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Research Publications - 2011
1) Bars R, Broeckaert F, Fegert I, Gross M, Hallmark N, Kedwards T, Lewis D, O'Hagan S, Panter GH, Weltje L, Weyers A, Wheeler JR, Galay-Burgos M. Science based guidance for the assessment of endocrine disrupting properties of chemicals. Regul Toxicol Pharmacol. 2011 Feb;59(1):37-46.
http://www.sciencedirect.com/science/article/pii/S027323001000156X
Abstract
The European legislation on plant protection products (Regulation (EC) No. 1107/2009) and biocides (Directive 98/8/EC), as well as the regulation concerning chemicals (Regulation (EC) No. 1907/2006 ‘REACH’) only support the marketing and use of chemical products on the basis that they do not induce endocrine disruption in humans or non-target species. However, there is currently no agreed guidance on how to identify and evaluate endocrine activity and disruption. Consequently, an ECETOC task force was formed to provide scientific criteria that may be used within the context of these three legislative documents. Specific scientific criteria for the determination of endocrine disrupting properties that integrate information from both regulatory (eco)toxicity studies and mechanistic/screening studies are proposed. These criteria combine the nature of the adverse effects detected in studies which give concern for endocrine toxicity with an understanding of the mode of action of toxicity so that adverse effects can be explained scientifically. The criteria developed are presented in the form of flow charts for assessing relevant effects for both humans and wildlife species. In addition, since not all chemicals with endocrine disrupting properties are of equal hazard, assessment of potency is also proposed to discriminate chemicals of high concern from those of lower concern. The guidance presented in this paper includes refinements made to an initial proposal following discussion of the criteria at a workshop of invited regulatory, academic and industry scientists.
2) Bartram AE, Winter MJ, Huggett DB, McCormack P, Constantine LA, Hetheridge MJ, Hutchinson TH, Kinter LB, Ericson JF, Sumpter JP, Owen SF. In vivo and in vitro liver and gill EROD activity in rainbow trout (Oncorhynchus mykiss) exposed to the beta-blocker propranolol. Environ Toxicol. 2011 Mar 7. doi: 10.1002/tox.20684. [Epub ahead of print]
http://onlinelibrary.wiley.com/doi/10.1002/tox.20684/abstract
Abstract
The conservation of common physiological systems across vertebrate classes suggests the potential for certain pharmaceuticals, which have been detected in surface waters, to produce biological effects in non-target vertebrates such as fish. However, previous studies assessing the effects of such compounds in fish have not taken into account the potential for metabolism and elimination. This study aimed to assess if propranolol, a β-adrenergic receptor antagonist or β-blocker, could modulate EROD activity (indicative of CYP1A activity) in rainbow trout (Oncorhynchus mykiss) gills and liver. For this, an in vivo time course exposure with 1 mg/L was conducted. Additionally, using measured in vivo plasma concentrations, an in vitro exposure at human therapeutic levels was undertaken. This allowed comparison of in vitro and in vivo rates of EROD activity, thus investigating the applicability of cell preparations as surrogates for whole animal enzyme activity analysis. In vitro exposure of suspended liver and gill cells at concentrations similar to in vivo levels resulted in EROD activity in both tissues, but with significantly higher rates (up to six times in vivo levels). These results show that propranolol exposure elevated EROD activity in the liver and gill of rainbow trout, and that this is demonstrable both in vivo (albeit nonsignificantly in the liver) and in vitro, thus supporting the use of the latter as a surrogate of the former. These data also provide an insight into the potential role of the gill as a site of metabolism of pharmaceuticals in trout, suggesting that propranolol (and feasibly other pharmaceuticals) may undergo “first pass” metabolism in this organ. © 2011 Wiley Periodicals, Inc. Environ Toxicol 2011.
3) Brown, A.R., Bickley, L.K., Le Page, G., Hosken, D.J., Paull, G.C., Hamilton, P.B., Owen, S.F., Robinson, J., Sharpe, A.D., Tyler, C.R. (2011). Are toxicological responses in laboratory (inbred) Zebrafish representative of those in outbred (wild) populations? A case study with an endocrine disrupting chemical. Environ. Sci. Technol. 45, 4166–4172.
http://pubs.acs.org/doi/abs/10.1021/es200122r
Abstract
Laboratory animals tend to be more inbred and less genetically diverse than wild populations, and thus may differ in their susceptibility to chemical stressors. We tested this hypothesis by comparing the responses of related inbred (theoretical inbreeding FIT = n + 0.25) and outbred (FIT = n) zebrafish (Danio rerio) WIK/Wild family lines to an endocrine disrupting chemical, clotrimazole. Exposure of inbred and outbred zebrafish to 2.9 μg clotrimazole/L had no effect on survival, growth, or gonadal development. Exposure of both lines to 43.7 μg clotrimazole/L led to male-biased sex ratios compared with controls (87% versus 55% and 92% vs 64%, for inbred and outbred males, respectively), advanced germ cell development, and reduced plasma 11-ketotestosterone concentrations in males. However, outbred males (but not inbred males) developed testis that were more than twice the weight of controls, which corresponded with a proliferation of Leydig cells and maintenance of the expression (rather than down-regulation occurring in inbreds) of gonadal aromatase (cyp19a1a) and insulin-like growth factor (igf1). Our results illustrate that the effects of an endocrine disrupting chemical (clotrimazole) on some end points (here testis development) can differ between inbred and outbred zebrafish. This highlights the need for reporting pedigree/genetic information and consistency in the responses of laboratory animals (e.g., by using model compounds as positive controls).
