bluuebunny/crossref_metadata_2025 huggingface dataset:
Overview of a workshop on screening methods for detecting potential (anti-) estrogenic/androgenic chemicals in wildlife
Authors: Ankley Gerald , Mihaich Ellen , Stahl Ralph , Tillitt Donald , Colborn Theo , McMaster Suzzanne , Miller Ron , Bantle John , Campbell Pamela , Denslow Nancy , Dickerson Richard , Folmar Leroy , Fry Michael , Giesy John , Gray L Earl , Guiney Patrick , Hutchinson Thomas , Kennedy Sean , Kramer Vincent , LeBlanc Gerald , Mayes Monte , Nimrod Alison , Patino Reynaldo , Peterson Richard , Purdy Richard , Ringer Robert , Thomas Peter , Touart Les , Van Der Kraak Glen , Zacharewski Tim
Published: March 2010

The U.S. Congress has passed legislation requiring the U.S. Environmental Protection Agency (U.S. EPA) to develop, validate, and implement screening tests for identifying potential endocrine-disrupting chemicals within 3 years. To aid in the identification of methods suitable for this purpose, the U.S. EPA, the Chemical Manufacturers Association, and the World Wildlife Fund sponsored several workshops, including the present one, which dealt with wildlife species. This workshop was convened with 30 international scientists representing multiple disciplines in March 1997 in Kansas City, Missouri, USA. Participants at the meeting identified methods in terms of their ability to indicate (anti-) estrogenic/androgenic effects, particularly in the context of developmental and reproductive processes. Data derived from structure-activity relationship models and in vitro test systems, although useful in certain contexts, cannot at present replace in vivo tests as the sole basis for screening. A consensus was reached that existing mammalian test methods (e.g., with rats or mice) generally are suitable as screens for assessing potential (anti-) estrogenic/ androgenic effects in mammalian wildlife. However, due to factors such as among-class variation in receptor structure and endocrine function, it is uncertain if these mammalian assays would be of broad utility as screens for other classes of vertebrate wildlife. Existing full and partial life-cycle tests with some avian and fish species could successfully identify chemicals causing endocrine disruption; however, these long-term tests are not suitable for routine screening. However, a number of short-term tests with species from these two classes exist that could serve as effective screening tools for chemicals inducing (anti-) estrogenic/androgenic effects. Existing methods suitable for identifying chemicals with these mechanisms of action in reptiles and amphibians are limited, but in the future, tests with species from these classes may prove highly effective as screens. In the case of invertebrate species, too little is known at present about the biological role of estrogens and androgens in reproduction and development to recommend specific assays.
Developmental neurotoxic effects of dioxin and dioxin-like compounds on domestic and wild avian species
Authors: Henshel Diane S
Published: March 2010

In ovo exposure to dioxin and dioxin-like compounds has been shown to be associated with the development of grossly asymmetric avian brains. This asymmetry is primarily seen in two major brain regions, the forebrain and the tectum, and is detectable in the intact (but isolated) brain or in cross sections, as in computer tomographic (CT) images of the brain. Brain asymmetry has been observed in several wildlife species (heron, cormorant, and eagle) exposed to a mixture of contaminants in the wild, as well as in a domestic species (chicken) exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in ovo under controlled conditions. Asymmetry appears with increasing frequency and severity in embryos and hatchlings exposed to increasing doses of TCDD beginning early in embryonic development. Since asymmetry is evident in early embryos (embryonic day 9) when the braincase is just a thin covering, it is unlikely that brain asymmetry is caused by effects on the braincase rather than on the brain itself. In addition, preliminary histological evaluation of heron hatchling brains indicates that the pyriform (striate) cortex has increased cell density in contaminated versus control brains, although it is not yet clear whether this change in cell density is also manifested asymmetrically. Immunohistochemical analysis of embryonic chicken spinal cord demonstrated that TCDD exposure in ovo also induces a dysmyelination.
Phytoestrogens and anthropogenic estrogenic compounds
Authors: Safe Stephen H , Gaido Kevin
Published: March 2010

The human diet contains a diverse spectrum of endogenous chemicals that exhibit either direct or indirect hormonal activity. These include natural compounds that bind the estrogen, androgen, aryl hydrocarbon, retinoic acid, and retinoic X receptors. In addition, several studies have identified a large number of chemical contaminants that exhibit estrogenic activity (xenoestrogens), and humans are also exposed to these compounds in the diet. Some of these chemicals include diverse phenolics such as bisphenol A, phthalates, polychlorinated biphenyls, and diverse organochlorine pesticides. Most of the endogenous dietary estrogens (including flavonoids and other phytoestrogens) and xenoestrogens are weak estrogen receptor agonists, and based on mass intake, human exposure to phytoestrogens is much higher than to xenoestrogens. The relative importance of dietary exposure to estrogenic compounds is unknown, and their effects will depend on a number of factors, including metabolism and pharmacokinetics, compound potency, serum concentrations, relative binding to serum proteins, levels of exposure during critical periods, and interactions or cross-talk with other endocrine response pathways.
Association of mercury and selenium with altered glutathione metabolism and oxidative stress in diving ducks from the San Francisco bay region, USA
Authors: Hoffman David J , Ohlendorf Harry M , Marn Carolyn M , Pendleton Grey W P
Published: March 2010

