Overcompensation of CoA Trapping by Di(2-ethylhexyl) Phthalate (DEHP) Metabolites in Livers of Wistar Rats.

Di(2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in various industrial and household plastic products, ensuring widespread human exposures. Its routine detection in human bio-fluids and the propensity of its monoester metabolite to activate peroxisome proliferator activated receptor-α (PPARα) and perturb lipid metabolism implicate it as a metabolic disrupter. In this study we evaluated the effects of DEHP exposure on hepatic levels of free CoA and various CoA esters, while also confirming the metabolic activation to CoA esters and partial ß-oxidation of a DEHP metabolite (2-ethyhexanol). Male Wistar rats were exposed via diet to 2% (w/w) DEHP for fourteen-days, following which hepatic levels of free CoA and various CoA esters were identified using liquid chromatography-mass spectrometry. DEHP exposed rats showed significantly elevated free CoA and increased levels of physiological, DEHP-derived and unidentified CoA esters. The physiological CoA ester of malonyl-CoA and DEHP-derived CoA ester of 3-keto-2-ethylhexanoyl-CoA were the most highly elevated, at eighteen- and ninety eight-times respectively. We also detected sixteen unidentified CoA esters which may be derivative of DEHP metabolism or induction of other intermediary metabolism metabolites. Our results demonstrate that DEHP is a metabolic disrupter which affects production and sequestration of CoA, an essential cofactor of oxidative and biosynthetic reactions.

Long-term hypoxia exposure alters the cardiorespiratory physiology of steelhead trout (Oncorhynchus mykiss), but does not affect their upper thermal tolerance.

It has been suggested that exposure to high temperature or hypoxia may confer tolerance to the other oxygen-limited stressor (i.e., 'cross-tolerance'). Thus, we investigated if chronic hypoxia-acclimation (>3 months at 40% air saturation) improved the steelhead trout's critical thermal maximum (CTMax), or affected key physiological variables that could impact upper thermal tolerance. Neither CTMax (24.7 vs. 25.3°C) itself, nor oxygen consumption ( [Formula: see text] ), haematocrit, blood haemoglobin concentration, or heart rate differed between hypoxia- and normoxia-acclimated trout when acutely warmed. However, the cardiac output (Q̇) of hypoxia-acclimated fish plateaued earlier compared to normoxia-acclimated fish due to an inability to maintain stroke volume (SV), and this resulted in a ~50% lower maximum Q̇. Despite this reduced maximum cardiac function, hypoxia-acclimated trout were able to consume more O2 per volume of blood pumped as evidenced by the equivalent [Formula: see text] . These results provide additional evidence that long-term hypoxia improves tissue oxygen utilization, and that this compensates for diminished cardiac pumping capacity. The limited SV in hypoxia-acclimated trout in vivo was not associated with changes in cardiac morphology or in vitro maximum SV, but the affinity and density of myocardial ß-adrenoreceptors were lower and higher, respectively, than in normoxia-acclimated fish. These data suggest that alterations in ventricular filling dynamics or myocardial contractility constrain cardiac function in hypoxia-acclimated fish at high temperatures. Our results do not support (1) 'cross-tolerance' between high temperature and hypoxia when hypoxia is chronic, or (2) that cardiac function is always the determinant of temperature-induced changes in fish [Formula: see text] , and thus thermal tolerance, as suggested by the oxygen- and capacity-limited thermal tolerance (OCLTT) theory.

Effect of Acute Alcohol Ingestion on Resistance Exercise-Induced mTORC1 Signaling in Human Muscle.