Research Publications - 2010
1. Jones H, Panter GH, Hutchinson TH, Chipman JK. (2010). Oxidative and conjugative metabolism in zebrafish larvae in vivo. Zebrafish, 7: 23-30.
http://online.liebertpub.com/doi/abs/10.1089/zeb.2009.0630
Abstract
As zebrafish larvae are being increasingly applied to toxicity testing, there is a need to understand the potential for xenobiotic metabolism by these early life-stage organisms. The expression of genes similar to mammalian cytochromes P450 (CYP) 2B6, CYP3A5, and UDP-glucuronosyl transferase (UGT) 1A1, as well as the zebrafish CYP1A was assessed across embryonic development. Activities toward 7-ethoxyresorufin O-deethylase (EROD assay), 7-ethoxycoumarin O-deethylase (ECOD assay), and octyloxymethylresorufin (OOMR assay) were detected at 96 h postfertilization, as was significant phenolic conjugation in the EROD assay (p < 0.001). The induction of CYP1A, the CYP gene zgc:153269, and UGT1A1 after exposure to Aroclor 1254 (100 μg/L, 24 h) was observed, with significant CYP1A induction (p < 0.01). Aroclor exposure also significantly induced EROD activity (p < 0.005), as did coexposure of α-naphthoflavone in a dose-dependent manner (p < 0.05; 5 and 10 μM exposures). Inhibition of CYP activity by SKF525A (5 μM) could not be demonstrated because of significant CYP induction as evidenced by OOMR activity (p < 0.05). This study demonstrates that zebrafish larvae express genes similar to mammalian CYP and UGT isoforms throughout early development and have activities toward model CYP substrates. The modulation of these genes and activities by CYP inducers is also reported. The continued use of these model organisms in toxicity testing is supported by this study.
2. Panter GH, Hutchinson TH, Hurd KS, Bamforth J, Stanley RD, Wheeler JR and Tyler CR. (2010). Effects of a weak oestrogenic active chemicals (4-tert-pentylphenol) on pair-breeding and F1 development in the fathead minnow (Pimephales promelas). Aquatic Toxicology, 97: 314-323.
http://www.sciencedirect.com/science/article/pii/S0166445X09004445
Abstract
A fish full life-cycle (FFLC) is the most comprehensive test to determine reproductive toxicity of chemicals to fish and this is likely to apply equally to endocrine active chemicals (EACs). However, FFLC tests use large numbers of animals, are expensive and time consuming. Alternative chronic tests, to the FFLC, potentially include sensitive life-stage windows of effect, such as sexual differentiation, early gonadal development and reproduction. In this paper, a fish pair-breeding study was applied to assess the biological effects of a weak environmental oestrogen, 4-tert-pentylphenol (4TPP), on reproduction and subsequent development of the F1 generation. The results of this study were then compared with the results for a published FFLC study, with this chemical. Fathead minnows (Pimephales promelas) were held in pairs and their reproductive performance assessed over two concurrent 21-day periods, the first without exposure to the test chemical, followed by the second with exposure to the test chemical, in a flow-through system at 25+/-1 degrees C. Embryos from two pairs, per treatment, were subsequently grown up in clean water until 90 days post-hatch to assess developmental effects of the parental exposure on the F1 generation. Nominal (measured geometric mean, time weighted) test concentrations of 4TPP were 56 (48), 180 (173) and 560 (570) microg l(-1). A significant decrease in fecundity was observed in all 4TPP exposed fish (mean number of eggs spawned per pair and number of spawns per pair) when compared to the solvent control. Vitellogenin (VTG) was significantly elevated in F0 males exposed to 560 microg 4TPPl(-1). Somatic endpoints, secondary sexual characteristics (SSC) and gonadosomatic index (GSI) were not affected by the 4TPP exposure. In the F1 generation, there were no treatment-related effects on hatching success, survival, growth, SSC or GSI. Histological examination of the gonads of the F1 fish revealed no treatment-related effects on sex ratio, sexual differentiation or sexual development. However, plasma VTG concentrations were significantly elevated in F1 male fish, derived from parents that had previously been exposed to 4TPP at concentrations of > or = 180 microg l(-1). These data show that the reproductive performance test is suitable for detecting weak environmental oestrogenic chemicals and that exposure of adult fish to oestrogens can result in altered biomarker expression (VTG) of the F1 generation. Our findings indicate that the reproductive performance test was as sensitive for detecting effects on reproduction when compared with a published FFLC test for 4TPP.
3. Winter MJ, Owen SF, Murray-Smith R, Panter GH, Hetheridge MJ and Kinter LB. (2010). Using data from drug discovery and development to aid the aquatic Environmental Risk Assessment of human pharmaceuticals: concepts, considerations and challenges. Integrated Environmental Assessment and Management, 6: 38-51.
http://onlinelibrary.wiley.com/doi/10.1897/IEAM_2009-044.1/full
Abstract
Over recent years, human pharmaceuticals have been detected in the aquatic environment. This, combined with the fact that many are (by design) biologically active compounds, has raised concern about potential impacts in wildlife species. This concern was realized with two high-profile cases of unforeseen environmental impact (i.e., estrogens and diclofenac), which have led to a flurry of work addressing how best to predict such effects in the future. One area in which considerable research effort has been made, partially in response to regulatory requirements, has been on the potential use of preclinical and clinical pharmacological and toxicological data (generated during drug development from nonhuman mammals and humans) to predict possible effects in nontarget, environmentally relevant species: so-called read across. This approach is strengthened by the fact that many physiological systems are conserved between mammals and certain environmentally relevant species. Consequently, knowledge of how a pharmaceutical works (the “mode-of-action,” or MoA) in nonclinical species and humans could assist in the selection of appropriate test species, study designs, and endpoints, in an approach referred to as “intelligent testing.” Here we outline the data available from the human drug development process and suggest how this might be used to design a testing strategy best suited to the specific characteristics of the drug in question. In addition, we review published data that support this type of approach, discuss the potential pitfalls associated with read across, and identify knowledge gaps that require filling to ensure accuracy in the extrapolation of data from preclinical and clinical studies, for use in the environmental risk assessment of human pharmaceuticals.