Ault male greater scaup (Aythya marila), surf scoters (Melanitta perspicillata), and ruddy ducks (Oxyurajamaicensis) were collected from Suisun Bay and coastal Tomales Bay in the greater San Francisco Bay area to assess exposure to inorganic contaminants. Hepatic Se concentrations were highest in greater scaup (geometric mean = 67 ppm dry weight) and surf scoters (119 ppm) in Suisun Bay, whereas hepatic Hg was highest (19 ppm) in greater scaup and surf scoters from Tomales Bay. Hepatic Se and Hg were lower in ruddy ducks and did not differ between locations. Hepatic supernatants were assayed for enzymes related to glutathione metabolism and antioxidant activity, including glucose-6-phosphate dehydrogenase (G-6-PDH), glutathione peroxidase (GSH peroxidase), glutathione reductase (GSSG reductase), and glutathione-S-transferase (GSH transferase). Glutathione peroxidase activity was higher in surf scoters and ruddy ducks, and G-6-PDH was higher in greater scaup and surf scoters from Suisun Bay than Tomales Bay. Glutathione reductase (GSSG) was higher in SS from Suisun Bay. The ratio of oxidized glutathione (GSSG) to reduced glutathione (GSH) was greater in all species from Tomales Bay. The following significant relationships were found in one or more species with increasing hepatic Hg concentration: lower body, liver, and heart weights; decreased hepatic GSH concentration and G-6-PDH and GSH peroxidase activities; increased ratio of GSSG to GSH; and increased GSSG reductase activity. With increasing hepatic Se concentration, GSH peroxidase increased, but GSH decreased. It is concluded that measurement of associated enzymes in conjunction with thiol status may be a useful bioindicator to discriminate between Hg and Se effects. Concentrations of Hg and Se and the above variables affected have been associated with adverse effects on reproduction and neurological function in experimental studies with mallards.
Geographic trend in mercury measured in common loon feathers and blood
Authors: Evers David C , Kaplan Joseph D , Meyer Michael W , Reaman Peter S , Braselton W Emmett , Major Andrew , Burgess Neil , Scheuhammer Anton M
Published: March 2010

The common loon (Gavia immer) is a high-trophic-level, long-lived, obligate piscivore at risk from elevated levels of Hg through biomagnification and bioaccumulation. From 1991 to 1996 feather (n = 455) and blood (n = 381) samples from adult loons were collected between June and September in five regions of North America: Alaska, northwestern United States, Upper Great Lakes, New England, and the Canadian Maritimes. Concentrations of Hg in adults ranged from 2.8 to 36.7 μg/g (fresh weight) in feathers and from 0.12 to 7.80 μg/g (wet weight) in whole blood. Blood Hg concentrations in 3 to 6-week-old juveniles ranged from 0.03 to 0.78 μg/g (wet weight) (n = 183). To better interpret exposure data, relationships between blood and feather Hg concentrations were examined among age and sex classes. Blood and feather Hg concentrations from the same individuals were significantly correlated and varied geographically (r2 ranged from 0.03 to 0.48). Blood and feather Hg correlated strongest in areas with the highest blood Hg levels, indicating a possible carryover of breeding season Hg that is depurated during winter remigial molt. Mean blood and feather Hg concentrations in males were significantly higher than concentrations in females for each region. The mean blood Hg concentration in adults was 10 times higher than that in juveniles, and feather Hg concentrations significantly increased over 1 to 4-year periods in recaptured individuals. Geographic stratification indicates a significant increasing regional trend in adult and juvenile blood Hg concentrations from west to east. This gradient resembles U.S. Environmental Protection Agency-modeled predictions of total anthropogenic Hg deposition across the United States. This gradient is clearest across regions. Within-region blood Hg concentrations in adults and juveniles across nine sites of one region, the Upper Great Lakes, were less influenced by variations in geographic Hg deposition than by hydrology and lake chemistry. Loons breeding on low-pH lakes in the Upper Great Lakes and in all lake types of northeastern North America are most at risk from Hg.
Mercury and selenium accumulation in common loons (Gavia immer) and common mergansers (Mergus merganser) from Eastern Canada
Authors: Scheuhammer Anton M , Wong Allan H K , Bond Della
Published: March 2010

Liver, kidney, and breast muscle tissue from common loons (Gavia immer) and common mergansers (Mergus merganser) from eastern Canada were analyzed for total Hg, organic Hg, and Se concentrations. In both species, Hg and Se concentrations were generally highest in liver, followed by kidney, then breast muscle. As total Hg concentrations increased in liver and kidney tissues, the fraction that was methylmercury (MeHg) decreased. Livers and kidneys with the highest total Hg concentrations (> 100 μg/g dry weight) had only 5 to 7% of the total as MeHg. Concentrations of MeHg were <10 μg\g (dry weight) regardless of the total Hg concentration in liver and kidney. In contrast, the proportion of MeHg in breast muscle remained high (80–100%) in both loons and mergansers regardless of total Hg concentration, which ranged from 0.7 to 35 μg\ (dry weight7rpar;. Strong positive correlations were observed between total Hg and Se concentrations, but not between MeHg and Se, in kidney and liver tissues for both loons and mergansers. Mercury concentrations were significantly higher (analysis of variance, p < 0.0001) in all three tissues of loons found in an emaciated condition compared with apparently healthy loons. Non-emaciated loons had Hg concentrations comparable to those of healthy mergansers, and concentrations were lower than those associated with Hg toxicity in birds. The elevated Hg concentrations in emaciated loons may have contributed to their impaired conditions; alternatively, the wasting of their muscle and other tissues may have caused apparent tissue Hg concentrations to increase. In any case, total Hg concentrations in liver and/or kidney tissue are insufficient criteria for making toxicologically relevant judgments of possible Hg toxicity. Because of the varying degrees of apparent Hg demethylation in liver, kidney, and other tissues and the association of the resulting inorganic Hg with Se in an apparently stable, toxicologically inert complex, estimates of organic Hg and Se concentrations, in addition to total Hg, in these organs are recommended.
A biological and chemical characterization strategy for small and medium-sized industries connected to municipal sewage treatment plants
Authors: Tarkpea Maria , Andrén Cecilia , Eklund Britta , Gravenfors Erik , Kukulska Zofia
Published: March 2010

