bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity assessment of water from lakes and wetlands receiving irrigation drain water
Authors: Dickerson Kimberly K. , Hubert Wayne A. , Bergman Harold L.
Published: March 2010

A method for reconnaissance-level assessments of the potential toxicity of water in lakes and wetlands that receive irrigation drain water is needed. We evaluated a model that predicts toxicity to aquatic organisms due to major ionic composition as a primary means of assessing water quality. The model was used in conjunction with acute toxicity tests and trace element analyses. Mortality of Ceriodaphnia dubia and fathead minnows (Pimephales promelas) observed in acute toxicity tests was compared to mortality predicted by the model. The method was applied at 22 lakes and wetlands on federally administered lands in Colorado, Montana, Utah, and Wyoming. Fourteen of 22 locations had water that was not toxic to test organisms. Six locations had undiluted water that was toxic to C. dubia due to major ionic composition, and two locations had undiluted water that showed toxic effects caused by factors other than elevated levels of major ions. The model for C. dubia seemed to be sufficiently accurate for future application using our approach to assess lakes and wetlands receiving irrigation drain water.
Toxicity, silver accumulation and metallothionein induction in freshwater rainbow trout during exposure to different silver salts
Authors: Hogstrand Christer , Galvez Fernando , Wood Chris M.
Published: March 2010

Static-renewal 168-h toxicity tests of silver nitrate (AgNO3), silver chloride (AgCln), and silver thiosulfate (Ag(S2O3)n) with juvenile rainbow trout (Oncorhyncus mykiss) were performed by standard methods. Because of low solubility of AgCl(s), bioassays for AgCln were performed in two separate ways. In one test series, AgCl(s) was added to freshwater and in another, AgCln(aq) was generated by adding AgNO3 to freshwater supplemented with 50 mM NaCl. Concentrations of Ag and metallothionein (MT) were analyzed in gills and livers offish that survived the exposures. Although Ag added as AgNO3 was found to be highly toxic to rainbow trout (168-h LC50 = 9.1 μg Ag L−1), the toxicities of the other Ag salts were low. The 168-h LC50 for Ag(S2O3)n was 137,000 μg Ag L−1 and no mortality was observed in AgCln (100,000 μg Ag L−1). Exposure to AgNO3, Ag(S2O3)n, or AgCln caused accumulation of Ag and induction of MT. Highest Ag levels were found in livers of trout exposed to 164,000 μg Ag L−1 as Ag(S2O3)n. In these fish, the hepatic Ag concentration was increased 335 times from the control value. The MT levels in gills and liver increased with the water Ag concentration and the highest level of MT was found in liver of fish exposed to Ag(S2O3)n.
Effects of boron and selenium on mallard reproduction and duckling growth and survival
Authors: Stanley Thomas R. , Smith Gregory J. , Hoffman David J. , Heinz Gary H. , Rosscoe Roger
Published: March 2010

Boron (B) and selenium (Se) sometimes occur together in high concentrations in the environment and can accumulate in plants and invertebrates consumed by waterfowl. One hundred twenty-six pairs of breeding mallards (Anas platyrhynchos) were fed diets supplemented with B (as boric acid) at 0, 450, or 900 ppm, in combination with Se (as seleno-DL-methionine) at 0, 3.5, or 7 ppm, in a replicated factorial experiment. Ducklings produced received the same treatment combination as their parents. Boron and Se accumulated in adult liver, egg, and duckling liver. In adults, B and Se caused weight loss, and B decreased hemoglobin concentration, egg weight, and egg fertility. Both B and Se reduced hatching success and duckling weight, and B reduced duckling growth and duckling production, and caused several alterations in duckling liver biochemistry. Duckling survival was not reduced by B or Se, and neither B nor Se had histopathologic effects on adult or duckling liver, kidney, or spleen. There was little evidence of interaction between B and Se. This study demonstrated that B and Se, in the chemical forms and at the dietary levels administered in this study, can adversely affect mallard reproduction and duckling growth.
Small mammal populations in maryland meadows during four years of herbicide (brominal®) applications
Authors: Clark Donald R. , Moulton Cynthia A. , Hines James E. , Hoffman David J.
Published: March 2010