4. Langston WJ, Pope ND, Jonas PJ, Nikitic C, Field MD, Dowell B, Shillabeer N, Swarbrick RH, Brown AR. Contaminants in fine sediments and their consequences for biota of the Severn Estuary. Mar Pollut Bull., 61(1-3): 68-82.
http://www.sciencedirect.com/science/article/pii/S0025326X09005165
Abstract
When the first MPB special issue was published 25 years ago it was suggested that high body burdens of metals and selected organic pollutants in the Severn Estuary were the result of anthropogenic loadings from a variety of sources. The objective of this synopsis is to illustrate recent trends for contaminants (metals, PAHs, PCBs) in sediments and benthic biota and to consider the evidence for improved environmental quality over the last quarter of a century. Contaminants in sediments and sediment-dwelling fauna such as Hediste(=Nereis)diversicolor are, generally, evenly distributed over the estuary - which is the consequence of extensive re-suspension and redistribution of fine sediment by strong tidal currents. Such dispersal tends to mask the influences of individual discharges and physical characteristics are considered to be the major drivers affecting biodiversity in the Severn Estuary, often overshadowing contaminant concerns. Following the closure of major industries and the introduction of stricter pollution control, many inputs have ceased or been reduced and there are indications that environmental concentrations are now lower. Bioaccumulation of most contaminants has declined accordingly (with the possible exception of Cr). Intuitively, better environmental quality should be linked to ecological improvements. However, due to the dynamic nature of the system (and a lack of biological-effects data) it is difficult to establish direct relationships between inputs, body burdens and biological/ecological consequence. Uniquely, the long-term integrated monitoring program of AstraZeneca (Avonmouth) indicates that recovery of faunal diversity and abundance has occurred in mid-sections of the estuary in recent years implying that contaminants have indeed been a forcing feature for Severn biota. In this context, we highlight contaminant issues and biogeochemical changes which may need to be addressed in connection with the development of proposals for tidal energy schemes. (c) 2010 Elsevier Ltd. All rights reserved.
5. Crane M, Gross M, Matthiessen P, Ankley GT, Axford S, Bjerregaard P, Brown R, Chapman P, Dorgeloh M, Galay-Burgos M, Green J, Hazlerigg C, Janssen J, Lorenzen K, Parrott J, Rufli H, Schäfers C, Seki M, Stolzenberg HC, van der Hoeven N, Vethaak D, Winfield IJ, Zok S, Wheeler J. (2010). Multi-criteria decision analysis of test endpoints for detecting the effects of endocrine active substances in fish full life cycle tests. Integrated Environmental Assessment and Management, 6(3) 378-389. DOI: 10.1002/ieam.43
http://onlinelibrary.wiley.com/doi/10.1002/ieam.43/abstract
Abstract
Fish full life cycle (FFLC) tests are increasingly required in the ecotoxicological assessment of endocrine active substances. However, FFLC tests have not been internationally standardized or validated, and it is currently unclear how such tests should best be designed to provide statistically sound and ecologically relevant results. This study describes how the technique of multi-criteria decision analysis (MCDA) was used to elicit the views of fish ecologists, aquatic ecotoxicologists and statisticians on optimal experimental designs for assessing the effects of endocrine active chemicals on fish. In MCDA qualitative criteria (that can be valued, but not quantified) and quantitative criteria can be used in a structured decision-making process. The aim of the present application of MCDA is to present a logical means of collating both data and expert opinions on the best way to focus FFLC tests on endocrine active substances. The analyses are presented to demonstrate how MCDA can be used in this context. Each of 3 workgroups focused on 1 of 3 species: fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), and zebrafish (Danio rerio). Test endpoints (e.g., fecundity, growth, gonadal histopathology) were scored for each species for various desirable features such as statistical power and ecological relevance, with the importance of these features determined by assigning weights to them, using a swing weighting procedure. The endpoint F1 fertilization success consistently emerged as a preferred option for all species. In addition, some endpoints scored highly in particular species, such as development of secondary sexual characteristics (fathead minnow) and sex ratio (zebrafish). Other endpoints such as hatching success ranked relatively highly and should be considered as useful endpoints to measure in tests with any of the fish species. MCDA also indicated relatively less preferred endpoints in fish life cycle tests. For example, intensive histopathology consistently ranked low, as did measurement of diagnostic biomarkers, such as vitellogenin, most likely due to the high costs of these methods or their limited ecological relevance. Life cycle tests typically do not focus on identifying toxic modes and/or mechanisms of action, but rather, single chemical concentration–response relationships for endpoints (e.g., survival, growth, reproduction) that can be translated into evaluation of risk. It is, therefore, likely to be an inefficient use of limited resources to measure these mechanism-specific endpoints in life cycle tests, unless the value of such endpoints for answering particular questions justifies their integration in specific case studies. Integr Environ Assess Manag 2010;6:378–389. © 2010 SETAC
6. Corcoran J, Winter MJ, Tyler CR. Pharmaceuticals in the aquatic environment: a critical review of the evidence for health effects in fish. Crit Rev Toxicol 2010 40(4): 287-304.