A cost-effectives strategy for the characterization of wastewater from small and medium-sized industries is described. A mobile laboratory, equipped for performing on-site biological tests, was established near wastewater treatment facilities in two cities in Sweden for 1 week each in November 1992 and November 1993. The biological and chemical characterization was done on 24-h samples from 29 industries representing 12 types of activity with a bias toward the surface treatment and graphics industries. The biological testing program included a modified nitrification test, the Microtox® test, and a modified growth inhibition test using Selenastrum capricornutum (an alga test). A Ceriodaphnia dubia (crustacean) test was also used for some industries. Different chemical assessments, aimed at indicating toxic, persistent, and bioaccumulating substances, were chosen for each industry on the basis of information they provided. Results show that sampling period and time are important factors to consider when designing a characterization strategy. Twenty-four-hour sampling is preferred to weekly sampling because highly toxic emissions of short duration that are detrimental to the biological treatment plant may occur. Variability in emissions was shown in this study but would not have been detected by a study based on weekly sampling. The strategy developed in this study was shown to be both a cost-effective and efficient tool for characterizing effluents from small and medium-sized industries.
Physicochemical properties of polycyclic aromatic hydrocarbons: Aqueous solubilities,n-octanol/water partition coefficients, and Henry's law constants
Authors: de Maagd P Gert-Jan , ten Hulscher Dorien Th E M , van den Heuvel Henny , Opperhuizen Antoon , Sijm Dick T.H.M
Published: March 2010

Aqueous solubilities, n-octanol/water partition coefficients (Kows), and Henry's law constants were determined for a range of polycyclic aromatic hydrocarbons (PAHs) using a generator-column, slow-stirring, and gas-purge method, respectively. The currently obtained data were compared to available literature data. For seven of the PAHs no Kows previously were determined with the slow-stirring method. For four of the PAHs the present study reports the first experimental Henry's law constants. Relationships between subcooled liquid solubilities, Kows, and Henry's law constants as a function of molar volume are discussed. A consistent data set was obtained, for which an excellent correlation was found between subcooled liquid solubility and molar volume. A linear fit did not accurately describe the relationship between log Kow and molar volume. This is probably due to a decreasing solubility in n-octanol with increasing molar volume. Finally, a high correlation was found between Henry's law constant and molar volume. The presently obtained dataset can be used to predict the fate and behavior of unsubstituted homocyclic PAHs.
Metabolism of [14C]acrolein (Magnacide H® herbicide): Nature and magnitude of residues in freshwater fish and shellfish
Authors: Nordone Adrian J , Dotson Timothy A , Kovacs Martin F , Doane Rebecca , Biever Ron C
Published: March 2010

Arolein, anaquaticherbicide, is appliedas MAGNAIDE H® herbicide directly into the water of irrigation canals at concentrations of 1 to 15 ppm. Two representative freshwater fish species, the bluegill sunfish (Lepomis macrochirus) and the channel catfish (Ictalurus punctatus), and two representative freshwater shellfish species, a unionacean clam (Elliptio complanata) and the northern crayfish (Orconectes virilis), were exposed separately to two applications of [14C]acrolein, with 7 d between the two dosings. The nominal water concentrations were 0.02 and 0.1 ppm acrolein for fish and shellfish, respectively. Exposures were terminated 1 d after the second application. Metabolites were identified from the edible tissues of each test species; there was very little similarity in the metabolism of acrolein between them. The most notable observation was that acrolein was never detected in any of the tissues sampled. Glycidol, glycerol, 1,3-propanediol, and glyceric acid were the major metabolites found in the catfish, crayfish, bluegill, and clams, respectively. This study demonstrated that these test species, when exposed under static conditions to [14C]acrolein, are able to metabolize the parent compound and its residues in their edible tissues. The metabolism of [14C]acrolein is so rapid in the edible tissues of these species that neither acrolein nor its major oxidative and reductive metabolites, acrylic acid and allyl alcohol, respectively, were detected.
Genotoxic substances in the St. Lawrence system II: Extracts of fish and macroinvertebrates from the St. Lawrence and Saguenay rivers, Canada
Authors: White Paul A , Rasmussen Joseph B , Blaise Christian
Published: March 2010