Duplanty, AA, Budnar, RG, Luk, HY, Levitt, DE, Hill, DW, McFarlin, BK, Huggett, DB, and Vingren, JL. Effect of acute alcohol ingestion on resistance exercise-induced mTORC1 signaling in human muscle. J Strength Cond Res 31(1): 54-61, 2017-The purpose of this project was to further elucidate the effects postexercise alcohol ingestion. This project had many novel aspects including using a resistance exercise (RE) only exercise design and the inclusion of women. Ten resistance-trained males and 9 resistance-trained females completed 2 identical acute heavy RE trials (6 sets of Smith machine squats) followed by ingestion of either alcohol or placebo. All participants completed both conditions. Before exercise (PRE) and 3 (+3 hours) and 5 (+5 hours) hours postexercise, muscle tissue samples were obtained from the vastus lateralis by biopsies. Muscle samples were analyzed for phosphorylated mTOR, S6K1, and 4E-BP1. For men, there was a significant interaction effect for mTOR and S6K1 phosphorylation. At +3 hours, mTOR and S6K1 phosphorylation was higher for placebo than for alcohol. For women, there was a significant main effect for time. mTOR phosphorylation was higher at +3 hours than at PRE and at +5 hours. There were no significant effects found for 4E-BP1 phosphorylation in men or women. The major findings of this study was that although RE elicited similar mTORC1 signaling both in men and in women, alcohol ingestion seemed to only attenuate RE-induced phosphorylation of the mTORC1 signaling pathway in men. This study provides evidence that alcohol should not be ingested after RE as this ingestion could potentially hamper the desired muscular adaptations to RE by reducing anabolic signaling, at least in men.

Exposures to a selective serotonin reuptake inhibitor (SSRI), sertraline hydrochloride, over multiple generations: changes in life history traits in Ceriodaphnia dubia.

Selective serotonin reuptake inhibitors (SSRIs) have been reported to range from low parts per trillion to parts per billion levels in surface waters, wastewater effluents, and sediments. These low levels have led to concern for their potential long-term risks to the survival, growth, and reproduction of aquatic organisms. We investigated the acute and chronic effects of sertraline on the life history traits of Ceriodaphnia dubia over the course of three generations under environmentally realistic concentrations. Acute toxicity of sertraline in C. dubia offspring resulted in a 48h median effective concentration of 126µgL(-1). Under chronic exposure, the lowest concentration to affect fecundity and growth was at 53.4µgL(-1) in the first two generations. These parameters become more sensitive during the third generation where the LOEC was 4.8µgL(-1). The median effective concentrations (EC50) for the number of offspring per female, offspring body size, and dry weight were 17.2, 21.2, and 26.2µgL(-1), respectively. Endpoints measured in this study demonstrate that chronic exposure of C. dubia to sertraline leads to effects that occur at concentrations only an order of magnitude higher than predicted environmental concentrations. However, this study also demonstrates that multigenerational effects should be considered in chronic exposure studies because standard toxicity tests do not account for increases in sensitivity in successive generations to toxicants.

Involvement of ß(3)-adrenergic receptors in in vivo cardiovascular regulation in rainbow trout (Oncorhynchus mykiss).

Currently, we have little information concerning the involvement of ß(3)-adrenergic receptors (AR) in cardiovascular regulation in fishes. The goal of this study was to investigate the effect of ß(3)-AR ligands on in vivo cardiovascular function in larval and adult rainbow trout (Oncorhynchus mykiss). In adult fish, injection of BRL(37344) (ß(3)-AR agonist) resulted in an increase in heart rate (f(H)) (~31%) while stroke volume (Sv) was reduced (-25.9%). Injection of SR(59230A) (ß(3)-AR antagonist) and propranolol (ß(1)/ß(2)-AR antagonist) resulted in increases in dorsal aorta blood pressure (P(DA)) with differing effect on cardiac variables (f(H) and Sv). To confirm specificity of the results, BRL(37344) was injected following sequential injections of phentolamine (α(1)-AR antagonist), atropine (muscarinic antagonist), propranolol and SR(59230A). While phentolamine had no effect on BRL(37344), atropine completely abolished the influence of BRL(37344) on f(H), Sv and cardiac output (Q). In larval trout, BRL(37344) (10 and 100 µM) induced a significant concentration-dependent increase in f(H) while SR(59230A) (1 and 10 µM) and propranolol (1 and 10 µM) separately caused a significant concentration-dependent decrease. These data suggest that ß(3)-ARs have an important role in regulation of cardiovascular function, and provide evidence for a potential interaction between muscarinic and adrenergic receptors in rainbow trout.