http://informahealthcare.com/doi/abs/10.3109/10408440903373590
Abstract
The authors review the current data on the presence and reported biological effects in fish of some of the most commonly detected pharmaceuticals in the aquatic environment; namely nonsteroidal anti-inflammatory drugs (NSAIDs), fibrates, beta-blockers, selective serotonin reuptake inhibitors (SSRIs), azoles, and antibiotics. Reported biological effects in fish in the laboratory have often been shown to be in accordance with known effects of pharmaceuticals in mammals. Water concentrations at which such effects have been reported, however, are generally, between microg L(-1) and mg L(-1), typically at least 1 order of magnitude higher than concentrations normally found in surface waters (ng L(-1)). There are exceptions to this, however, as for the case of synthetic oestrogens, which can induce biological effects in the low ng L(-1) range. Although generally effect levels for pharmaceuticals are higher than those found in the environment, the risks to wild fish populations have not been thoroughly characterised, and there has been a lack of consideration given to the likely chronic nature of the exposures, or the potential for mixture effects. As global consumption of pharmaceuticals rises, an inevitable consequence is an increased level of contamination of surface and ground waters with these biologically active drugs, and thus in turn a greater potential for adverse effects in aquatic wildlife.
7. Whatling RD, Hedges P, Brown AR, Fermor P. (2010). Corporate responsibility reporting of biodiversity in the supply chain. International Journal of Innovation & Sustainable Development 2010 5(1): 51-64. DOI: 10.1504/IJISD.2010.034557
http://www.inderscience.com/browse/index.php?journalID=33&year=2010&vol=5&issue=1
Abstract
Industrial development, accompanying human population growth, has had a major role in creating the situation where bio-diverse materials and services essential for sustaining business are under threat. A major contributory factor to biodiversity decline comes from the cumulative impacts of extended supply chain business operations. However, within Corporate Responsibility (CR) reporting impacts on biodiversity due to supply chain operations have not traditionally been given equal weighting with other environmental issues. This paper investigates the extent of CR reporting in managing and publicising company biodiversity supply chain issues by reviewing a cross-sector sample of publicly available CR reports. The report contents were examined for suggestions of industrial sectorial trends in the level of biodiversity consideration. The reporting of environmental management system use within company supply chain management is assessed in the samples and is considered as a mechanism for responsible supplier partnership working.
8. Owen SF, Huggett DB, Hutchinson TH, Hetheridge MJ, McCormack P, Kinter LB, Ericson JF, Constantine LA, Sumptor JP. The value of repeating studies and multiple controls: Replicated 28-day growth studies of rainbow trout exposed to clofibric acid. Environ Toxicol & Chem. 29(12): 2831-2839.
http://onlinelibrary.wiley.com/doi/10.1002/etc.351/abstract
Abstract
Two studies to examine the effect of waterborne clofibric acid (CA) on growth-rate and condition of rainbow trout were conducted using accepted regulatory tests (Organisation for Economic Co-operation and Development [OECD] 215). The first study (in 2005) showed significant reductions after 21 d of exposure (21-d growth lowest-observed-effect concentration [LOEC] = 0.1 µg/L, 21-d condition LOEC = 0.1 µg/L) that continued to 28 d. Growth rate was reduced by approximately 50% (from 5.27 to 2.67% per day), while the condition of the fish reduced in a concentration-dependant manner. Additionally, in a concentration-dependent manner, significant changes in relative liver size were observed, such that increasing concentrations of CA resulted in smaller livers after 28-d exposure. A no-observed-effect concentration (NOEC) was not achieved in the 2005 study. An expanded second study (in 2006) that included a robust bridge to the 2005 study, with four replicate tanks of eight individual fish per concentration, did not repeat the 2005 findings. In the 2006 study, no significant effect on growth rate, condition, or liver biometry was observed after 21 or 28 d (28-d growth NOEC = 10 µg/L, 28-d condition NOEC = 10 µg/L), contrary to the 2005 findings. We do not dismiss either of these findings and suggest both are relevant and stand for comparison. However, the larger 2006 study carries more statistical power and multiple-tank replication, so probably produced the more robust findings. Despite sufficient statistical power in each study, interpretation of these and similar studies should be conducted with caution, because much significance is placed on the role of limited numbers of individual and tank replicates and the influence of control animals. Environ. Toxicol. Chem. 2010;29:2831–2839. © 2010 SETAC
9. Roberts GC, Penwell AJ, Peurou F, Sharpe AD. The effect of soil moisture content on nitrogen transformation using OECD test guideline 216. Applied Soil Ecology. 46(3): 478-482.
http://www.sciencedirect.com/science/article/pii/S0929139310001666
Abstract
One of the most important microbial processes in soil is the mineralisation of nitrogen in organic matter and this is vital for the maintenance of soil fertility. When performing a risk assessment for a substance that may enter the soil environment it is important to consider the potential effects the substance may have on the soil's microbial activity. The standardised test produced by the OECD (Organisation for Economic Co-operation and Development) (OECD, 2000) to address this requires that the soil moisture content should be maintained at between 40% and 60% of the maximum water holding capacity (MHC) with a range of ±5%. However, our investigations have suggested that the soil moisture content may adversely affect the performance of the test. The current research aimed to identify the moisture content range, within which the measured concentration of nitrate-N was sufficiently above background levels in soil. This moisture content range, which will be different for soils of different texture types, focused on a sandy loam soil fulfilling the criteria of the OECD 216 guideline (OECD, 2000). The nitrate-N yield and the EC50 (the concentration causing 50% inhibition of nitrogen transformation) of the reference substance, nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine), were determined at varying soil moisture contents. The results indicate that the current OECD recommended upper limit for the soil moisture content (60% MHC) may be too high. The yield of nitrate-N and the EC50 for nitrapyrin, were relatively constant between 20 and 40% MHC. Other reported data (Roberts et al., 2003) suggests that 50% MHC produced similar results. Therefore, we suggest that the OECD test be conducted between 20 and 50% MHC.
