blood lipid regulators). Toxicological investigations into the potency of these compounds indicates susceptibility across multiple plant species, although sensitivity to these compounds varies widely between blue-green algae, green algae, and higher plants in a rather inconsistent manner, except that Cyanobacteria are largely the most sensitive to antibiotic compounds. This differential sensitivity is likely dependent on differences in metabolic potential as well as uptake kinetics, which has been demonstrated for a number of compounds from another class of biologically active compounds, pesticides. The demonstration of conserved receptors and pathways in plants is not surprising, although it has been largely overlooked in the risk assessment process to date, which typically relies heavily on physiological and/or morphological endpoints for deriving toxicity data. However, a small number of studies have indicated that measuring the response of a pathway- or receptor-specific target in conjunction with a physiological endpoint with direct relatedness can yield sublethal responses that are two to three times more sensitive that the traditional gross morphological endpoints typically employed in risk assessment. The risk assessment for this review was based almost entirely on evaluations of gross morphological endpoints, which generally indicated that the risk pharmaceuticals pose to aquatic plants is generally low, with a few exceptions, particularly blue-green algae exposed to antibiotics, and both green and blue-green algae exposed to triclosan. It is critical to note, however, that the application of sublethal pathway or receptor-specific responses in risk assessment has largely been unconsidered, and future research is needed to elucidate whether evaluating the toxicity of pharmaceuticals using these endpoints provides a more sensitive, subtle, yet meaningful indication of toxicity than the traditional endpoints used in prospective and retrospective risk assessments for aquatic plants.

Ecotoxicological quantitative structure-activity relationships for pharmaceuticals

This paper examined active pharmaceutical ingredients (APIs) acute ecotoxicological modes of action (MOA). It was concluded that the vast majority of APIs acute MOA was non-specific narcosis as; 85% out of 59 APIs had an excess toxicity ratio <7; 70% of the APIs ecotoxicity was overestimated based on a narcotic model; and the majority of APIs Log EC(50)-Log K (ow )regression slopes (-0.49 to -0.86) were within the range of the universal narcosis slopes. However, hydrophobicity is likely not the proper descriptor for assessment of pharmacodynamic APIs chronic ecotoxicity, to asses this accurately new experimental methods need development.

Occurrence and risk assessment of pharmaceutically active compounds in wastewater treatment plants. A case study: Seville city (Spain)

The occurrence of four anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen and naproxen), an antiepileptic drug (carbamazepine) and a nervous stimulant (caffeine) in influent and effluent samples from four wastewater treatment plants (WWTPs) in Seville was evaluated. Removal rates in the WWTPs and risk assessment of the pharmaceutically active compounds have been studied. Analytical determination was carried out by high performance liquid chromatography (HPLC) with diode array (DAD) and fluorescence (Fl) detectors after sample clean up and concentration by solid phase extraction. All pharmaceutically active compounds, except diclofenac, were detected not only in wastewater influents but also in wastewater effluents. Mean concentrations of caffeine, carbamazepine, ketoprofen and naproxen ranged between 0.28-11.44 microg l(-1) and 0.21-2.62 microg l(-1) in influent and effluent wastewater, respectively. Ibuprofen was present in the highest concentrations in the range 12.13-373.11 microg l(-1) and 0.78-48.24 microg l(-1) in influent and effluent wastewater, respectively. Removal rates of the pharmaceuticals ranged between 6 and 98%. Risk quotients, expressed as ratios between the measured environmental concentration (MEC) and the predicted no effect concentrations (PNEC) were higher than 1 for ibuprofen and naproxen in influent wastewater and for ibuprofen in effluent wastewater.