Chronic effects of carbamazepine on life-history strategies of Ceriodaphnia dubia in three successive generations.

Trace quantities of pharmaceuticals are continuously being discharged into the environment through domestic and industrial wastewater effluents, causing concern among scientists and regulators regarding potential long-term impacts on aquatic ecosystems. These compounds and their metabolites are constantly interacting with organisms at various life-cycle stages and may differentially influence the development of embryonic, larval, juvenile, and adult stages. To understand the possible cumulative effects of exposure to carbamazepine (CBZ), a multigenerational approach was taken in which survival, reproduction, respiration, growth, brood size, and biomass of Ceriodaphnia dubia were assessed at sublethal concentrations over the course of three successive generations. CBZ exposure significantly decreased fecundity at 196.7 µg/L in the F0 and F1 generations over 2 weeks and acclimatized at 264.6 µg/L in the F2 generation. Similarly, a significant decrease of neonate dry weight was observed at the 196.7 µg/L CBZ treatment in the F1 generation, and it acclimatized at 264.6 µg/L treatment level in the F2 generation. Median time to first brood release was significantly delayed at 264.6 µg/L in the F2 generation, indicating slower maturation. Results over three successive generations are not different than what one would obtain by testing simply the F0 generation. Furthermore, the effects measured were observed at concentrations two orders of magnitude higher than are environmentally relevant, and it is unlikely that CBZ poses a substantial risk to the environment regarding the end points measured in this study. However, additional research through laboratory and field multigenerational studies may be required to understand the overall risk of CBZ to other nontarget organisms.

Constraints-based stoichiometric analysis of hypoxic stress on steroidogenesis in fathead minnows, Pimephales promelas.

In this study, an in silico genome-scale metabolic model of steroidogenesis was used to investigate the effects of hypoxic stress on steroid hormone productions in fish. Adult female fathead minnows (Pimephales promelas) were exposed to hypoxia for 7 days with fish sub-sampled on days 1, 3 and 7 of exposure. At each time point, selected steroid enzyme gene expressions and steroid hormone productions were quantified in ovaries. Fold changes in steroid enzyme gene expressions were used to qualitatively scale transcript enzyme reaction constraints (akin to the range of an enzyme's catalytic activity) in the in silico model. Subsequently, in silico predicted steroid hormone productions were qualitatively compared with experimental results. Key findings were as follows. (1) In silico gene deletion analysis identified highly conserved 'essential' genes required for steroid hormone productions. These agreed well (75%) with literature-published genes downregulated in vertebrates (fish and mammal) exposed to hypoxia. (2) Quantification of steroid hormones produced ex vivo from ovaries showed a significant reduction for 17ß-estradiol and 17α,20ß-dihydroxypregnenone production after 24 h (day 1) of exposure. This lowered 17ß-estradiol production was concomitant with downregulation of cyp19a1a gene expression in ovaries. In silico predictions showed agreement with experimentation by predicting effects on estrogen (17ß-estradiol and estrone) production. (3) Stochastic sampling of in silico reactions indicated that cholesterol uptake and catalysis to pregnenolone along with estrogen methyltransferase and glucuronidation reactions were also impacted by hypoxia. Taken together, this in silico analysis introduces a powerful model for pathway analysis that can lend insights on the effects of various stressor scenarios on metabolic functions.

Field and laboratory fish tissue accumulation of the anti-convulsant drug carbamazepine.