Research Publications - 2009
1. Küster A, Alder AC, Escher B, Duis K, Fenner K, Garric J, Hutchinson T, Lapen D, Péry A, Römbke J, Snape JR, Ternes T, Topp E, Wehrhan A, Knacker T. Environmental Risk Assessment of human pharmaceuticals in the European Union - A case study with the beta-blocker Atenolol. Integrated Environment Assessment and Management. 2009 Oct 30:1. [Integr Environ Assess Manag. 2010 Jul;6 Suppl:514-23.]
http://onlinelibrary.wiley.com/doi/10.1897/IEAM_2009-050.1/full
Abstract
β-Adrenergic receptor blockers (β-blockers) are applied to treat high blood pressure, ischemic heart disease, and heart rhythm disturbances. Due to their widespread use and limited human metabolism, β-blockers are widely detected in sewage effluents and surface waters. β-Adrenergic receptors have been characterized in fish and other aquatic animals, so it can be expected that physiological processes regulated by these receptors in wild animals may be affected by the presence of β-blockers. Because ecotoxicological data on β-blockers are scarce, it was decided to choose the β-blocker atenolol as a case study pharmaceutical within the project ERAPharm. A starting point for the assessment of potential environmental risks was the European guideline on the environmental risk assessment of medicinal products for human use. In Phase I of the risk assessment, the initial predicted environmental concentration (PEC) of atenolol in surface water (500 ng L−1) exceeded the action limit of 10 ng L−1. Thus, a Phase II risk assessment was conducted showing acceptable risks for surface water, for groundwater, and for aquatic microorganisms. Furthermore, atenolol showed a low potential for bioaccumulation as indicated by its low lipophilicity (log KOW = 0.16), a low potential for exposure of the terrestrial compartment via sludge (log KOC = 2.17), and a low affinity for sorption to the sediment. Thus, the risk assessment according to Phase II-Tier A did not reveal any unacceptable risk for atenolol. Beyond the requirements of the guideline, additional data on effects and fate were generated within ERAPharm. A 2-generation reproduction test with the waterflea Daphnia magna resulted in the most sensitive no-observed-effect concentration (NOEC) of 1.8 mg L−1. However, even with this NOEC, a risk quotient of 0.003 was calculated, which is still well below the risk threshold limit of 1. Additional studies confirm the outcome of the environmental risk assessment according to EMEA/CHMP (2006). However, atenolol should not be considered as representative for other β-blockers, such as metoprolol, oxprenolol, and propranolol, some of which show significantly different physicochemical characteristics and varying toxicological profiles in mammalian studies.
2. Winter MJ, Owen SF, Murray-Smith R, Panter GH, Hetheridge MJ, Kinter LB. Using data from drug discovery and development to aid the aquatic Environmental Risk Assessment of human pharmaceuticals: concepts, considerations and challenges. Integrated Environmental Assessment and Management (2009) 6(1), 38-51
http://onlinelibrary.wiley.com/doi/10.1897/IEAM_2009-044.1/full
Abstract
Over recent years, human pharmaceuticals have been detected in the aquatic environment. This, combined with the fact that many are (by design) biologically active compounds, has raised concern about potential impacts in wildlife species. This concern was realized with two high-profile cases of unforeseen environmental impact (i.e., estrogens and diclofenac), which have led to a flurry of work addressing how best to predict such effects in the future. One area in which considerable research effort has been made, partially in response to regulatory requirements, has been on the potential use of preclinical and clinical pharmacological and toxicological data (generated during drug development from nonhuman mammals and humans) to predict possible effects in nontarget, environmentally relevant species: so-called read across. This approach is strengthened by the fact that many physiological systems are conserved between mammals and certain environmentally relevant species. Consequently, knowledge of how a pharmaceutical works (the “mode-of-action,” or MoA) in nonclinical species and humans could assist in the selection of appropriate test species, study designs, and endpoints, in an approach referred to as “intelligent testing.” Here we outline the data available from the human drug development process and suggest how this might be used to design a testing strategy best suited to the specific characteristics of the drug in question. In addition, we review published data that support this type of approach, discuss the potential pitfalls associated with read across, and identify knowledge gaps that require filling to ensure accuracy in the extrapolation of data from preclinical and clinical studies, for use in the environmental risk assessment of human pharmaceuticals.