Toxicological effects of the lipid regulator gemfibrozil in four aquatic systems

Gemfibrozil is a lipid-regulating agent widely used in patients at risk of coronary disease. Pharmaceutical products, such as gemfibrozil, are found in municipal effluents and represent a major source of contamination. To date, there is little available information about the adverse effects of gemfibrozil in aquatic organisms. For this reason, the toxic effects were investigated using model systems from four trophic levels. The most sensitive system was the immobilization of Daphnia magna, with a non-observed adverse effect level of 30 microM and a mean effective concentration of 120 microM after 72 h, followed by the inhibition of bioluminescence of Vibrio fischeri, the hepatoma fish cell line PLHC-1 line and the inhibition of the growth of Chlorella vulgaris. Although protein content, neutral red uptake, methylthiazol metabolization and lysosomal function were reduced in PLHC-1 cells, stimulations were observed for lysosomal function, metallothionein levels and succinate dehydrogenase, glucose-6-phosphate dehydrogenase and acetylcholinesterase activities. No changes were observed in ethoxyresorufin-O-deethylase activity. The main morphological alterations were hydropic degeneration and loss of cells. Modulation studies on gemfibrozil toxicity were also carried out. General antioxidants and calcium chelators did not modify the toxicity of gemfibrozil, whereas a Fe(III) chelator, a membrane permeable sulphydryl-protecting compound and glutathione level modifying agents did change the toxicity. One of the possible mechanisms of gemfibrozil toxicity seems to be the binding to sulphydryl groups, including those of glutathione. According to the result, gemfibrozil should be classified as harmful to aquatic organisms. However, comparing the concentrations in water and the toxicity quantified in the assayed systems, gemfibrozil is not expected to represent acute risk to the aquatic biota.

Can aquatic distribution of human pharmaceuticals be related to pharmacological data?

The recognition of pharmaceuticals as significant environmental contaminants has only been a recent phenomenon. Therefore there is a paucity of data relating to the fate and effects of pharmaceuticals once they enter an aquatic receiving system. The amount of work that needs to be done in terms of risk assessment for pharmaceuticals required by regulatory agencies is substantial. This paper has determined the environmental partitioning coefficient (K(d)) of 13 diverse human pharmaceuticals in three model systems of differing combinations of solid phases and solutions. The K(d) values were then compared with distribution values of the pharmaceuticals in the human body determined from pharmacological studies. This was done to assess the functional relationship between K(d) and distribution values in the human body (V(D)). K(d) values ranged from 3 to 2450 L kg(-1). Regression coefficients ranged from r(2)=0.62-0.72, indicating that V(D) values are a useful indicator for the K(d) values of the tested pharmaceuticals within the batch sorption systems. The relationship between K(d) and V(D) should therefore be further explored to determine whether this relationship can be applied to a broader range of pharmaceuticals in more diverse environmental systems. Exploiting available human pharmacological data in such a way would be of great benefit in prioritising human pharmaceuticals as environmental contaminants in the risk assessment process.

Comparative ecotoxicological hazard assessment of beta-blockers and their human metabolites using a mode-of-action-based test battery and a QSAR approach

We analyzed nontarget effects of the beta-blockers propranolol, metoprolol, and atenolol with a screening test battery encompassing nonspecific, receptor-mediated, and reactive modes of toxic action. All beta-blockers were baseline toxicants and showed no specific effects on energy transduction nor endocrine activity in the yeast estrogen and androgen screen, and no reactive toxicity toward proteins and DNA. However, in a phytotoxicity assay based on the inhibition of the photosynthesis efficiency in green algae, all beta-blockers were 10 times more toxic than their modeled baseline toxicity. Baseline- and phytotoxicity effects increased with hydrophobicity. The beta-blockers showed concentration addition in mixture experiments, indicating a mutual specific nontarget effect on algae. Using literature data and quantitative structure-activity relationships (QSAR), we modeled the total toxic potential of mixtures of the beta-blockers and their associated human metabolites for the phytotoxicity endpoint with two scenarios. The realistic scenario (I) assumes that the metabolites lose their specific activity and act as baseline toxicants. In the worst-case scenario (II) the metabolites exhibitthe same specific mode of action as their parent drug. For scenario (II), metabolism hardly affected the overall toxicity of atenolol and metoprolol, whereas propranolol's hazard potential decreased significantly. In scenario (I), metabolism reduced the apparent EC50 of the mixture of parent drug and metabolite even further. The proposed method is a simple approach to initial hazard assessment of pharmaceuticals and can guide higher tier testing. It can be applied to other classes of pollutants, e.g., biocides, as well as to environmental transformation products of pollutants.