The herbicide Brominal® was applied at the recommended rate to one plot in each of three paired 0.6-ha plots; the other three plots were used as controls. Plots were sprayed once in the fall of 1988 and 1989 and twice in the spring of 1990 and 1991. Small mammals were trapped three times during each activity season (April-October) to obtain population estimates before and after spraying and in the spring preceding fall spraying or the fall following spring spraying. Population estimates immediately after spraying gave no evidence of direct mortality. By 1991, dicot vegetation on treated plots was suppressed and mean numbers of meadow voles (Microtus pennsylvanicus) were less than on control plots. Because meadow voles favor dicots over monocots in their diet, reduced availability of dicots may have been related to the smaller vole population estimates. Species diversity of small mammals was negatively correlated with size of vole populations, but was not different between treated and control plots. Brominal apparently induced opaque corneas in nine voles. The condition was found in two voles too small to have been conceived at the time of the last previous spray nearly 8 months earlier, suggesting exposure to residue alone.
A comparison of β-adrenoceptors and muscarinic cholinergic receptors in tissues of brown bullhead catfish (Ameiurus nebulosus) from the black river and old woman creek, Ohio
Authors: Steevens Jeffery A. , Baumann Paul C. , Jones Susan B.
Published: March 2010

β-Adrenoceptors (βARs) and muscarinic cholinergic receptors were measured in brain, gill, and heart tissues of brown bullhead catfish exposed to polycyclic aromatic hydrocarbons in the Black River, Ohio, USA, and were compared to values from Old Woman Creek, Ohio, a reference site. A decreased number of βARs were found in the gill from Black River fish, possibly indicating a compensatory response subsequent to chemical stress.
Evaluation of PCB and hexachlorobenzene biota-sediment accumulation factors based on ingested sediment in a deposit-feeding clam
Authors: Boese Bruce L. , Lee Ii Henry , Specht David T. , Randall Robert , Pelletier Judith
Published: March 2010

Contaminated sediment exposure experiments were conducted using a marine deposit-feeding clam (Macoma nasuta) to determine biota-sediment accumulation factors (BSAFs) based on ingested sediment and fecal organic carbon. Internal, or gut, BSAFs were determined for hexachlorobenzene and 13 polychlorinated biphenyl congeners and were compared to those found with the standard method of calculating BSAFs, which uses the organic carbon and contaminant concentration of the whole or external sediment. The results of these experiments indicated that gut BSAFs were consistently smaller and less variable across sediment types than the corresponding standard BSAFs. Although these results indicate that using ingested sediment concentrations and fecal total organic carbon to calculate gut BSAFs might improve the predictive ability of the standard BSAF model, the benefit is small when compared to the difficulty in measuring the contaminant concentration on ingested sediment and the organic carbon content of feces.
Dietary accumulation of C12- and C16-chlorinated alkanes by juvenile rainbow trout (Oncorhynchus mykiss)
Authors: Fisk Aaron T. , Bergman ÅKe , Cymbalisty Chris D. , Muir Derek C. G.
Published: March 2010

Dietary exposures using juvenile rainbow trout (Oncorhynchus mykiss) were conducted with four 14C-polychlorinated alkanes (C12H20Cl6 [56% Cl by weight], C12H16Cl10 [69% Cl], C16H31Cl3 [35% Cl], and C16H21Cl13 [69% Cl]) in order to measure bioaccumulation parameters, metabolism, and tissue distributions. These chlorinated alkanes are found in industrial chlorinated paraffin (CP) products, although their method of synthesis is different than that of CPs. Trout were exposed for 40 d to nominal concentrations of 20 and 200 ng/g of each chlorinated alkane, as well as to 2,000 ng/g for C16H21Cl13, followed by an elimination period of up to 173 d. Whole-body half-lives in the rainbow trout ranged from 37 ± 2 d for C16H31Cl3 to 87 ± 11d for C12H16Cl10, and assimilation efficiencies of C16H31Cl3 (33 to 35%) and C12H16Cl10 (34 to 38%) were highest among the four alkanes. Biomagnification factors ranged from 0.44 for C16H21Cl13 to 2.15 for C12H16Cl10. Accumulation of C16H21Cl13 (molecular weight = 674) may be sterically hindered due to its large molecular size. Lower chlorinated alkanes, e.g., C16H31Cl3, had shorter half-lives than highly chlorinated alkanes, probably due to increased metabolism. High-performance liquid chromatography 14C analysis offish tissue extracts revealed that the chlorinated alkane mixtures were selectively biotransformed with certain unknown components persisting in tissues. Lower chlorinated alkanes had greater proportions of polar 14C, which implies greater metabolism of these compounds. Highly chlorinated, short-carbon-chain (C10–13) alkanes and lower chlorinated, medium-carbon-chain (C14–18) alkanes appear to have the greatest potential for biomagnification among CP components. No reduced growth rates or hepatic monooxygenase enzyme induction were seen in any of the chlorinated alkane exposures when compared with controls.
Investigations of enzymatic alterations of 2,4-dichlorophenol using 13C-nuclear magnetic resonance in combination with site-specific 13C-labeling: Understanding the environmental fate of this pollutant
Authors: Nanny Mark A. , Bortiatynski Jacqueline M. , Hatcher Patrick G. , Tien Ming
Published: March 2010