3. Owen SF, Huggett DB, Hutchinson TH, Hetheridge MJ, Kinter LB, Ericson JF, Sumpter JP. Uptake of propranolol, a cardiovascular pharmaceutical, from water into fish plasma and its effects on growth and organ biometry. Aquatic Toxicology (2009). 93(4):217-224.
http://www.sciencedirect.com/science/article/pii/S0166445X09001635
Abstract
Pharmaceuticals in the environment (PIE) are of importance since these compounds are designed to affect biological receptors/enzymes that are often conserved across vertebrate families. Across-species extrapolation of these therapeutic targets suggests potential for impacting amphibia and fish in the aquatic environment. Due to the scarcity of relevant ecotoxicological data, the long-tem impact of PIE remains a research question. Efficient use of mammalian data has been proposed to better understand and predict the potential for a given pharmaceutical to impact the environment. Using a model cardiovascular pharmaceutical (propranolol, a non-specific beta(1)/beta(2)-adrenergic antagonist), the hypothesis that mammalian data can be used to predict toxicity in fish was tested. Rainbow trout (Oncorhynchus mykiss (Walbaum)) have beta-adrenergic signalling mechanisms analogous to human cardiovascular receptors that respond to pharmacological doses of agonists and antagonists. Trout absorbed propranolol from water such that after 40 days of exposure, the linear relationship was [plasma] - 0.59[water] (n - 31, r - 0.96). Growth rate was affected only at very high aqueous concentrations (10-day (growth)NOEC - 1.0 and (growth)LOEC - 10 mg/l). Growth recovered with time (40-day (growth)NOEC - 10 mg/l), suggesting possible adaptation to the pharmaceutical, although the internal plasma concentration in trout exposed to 10mg propranolol/l of water was higher than the mammalian therapeutic plasma concentration. Additional endpoints suggested subtle changes of liver and heart size at much lower concentrations may have occurred, although these were not concentration-related. There was, however, a dose-dependent effect upon overall body condition. The trout plasma concentrations at these effective aqueous concentrations fell within the range of mammalian effective plasma concentrations, supporting the potential for developing 'read-across' from mammalian pharmacology safety data to fish ecotoxicology. Despite these effects at relatively high concentrations, propranolol is not expected to pose a risk to fish at the concentrations considered to be present in the aquatic environment.
4. Liu Q-T, Cumming RI, Sharpe AD. Photo-induced environmental depletion processes of b-blockers in river waters. Photochem. Photobiol. Sci., 2009, 8, 768 - 777, DOI: 10.1039/b817890a.
http://onlinelibrary.wiley.com/doi/10.1897/09-071.1/pdf
Abstract
In order to improve the understanding of the fate and behaviour of pharmaceuticals in the environment there is a need to investigate in-stream depletion mechanisms, e.g. phototransformation of active pharmaceutical ingredients (APIs) in natural surface waters. In this study, abiotic and biotic degradation of selected beta-blockers was measured simultaneously in non-sterilised and sterilised river waters and deionised water (DIW) under simulated sunlight (lambda: 295-800 nm) and dark conditions, and at environmentally relevant concentrations, i.e.
5. Brown AR, Hosken DJ, Balloux F, Bickley LK, LePage G, Owen SF, Hetheridge MJ, Tyler CR. Genetic variation, inbreeding and chemical exposure--combined effects in wildlife and critical considerations for ecotoxicology. Philos Trans R Soc Lond B Biol Sci. 2009 Nov 27;364(1534):3377-90. Review.
http://rstb.royalsocietypublishing.org/content/364/1534/3377.abstract
Abstract
Exposure to environmental chemicals can have negative consequences for wildlife and even cause localized population extinctions. Resistance to chemical stress, however, can evolve and the mechanisms include desensitized target sites, reduced chemical uptake and increased metabolic detoxification and sequestration. Chemical resistance in wildlife populations can also arise independently of exposure and may be spread by gene flow between populations. Inbreeding—matings between closely related individuals—can have negative fitness consequences for natural populations, and there is evidence of inbreeding depression in many wildlife populations. In some cases, reduced fitness in inbred populations has been shown to be exacerbated under chemical stress. In chemical testing, both inbred and outbred laboratory animals are used and for human safety assessments, iso-genic strains (virtual clones) of mice and rats are often employed that reduce response variation, the number of animals used and associated costs. In contrast, for environmental risk assessment, strains of animals are often used that have been selectively bred to maintain heterozygosity, with the assumption that they are better able to predict adverse effects in wild, genetically variable, animals. This may not necessarily be the case however, as one outbred strain may not be representative of another or of a wild population. In this paper, we critically discuss relationships between genetic variation, inbreeding and chemical effects with the intention of seeking to support more effective chemical testing for the protection of wildlife.
6. Whatling DR, Brown AR, Hedges P and Fermor P (2009). Supply chain corporate responsibility reporting: An assessment of the extent of industry reporting on biodiversity. In Mumba, Amos and Ketola, Tarja (Eds.) 2009. Responsible Leadership: Proceedings of the Corporate Responsibility Research (CRR) 2009 Conference. Proceedings of the University of Vaasa, Reports 157, Vaasa, Finland. ISBN 978- 952-476-285-4, ISSN 1238-7118.
http://www.uwasa.fi/materiaali/pdf/isbn_978-952-476-285-4.pdf.
Industrial development has had a major role in creating the situation where bio-diverse materials and services essential for sustaining business are under threat. A major contributory factor to biodiversity decline comes from the cumulative impacts of extended supply chain business operations. There is an increasing call for companies to manage and report on the potential risks and opportunities that may affect sustainable production, corporate responsibility and reputation. However, within Corporate Responsibility (CR) reporting impacts on biodiversity due to supply chain operations have not traditionally been given equal weighting with other environmental issues. The situation is seeing little change despite widely publicised assessments of deteriorating natural resources aimed at increasing business and public awareness.
This paper investigates the extent of CR reporting in managing and publicising company biodiversity supply chain issues by reviewing a cross-sector sample of publicly available CR reports. The report contents were examined for suggestions of industrial sectorial trends in the level of biodiversity consideration. The reporting of environmental management system use within company supply chain management is assessed in the samples and is considered as a mechanism for responsible supplier partnership working.