LC-MS analysis and environmental risk of lipid regulators

This article presents a review of liquid chromatography-mass spectrometric (LC-MS) methods applied to the determination of lipid-regulating agents, "fibrate" and "statin" classes, and some of their metabolites (clofibric acid and fenofibric acid) in environmental samples. Concentration levels of this therapeutical group have been reported in the ppt to ppb range for different compartments (wastewater, surface water and sediments) in several monitoring studies. Part of this article is dedicated to hazard assessment of lipid-regulating agents according to the approaches of the European Union (EU) and Environmental Protection Agency (EPA) for identifying persistent, bioaccumulable and toxic (PBT) substances. The pharmacodynamic and pharmacokinetic activities of these pharmaceuticals are well known and, based on this information, the derivation of the potential long-term effects, which may be induced on eco-organisms at low concentration levels, is discussed. Studies of environmental risk assessment (ERA) for lipid regulators carried out through the framework of the European Agency for the Evaluation of Medicinal Products (EMEA) and Food and Drug Administration (FDA) are presented.

Herbicidal effects of statin pharmaceuticals in Lemna gibba

Statin pharmaceuticals, heavily prescribed in the treatment of hypercholesterolemia, are competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR). In plants, these compounds also inhibit HMGR, which regulates cytosolic isoprenoid biosynthesis in the mevalonic acid (MVA) pathway. Phytotoxicity was evaluated in the higher aquatic plant Lemna gibba exposed to atorvastatin and lovastatin for 7-days by measuring the concentrations of sterols and ubiquinone; products downstream in the MVA pathway. The efficiency of the parallel and unaffected methylerythritol phosphate pathway (MEP) was also evaluated by measuring the end product, plastoquinone. Statin treatment caused an accumulation of plastoquinone, and unexpectedly, ubiquinone, an artifact likely due to metabolite sharing from the plastidial MEP pathway. Statins were, however, highly phytotoxic to L. gibba and HPLC-UV analysis of plant extracts showed significantly decreased concentrations of both stigmasterol and beta-sitosterol, which are critical components of plant membranes and regulate morphogenesis and development. EC10 values for atorvastatin and lovastatin were as small as 26.1 and 32.8 microg/L, respectively. However, hazard quotients indicated that statins present little risk to the model higher aquatic plant Lemna gibba at environmentally relevant concentrations, even though pathway-specific endpoints were 2-3 times more sensitive than traditional gross morphological endpoints typically used in risk assessment.

Development and application of a brain-specific cDNA microarray for effect evaluation of neuro-active pharmaceuticals in zebrafish (Danio rerio)

The environmental fate and ecotoxicological effect of pharmaceuticals are poorly understood, and standardized tests to detect and evaluate their potential effects in the environment are not available. We developed a zebrafish brain-specific microarray containing 682 neurologically relevant cDNA-fragments. To investigate the applicability of this microarray for studying neurotoxic modes-of-action and impact assessment of neuro-active pharmaceuticals in zebrafish, chlorpromazine was used as a model compound. After exposure to chlorpromazine (75 microg/L) for 2, 4, 14 and 28 days or control treatment RNA was extracted from brains of males and females. Fluorescently labeled cDNA was prepared and hybridized to the custom microarray. In total, 56 genes were differentially expressed in brains of male and/or female zebrafish, of which most genes were down-regulated. A clear difference in response to chlorpromazine exposure between males and females was observed with exposure time as well as in functional classes of affected genes. The presented study is one of the first reports on molecular effects of human neuro-active pharmaceuticals in aquatic non-target organisms. This new genomic tool successfully detected gene expression effects of exposure to chlorpromazine in the brain of zebrafish. Reported gene expression effects are found to be consistent with literature data for other laboratory animals.

