bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress proteins HSP60 and HSP70 in three species of amphipods exposed to cadmium, diazinon, dieldrin and fluoranthene
Authors: Werner Ingeborg , Nagel Roland
Published: March 2010

To investigate the use of stress proteins hsp60 and hsp70 as sublethal biomarkers for contaminant exposure in sediments, two infaunal (Ampelisca abdita, estuarine; Rhepoxynius abronius, marine) and one epifaunal (Hyalella azteca, freshwater) amphipod species were exposed for 24 h to solutions of the heavy metal cadmium, the pesticides diazinon and dieldrin, and the polycyclic aromatic hydrocarbon fluoranthene. All three species are routinely used in standard sediment toxicity tests. Analysis of hsp60 and hsp70 was performed using western blotting techniques with subsequent comparative quantification by densitometry. Results demonstrated compound and species-specific induction of stress protein synthesis. Whereas one member of the hps70 protein family showed the most sensitive response to xenobiotic compounds in H. azteca, several members of the hsp60 protein family were the main proteins induced in A. abdita and R. abronius. Sensitivity of the detected stress protein response was highest in H. azteca with significant effects at concentrations 110-, 50-, >1,000-, and >1-fold lower than LC50 values for cadmium, diazinon, dieldrin, and fluoranthene, respectively. The corresponding values were >5 (cadmium), 0.7 (diazinon), >1 (dieldrin), and 2.9 (fluoranthene) for A. abdita, and >2 (cadmium), 3.1 (diazinon), >100 (dieldrin), and >2.9 (fluoranthene) for R. abronius.
The production of stress ethylene relative to the concentration of heavy metals and other elements in the lichen Hypogymnia physodes
Authors: Garty Jacob , Kauppi Matti , Kauppi Anneli
Published: March 2010

The objective of this study was to examine fluctuations in the production of ethylene by the lichen Hypogymnia physodes indicative of environmental stress caused by air pollutants. In addition, we investigated the accumulation capacity of H. physodes, transplanted in the vicinity of two streets having slow traffic and a highway in the city of Oulu, N. Finland, for a short period (45 d). The amounts of stress ethylene produced by the transplanted lichens was compared with the amounts of airborne elements accumulated in the thallus. H. physodes manifested a high accumulation capacity for Fe and Mg in thalli exposed in either one or both streets with slow traffic in Oulu in comparison with thalli left on the control site in the forest outside of the city. Two of the observed elements, Zn and Fe, exhibited a significant positive correlation with the ethylene concentration detected concomitant with the treatment of lichen thalli with either H2O (pH 6.8) or NaHSO3 (pH 4.0). The concentrations of Pb, Fe, Zn, Mn, and Cu in thalli retrieved from one or both streets with slow traffic (13,600 and 14,290 cars/d) were higher than the concentrations in thalli transplanted in a highway with 25,240 cars/d after 45 d of exposure. Our data thus suggest that the streets with slow traffic and fewer cars are more polluted than the highway.
Synergistic toxicity of atrazine and organophosphate insecticides contravenes the response addition mixture model
Authors: Pape-Lindstrom Pamela A , Lydy Michael J
Published: March 2010

A toxic unit (TU) approach was used to test the response addition model for mixtures of pesticides with differing modes of action. Atrazine was tested in binary and ternary combinations with the organochlorine insecticide methoxychlor and organophosphate insecticide methyl-parathion. Atrazine was also tested in binary combinations with additional organophosphates. The TU for atrazine was set slightly below its water solubility limits (TU = 20 ppm), which is well below its 96-h 50% effective concentration for the fourth instar of the midge, Chironomus tentans. In 96-h acute toxicity tests using C. tentans, atrazine was found to produce synergistic (greater than additive) toxicity in a binary mixture with methyl-parathion. Less than additive toxicity was found for the combination of atrazine with methoxychlor (likely due to the low TU assigned to atrazine). The ternary combination of atrazine + methyl-parathion + methoxychlor was found to be marginally synergistic. Results of toxicity tests with atrazine in binary combinations with other organophosphates indicate more than additive toxicity for all compounds except mevinophos. Possible hypotheses are presented in an attempt to explain the noted synergistic relationship between atrazine and various organophosphorous insecticides. These results suggest that the response addition model does not always accurately predict mixture toxicity for chemicals with differing modes of action.
Octanol/air partitioning of polychlorinated biphenyls
Authors: Kömp Peter , McLachlan Michael S
Published: March 2010

The partitioning of 16 polychlorinated biphenyls (PCBs) between air and 1-octanol was investigated using a fugacity meter. The measurements were conducted over an environmentally relevant temperature range (10–43°C). For a given congener the measured 1-octanol/air partition coefficient KOA was exponentially proportional to the reciprocal temperature. The enthalpy of phase change (octanol to air) ΔHOA ranged from 71 to 93 kJ/mol. Up to log KOA values of 9.37 (corresponding to 2,2′,3,4′,5′,6-hexachlorobiphenyl), the enthalpy of phase change was similar to the enthalpy of vaporization of the subcooled liquid PCB. For the less volatile congeners (log KOA > 9.37), the enthalpies of vaporization exceeded the enthalpies of phase change, the difference increasing with increasing log KOA. Solubilities of the PCBs in 1-octanol were calculated from the data, and the results were in excellent agreement with octanol solubilities calculated using the OCTASOL fragment method. A very good correlation between the measured octanol/air partition coefficients and values calculated from octanol/water and air/water partition coefficients was obtained. This yielded a method to estimate reliably the octanol/air partitioning of all PCB congeners.
Equilibrium partitioning of heavy metals in dutch field soils. I. Relationship between metal partition coefficients and soil characteristics
Authors: Janssen René P T , Peijnenburg Willie J G M , Posthuma Leo , Van Den Hoop Marc A G T
Published: March 2010