Understanding the potential for human and veterinary pharmaceuticals to accumulate in the tissues of biota is a topic of increasing importance in the pharmaceutical risk assessment process. However, few data are available in the literature that compare the ability of laboratory bioconcentration studies to predict field tissue concentrations. To begin to address this data gap, bioconcentration factors (BCF) for carbamazepine (CBZ), a human anticonvulsant that modulates Na+ channels, were determined using laboratory experiments with Pimephales notatus and Ictalurus punctatus. These data were compared to field derived bioaccumulation factors (BAFs) for Oreochromis niloticus from the Denton, Texas Wastewater Treatment Plant. The 42 d kinetic BCFs (BCFk) for white muscle and liver of P. notatus were 1.9 and 4.6, respectively, while the white muscle, liver, brain, and plasma BCFk's of I. punctatus were 1.8, 1.5, 1.6, and 7.1, respectively. Field derived BAF values (2.5-3.8) for O. niloticus were similar to those derived in laboratory studies. Partitioning values between blood plasma and individual tissues were calculated for I. punctatus and O. niloticus, with the values indicating that tissue levels of carbamazepine are similar or slightly higher than plasma concentrations. Collectively these data suggest that the fish laboratory BCF and field derived BCF/BAF values for carbamazepine are similar and much lower than the European Union regulatory threshold of 2000 for designation of a "B" substance.

In vivo and in vitro liver and gill EROD activity in rainbow trout (Oncorhynchus mykiss) exposed to the beta-blocker propranolol.

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 nontarget 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 ß-adrenergic receptor antagonist or ß-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.

Tissue-specific uptake and bioconcentration of the oral contraceptive norethindrone in two freshwater fishes.

The environmental presence of the oral contraceptive norethindrone (NET) has been reported and shown to have reproductive effects in fish at environmentally realistic exposure levels. The current study examined bioconcentration potential of NET in fathead minnow (Pimephales promelas) and channel catfish (Ictalurus punctatus). Fathead minnows were exposed to 50 µg/l NET for 28 days and allowed to depurate in clean water for 14 days. In a minimized 14-day test design, catfish were exposed to 100 µg/l NET for 7 days followed by 7-day depuration. In the fathead test, tissues (muscle, liver, and kidneys) were sampled during the uptake (days 1, 3, 7, 14, and 28) and depuration (days 35 and 42) phases. In the catfish test, muscle, liver, gill, brain, and plasma were collected during the uptake (days 1, 3, and 7) and depuration (day 14) stages. NET tissue levels were determined by gas chromatography-mass spectrometry (GC-MS). Accumulation of NET in tissues was greatest in liver followed by plasma, gill, brain, and muscle. Tissue-specific bioconcentration factors (BCFs) ranged from 2.6 to 40.8. Although NET has been reported to elicit reproductive effects in fish, the present study indicated a low potential to bioconcentrate in aquatic biota.

Ibuprofen metabolism in the liver and gill of rainbow trout, Oncorhynchus mykiss.

The presence of pharmaceuticals in the environment has become an important topic of discussion with respect to pharmaceutical absorption, metabolism and elimination in fish. This study investigates the metabolism of ibuprofen by rainbow trout (Oncorhynchus mykiss). In vitro metabolic loss of parent compound was measured in gill and liver S9 and microsomal fractions. Metabolite analysis found 2-hydroxy-ibuprofen as the major metabolite in uninduced S9 fractions. Supplementing S9 fractions with UDPGA did not significantly enhance metabolism. Additionally, assays involving the induction and inhibition of specific CYP isozymes support CYP1A2 as a possible metabolic pathway in fish.

Comparative physiology, pharmacology and toxicology of beta-blockers: mammals versus fish.