The human lipid regulator, gemfibrozil bioconcentrates and reduces testosterone in the goldfish, Carassius auratus

Human and veterinarian pharmaceuticals have been detected in the aquatic environment for a number of years, but the potential for biological effects in exposed aquatic organism is only now being reported. The lipid regulator, gemfibrozil (GEM) is detected at microg/L concentrations in domestic wastewater and ng/L concentrations in surface waters. We investigated the uptake of GEM in goldfish (Carassius auratus) over a 96 h time period by measuring GEM in blood plasma using LC-MS/MS. Results indicated that GEM can be taken up from water through the gills. In goldfish exposed to GEM by a single intraperitoneal injection, concentrations of GEM in the blood plasma declined rapidly over 96 h post-injection, with a half-life estimated at approximately 19 h. Exposure of goldfish to waterborne GEM at an environmentally relevant concentration over 14 days resulted in a plasma bioconcentration factor of 113. In goldfish exposed to aqueous concentrations of GEM for 96 h or 14 days, plasma testosterone (T) was reduced by over 50% in fish from all treatments. As a possible mechanistic explanation for the observed reduction in T, levels of steroid acute regulatory (StAR) protein transcript in goldfish testes were assessed by RT-PCR. StAR protein is involved in the transport of cholesterol from the outer to the inner mitochondrial membrane for transformation by the first enzyme in steroidogenesis. After exposure to GEM for 96 h, a 50% decrease in StAR mRNA levels was observed in goldfish. Gonadal StAR mRNA levels were not affected in the 14 days exposure, indicating that the observed decreases in plasma testosterone were not solely due to impaired delivery of cholesterol to the inner mitochondrial membrane. Our results demonstrate that exposure to environmental levels of GEM leads to bioconcentration of the drug in plasma and the potential for endocrine disruption in fish.

Prenatal and perinatal fenarimol-induced genotoxicity in leukocytes of in vivo treated rats

The identification of environmental compounds that have adverse effects on reproductive health and animal development is particularly challenging. Fenarimol, a systemic fungicide, is considered non or weakly genotoxic. However, its available toxicological data are controversial and incomplete. This study was conducted in rat in vivo to determine whether this compound (150 and 300 mg/kg) had adverse effects on DNA integrity in dams and pups after maternal subcutaneous exposure. The animals were exposed during early gestation (1-6 days), late gestation (last 6 days), or first 6 days of lactation. Findings on fenarimol genotoxicity showed an adverse effect when detected by the Comet assay, both in dams and pup, and state that animal sensitivity to fenarimol is higher during postnatal period. Since the DNA damage increases during the time of exposure (2 h to 6 days after the birth), our data on pups suggest that fenarimol can mainly act on cell DNA through direct exposure of litter via milk.