Aquatic biota frequently accumulate organic contaminants and maintain steady state tissue concentrations that are as much as 105 times higher than those in the surrounding water. Although many researchers have studied the accumulation of genotoxic polycyclic aromatic hydrocarbons (PAHs) by aquatic biota, few researchers have used bioassays to investigate the accumulation of genotoxins. In several previous studies we used the SOS Chromotest to investigate the genotoxicity of industrial effluent extracts, sediment extracts, and bivalve tissue extracts. In this study we use the SOS Chromotest to investigate the accumulation of organic genotoxins by macroinvertebrates and fish in the St. Lawrence and Saguenay rivers (Quebec, Canada). Tissue concentrations of genotoxins (expressed as μg benzo[a]pyrene genotoxic equivalents) reveal bioconcentration factors in the 102 to 103 range. Concentrations are partially determined by lipid content (r2 = 0.22). Lipid-normalized values indicate that genotoxin concentrations in invertebrate tissues are significantly higher than those in fish. Fish values indicate that tissue concentrations are biodiminished, with fish at higher trophic levels having lower tissue burdens of genotoxins. The biodiminution pattern observed corresponds exceptionally well with trophic position assignments made by other authors. More contaminated sites yielded less contaminated specimens. This may be due to the induction of phase I and phase II detoxification enzymes that is likely to occur at high levels of exposure. Although the results do not support PAHs as the putative genotoxins, the results do indicate that the accumulated genotoxins have similar properties. Tissue to sediment ratios of genotoxins are similar to those observed for genotoxic PAHs, and far lower than those of more persistent organochlorines. Although we did not investigate genotoxic effects, we might expect the most dramatic effects in fish that consume contaminated macroinvertebrates.
In vitro hepatic metabolism of CYP3A-mediated drugs quinine and midazolam in the common brush-tailed possum (Trichosurus vulpecula)
Authors: Ho Ping-Chuen , Luo Xiao-Xing , Macauley Jackie S , Grigor Murray R , Wanwimolruk Sompon
Published: March 2010

This report characterizes the P450 isoenzymes involved in quinine metabolism in liver microsomes of the common brush-tailed possum (Trichosurus vulpecula). The mean maximal velocity (Vmax) for 3-hydroxyquinine formation in possum livers was 1,512 ± 510 pmol/mg protein/min (males) and 1,680 ± 690 pmol/mg protein/min (females). The mean Vmax value for 3-hydroxyquinine formation in possums was approximately threefold higher than that found in human livers. The mean apparent Michaelis constant (Km) for 3-hydroxyquinine formation in possum livers was 31.9 ± 16 μM in males and 16.1 ± 5 μM in females. At low concentrations of quinine (40 μM), the quinine 3-hydroxylation was inhibited more than 90% by midazolam, 60% by troleandomycin, 40% by erythromycin, and 47% by nifedipine, all of which are CYP3A inhibitors. Other inhibitors for CYP2C9/10, CYP2D6, CYP2E1, and CYP1A1/2 showed little or no inhibition effect on 3-hydroxylation of quinine. Xenobiotic inhibition studies suggest that the liver CYP3A enzyme family or one similar to human liver CYP3A is responsible for 3-hydroxylation of quinine in possum livers. The metabolism of midazolam to 1′-hydroxy and 4-hydroxy metabolites was also studied. The in vitro metabolism of midazolam was found to be much lower in possum liver microsomes as compared to that observed in human liver microsomes. The mean Vmax values for 4-hydroxy- and 1′-hydroxymidazolam in male possums were 179 ± 53 and 479 ± 333 pmol/mg protein/min, respectively. For female possums, the mean Vmax values were 235 ± 31 and 671 ± 143 pmol/mg protein/min, respectively. These Vmax values for male possums were 23 and 8 times less (17 and 6 times less for female possums), respectively, than those observed with human liver microsomes. The present study has demonstrated that, although possums are able to metabolize both midazolam and quinine, the capacity to metabolize midazolam is considerably lower in possum livers than in human livers. This finding could be useful for the selection of alternative poisons to control populations of possums.
Metabolism of trichloroethylene and chloral hydrate by the Japanese medaka (Oryzias latipes) in vitro
Authors: Lipscomb John C , Confer Patricia D , Miller Michael R , Stamm Steven C , Snawder John E , Bandiera Stelvio M
Published: March 2010

Trichloroethylene (TRI), a common groundwater contaminant, is readily metabolized by mammals to produce chloral hydrate (CH), trichloroacetic acid (TCA), and trichloroethanol (TCOH). Cytochrome P450 (CYP) and other enzymes are responsible for formation of these metabolites, which are implicated in TRI's toxicity and carcinogenicity. To establish the validity of the Japanese medaka (Oryzias latipes) as an alternate test species for TRI, we examined the metabolism of TRI and CH, as well as CYP expression, in medaka liver preparations. Trichloroethylene was incubated with medaka microsomal protein, and metabolites were extracted and analyzed using gas chromatography. Microsome-mediated metabolism of TRI was observed, and a Km value for TRI oxidation of 540 μM and a Vmax value of 213 pmol/min·mg−1 protein were obtained. Conversion of TRI to CH, TCA, and TCOH was found with medaka hepatic subcellular fractions. In addition, a sex difference in hepatic microsomal TRI metabolism, specific CYP content, and ethoxyresorufin O-deethylase activity was noted. The lower specific activity of preparations from the livers of female medaka is compensated for by increased total protein in the larger liver mass of the female. Immunochemical analysis showed that CYP1A was readily detectable in medaka liver, but CYP2E1 was present at very low levels. These data suggest that TRI metabolism in medaka liver preparations mimics that observed in mammalian systems and supports their use as an alternative test species in the evaluation of the toxicity of TRI.
Relationship of atmospheric deposition to the water chemistry and biota of treehole habitats
Authors: Paradise Christopher J , Dunson William A
Published: March 2010