On the premise that human medicines may potentially induce similar pharmacological and toxicological profiles in fish and other lower vertebrates, we have applied this comparative approach to beta-adrenergic receptor antagonists ('beta-blockers') which are widely detected in surface waters. While reported concentrations of beta-blockers are typically in the low ng/L range, data are needed to define whether this contamination poses any long-term threat to fish or other aquatic organisms. We argue that gathering experimental data in fish for these compounds may be done more efficiently by considering mammalian toxicology data. Extensive mammalian pharmacological and toxicological studies are central to development of medicines and these can provide valuable information to guide ecotoxicological studies. For beta-blockers, we can increasingly exploit the knowledge from molecular approaches to understand phenotypes and functions of adrenergic receptors in mammals versus fish. Some beta-adrenergic receptors have been characterised in fish using both traditional molecular cloning methods, or via mining of genomic sequences from various organisms. These approaches demonstrate that fish have beta-adrenergic receptors very similar to those present in mammals. Since we believe that any effects of beta-blockers in fish are most likely to be mediated via beta-adrenergic receptors, it is the physiological processes regulated by these receptors that are most likely to be affected. Thus, cardiovascular dysfunction is one possible consequence of exposure of fish to these compounds, leading to impaired fitness (e.g. reduced growth and fecundity). More broadly, conceptual mathematical models suggest it might be possible to predict plasma concentrations of beta-blockers in fish from mammals, although these models cannot be regarded as reliable until thoroughly validated. Experimental data are therefore urgently needed to define plasma levels and metabolism of beta-blockers compared in fish with mammals. Finally, accurate citation of CAS numbers is essential for pharmaceuticals in order to compare nominal concentration data in terms of either the drug free base or the drug salt complex.

What training and skills will the ecotoxicologists of the future require?

Students and academic researchers conduct a diverse range of studies that add to the growing body of ecotoxicology research. Once an academic researcher entertains an applied research topic, there is potential for that research to be used in local, state, or federal regulatory decision or action. The ability of regulatory decision makers to use academic studies to inform decisions is dependent on: 1) the relevance of the experiment to regulatory decisions, 2) the reliability of the laboratory and the study itself, and 3) quality reporting of data such that study relevance and reliability are evident. The purpose of this brief communication is to highlight actions that can be taken by Society of Environmental Toxicology and Chemistry members to enhance the usability of academic research studies in regulatory decision making by promoting training, partnerships, and communication. Integr Environ Assess Manag 2017;13:580-584. © 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Bioconcentration of two basic pharmaceuticals, verapamil and clozapine, in fish.

The present study examined the bioconcentration of 2 basic pharmaceuticals: verapamil (a calcium channel blocker) and clozapine (an antipsychotic compound) in 2 fresh water fishes, fathead minnow and channel catfish. In 4 separate bioconcentration factor (BCF) experiments (2 chemicals × 1 exposure concentration × 2 fishes), fathead minnow and channel catfish were exposed to 190 µg/L and 419 µg/L of verapamil (500 µg/L nominal) or 28.5 µg/L and 40 µg/L of clozapine (50 µg/L nominal), respectively. Bioconcentration factor experiments with fathead consisted of 28 d uptake and 14 d depuration, whereas tests conducted on catfish involved a minimized test design, with 7 d each of uptake and depuration. Fish (n = 4-5) were sampled during exposure and depuration to collect different tissues: muscle, liver, gills, kidneys, heart (verapamil tests only), brain (clozapine tests only), and blood plasma (catfish tests only). Verapamil and clozapine concentrations in various tissues of fathead and catfish were analyzed using liquid chromatography-mass spectrometry. In general, higher accumulation rates of the test compounds were observed in tissues with higher perfusion rates. Accumulation was also high in tissues relevant to pharmacological targets in mammals (i.e. heart in verapamil test and brain in the clozapine test). Tissue-specific BCFs (wet wt basis) for verapamil and clozapine ranged from 0.7 to 75 and from 31 to 1226, respectively. Tissue-specific concentration data were used to examine tissue-blood partition coefficients.

Responses to various exposure durations of levonorgestrel during early-life stages of fathead minnows (Pimephales promelas).