In vitro assessment of modes of toxic action of pharmaceuticals in aquatic life

An ecotoxicological test battery based on a mode-of-action approach was designed and applied to the hazard identification and classification of modes of action of six pharmaceuticals (carbamazepine, diclofenac, ethinyl estradiol, ibuprofen, propranolol, and sulfamethoxazole). The rationale behind the design of the battery was to cover the relevant interactions that a compound may have with biological targets. It is thus not comprehensive but contains representative examples of each category of mode of toxic action including nonspecific, specific, and reactive toxicity. The test battery consists of one test system for nonspecific toxicity (baseline toxicity or narcosis), two test systems for specific effects, and two test systems for reactive toxicity. The baseline toxicity was quantified with the Kinspec test, which detects membrane leakage via measurements of membrane potential. This test system may also be used to detect the specific effects on energy transduction, although this was not relevant to any compound investigated in this study. As examples of specific receptor-mediated toxicity, we chose the yeast estrogen screen (YES) as a specific test for estrogenicity, and the inhibition of chlorophyll fluorescence in algae to assess specific effects on photosynthesis. Reactive modes of action were assessed indirectly by measuring the relevance of cellular defense systems. Differences in growth inhibition curves between a mutant of Escherichia coli that could not synthesize glutathione and its parent strain indicate the relevance of conjugation with glutathione as a defense mechanism, which is an indirect indicator of protein damage. DNA damage was assessed by comparing the growth inhibition in a strain that lacks various DNA repair systems with that in its competent parent strain. Most compounds acted merely as baseline toxicants in all test systems. As expected, ethinylestradiol was the only compound showing estrogenic activity. Propranolol was baseline-toxic in all test systems exceptforthe photosynthesis inhibition assay, where it surprisingly showed a 100-fold excess toxicity over the predicted baseline effect. The exact mode of toxic action could not be confirmed, but additional chlorophyll fluorescence induction experiments excluded the possibility of direct interference with photosynthesis through photosystem II inhibition. Mixture experiments were performed as a diagnostic tool to analyze the mode of toxic action. Compounds with the same mode of toxic action showed the expected concentration addition. In the photosynthesis inhibition assay, agreement between experimental results and prediction was best for two-stage predictions considering the assigned modes of action. In a two-stage prediction, concentration addition was used as a model to predict the mixture effect of the baseline toxicants followed by their independent action as a single component combined with the specifically acting compound propranolol and the reference compound diuron. A comparison with acute toxicity data for algae, daphnia, and fish showed generally good agreement for the nonspecifically acting compounds but also that the proposed test battery offered better diagnostic value in the case of the specifically acting compounds.

Microcosm evaluation of the effects of an eight pharmaceutical mixture to the aquatic macrophytes Lemna gibba and Myriophyllum sibiricum

Pharmaceuticals have been detected in surface waters of the US and Europe, originating largely from two sources, sewage effluent and agricultural runoff. These compounds often occur as mixtures leading to potential combined effects. In order to investigate the effects of a realistic pharmaceutical mixture on an ecosystem, a study utilizing 15 of 12,000 L aquatic microcosms treated with eight common pharmaceuticals (atorvastatin, acetaminophen, caffeine, sulfamethoxazole, carbamazepine, levofloxacin, sertraline, and trimethoprim) at total (summed) molar concentrations of 0, 0.044, 0.608, 2.664, and 24.538 micromol/L (n = 3) was conducted. Phytotoxicity was assessed on a variety of somatic and pigment endpoints in rooted (Myriophyllum sibiricum) and floating (Lemna gibba) macrophytes over a 35-day period. EC10, EC25 and EC50 values were calculated for each endpoint exhibiting a concentration-dependent response. Generally, M. sibiricum and L. gibba displayed similar sensitivity to the pharmaceutical mixture, with phytotoxic injury evident in both species, which was concentration dependent. Through single compound 7-day daily static renewal toxicity tests with L. gibba, the sulfonamide antibiotic sulfamethoxazole, the fluoroquinolone antibiotic levofloxacin and the blood lipid regulator atorvastatin were found to be the only compounds to elicit phytotoxic effects in the concentration range utilized (0-1000 microg/L). Atorvastatin concentration was highly correlated to decreased pigment content in L. gibba, likely inhibiting the known target enzyme HMGR, the rate-limiting enzyme in isoprenoid biosynthesis. Hazard quotients were calculated for both microcosm and laboratory studies; the highest HQ values were 0.235 (L. gibba) and 0.051 (L. gibba), which are below the threshold value of 1 for chronic risks. The microcosm data suggest that at an ecological effect size of >20%, biologically significant risks are low for L. gibba and M. sibiricum exposed to similar mixtures of pharmaceutical compounds. For M. sibiricum and L. gibba, respective minimum differences of 5 and 1%, were detectable, however, these effect sizes are not considered ecologically significant.