We monitored water chemistry of rain, stemflow, and treehole invertebrate communities in three landscape-scale regions in Pennsylvania receiving high, but different, atmospheric inputs of hydrogen and sulfate ions. We predicted that treeholes in the westernmost plateau region receiving the highest levels of those ions would have different water chemistry than those in other regions. We found that the plateau region had significantly lower pH and higher [SO4] than the central valley and easternmost ridge regions. This was correlated with higher [SO4] in plateau rain. Higher [SO4] in stemflow than rain indicated substantial dry deposition, and correlation of stemflow [SO4] and treehole [SO4] indicated that dry deposition influenced water chemistry of treeholes. Treehole [NO3] differed with time and region and was highest in August. Other chemical parameters in rain and stemflow were correlated with treehole water chemistry. Treehole [Mg] followed the pattern in stemflow, which was also correlated with rain [Mg]. However, higher [Mg], [Ca], and [K] in treehole water than in aqueous inputs indicated contribution of these cations via alternate pathways, such as the breakdown of leaf litter. No regional effects of deposition on treehole fauna were found, however, treehole insect densities and species richness were related to water volume, [SO4], [Na], and dissolved organic carbon (DOC).
Comparison of two models for predicting bioaccumulation of hydrophobic organic chemicals in a great lakes food web
Authors: Burkhard Lawrence P
Published: March 2010

The steady-state models of Gobas and Thomann for predicting chemical residues in aquatic food webs were compared. Bioaccumulation factors (BAFs) predicted on the basis of freely dissolved chemical in the water were not significantly different for piscivorous fish, based upon the 10th and 90th percentile predictions, except for chemicals with log n-octanol/water partition coefficients (Kows) ranging from 6.5 to 6.9, the region of maximum differences for chemicals with log Kows less than 8. For chemicals with log Kows greater than 8, the BAFs predicted by the models diverged. The BAFs predicted using the Gobas model were in slightly better agreement with measured BAFs (determined from Lake Ontario data) than those predicted using the Thomann model. Sensitivities of the input parameters used by both models were very similar. The most sensitive input parameters were lipid contents, Kow, and sediment–water column chemical concentration quotient (Πsocw) for both models, and the feeding preferences for benthic invertebrates (Diporeia) for the Thomann model. Simulations performed using uncertainties for the input parameters demonstrated that the Kow and Πsocw were the dominant sources of uncertainties for predicted BAFs by both models for the Great Lakes food web. For piscivorous fish, overall uncertainties in the predicted BAFs ranged from a factor of 3.3 to 5.5 (Gobas model) and from a factor of 3.3 to 8.7 (Thomann model) for chemicals with log Kows less than 7.6 (based upon the 10th and 90th percentile predictions).
Identification of the lampricide 3-trifluoromethyl-4-nitrophenol as an agonist for the rainbow trout estrogen receptor
Authors: Hewitt L Mark , Tremblay Louis , Kraak Glen J Van Der , Solomon Keith R , Servos Mark R
Published: March 2010

Lampricide formulations containing 3 -trifluoromethyl-4-nitrophenol (TFM) have been associated with induction of hepatic mixed function oxygenase (MFO) activity and altered levels of circulating steroids in fish. Bioassay-directed chemical fractionations have shown MFO induction to be associated with impurities in TFM field formulations. A similar toxicity identification/evaluation approach coupled to competitive binding to rainbow trout estrogen receptors (ER) was used to identify compounds associated with estrogenic responses in fish. In contrast to MFO induction, nearly all binding to the ER was associated with fractions containing TFM, TFM isomers, and p-chlorophenol.p-Chlorophenol did not show any affinity for the receptor when tested separately. Diphenyl ether impurities identified in the fractions causing MFO induction as well as analogues to dibenzo-p-dioxins suspected in these fractions also showed no affinity for the receptor when tested individually. Relative to estradiol, TFM demonstrated an affinity of 5.03 × 10−5, compared to 2.47 × 10−4 for p-nonylphenol, a reported estradiol agonist. Vitellogenin induction in primary cultures of rainbow trout hepatocytes indicated that TFM acts as an estradiol agonist.
Digestive proteases of the lugworm (Arenicola marina) inhibited by Cu from contaminated sediments
Authors: Chen Zhen , Mayer Lawrence M
Published: March 2010

We examined potential toxic effects of copper released from contaminated sediments during deposit feeding of the lugworm, Arenicola marina. Titration of Cu solution into gut fluids can result in decreases in protease activity if sufficient Cu is added. The effects of Cu on gut proteases were confirmed by incubation of gut fluids with Cu-contaminated harbor sediments. Monitoring of Cu titration into gut fluids shows that enzyme inhibition and quenching of gut protein fluorescence occur only when sufficient Cu has been added to allow inorganic Cu species to become abundant. This threshold level probably represents the exhaustion of strong binding sites that act as protection against enzyme inhibition. Thus, sediments contaminated with Cu may have inhibitory effects on digestive processes in lugworms.
Spatial and temporal variation in results of purple urchin (Strongylocentrotus purpuratus) toxicity tests with zinc
Authors: Phillips Bryn M , Anderson Brian S , Hunt John W
Published: March 2010