Pharmaceuticals are routinely detected in the environment; and several of these compounds have been extensively researched due to their potential impacts to the endocrine system of aquatic organisms. The negative reproductive consequences of synthetic progestins in teleost species have only recently been investigated. The current study examined different exposure periods that may be most sensitive for levonorgestrel (LNG) in early-life stages of fathead minnow larvae. Larvae were exposed to a single concentration of LNG (125ng/L) for different durations from fertilized egg through 28 days post hatch (dph) with growth and mRNA expression of FSH, 3ß-HSD, 20ß-HSD, and CYP19a1 measured. Regardless of the duration of exposure, LNG significantly decreased growth in the fathead minnow larvae at day 28. For both 20ß-HSD and CYP19a1, mRNA expression was decreased following LNG exposure durations ≥7 days. 3ß-HSD and FSH showed similar trends after exposure to LNG with later stages of development exhibiting decreased expression. 20ß-HSD and 3ß-HSD were the only transcripts to remain down regulated once larvae were moved to clean water after the 7-14dph LNG exposure. This study is the first to investigate the effects of exposure time to a synthetic progestin on developing fish. Future research is needed to understand what impacts these changes have on adult stages of development.

In Silico analysis of perturbed steroidogenesis and gonad growth in fathead minnows (P. promelas) exposed to 17α-ethynylestradiol.

The multi-factorial nature of adverse reproductive effects mediated by endocrine disrupting compounds (or EDCs) makes understanding the mechanistic basis of reproductive dysfunction a highly pertinent area of research. As a consequence, a main motivator for continued research is to integrate 'multi-leveled' complexity (i.e., from genes to phenotype) using mathematical methods capable of encapsulating properties of physiological relevance. In this study, an in silico stoichiometric model of piscine steroidogenesis was augmented with a 'biomass' reaction associating the underlying stoichiometry of steroidogenesis with a reaction representative of gonad growth. The ability of the in silico model to predict perturbed steroidogenesis and subsequent effects on gonad growth was tested by exposing reproductively active male and female fathead minnows (Pimephales promelas) to 88 ng/L of the synthetic estrogen, 17α-ethynylestradiol (EE2). The in silico model was parameterized (or constrained) with experimentally quantified concentrations of selected steroid hormones (using mass spectrometry) and fold changes in gene expression (using RT-qPCR) for selected steroidogenic enzyme genes, in gonads of male and female fish. Once constrained, the optimization framework of flux balance analysis (FBA) was used to calculate an optimal flux through the biomass reaction (analogous to gonad growth) and associated steroidogenic flux distributions required to generate biomass. FBA successfully predicted effects of EE2 exposure on fathead minnow gonad growth (%gonadosomatic index or %GSI) and perturbed production of steroid hormones. Specifically, FBA accurately predicted no effects of exposure on male %GSI and a significant reduction for female %GSI. Furthermore, in silico simulations accurately identified disrupted reaction fluxes catalyzing productions of androgens (in male fish) and progestogens (in female fish), an observation which agreed with in vivo experimentation. The analyses presented is the first-ever to successfully associate underlying flux properties of the steroidogenic network with gonad growth in fish, an approach which can incorporate in silico predictions with toxicological risk assessments.

Effects of progesterone and norethindrone on female fathead minnow (Pimephales promelas) steroidogenesis.

As knowledge of contaminants capable of adversely modulating endocrine functions increases, attention is focused on the effects of synthetic progestins as environmental endocrine disrupters. In the present study, effects of exposure to a synthetic progestin (norethindrone, 168 ± 7.5 ng/L) and endogenous progestogen (progesterone, 34 ± 4.1 ng/L) on steroidogenesis in adult female fathead minnows were examined. In vivo exposure to either compound lowered expression (nonsignificant) of luteinizing hormone (LHß) levels in the brain along with significantly down-regulating the beta isoform of membrane progesterone receptor (mPRß) in ovary tissue. The correspondence between lowered LHß levels in the brain and mPRß in the ovary is suggestive of a possible functional association as positive correlations between LHß and mPR levels have been demonstrated in other fish species. In vitro exposure of ovary tissue to progesterone resulted in significantly elevated progestogen (pregnenolone, 17α-hydroxyprogesterone, and 17α,20ß-dihydroxypregnenone) and androgen (testosterone) production. Whereas in vitro exposure to norethindrone did not significantly impact steroid hormone production but showed decreased testosterone production relative to solvent control (however this was not significant). Overall, this study showed that exposure to a natural progestogen (progesterone) and synthetic progestin (norethindrone), was capable of modulating LHß (in brain) and mPRß expression (in ovary).