Twenty Dutch soils were sampled at sites that were expected to have elevated levels of heavy metals compared to background values. Field-based partition coefficients (Kp) for As, Cd, Cr, Cu, Ni, Pb, and Zn were determined by calculating the ratio of the amount of metal extracted by concentrated HNO3 to the metal concentration in the pore water. Kp values varied widely with metal and soil type and correlated well with soil pH. To a lesser extent amorphous Fe-content and dissolved organic carbon (DOC) also explained part of the variation in Kp values. Thereupon, regression equations based on easily obtainable soil characteristics were derived. External validation of the regression equations showed that predicted log Kp values were in agreement with measured values.
Effects of terbufos on juvenile red swamp crayfish (Procambarus clarkii): Differential routes of exposure
Authors: Fornstrom Cynthia B , Landrum Peter F , Weisskopf Carol P , La Point Thomas W
Published: March 2010

During rain events, terbufos may be transported into aquatic ecosystems via agricultural runoff. Because crayfish are closely associated with sediment, they may be exposed to aqueous terbufos through the gills or by ingesting contaminated sediment, detritus, or plants. Bioavailability of terbufos in food and toxicity of terbufos to crayfish were examined by measuring mortality and acetylcholinesterase (AChE) inhibition and by observing behavior. A 96-h aqueous exposure and a 12-h dietary exposure of juvenile red swamp crayfish, Procambarus clarkii, to terbufos produced median lethal concentrations (LC50s) of 5.9 μg/L (95% CI: 4.4, 8.1) and 4.4 μg/g pellet (95% CI: 2.9, 6.7), respectively. Aberrant behavior, such as loss of motor control and equilibrium, was noted at concentrations almost 50% of the aqueous LC50 and 80% of the dietary LC50. As concentration increased, AChE activity decreased and mortality and aberrant behavior increased. I50s, the percentage of AChE inhibition at which 50% of the crayfish died, for aqueous and dietary exposures were 76.5% (95% CI: 67.4, 85.6) and 86.1% (95% CI: 78.1, 94.1) of control activity, respectively. Based on present study results, terbufos is available for uptake by crayfish through ingestion and causes detrimental effects at concentrations less than expected in agricultural runoff.
Trace-element accumulation by Hygrohypnum ochraceum in the upper Rio Grande Basin, Colorado and New Mexico, USA
Authors: Carter Lisa F , Porter Stephen D
Published: March 2010

Transplanted bryophytes can provide an indication of bioavailability. Rates of accumulation were related to the magnitude of ambient trace-element concentrations; maximal uptake occurred during the first 10 d of exposure. Trace-element concentrations in transplanted bryophytes could potentially be used to predict water and sediment concentrations that represent an integration of conditions over short to intermediate lengths of time, rather than instantaneous conditions as measured using water samples.
Sublethal toxicity of copper to a soil-dwelling springtail (Folsomia fimetaria) (Collembola: Isotomidae)
Authors: Scott-Fordsmand Janeck J , Krogh Paul Henning , Weeks Jason M
Published: March 2010

The collembolan Folsomia fimetaria was exposed to a range of elevated copper (Cu) concentrations in a LUFA-Speyer soil for 7, 14, and 21 d, in a microcosm test. The results showed that F. fimetaria was sensitive to copper, with reproduction being a more sensitive parameter of effect than either growth (measured as final body size) or survivorship. A 10% effective concentration (EC10) of 38 mg Cu/kg was calculated for reproduction, and an EC10 between 509 to 845 mg Cu/kg (depending on sex and developmental stage) was calculated for growth. No mortality was observed for soil concentrations up to 1,000 mg Cu/kg. This study has shown that F. fimetaria populations may with time become severly reduced or may even become extinct (in extreme circumstances) as a result of copper exposure. Although survival of the adults was not affected, toxicity was expressed solely through reproductive failure. The present study has also shown that the duration of copper exposure was not an important factor for the determination of effects during short-term tests with F. fimetaria.
Trophic transfer of sediment-associated polychlorinated biphenyls from meiobenthos to bottom-feeding fish
Authors: DiPinto Lisa M , Coull Bruce C
Published: March 2010

Experiments were conducted to examine the dynamics of the sediment-associated polychlorinated biphenyl (PCB) Aroclor® 1254 using a benthic-based trophic transfer model (sediments to benthic copepods to juvenile fish). Field-collected benthic copepods were exposed to sublethal levels of Aroclor 1254 in sediments for 96 h. Accumulation of PCB was measured in the copepods, and these contaminated copepods were fed to the juvenile fish predator Leiostomus xanthurus in uncontaminated sediments. After gut clearance, whole fish were homogenized and examined for PCB accumulation. Similar experiments with L. xanthurus in which meals of uncontaminated copepods were fed in PCB-contaminated sediments were conducted to determine the relative roles of contaminated sediments and contaminated copepod prey ingestion to PCB transfer. Total PCB transfer as well as PCB congener group contributions were examined. A total of 30 congeners were grouped according to log Kow increments and according to chlorine homologue groups. Copepods exposed to PCB-contaminated sediments to 90 μg/g accumulated PCBs to 326 μg/g dry weight. Accumulation of PCB in fish feeding in contaminated sediments was five times higher than that in fish feeding on contaminated prey in uncontaminated sediments (p = 0.0498). In terms of congener patterns, log Kow grouping provided clearer discrimination between groups. Congener patterns were similar in PCB stock solution, sediments, and copepods and were different in the two fish treatments. Kow group relative accumulation patterns in fish were mixed. The chlorine homologue groups revealed that the fish preferentially accumulated the tetrachlorinated congeners relative to copepods and sediments.
Development and evaluation of triggers for sediment toxicity testing of pesticides with benthic macroinvertebrates
Authors: Maund Steve , Barber Ian , Dulka Joseph , Gonzalez-Valero Juan , Hamer Mick , Heimbach Fred , Marshall Monte , McCahon Peter , Staudenmaier Horst , Wustner David
Published: March 2010