Purple urchins (Strongylocentrotus purpuratus) were maintained in year-round spawning condition in the laboratory for use in fertilization and larval development experiments designed to assess temporal variability in response to zinc. Results of these tests were compared to those from tests using gametes obtained from a field-collected population. Fertilization and larval development tests were also conducted comparing field-collected purple urchins from three geographically distinct groups on the West Coast of the United States. Fertilization tests conducted to assess temporal variability produced variable median effects concentrations (EC50s) ranging from 4.1 to >100 μg/L zinc. Larval development tests produced more consistent EC50s, which averaged 107.4 ± 21.9 μg/L zinc for laboratory purple urchins and 97.2 ± 19.2 μg/L zinc for field-collected purple urchins. Larval development tests did not demonstrate significant differences in response to zinc between geographically distinct purple urchin populations. Fertilization test variability was examined in terms of sperm concentration and sperm collection method during two seasons. Reduced variability was found with dry sperm collection in tests conducted in March 1995 but increased again in tests conducted in June 1995, regardless of sperm collection method. Increased variability in response to zinc may be caused by seasonal temperature effects.
Bioaccumulation of polychlorinated biphenyls from sediments to aquatic insects and tree swallow eggs and nestlings in Saginaw Bay, Michigan, USA
Authors: Froese Kenneth L , Verbrugge David A , Ankley Gerald T , Niemi Gerald J , Larsen Christen P , Giesy John P
Published: March 2010

Sediments in the Saginaw Bay region of the Great Lakes contain concentrations of polychlorinated biphenyls (PCBs) that may adversely affect biotic species in various trophic levels. In this study we collected and analyzed sediments, benthic invertebrates, tree swallow eggs, and nestlings to evaluate linkages between PCBs in sediments and at various trophic levels in the Saginaw River, Michigan, USA. Our results indicate that patterns of relative concentrations of PCB congeners change with trophic level, specifically from sediment to invertebrates and from tree swallow eggs to nestlings. However, if biota–sediment accumulation factor (BSAF) values are based on only the non- and mono-ortho-substituted PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEq), calculated BSAF values are close to those predicted by fugacity theory. The use of site-specific BSAF values and reference doses for toxic effects in wildlife can be used to derive sediment quality criteria (SQC) that are protective of wildlife at the top of the sediment-based food chain. The threshold concentration of TEq in sediments that would protect sensitive avian species at the same trophic level as tree swallows was calculated to be 1.5 × 10−1 TEq/g total organic carbon. Based on this value and the BSAF determined for tree swallow nestlings, the hazard quotient for sediments in this area was determined to be 0.7. This indicates that current concentrations of TEq due to PCB congeners in the sediments should be below the threshold for adverse effects on tree swallows. The uncertainty in the concentrations of PCB congeners in the sediments was approximately a factor of 2, which determined the degree of resolution that could be obtained from the observations made in this study.
Toxicology of white phosphorus (P4) to ducks and risk for their predators: Effects of particle size
Authors: Roebuck Bill D , Nam Sae-Im , MacMillan Denise L , Baumgartner Karen J , Walsh Marianne E
Published: March 2010

Particles of white phosphorus (P4) in pond sediments at Eagle River Flats, Alaska, USA, a military artillery range are acutely toxic to dabbling ducks and swans. We determined if toxicity of P4 to ducks varied by its form (i.e., dissolved or particulate) or particulate size. Residual P4 in the digestive tracts of ducks was measured to assess risks posed to predators and scavengers of ducks. Farm-reared mallards were treated with 12 mg P4/kg body weight, either dissolved in oil, or as numerous small, or one to two large particles. At the first major convulsion, ducks were euthanized and the quantity and location of P4 in the digestive tract were determined. These data were compared to data from dead ducks collected from the artillery range. Dissolved, small, or large particles of P4 produced similar acute toxicity. Residual P4 in digestive tracts was greatest in ducks treated with small particles and was as great as 3.5 mg P4. Similar quantities of residual P4 were found in dead ducks collected at Eagle River Flats. For dabbling ducks, P4 particle size is not as important as the dose ingested. For predators, the P4 contents of the entire digestive tract is important for assessment of the risk of poisoning.
Sources of silver in the environment
Authors: Purcell Thomas W , Peters Jennifer J
Published: March 2010

Silver is a naturally occurring metal that is extensively utilized in the photographic and imaging industry, as well as in electronics and electrical applications and other lesser uses. It is known to be discharged to the environment from its industrial applications, and this leads to the possibility for exposure to aquatic and terrestrial organisms. Because of great differences in toxicity between silver compounds, the form in which silver enters the environment is important. While the ionic form of silver has been shown to be toxic to a variety of aquatic organisms, forms of silver other than ionic, or free, silver are significantly less toxic. Ionic silver is known to convert to the more innocuous forms as it reacts rapidly with natural chemical ligands in sewer systems, sewage treatment facilities, and the environment. This paper reviews information on the industries that use silver, the quantities they employ, and the forms and amounts of silver that may be discharged from each into the environment.
Toward a better understanding of the bioavailability, physiology, and toxicity of silver in fish: Implications for water quality criteria
Authors: Hogstrand Christer , Wood Chris M
Published: March 2010