7. Brown AR, Robinson PF, Riddle AM, Panter GH (2009). Population dynamics modelling: a tool for environmental risk assessment of endocrine disrupting chemicals. Chapter 3 pages 47-82 in: Endocrine disruption modelling, Ed. J Devillers, Publ. CRC Press.
Abstract
Environmental Risk Assessment (in Europe) and equivalent processes including Ecological Risk Assessment (USA) and Ecosystem Risk Assessment (Japan) are collectively referred to in this chapter as ERA. They each involve the scientific analysis and characterisation of environmental hazards (frequently chemicals) based on the predicted likelihood and level of exposure, versus the predicted severity of any consequent adverse effects. The discovery of “endocrine disruption” in wildlife due to natural hormones and synthetic mimics (endocrine disrupting chemicals, EDCs) in the last two decades has challenged the established ERA process, since very low exposure levels may illicit adverse effects including non-monotonic responses in exposed organisms (Section 3.1.2). Accepting that it is impossible to legislate to protect every organism, especially when some natural losses are inevitable (For example due to climatic stress or predation), the aims of ERA are to ensure the sustainability of populations to protect species and maintain the structure and functioning of ecosystems in which they live. Ultimately ERA requires clear understanding and communication of risks and objective decision-making on the part of risk managers. This is based on an assessment of the most relevant data or facts (assessment endpoints) concerning the predicted behaviour, fate and effects of chemicals in the environment. A number of mathematical models are available to risk assessors, which have enormous potential in helping to relate chemical properties to potential behaviour and/or understand empirical data concerning exposure, uptake and effects experienced by individual organisms (see Chapters 6, 7, 11, 13). Population modelling can offer additional help in linking individual exposure to population effect, extrapolating from lab to field, but more importantly by providing a means of communicating risk and uncertainty to risk managers in a form that they can clearly understand and apply. By focusing on ecologically relevant effects and scales, population-level ERA can aid regulatory decision-making and help focus finite resources on managing ecologically significant risks (Section 3.1.1). This chapter illustrates how population dynamics modelling can support the established ERA process. Case studies are presented concerning endocrine disruption in fish (Section 3.1).
8. Boethling R, Fenner K, Howard P, Klecka G, Madsen T, Snape JR, Whelan MJ. Environmental persistence of organic pollutants: guidance for development and review of POP risk profiles. Integrated Environment Assessment and Management. 2009 5(4):539-56.
http://onlinelibrary.wiley.com/doi/10.1897/IEAM_2008-090.1/abstract
Abstract
Environmental persistence is an important property that can enhance the potential of a chemical substance to exert adverse effects and be transported to remote environments. The persistence of organic compounds is governed by the rates at which they are removed by biological and chemical processes, such as biodegradation, hydrolysis, atmospheric oxidation, and photolysis. The persistence workgroup in a recent Society of Environmental Toxicology and Chemistry (SETAC) Pellston workshop (Pensacola, FL, USA, January 2008) focused on evaluating persistence of organic compounds in environmental media (air, water, soil, sediment) in terms of their single-medium degradation half-lives. The primary aim was to provide guidance to authors and reviewers of chemical dossiers for persistent organic pollutants (POPs) and persistent, bioaccumulative, and toxic substances (PBTs) proposed for action. A second objective was to provide a summary of the current state of the science with respect to POP fate assessment. Assessing the persistence of chemical substances in the environment is not straightforward. A common misconception is that, like many chemical properties, environmental persistence is an inherent property of the substance and can be readily measured. In fact, rates of degradation of a substance in the environment are determined by a combination of substance-specific properties and environmental conditions. This article addresses how persistence can be evaluated based on an assortment of supporting information. Special attention is given to several critical issues, including transformation products, nonextractable residues, and treatment of uncertainty and conflicting data as part of a weight-of-evidence assessment.
9. Liu Q-T, Williams TD, Cumming RI, Holm G, Hetheridge MJ, Murray-Smith R. Comparative aquatic toxicity of propranolol and its photodegraded mixtures: algae and rotifer screening. Environ. Toxicol. Chem. 28(12), 2622-2631.
http://onlinelibrary.wiley.com/doi/10.1897/09-071.1/abstract
Abstract
Transformation products of pharmaceuticals formed by human metabolism within sewage treatment plant or receiving waters are predicted, in most cases, to be less toxic than the parent compound to common aquatic species. However, there is little available data to demonstrate whether this is generally the case. In the present study, a framework was developed to guide testing of transformation products using phototransformation of the β-blocker propranolol to test the hypothesis for this particular transformation route. Phototransformation is an important depletion mechanism of some pharmaceuticals in surface waters with fast reaction rate constants at environmentally relevant conditions. Samples of propranolol in deionized water (DIW) and river water (RW) were exposed to a solar simulator (λ: 295–800 nm) and comparative toxicity of propranolol and its degraded mixtures measured using algal (Pseudokirchneriella subcapitata) and rotifer (Brachionus calyciflorus) screening tests. Results suggested a reduction of toxicity in photodegraded mixtures compared to the parent active pharmaceutical ingredient in all samples tested. Chemical analysis of effect test solutions supported the hypothesis that propranolol was transformed into compounds that appear to be less toxic to the organisms tested under the study conditions. Although the reactions were much faster in RW than in DIW, profiles of transformation products were similar in both matrices at two starting concentrations (1 and 10 mg/L). Results for propranolol implied that the reduction of toxicity using algal and rotifer screening tests was probably due to the production of more hydrophilic and more polar transformation products. Such results will provide useful insights into the environmental risk assessment of pharmaceuticals by taking into account their transformation products.