Concerns regarding the potential of pesticides that partition into sediments to affect benthic organisms have led to the development of sediment toxicity test methods. However, not all pesticides have the potential to accumulate in sediments or affect benthic organisms. Thus, a scientific rationale for identifying appropriate compounds (triggering) for regulatory sediment toxicity testing is required. Here we propose that testing should only be required for compounds that are relatively adsorptive and persistent in sediment, and also have the potential for toxicity to invertebrates. Trigger endpoints and values are proposed and include soil aerobic degradation rate (time for 50% degradation to occur ≥ 30 d), soil adsorption coefficients (organic carbon partition coefficient ≥ 1000), and Daphnia acute and chronic toxicity (48-h median effective concentration < 1 mg/L or 21-d no-observed-effect concentration < 0.1 mg/L). These data are available internationally for the majority of pesticides. Where appropriate, these preliminary triggers can be augmented by additional data (e.g., water-sediment degradation studies, toxicity data on benthic species) to make more sophisticated triggering cases or risk assessments. An evaluation of the proposed triggers was performed by reviewing regulatory data from standardized studies on 140 pesticides. A total of 22% of the compounds triggered sediment toxicity testing, of which the majority were insecticides and fungicides. For insecticides, fungicides, and herbicides 44, 27, and 6% of compounds within the group met the triggers, respectively. Those compounds that triggered testing are probably representative of the classes of pesticides that might be expected to raise concerns for sediment toxicity.
Exoestrogens: Mechanisms of action and strategies for identification and assessment
Authors: Gillesby Bradley E , Zacharewski Timothy R.
Published: March 2010

Public attention has recently been focused on the increased incidence of hormone-dependent cancers. However, less than one half of these increases can be attributed to improved detection methods and/or recently identified genetic factors. Consequently, it has been suggested that certain exogenous compounds are able to modulate the endocrine system by augmenting the sex steroid burden. This hypothesis is supported by a number of studies demonstrating physiologic and morphologic changes in wildlife exposed to high concentrations of environmental contaminants that are capable of eliciting responses typically induced by sex steroids. Due to associated steroidlike activities, these chemicals have been termed endocrine disrupters. The most well-characterized endocrine disrupters are exoestrogens, whose effects are similar to those produced by endogenous estrogens such as 17β-estradiol, although they are structurally unrelated. This broad structural diversity suggests that exoestrogens may elicit effects through a number of divergent pathways including direct binding and activation of the estrogen receptor (ER); binding to other nuclear receptors, which then interact with an estrogen responsive element; and through other receptor and/or signal transduction pathways. One such pathway involves the aryl hydrocarbon receptor (AhR), which binds a number of environmental contaminants such as polychlorinated biphenyls, dioxins, and furans. Several mechanisms have been elucidated that partially explain the AhR-mediated antiestrogenic activities of dioxins and related compounds. These include increased estrogen metabolism, down-regulation of estrogen receptor protein levels and binding activity, and decreased ER-mediated gene expression. A number of assays, both in vitro and in vivo, have been developed to identify and assess the endocrine disrupting potential of a compound. However, due to the broad structural diversity and number of potential mechanisms of action, a battery of complementary in vitro and in vivo assays is required to comprehensively assess the endocrine disrupting capability of exoestrogens.
Fish reproduction: An ecologically relevant indicator of endocrine disruption
Authors: Arcand-Hoy Lisa D , Benson William H
Published: March 2010

Endocrine-disrupting compounds have the potential to alter hormone pathways that regulate reproductive processes. With the exception of endocrine effects leading to reproductive impairment and population declines in a few wildlife species (e.g., Great Lake [USA] bald eagles, Lake Apopka [Florida, USA] American alligators), the ecological implications of exposure to endocrine disrupting compounds has not been adequately investigated. For example, male fish exposed to estrogenic compounds show induced production of vitellogenin, an egg yolk precursor, but the biological significance of elevated vitellogenin levels is speculative. The development of techniques to predict and more accurately assess the ecological relevance of exposure to endocrine-disrupting compounds is needed. In this review, we focus on fish reproduction as an ecologically relevant indicator of endocrine disruption, specifically estrogenic activity. The following will provide a brief review of gonochoristic reproductive and endocrine physiology, as well as outline some of the commonly used techniques to screen for estrogenic activity in fish. Last, a proposed model reproductive assay using Japanese medaka (Oryzias latipes) is presented.
A critical evaluation of safety (uncertainty) factors for ecological risk assessment
Authors: Chapman Peter M , Fairbrother Anne , Brown Derek
Published: March 2010