Toxicity classification and evaluation of four pharmaceuticals classes: antibiotics, antineoplastics, cardiovascular, and sex hormones

Four different classes of environmental concern are quantitatively and qualitatively assessed for environmental hazards; antibiotics (n = 226), antineoplastics (n = 81), cardiovascular (n = 272), and sex hormones (n = 92). These along with an ECOSAR scan of all pharmaceuticals (n = 2848) were then classified according to the OECD aquatic toxicity classification system. The predicted species susceptibility is: daphnid > fish > algae, and the predicted rank order of relative toxicity: sex hormones > cardiovascular = antibiotics > antineoplastics (Table 1). Generally, a relatively large proportion (1/3) of all pharmaceuticals are potentially very toxic to aquatic organisms (Table 2). The qualitative risk assessment ranking relative to probability and potential severity for human and environmental health effects is: antibiotics > sex hormones > cardiovascular > antineoplastics. (Q)SARs and pharmacodynamic information should be used to prioritize and steer experimental risk assessments of pharmaceuticals, and potentially, also be used in new drug discovery optimizing efficacy and in minimising environmental hazards of new products. Nuclear receptors are relatively well conserved in evolution. Currently, antibacterial resistance represents the most significant human health hazard, and potentially the largest non-target organism hazard is sex hormones acting as endocrine modulators in wildlife. Data for the individual compounds are accessible via.

Pharmaceuticals in the aquatic environment--a comparison of risk assessment strategies

The growing concern over the release of pharmaceutically active compounds and personal care products into the environment has prompted the introduction of risk assessment guidelines in both the European Union by the European Medicines Evaluation Agency (EMEA) and in the United States by the Food and Drug Administration (FDA), details of which are presented herein. Both employ a similar tiered system that compares the predicted environmental concentrations (PEC) with the worst-case no effect concentrations estimated from standard toxicity assays. These approaches are compared and contrasted. Results demonstrate room for improvement in areas such as the use of threshold values to trigger investigations, chronic and mechanism specific toxicity screening and mixture toxicity for which possible solutions are proposed.

Ranking and prioritization of environmental risks of pharmaceuticals in surface waters

Pharmaceuticals have been reported in surface waters, prompting legitimate public concern, as pharmaceuticals are biologically active compounds used daily by the public. Currently there are ecotoxicological data available for <1%, thus, the European Union Commission's Scientific committee on Toxicity, Ecotoxicity, and Environment (CSTEE) recommended use of (Q)SAR models and precaution to prioritize further risk assessment of approximately 4500 compounds and their adjuvants. We ranked 2986 different pharmaceutical compounds in 51 classes relative to hazard toward algae, daphnids, and fish using the EPIWIN program. This ranking cannot be used to acquit a compound based on predicted relative ranking. Modifying additives were the most toxic classes. Cardiovascular, gastrointestinal, antiviral, anxiolytic sedatives hypnotics and antipsychotics, corticosteroid, and thyroid pharmaceuticals were the predicted most hazardous therapeutic classes. The overall relative order of susceptibility was estimated to be daphnids > fish > algae. Expert judgment is needed to assess specific hazards for classes like microbial resistance and antibiotics, sex hormones, and endocrine disruptors. As human health and the function of ecological systems are interconnected and subject to the precautionary principle, harmonization of evidence for correlation and causality of adverse effects seems sensible in an ethical and cost-effective context to facilitate substitution of hazardous compounds. Data available: http://www.uoguelph.ca/~hsander/.