10. Williams TD, Readman GD, Owen SF. (2009). Key issues concerning environmental enrichment for laboratory-held fish species. Laboratory Animals 43:1-14.
Abstract
An improved knowledge and understanding of the fundamental biological requirements is needed for many of the species of fish held in captivity and, without this knowledge it is difficult to determine the optimal conditions for laboratory culture. The aim of this paper is to review the key issues concerning environmental enrichment for laboratory-held fish species and identify where improvements are required. It provides background information on environmental enrichment, describes enrichment techniques currently used in aquatic ecotoxicology studies, identifies potential restrictions in their use and discusses why more detailed and species-specific guidance is needed.
11. Bickley LK, Lange A, Winter MJ, Tyler CR. Evaluation of a carp primary hepatocyte culture system for screening chemicals for oestrogenic activity. Aquatic Toxicology 2009 Sep 14;94(3):195-203. Epub 2009 Jul 16.
http://www.sciencedirect.com/science/article/pii/S0166445X0900229X
Abstract
The presence of endocrine disrupting chemicals (EDCs) in the environment has driven the development of screening and testing assays to both identify chemicals with hormonal activity and evaluate their potential to cause adverse effects. As the number of animals used for research and regulatory purposes rises, and set against a desire to reduce animal testing, there is increased emphasis on the development and application of in vitro techniques to evaluate chemical risks to the environment. Induction of vitellogenin (VTG) in isolated fish liver cells has been used successfully to identify a wide range of EDCs, including both natural and synthetic oestrogens and a variety of other xenoestrogens. However, the vitellogenic response reported for hepatocytes in culture has been shown to vary widely, making comparisons between studies difficult. The work presented in this paper explored the variability of the vitellogenic response in primary cultures of common carp (Cyprinus carpio) hepatocytes following exposure to the model oestrogenic compound, 17β-oestradiol (E2). As expected, variability in the vitellogenic response was observed, both in terms of the sensitivity and magnitude of VTG induction, for hepatocytes isolated from different fish. An apparent difference was observed in the response of isolated hepatocytes based on the sex of the donor fish; maximum levels of E2-stimulated VTG synthesis in hepatocytes derived from females appeared higher (1962 ng mL−1 ± 487 [n = 9] compared with 1194 ng mL−1 ± 223 for hepatocytes from males [n = 9]) and EC50 values lower (1.61 ± 0.4 μM E2 for females and 2.12 ± 0.2 μM E2 for males). However, these differences were not statistically significant, likely in part due to the variation observed in the vitellogenic response. In particular, hepatocytes derived from female fish showed more variation than their male counterparts (the co-efficient of variation for females was 77% compared to 28% for males). Despite the variation observed in the vitellogenic response between different cultures, data from the different donor fish could be compared by standardising responses relative to the maximum VTG induction in each culture following exposure to E2. Adopting this approach in the future will allow for data from different hepatocyte cultures and from donor fish of different sexes, age and stage of maturity to be compared with greater consistency. Measurement of vtg mRNA expression was relatively more sensitive to the oestrogenic effects of E2 exposure than measurement of VTG protein (the LOEC at the transcriptome level was 10-fold lower [0.01 μM E2] than at the protein level [0.1 μM E2]) and changes in vtg mRNA expression showed less variation between individual hepatocyte isolations. Measurement of vtg mRNA in the hepatocyte culture system therefore may offer the most sensitive and consistent option for the screening of chemicals with oestrogenic activity in fish primary hepatocyte cultures.
12. Tyler CR, Filby AL, Bickley LK, Cumming RI, Gibson R, Labadie P, Katsu Y, Liney KE, Shears JA, Silva-Castro V, Urushitani H, Lange A, Winter MJ, Iguchi T, Hill EM. Environmental health impacts of equine estrogens derived from hormone replacement therapy. Environ Science and Technology. 2009 May 15;43(10):3897-904.
http://pubs.acs.org/doi/abs/10.1021/es803135q
Many factors have been considered in evaluations of the risk−benefit balance of hormone replacement therapy (HRT), used for treating menopausal symptoms in women, but not its potential risks for the environment. We investigated the possible environmental health implications of conjugated equine estrogens (CEEs), the most common components of HRT, including their discharge into the environment, their uptake, potency, and ability to induce biological effects in wildlife. Influents and effluents from four UK sewage treatment works (STWs), and bile of effluent-exposed fish, were screened for six equine estrogens. In vitro estrogen receptor (ER) activation assays were applied in humans and fish to compare their potencies, followed by in vivo exposures of fish to equine estrogens and evaluation of bioaccumulation, estrogenic responses, and ER gene expression. The equine estrogen equilenin (Eqn), and its metabolite 17β-dihydroequilenin (17β-Eqn), were detected by tandem GC-MSMS in all STW influent samples and 83% of STW effluent samples analyzed, respectively, at low concentrations (0.07−2.6 ng/L) and were taken-up into effluent-exposed fish. As occurs in humans, these estrogens bound to and activated the fish ERs, with potencies at ERα 2.4−3490% of that for 17β-estradiol. Exposure of fish for 21 days to Eqn and 17β-Eqn induced estrogenic responses including hepatic growth and vitellogenin production at concentrations as low as 0.6−4.2 ng/L. Associated with these effects were inductions of hepatic ERα and ERβ1 gene expression, suggesting ER-mediated mechanism(s) of action. These data provide evidence for the discharge of equine estrogens from HRT into the aquatic environment and highlight a strong likelihood that these compounds contribute to feminization in exposed wildlife.