Evaluation of environmental risks posed by potentially hazardous substances requires achieving a balance between over- and underprotection, i.e., between societal benefits posed by the use of particular substances and their potential risks. Uncertainty (e.g., only laboratory data may be available, field or epidemiological data may be limited and less than clear-cut, etc.) will always exist and is often conservatively dealt with by the use of so-called “safety” or “uncertainty” factors, some of which remain relatively little changed since their origin in 1945. Extrapolations involving safety factors for both aquatic and terrestrialenvironments include inter- and intraspecies, acute-to-chronic, lowest- to no-observed-effect concentration (NOEC), and laboratory-to-field extrapolation (e.g., extrapolation of laboratory results to the field). To be realistic, such extrapolations need to have a clear relationship with the field effect of concern and to be based on good science. The end result is, in any case, simply an estimate of a field NOEC, not an actual NOEC. Science-based versus policy-driven safety factors, including their uses and limitations, are critically examined in the context of national and international legislation on risk assessment. Key recommendations include providing safety factors as a potential threshold effects range instead of a discrete number and using experimental results rather than defaulting to safety factors to compensate for lack of information. This latter recommendation has the additional value of rendering safety factors predictive rather than simply protective. We also consider the so-called “Precautionary Principle”, which originated in 1980 and effectively addresses risk by proposing that the safety factor should be infinitely large.
The value of mechanistic studies in laboratory animals for the prediction of reproductive effects in wildlife: Endocrine effects on mammalian sexual differentiation
Authors: Gray L Earl , Ostby Joseph , Wolf Cynthia , Lambright Christy , Kelce William
Published: March 2010

Wildlife populations from contaminated ecosystems display a variety of reproductive alterations, including cryptorchidism in the Florida panther, small baculum in young male otters, small penises in alligators, sex reversal in fish, and altered social behavior in birds. The formation of biologically plausible hypotheses regarding disruption of reproduction in wildlife can be facilitated by mechanistic studies on laboratory animals. To this end, we are investigating the in vivo and in vitro effects of endocrine-disrupting toxicants in rodents. In vitro studies have used receptor binding and transfected cell assays to confirm the suspected mechanism of action, whereas in vivo rodent studies examine altered sexual differentiation. Antiandrogenic pesticides compete with the natural ligands for both rat and human androgen receptors, block androgen-induced gene expression in vitro and in vivo, delay puberty, reduce sex accessory gland size, and alter male rat sex differentiation. In contrast, xenoestrogens affect female central nervous system sex differentiation and fecundity without producing malformations or infertility in male offspring. Prenatal administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or the TCDD-like polychlorinated biphenyls produce yet another profile of effects in the offspring, reducing numbers of ejaculated sperm in male progeny and inducing urogenital malformations in females. Although phthalates are reported to be estrogenic in vitro, in vivo exposure causes developmental alterations that more closely resemble antiandrogenic activity. The mammalian data indicate that exposure to endocrine-disrupting chemicals produces effects that are pathognomonic for mechanisms by which they act. Mechanistic information derived from mammalian studies can enhance our ability to predict toxicant effects on reproduction in fish and wildlife.
Effects of mercury on wildlife: A comprehensive review
Authors: Wolfe Marti F , Schwarzbach Steven , Sulaiman Rini A
Published: March 2010

Wildlife may be exposed to mercury (Hg) and methylmercury (MeHg) from a variety of environmental sources, including mine tailings, industrial effluent, agricultural drainwater, impoundments, and atmospheric deposition from electric power generation. Terrestrial and aquatic wildlife may be at risk from exposure to waterborne Hg and MeHg. The transformation of inorganic Hg by anaerobic sediment microorganisms in the water column produces MeHg, which bioaccumulates at successive trophic levels in the food chain. If high trophic level feeders, such as piscivorous birds and mammals, ingest sufficient MeHg in prey and drinking water, Hg toxicoses, including damage to nervous, excretory and reproductive systems, result. Currently accepted no observed adverse effect levels (NOAELs) for waterborne Hg in wildlife have been developed from the piscivorous model in which most dietary Hg is in the methyl form. Such model are not applicable to omnivores, insectivores, and other potentially affected groups, and have not incorpotated data from other important matrices, such as eggs and muscle. The purpose of this paper is to present a comprehensive review of the Hg literature as it relates to effects on wildlife, including previously understudied groups. We present a critique of the current state of knowledge about effects of Hg on wildlife as an aid to identifying missing information and to planning research needed for conducting a complete assessment of Hg risks to wildlife. This review summarizes the toxicity of Hg to birds and mammals, the mechanisms of Hg toxicity, the measurement of Hg in biota, and interpretation of residue data.
Patterns of common loon (Gavia immer) mercury exposure, reproduction, and survival in wisconsin, USA
Authors: Meyer Michael W , Evers David C , Hartigan Jerry J , Rasmussen Paul S
Published: March 2010