In its ionic form, silver (Ag+) is highly toxic to fish (96-h 50% lethal concentration [LC50]: low μg/L range). However, concentrations of Ag+ in aquatic environments are extremely low and other more common forms of silver show only low to moderate toxicities (e.g., 96-h LC50: silver thiosulfate >100,000 μg Ag/L; silver chlorides >100 μg Ag/L). In bioassays with freshwater fish, acute toxicity appears to be derived exclusively from the Ag+ ion concentration of the water. Some other forms of silver are bioavailable but do not show obvious contribution to acute toxicity. Complexation of Ag+ by chloride, dissolved organic carbon, and sulfide are important in reducing silver toxicity. The protective action of hardness (i.e. calcium) is modest. When added as the readily dissociating silver nitrate salt, the toxicity of silver is considerably lower in seawater (96-h LC50 range: 330–2,700 μg Ag/L) than in freshwater (96-h LC50 range: 5–70 μg Ag/L). Acute silver toxicity to fish is caused by failure of the organism to maintain constant Na+ and Cl− concentrations in the blood plasma. In freshwater fish, Ag+ exerts its toxic effects on the Na+ and Cl− transport across the gills, whereas the intestine has been indicated as the site of toxicity in seawater fish. Although there are still many gaps in our understanding of silver effects on fish, it can be concluded that present regulatory standards for silver can be much improved by taking into account the important geochemical modifiers of silver toxicity.
Physiological analysis of the stress response associated with acute silver nitrate exposure in freshwater rainbow trout (Oncorhynchus mykiss)
Authors: Webb Nathan A , Wood Chris M
Published: March 2010

Rainbow trout were exposed to AgNO3 (9.2 μg/L total Ag, of which 35% was as the free ion, Ag+) for a 6-d period in dechlorinated Hamilton tapwater. Our findings suggest that the primary toxic mechanism of Ag is an interruption of ionoregulation at the gills, stopping active Na+ and Cl− uptake without increasing passive efflux, thereby causing net ion loss. There is no recovery of influxes over 6 d, whereas effluxes are gradually reduced below control levels, and ion balance remains negative. The resulting fall in plasma [Na+] and [Cl−] leads to a decrease in plasma volume and hemoconcentration, but the red blood cells do not swell. A substantial metabolic acidosis with partial respiratory compensation occurs in the blood, due to a net uptake of acidic equivalents from the environmental water. This uptake greatly exceeds the measured acid load in the extracellular fluid, suggesting that acidosis also occurs in the intracellular compartment, which in turn explains the continual loss of K+ to the water in the absence of any change in plasma [K+]. Plasma ammonia, glucose, and cortisol rise. As there is no reduction but rather a progressive rise in ammonia excretion, the increase in plasma ammonia is due to elevated metabolic production rather than inhibited excretion. The cause is probably the stress-induced mobilization of cortisol. This increased plasma ammonia, in conjunction with hyperventilation, helps to counteract metabolic acidosis. However, because the fish is unable to counteract the loss of plasma ions, death eventually results from a severe ionoregulatory disturbance.
Acute silver toxicity to seawater-acclimated rainbow trout: Influence of salinity on toxicity and silver speciation
Authors: Ferguson Elizabeth A , Hogstrand Christer
Published: March 2010

While there is considerable information on freshwater toxicity of Ag to fish, little is known about the toxicity of Ag in marine systems. In the present study, standard 96-h acute toxicity tests were performed on seawater-acclimated rainbow trout in water at 25‰salinity. Toxicity tests were repeated in various salinities (15, 20, 25, and 30‰) at the 50% lethal concentration (LC50) for Ag in 25‰ to investigate the influence of salinity on toxicity. Computer speciation modeling by MINEQL+ was performed in order to gain insight into the variation of Ag species over a range of salinities from freshwater to oceanic seawater at S2–-free conditions. At 25‰salinity the LC50 was determined to be 3.75 μM (401 μg/L) Ag. No mortality was observed at this Ag concentration in 15 or 20‰ salinities. Mortality increased to 50% in 25‰ seawater and again to 67% at 30‰. Based on the results of speciation modeling, an increase in a more toxic AgCln species is unlikely. The increased toxicity with salinity may instead be linked to an incomplete hypoosmoregulatory ability of the rainbow trout.
Toxicity of silver sulfide-spiked sediments to the freshwater amphipod (Hyalella azteca)
Authors: Hirsch Marianne P
Published: March 2010

Natural freshwater sediments were spiked in the laboratory with silver sulfide (Ag2S), and semistatic toxicity tests were conducted with a series of sediment silver (Ag) concentrations ranging from 1.27 to 753.3 mg/kg of sediment. Water was added to glass beakers containing either the Ag2S-amended or the control sediment. Each of the Ag2S-amended and control sediments was tested in replicates of eight. Ten juvenile Hyalella azteca were added to each beaker at test start. The overlying water was renewed twice daily. The 10-d 50% lethal concentration value for Ag as Ag2S for H. azteca was determined to be >753.3 mg/kg, the highest analyzed concentration tested. There were no statistically significant differences in survival rates of H. azteca exposed to any of the Ag2S-amended sediments when compared to the control. In addition, there were no concentration–response trends for mean survival or average dry weight data from this study, indicating that this form of silver was not bioavailable under these conditions.
Removal, partitioning, and fate of silver and other metals in wastewater treatment plants and effluent-receiving streams
Authors: Shafer Martin M , Overdier Joel T , Armstong David E
Published: March 2010