Effects of human pharmaceuticals on cytotoxicity, EROD activity and ROS production in fish hepatocytes

Pharmaceuticals are found in the aquatic environment but their potential effects on non-target species like fish remain unknown. This in vitro study is a first approach in the toxicity assessment of human drugs on fish. Nine pharmaceuticals were tested on two fish hepatocyte models: primary cultures of rainbow trout hepatocytes (PRTH) and PLHC-1 fish cell line. Cell viability, interaction with cytochrome P450 1A (CYP1A) enzyme and oxidative stress were assessed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrasodium bromide tetrazolium (MTT), 7-ethoxyresorufin-o-deethylase (EROD) and dichlorofluorescein (DCFH-DA) assays, respectively. The tested drugs were clofibrate (CF), fenofibrate (FF), carbamazepine (CBZ), fluoxetine (FX), diclofenac (DiCF), propranolol (POH), sulfamethoxazole (SFX), amoxicillin (AMX) and gadolinium chloride (GdCl(3)). All substances were cytotoxic, except AMX at concentration up to 500 microM. The calculated MTT EC(50) values ranged from 2 microM (CF) to 651 microM (CBZ) in PLHC-1, and from 53 microM (FF) to 962 microM (GdCl(3)) in PRTH. CF, FF, and FX were the most cytotoxic drugs and induced oxidative stress before being cytotoxic. Compared to hepatocytes from human and dog, fish hepatocytes seemed to be more susceptible to the peroxisome proliferators (PPs) CF and FF. In PLHC-1 cells none of the tested drugs induced the EROD activity whereas POH appeared as a weak EROD inducer in PRTH. Moreover, in PRTH, SFX, DiCF, CBZ and to a lesser extend, FF and CF inhibited the basal EROD activity at clearly sublethal concentrations which may be of concern at the biological and chemical levels in a multipollution context.

Ecotoxicological evaluation of carbamazepine using six different model systems with eighteen endpoints

The occurrence of pharmaceutically active compounds in the aquatic environment has been recognized as one of the emerging issues in environmental chemistry. However, the ecotoxicological effects of pharmaceuticals have still not been researched adequately. Carbamazepine, an anticonvulsant commonly present in surface and groundwater, was studied, using six ecotoxicological model systems with eighteen endpoints evaluated at different exposure time periods. The battery included the immobilization of Daphnia magna, bioluminescence inhibition in the bacterium Vibrio fischeri, growth inhibition of the alga Chlorella vulgaris, and micronuclei induction and root growth inhibition in the plant Allium cepa. Cell morphology, neutral red uptake, total protein content, MTS metabolization, lactate dehydrogenase leakage and activity and glucose-6-phosphate dehydrogenase activity were studied in the salmonid fish cell line RTG-2. The total protein content, LDH activity, neutral red uptake and MTT metabolization in Vero monkey kidney cells were also investigated. The most sensitive system to carbamazepine was the Vero cell line, followed by Chlorella vulgaris, Vibrio fischeri, Daphnia magna, Allium cepa, and RTG-2 cells. EC50 values from 19 microM in Vero cells at 72 h to more than 1200 microM in other systems, were obtained. Comparing the concentrations in water and the toxicity quantified in our assay systems, carbamazepine is not expected to produce acute toxic effects in the aquatic biota under these circumstances, but chronic and synergistic effects with other chemicals cannot be excluded.

Residue analysis of the pharmaceutical diclofenac in different water types using ELISA and GC-MS

A highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of diclofenac in water samples was developed. With pure water, the limit of detection (LOD, S/N = 3) and IC50 were found to be 6 ng/L and 60 ng/L, respectively. The analytical working range was about 20-400 ng/L. Highest cross-reactivity (CR) of 26 tested pharmaceuticals, metabolites, and pesticides was found for 5-hydroxydiclofenac (100%). Other estimated values were well below 4% and, therefore, are negligible. The assay was applied for the determination of diclofenac in tap and surface water samples as well as wastewater collected at 20 sewage treatment plants (STPs) in Austria and Germany. Humic substances were identified as main interference in surface water. Wastewater samples which were only submitted to filtration and dilution yielded about 25% higher diclofenac concentrations using the ELISA compared to GC-MS. However, the ELISA turned out to be a simple, inexpensive, and accurate method for the determination of diclofenac both in influent and effluent wastewater after rather simple sample preparation, i.e., filtration, acidification, and readjustment to neutral pH-value, and at least 10-fold dilution with pure water.