A long-term study was initiated in 1992 to investigate whether elevated Hg exposure measured in Wisconsin common loons was associated with reduced reproductive performance or survival. Adults loons (n = 99) and chicks (n = 56) were captured on 45 lakes during 1992 and 1993, each was individually color-marked with plastic leg bands, and blood and feathers were collected for Hg analysis. Adult return rates and reproductive outcome were then recorded for the 45 lakes from 1993 to 1996. A significant linear relationship was observed between lake pH and log-transformed adult blood Hg (r2 = 0.22, p < 0.01) and chick blood Hg (r2 = 0.56, p < 0.001) concentrations. Egg Hg concentrations (mean = 0.9 ± 0.3 μg Hg/g fresh weight) were within the range associated with reduced hatching success or reduced survival of embryos or hatchlings in other sensitive avian species. Chick production was lower at lakes where chick blood Hg concentrations were elevated. However, no relationship was observed between levels of adult Hg exposure and reproductive performance or annual adult return rates (an index of survival). Establishing a cause-and-effect relationship between Hg exposure and loon fitness is complicated by the negative correlation between lake pH and Hg exposure and potential confounding with other influences on productivity that may also be related to lake pH.
Mercury exposure in breeding common loons (Gavia immer) in central Ontario, Canada
Authors: Scheuhammer Anton M , Atchison Carolyn M , Wong Allan H K , Evers David C
Published: March 2010

Total Hg concentrations were determined in blood and feather samples of breeding common loons (Gavia immer) and their chicks from 24 lakes in Ontario with a range of water chemistry and fish Hg concentrations. In paired comparisons, males had significantly higher blood (p < 0.005) and feather (p < 0.05) Hg concentrations than their female mates. Sex differences in Hg concentrations were attributable to size differences between the two sexes and to the possible transfer of Hg to eggs by females during egg-laying. Significantly higher blood (p < 0.001) and feather (p < 0.01) Hg concentrations were found in adult loons compared to their chicks. Adult blood Hg concentrations were significantly correlated with those of their chicks (r = 0.62, p < 0.05). Adult blood concentrations averaged about 13 times those of corresponding chicks. Both adult and chick blood Hg concentrations were positively correlated with fish Hg concentrations (r = 0.71 and 0.51, respectively), indicating that adult loons in central Ontario, like their chicks, probably feed mainly on their breeding lakes and reflect the fish Hg concentrations of those lakes. Three of 24 lakes had 20- to 50-g fish (mainly perch and sunfish) with Hg concentrations at or exceeding the critical concentration (0.3–0.4 μg/g wet weight or ∼1–2 μg/g dry weight) reported to cause reproductive impairment in loons. Monitoring Hg in blood (adult and chick) and feathers (chicks only) is useful for assessing the local bioavailability of methylmercury and the degree of current dietary Hg exposure in loons and other piscivorous birds.
Mercury levels, reproduction, and hematology in western grebes from three California Lakes, USA
Authors: Elbert Ruth Anne , Anderson Daniel W
Published: March 2010

Twenty-three healthy adult western and Clark's grebes (Aechmophorus occidentalis and Aechmophorus clarkii) were collected at three study sites in California, USA, in 1992: Clear Lake, Lake County; Eagle Lake, Lassen County; and Tule Lake, Siskiyou County. Liver, kidney, breast muscle, and brain were analyzed for total mercury (Hg) concentration (ppm wet weight), and blood was analyzed for various blood parameters. Clear Lake birds (n = 13) had greater Hg concentrations in kidney, breast muscle, and brain than birds from the other two lakes (p < 0.05), whereas liver concentrations were not statistically different (p > 0.05). Average concentrations for Clear Lake birds were 2.74 ppm for liver, 2.06 ppm for kidney, 1.06 ppm for breast muscle, and 0.28 ppm for brain. The tissue levels of kidney, breast muscle, and brain at the other two study sites were one half the levels found at Clear Lake. These mean tissue levels were near, but below, those known to cause adverse effects. When data from all sites were merged, kidney, breast muscle, and brain concentrations are positively correlated to each other (p < 0.05). Liver concentrations were not correlated to any other value. Brain Hg concentrations were also negatively correlated to blood potassium and blood phosphorus levels (n = 11, p < 0.05). Kidney Hg levels were positively correlated to percent blood heterophils and negatively correlated to percent eosinophils (n = 13, p < 0.05), suggesting that mercury levels might be affecting immune function. These biomarkers could not be related to any obvious ecological effects.
Investigation of the photochemistry of urea herbicides (chlorotoluron and isoproturon) and quantum yields using polychromatic irradiation
Authors: Millet Maurice , Palm Wolf-Ulrich , Zetzsch Cornelius
Published: March 2010

This paper presents the investigation of the photochemical reaction of chlorotoluron (3-(3-chloro-4-methyl-phenyl)-1,1-dimethylurea) in CH3CN, hexane, and aqueous and buffered solutions (pH = 4, 7, and 9) and of isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) in aqueous and buffered solutions using a polychromatic light source at a temperature of 22°C. For chlorotoluron, isosbestic points were found (with the exception of hexane as solvent) and ultraviolet spectroscopy was used to obtain kinetic data. The main photoproduct for the photolysis of chlorotoluron in aqueous solutions was identified as 3-(3-hydroxy-4-methyl-phenyl)-1,1 dimethylurea. Quantum yields found in aqueous and buffered solutions were comparable (about 0.07) and 2 times lower and 10 times higher in CH3CN and hexane, respectively. No isosbestic points were found for isoproturon, and quantum yields of about 0.004 were calculated in all solutions. Chlorotoluron and isoproturon present very low molar extinction coefficients above 290 nm, and they can be assumed to be photostable with respect to direct irradiation by sunlight.
Effects of benzidine and benzidine analogues on growth of bacteria including Azotobacter vinelandii
Authors: Chung King-Thom , Chen Ssu-Ching , Wong Tit Yee , Wei Chen-I
Published: March 2010