We investigated the removal of silver in five publicly owned treatment works (POTWs) and the fate of Ag in effluent receiving streams. Comparisons were made to several other metals. Silver was removed efficiently (>94%) in all POTWs. The percentage of total Ag removed was independent of the influent Ag concentration, while the concentration of Ag in effluents was directly related to influent concentration. A good correlation (r2 = 0.77) between metal removal (%) and partition coefficient (Kd) indicated that differences among metals in removal efficiency were controlled mainly by metal partitioning (sorption) to particles removed by settling and/or filtration. A large fraction (19–53%) of Ag in the filterable (< 1.0-μm) fraction of POTW effluents was associated with submicron particles or colloids (>0.05 μm), and the percentage filterable Ag was directly related to DOC concentration (r2 = 0.96). Effluent Ag concentrations (0.06–2.6 μg/L) were several orders of magnitude higher that typical “background” stream levels (1–2 ng/L), but Ag discharged to streams was rapidly dissipated by dilution and incorporation into stream sediments.
Determination of silver ions at submicrogram-per-liter levels using anodic square-wave stripping voltammetry
Authors: Schildkraut Deniz E , Dao Phat Tan , Twist John P , Davis Ann T , Robillard Ken A
Published: March 2010

Square-wave stripping voltammetry at a carbon paste electrode was used to develop a method to measure silver ions at concentrations as low as 0.2 μg/L in surface waters. Sample matrix was found to be an important factor affecting the measurement results. Because of these matrix effects, the peak shape of the voltammograms varied, and multiple stripping peaks for silver were observed. Total charge provided a more reliable measure of deposited silver than did peak height. The precision of the method for the analysis of standard reference materials containing silver was estimated to be 7.2% relative SD at 1 SD using a 95% confidence interval of the individuals. A full factorial experiment was performed to determine how the following factors affected measurement variability: electrode, renewal of the carbon paste electrode surface, silver ion concentration, preparation of standards and samples, and day-to-day variability. Samples of lake and river water were collected and analyzed for silver ion. In all samples the measured concentration of silver ion was <0.2 μg/L, whereas the concentration of total silver was typically >0.5 μg/L. Spiking experiments showed that the constituents of the river water samples had a greater ability to bind (remove) silver ion than did the lake water.
Partitioning and mineralization of [14C]lindane in a laboratory sediment–water system
Authors: Kalsch Wolfgang , Knacker Thomas , Robertz Markus , Studinger Gabriele , Franke Christian
Published: March 2010

To develop a guideline for a simulation test for aerobic degradability in surface water, the fate of [14C]lindane (γ-hexachlorocyclohexane) was studied in laboratory systems using natural river water and sediments. No sterilized controls were set up. Thus, measured data reflect the sum of biotic and abiotic processes. Tests were carried out under various experimental conditions to investigate which of these would affect the feasibility of the test, the fate of lindane, the physicochemical state, and the biological activity within the sediment–water systems. Lindane (37.7 nmol) was applied either to the water (3 L) or the sediment (0.33 L). Sediments remained nonreducing, and there was no serious decline of nutrients nor enzymatic activities. In one experiment up to 14.1% of the applied lindane was mineralized to 14CO2 within 50 d and in a second one up to 35.3%. At day 91 of the latter experiment up to 46.8% were found to have been mineralized. Among the experimental factors tested, the method of lindane application and temperature predominantly affected mineralization. The type of aeration and the semicontinuous addition of organic nutrients were of minor importance. Sediments and water collected at the same site but at different times showed variation in carbon content as well as in esterase and dehydrogenase activities. Nevertheless, these parameters could not be correlated with mineralization of lindane during the tests. Between 1 and 9% of the radioactivity volatilized during the tests. At the end, 23 to 66% were bound to sediments and 15 to 45% of the total activity was neither extractable by water nor by cyclohexane.
Fluctuating concentrations of organochlorine pollutants during a breeding season in two Antarctic seabirds: Adelie penguin and southern fulmar
Authors: van den Brink Nico W , van Franeker Jan A , de Ruiter-Dijkman Elze M
Published: March 2010

During the reproductive cycle significant fluctuations of concentrations of organochlorine pollutants were detected in blood and uropygial oil from Adélie penguins (Pygoscelis adeliae) and southern fulmars (Fulmarus glacialoides) from Hop Island, Antarctica. In the Adélie penguin, concentrations of polychlorinated biphenyls (PCBs) and dieldrin were significantly higher at the moment of egg laying, while hexachlorobenzene (HCB) and 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p′-DDE) concentrations peaked at the creche stage. Subcutaneous fat is the main pool for HCB and p,p′-DDE, while PCBs and dieldrin are also stored in the pectoral muscle. It is hypothesized that the observed differences in seasonal fluctuations in organochlorine levels are related to utilization of different storage pools by the Adélie penguins at different moments in the breeding season. In the southern fulmar the fluctuations in concentrations of HCB and p,p′-DDE can be related to changes in body mass. However, concentrations of PCBs and dieldrin did not vary significantly during the season. It seems that the two groups of compounds are governed more or less independently in the southern fulmar as well. Age-dependent accumulation of most organochlorines studied reached a steady state before the age at which both species start to breed. This allows monitoring of individual birds to analyze changes in concentrations of organochlorine pollutants in the ecosystem, without having to correct for age differences. Differences in levels of organochlorine pollutants between the Adélie penguin and southern fulmar were probably the result of differences in feeding ecology.