Bioaccumulation of decamethylpentacyclosiloxane (D5): A review.

Decamethylpentacyclosiloxane (D5) is a widely used, high-production volume personal care product with an octanol-water partition coefficient (log K(OW)) of 8.09. Because of D5's high K(OW) and widespread use, it is subject to bioaccumulation assessments in many countries. The present study provides a compilation and an in-depth, independent review of bioaccumulation studies involving D5. The findings indicate that D5 exhibits depuration rates in fish and mammals that exceed those of extremely hydrophobic, nonbiotransformable substances; that D5 is subject to biotransformation in mammals and fish; that observed bioconcentration factors in fish range between 1040 L/kg and 4920 L/kg wet weight in laboratory studies using non-radiolabeled D5 and between 5900 L/kg and 13 700 L/kg wet weight in an experiment using C(14) radiolabeled D5; and that D5 was not observed to biomagnify in most laboratory experiments and field studies. Review of the available studies shows a high degree of internal consistency among findings from different studies and supports a broad comprehensive approach in bioaccumulation assessments that includes information from studies with a variety of designs and incorporates multiple bioaccumulation measures in addition to the K(OW) and bioconcentration factor.

Comparison of in vitro and in vivo bioassays for estrogenicity in effluent from North American municipal wastewater facilities.

Attempts to better understand causal factors affecting estrogenicity in municipal wastewater have primarily focused on analytical evaluation of specific chemical estrogens and the use of estrogen receptor (ER) based in vitro assays. To compare analytical,in vitro, and in vivo assays for estrogenicity, wastewater from four New York and one Texas municipal wastewater facilities was evaluated for estrogenic activity using the yeast estrogen screen assay (YES) and an in vivo fish vitellogenin (VTG) assay. Estrogenic activity, as measured by the YES assay, was observed in methanol and/or methylene chloride eluents from C18 extracts in two of the New York treatment facilities and the Texas facility. Estradiol equivalents for the YES assay data ranged from

Waterborne and sediment toxicity of fluoxetine to select organisms.

Ecological risk assessments of pharmaceuticals are currently difficult because little-to-no aquatic hazard and exposure information exists in the peer-reviewed literature for most therapeutics. Recently several studies have identified fluoxetine, a widely prescribed antidepressant, in municipal effluents. To evaluate the potential aquatic toxicity of fluoxetine, single species laboratory toxicity tests were performed to assess hazard to aquatic biota. Average LC(50) values for Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas were 0.756 (234 microg/l), 2.65 (820 microg/l), and 2.28 microM (705 microg/l), respectively. Pseudokirchneriella subcapitata growth and C. dubia fecundity were decreased by 0.044 (14 microg/l) and 0.72 microM (223 microg/l) fluoxetine treatments, respectively. Oryias latipes survival was not affected by fluoxteine exposure up to a concentration of 28.9 microM (8.9 mg/l). An LC(50) of 15.2 mg/kg was estimated for Chironomus tentans. Hyalella azteca survival was not affected up to 43 mg/kg fluoxetine sediment exposure. Growth lowest observed effect concentrations for C. tentans and H. azteca were 1.3 and 5.6 mg/kg, respectively. Our findings indicate that lowest measured fluoxetine effect levels are an order of magnitude higher than highest reported municipal effluent concentrations.