Benzidine and benzidinea aloguesare mutagenic and carcinogenic metabolites ofazodyes that are widely found in the environment. The toxicities of benzidine and nine of its analogues against 18 bacterial strains including nitrogen-fixing Azotobacter vinelandii were tested using the well diffusion assay technique. 2-Aminobiphenyl and 3-aminobiphenyl were the most inhibitory to all bacterial species tested except A. vinelandii. 4-Aminobiphenyl was inhibitory to the growth of A. vinelandii using a plate count assay, although it failed to show an inhibitory effect in the well diffusion assay. 3,3′-4,4′-Tetraaminobiphenyl was inhibitory to both A. vinelandii and Aeromonas hydrophila, whereas benzidine, 3,3′-dimethoxybenzidine, 4,4′-dinitro-2-biphenylamine, 3,3′-5,5′-tetramethylbenzidine, N,N-N′,N′-tetramethylbenzidine, and o-tolidine were not inhibitory to any of the bacterial species tested. Of all these compounds tested, only 3,3′-4,4′-tetraaminobiphenyl and 4-aminobiphenyl inhibited the nitrogenase activity of A. vinelandii.
Reduction of 2,4,6-trinitrotoluene by Clostridium acetobutylicum through hydroxylamino-nitrotoluene intermediates
Authors: Hughes Joseph B , Wang Chuan Yue , Bhadra Rajiv , Richardson Adam , Bennett George N , Rudolph Fred B
Published: March 2010

Studies were conducted to isolate and identify intermediates of 2,4,6-trinitrotoluene (TNT) transformation by Clostridium acetobutylicum and to quantify their concentrations in active whole cell cultures. Only two intermediates of TNT reduction were detected in cell cultures and were identified as 4-hydroxylamino-2,6-dinitrotoluene and 2,4-dihydroxylamino-6-nitrotoluene. Structures were confirmed with 1H-NMR, 13C-NMR, and desorption chemical ionization mass spectroscopy. When cells were suspended in a non-growth saline medium, both hydroxylamine forms accumulated. In media capable of supporting cell growth, the 2,4-dihydroxylamino-6-nitrotoluene accumulated with concentrations of 4-hydroxylamino-2,6-dinitrotoluene remaining near detection limits. Studies using purified 2,4-dihydroxylamino-6-nitrotoluene confirmed that its biotransformation rate in active cultures greatly exceeded abiotic decomposition in aqueous medium.
Identification of fluoroquinolone antibiotics as the main source of umuC genotoxicity in native hospital wastewater
Authors: Hartmann Andreas , Alder Alfredo C , Koller Theo , Widmer Rosa M
Published: March 2010

Previous work revealed genotoxic effects in the wastewater of a large university hospital using a bacterial short-term genotoxicity assay, based on a umuC::lacZ fusion gene (umuC assay). These studies ruled out disinfectants and detergents as main causative agents of the genotoxic effects. This paper focuses on specific hospital-related drugs as the cause. The ratio of theoretical mean wastewater concentrations (derived from consumption data) and lowest observable effect concentrations of selected pharmaceuticals were used to calculate umuC induction probabilities. The fluoroquinolone antibiotics Ciproxin® and Noroxin® showed the highest induction probabilities and exceeded all other investigated drugs by at least one order of magnitude in significance. Antineoplastic drugs, originally thought to be the main effectors, were found to be of marginal significance using the umuC assay. These findings were further supported by investigation of urine samples of hospital patients with the umuC assay. The determination of ciprofloxacin in native hospital wastewater by reversed-phase high-performance liquid chromatography and fluorescence detection revealed concentrations from 3 to 87 μg/L. umuC induction factor and ciprofloxacin concentrations in 16 hospital wastewater samples showed a log-linear correlation (r2 = 0.84, p < 0.0001). These results suggest that the previously measured umuC genotoxicity in the wastewater of the hospital under investigation is caused mainly by fluoroquinolone antibiotics, especially by ciprofloxacin. On the basis of these findings, the role of the umuC assay as a screening tool for wastewater genotoxicity assessment is discussed.
Biomarker responses in cyprinids of the middle stretch of the River Po, Italy
Authors: Viganò Luigi , Arillo Attilio , Melodia Federico , Arlati Patrizia , Monti Cinzia
Published: March 2010

Fish belonging to three species of cyprinids, that is, barbel (Barbus plebejus), chub (Leuciscus cephalus), and Italian nase (Chondrostoma söetta), were collected from two sites of the River Po, located upstream and downstream from the confluence of one of its middle-reach polluted tributaries, the River Lambro. The two groups of individuals caught for each species were analyzed and compared for several microsomal and cytosolic biochemical markers. The enzymatic activities assayed in fish liver included ethoxyresorufin O-deethylase (EROD), aminopyrine-N-demethylase (APDM), uridine diphosphate glucuronyltransferase (UDPGT), glutathione S-transferase (GST), glutathione reductase, and glutathione peroxidase. In addition, the contents of reduced glutathione and nonprotein thiols were measured. Despite some differences among species, all microsomal activities (EROD, APDM, UDPGT) were found to be significantly induced in fish living downstream the River Lambro. With the exception of a higher GST enzyme activity of barbel from the downstream reach, no significant modification was evident in any of the tested cytosolic biomarkers. Results showed that barbel and nase better discriminated the two reaches of the River Po. In general, the alterations observed in feral fish are consistent with the results found in previous studies conducted with rainbow trout (Oncorhynchus mykiss) under both laboratory and field conditions in the same middle reach of the River Po. All of the data indicate that the downstream tract of the main river is exposed to the load of pollutants transported by the River Lambro, including known inducers such as polychlorinated biphenyls and polycyclic aromatic hydrocarbons (PAHs). The latter were analyzed in sediments sampled at the two sites of fish collection, and the downstream sediment showed the highest concentrations of PAHs, although their levels are comparable to those present in moderately polluted locations. Regardless of the site of exposure, barbel seem to be characterized by more efficient antioxidant defenses. This observation could partly explain the lower prevalence of pathological lesions and parasites observed in this cyprinid in a previous study.
Detection of cytochrome P4501A in several species using antibody against a synthetic peptide derived from rainbow trout cytochrome P4501A1
Authors: Lin Song , Bullock Peter L , Addison Richard F , Bandiera Stelvio M
Published: March 2010

Induction of cytochrome P4501A (CYP1A) is being used increasingly as a biomarker to indicate exposure of organisms to environmental contaminants such as some polycyclic and polychlorinated aromatic hydrocarbons. Measurement of CYP1A protein in wildlife would be facilitated by the use of a specific antibody that recognized the isozyme in several species. In the present study, a polyclonal antibody targeted to CYP1A1 was generated using a synthetic peptide corresponding to amino acids 277–294 of the trout enzyme as the antigen of immunization. Specificity of the resulting antibody was assessed by noncompetitive enzyme-linked immunosorbent assay with several purified rat CYP isozymes and by immunoblot analysis with liver microsomes from diverse species. The antibody reacted strongly with the immunizing peptide and with purified rat cytochrome P4501A1 but did not react with rat CYP1A2, a closely related isozyme, or with six other purified rat CYP proteins in enzyme-linked immunosorbent assay. On immunoblots, the antibody recognized a single protein band in hepatic microsomes from the various mammal and fish species tested. Two protein bands were detected in liver microsomes from 3-methylcholanthrene-treated chickens. The results suggest that the antigenic determinant to which the antibody binds is unique to CYP1A and is conserved in different species. Because of its specificity, this anti-peptide antibody should be suitable as a probe to measure CYP1A protein levels in wildlife.
Sex-steroid and thyroid hormone concentrations in juvenile alligators (Alligator mississippiensis) from contaminated and reference lakes in Florida, USA
Authors: Crain D Andrew , Guillette Louis J , Pickford Daniel B , Percival H Franklin , Woodward Allan R
Published: March 2010

Sex-steroid and thyroid hormones are critical regulators of growth and reproduction in all vertebrates, and several recent studies suggest that environmental chemicals can alter circulating concentrations of these hormones. This study examines plasma concentrations of estradiol-17β (E2), testosterone (T), triiodothyronine (T3), and thyroxine (T4) in juvenile alligators (60–140 cm total length) from two contaminated lakes and one reference lake in Florida. First, the data were analyzed by comparing hormone concentrations among males and females from the different lakes. Whereas there were no differences in plasma E2 concentrations among animals of the three lakes, male alligators from the contaminated lakes (Lake Apopka and Lake Okeechobee) had significantly lower plasma T concentrations compared to males from the reference lake (Lake Woodruff). Concentrations of thyroid hormones also differed in animals of the three lakes, with T4 concentrations being elevated in Lake Okeechobee males compared to Lake Woodruff males. Second, the relationship between body size and hormone concentration was examined using regression analysis. Most notably for steroid hormones, no clear relationship was detected between E2 and total length in Apopka females (r2 = 0.09, p = 0.54) or between T and total length in Apopka males (r2 = 0.007, p = 0.75). Females from Apopka (r2 = 0.318, p = 0.09) and Okeechobee (r2 = 0.222, p = 0.09) exhibited weak correlations between T3 and total length. Males from Apopka (r2 = 0.015, p = 0.66) and Okeechobee (r2 = 0.128, p = 0.19) showed no correlation between T4 and total length. These results indicate: some of the previously reported abnormalities in steroid hormones of hatchling alligators persist, at least, through the juvenile years; steroid and thyroid hormones are related to body size in juvenile alligators from the reference lake, whereas alligators living in lakes Apopka and Okeechobee experience alterations in circulating thyroid and steroid hormones in relationship to body size; and a number of the hormone abnormalities reported previously for Lake Apopka alligators are observed in alligators from Lake Okeechobee—a lake associated with numerous contaminant sources but no major chemical spill. The endocrine alterations reported in this study are hypothesized to be a response to embryonic exposure to endocrine-disrupting contaminants.
Comparative toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin to seven freshwater fish species during early life-stage development
Authors: Elonen Gregory E , Spehar Robert L , Holcombe Gary W , Johnson Rodney D , Fernandez Joseph D , Erickson Russell J , Tietge Joseph E , Cook Philip M
Published: March 2010

The toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to fathead minnow (Pimephales promelas), channel catfish (Ictalurus punctatus), lake herring (Coregonus artedii), medaka (Oryzias latipes), white sucker (Catastomus commersoni), northern pike (Esox lucius), and zebrafish (Danio danio) were observed during early life-stage development after waterborne exposure of fertilized eggs. Species sensitivity based on TCDD-Cegg (TCDD concentration in eggs) was determined by effects observed over a 32-d period for all species except lake herring in which a 100-d period was used. Signs of TCDD toxicity, including edema, hemorrhaging, and craniofacial malformations were essentially identical to those observed in salmonids following TCDD egg exposure and preceded or accompanied mortality most often during the period from hatch through swim-up. The no-observed-effect concentrations and lowest-observed-effect concentrations, based on significant decreases in survival and growth as compared to the controls, ranged from 175 and 270 pg/g for lake herring to 424 and 2,000 pg/g for zebrafish, respectively. Shapes of concentration–response curves, expressed as TCDD-Cegg versus percent mortality, were similar for all species and were consistently steep suggesting that the mechanism of action of TCDD is the same among these species. The LCegg50s (concentrations in eggs causing 50% lethality to fish at test termination) ranged from 539 pg/g for the fathead minnow to 2,610 pg/g for zebrafish. Comparisons of LCegg50s indicate that the tested species were approximately 8 to 38 times less sensitive to TCDD than lake trout, the most sensitive species evaluated to date. When LCegg50s are normalized to the fraction lipid in eggs (LCegg,l50s), the risk to early life stage survival for the species tested ranges from 16- to 180-fold less than for lake trout.
Kinetics and conductivity parameters of uptake and transport of polychlorinated biphenyls in the Caco-2 intestinal cell line model
Authors: Dulfer Wiegert J , Govers Harrie A J , Groten John P
Published: March 2010

Most of the accumulation of polychlorinated biphenyls (PCBs) over the food chain can be attributed to contaminant uptake from food. The effect of fatty acid absorption on net uptake and transport fluxes of a selection of 14 PCBs over the organismal gut epithelium has been determined in monolayers of the colon carcinoma cell line Caco-2 as a model system. The thermodynamic fugacity approach and the physiology of enterocyte lipid digestion are combined to investigate gastrointestinal absorption of polychlorinated biphenyls. The resistances of the subsequent transport steps from the apical compartment through the enterocytes to the basolateral compartment were quantified in terms of conductivity parameters. During uptake of PCBs into the enterocytes, the resistance of the aqueous diffusion barrier adjacent to the brush-border membrane is overcome for more than 99% by means of micellar transport. In the interior of the cells, the aquatic cytoplasm compartment also provides an important route of transport to the PCBs with up to three chlorine atoms, but the more hydrophobic PCBs are preferentially transported by triglyceride particles and lipoproteins. Calculated triolein/water partition coefficients, Ktri, in general are higher than taurocholate micelle/water, dimyristoylphosphatidylcholine membrane/water and n-octanol/water partition coefficients, KTC, KDMPC, and Kow, respectively. Calculations suggest that the correlation between log Kow and log Ktri is nonlinear.
Effect of chemical synergy and larval stage on the toxicity of atrazine and alachlor to amphibian larvae
Authors: Howe George E , Gillis Rick , Mowbray Rodney C
Published: March 2010

We determined the acute toxicity of field-grade formulations of atrazine, alachlor, and a 50:50 mixture of the chemicals to early and late larval stages of northern leopard frogs (Rana pipiens) and American toads (Bufo americanus). We conducted identical tests with rainbow trout (Onchorhynchus mykiss) and channel catfish (Ictalurus punctatus) to compare their sensitivity as bioindicators. The acute toxicity (96-h median lethal concentrations [LC50s]) of herbicides to amphibian larvae ranged from 47.6 mg/L for early-stage R. pipiens exposed to atrazine to 3.3 mg/L for late-stage B. americanus exposed to alachlor. The toxicity of a 50:50 mixture of atrazine and alachlor after a 96-h exposure was greater than additive (chemical synergy present) for most species and life stages tested, with 96-h LC50s as low as 1.5 mg/L for late-stage B. americanus larvae. Older amphibian larvae appeared to be more sensitive than younger larvae for both species and chemicals tested. Overall, rainbow trout and channel catfish appeared to be less sensitive than amphibian larvae. The 96-h LC50s ranged from 23.8 mg/L for channel catfish exposed to atrazine to 9.1 mg/L for rainbow trout exposed to alachlor. A noteworthy sublethal effect observed in amphibian larvae exposed to atrazine was edema, probably caused by renal disfunction. Chronic predicted no-observed-effect concentrations (PNOECs) for lethality after a 30-d exposure were estimated from mortality data at 3, 6, 24, 48, 72, and 96 h and found to be approximately 10- to 20-fold lower than 96-h LC50s. The calculated PNOECs are close enough to concentrations actually found in the environment to warrant concern and further tests. Additional research on environmental concentrations, chronic effects, and the effects of chemical synergy is needed before definitive conclusions can be drawn. Chemical synergy and life-stage sensitivity should be addressed to properly assess the toxicity of herbicides to nontarget organisms.
Individual-based risk estimation for count responses
Authors: Bailer A John , See Kyoungah
Published: March 2010

An individual-based risk assessment strategy is developed and presented for count responses as are commonly encountered in reproductive toxicology experiments. This strategy is predicated on the availability of a fitted concentration–response regression model. Adverse response is defined in terms of the production of young being suppressed below a certain specified level. The probability of this adverse response is defined in light of the concentration–response regression model. Added risk, the probability of adverse response in individuals exposed to a particular concentration condition relative to the probability of adverse response in unexposed organisms, serves as the basis of the individual-based risk estimation procedures. In particular, estimates of the added risk associated with a specified concentration and the concentration associated with a specified level of added risk are presented. Confidence intervals are developed for these two statistical endpoints using the delta method. These ideas are illustrated with two studies of Ceriodaphnia dubia exposed to nitrofen and atrazine.