The biodegradation of 13C-labeled 2,4-dichlorophenol (DCP labeled at the C-2 and C-6 positions), in the presence and absence of natural organic matter (NOM), by the white-rot fungus Phanerochaete chrysosporium, was examined using 13C-nuclear magnetic resonance (NMR). Using this method permitted the chemistry occurring at or near the labeled site to be followed. The formation of alkyl ethers and alkene ethers was observed. No aromatic by-products were detected, indicating that aromatic compounds are quickly degraded. Examining the reaction with time shows the exponential removal of 2,4-DCP and the consequential formation of labeled by-products, whose concentration reaches a maximum just before all 2,4-DCP is consumed. After this, the by-products degrade exponentially. The presence of NOM causes 2,4-DCP to be removed from the aqueous phase more quickly than in its absence and also causes the by-products to reach their maximum concentration much earlier. Degradation of the by-products occurs at a much greater rate in the presence of NOM. One hypothesis for this behavior is that the NOM interacts with 2,4-DCP and its by-products, allowing them to be incorporated into the fungal biomass. 13C-nuclear magnetic resonance spectra of the fungal biomass after NaOH extraction show the presence of alkanes and a small amount of 2,4-DCP.
Limited bioavailability of sediment pah near an aluminum smelter: Contamination does not equal effects
Authors: Paine Michael D. , Chapman Peter M. , Allard Patrick J. , Murdoch Mary H. , Minifie David
Published: March 2010

A Sediment Quality Triad study involving synoptic measures of polycyclic aromatic hydrocarbon (PAH) contamination, toxicity, and resident community (benthic infauna, crab) alteration was conducted to assess impacts from an aluminum smelter discharge. No sediment toxicity was observed, despite extensive testing since 1988 on four test species. Evidence of effects on resident communities was minimal. Effects were not expected in areas >1 km from the smelter, because PAH concentrations have decreased with recent effluent improvements to below levels associated with effects in other studies. However, concentrations within 1 km of the smelter were high (maximum concentration was 10,000 mg/kg total PAH, although most were <150 mg/kg). Based on the literature, those concentrations should have had significant effects on toxicity test responses and benthic communities. Because they did not, we conclude that availability of sediment PAH was limited. Concentrations of parent PAH and metabolites in Dungeness crab (Cancer magister) were also low, supporting the hypothesis of limited bioavailability. Bioavailability may be limited because much of the PAH is present as pitch or coal particles. This study indicates that high contaminant concentrations may not be associated with effects, if availability is limited.
Bioavailability and chronic toxicity of cadmium in sediment to the estuarine amphipodLeptocheirus plumulosus
Authors: Dewitt Theodore H. , Swartz Richard C. , Hansen David J. , McGovern Douglas , Berry Walter J.
Published: March 2010

Numerous studies have demonstrated the efficacy of interstitial water metal concentrations and simultaneously extracted metals/acid-volatile sulfide (SEM/AVS) ratios in explaining the acute toxicity of sediment-associated metals to benthic organisms. However, no full life-cycle chronic marine or estuarine tests have been conducted for this purpose. In this study, cohorts of newborn amphipods, Leptocheirus plumulosus, were exposed to cadmium-spiked estuarine sediment for 28 d to determine effects on mortality, growth, and reproduction relative to interstitial water and SEM/AVS normalization. Seven treatments of cadmium were tested: 0 (control), 0.34, 0.74, 1.31, 1.55, 2.23, and 4.82 M SEMcd/AVS ratios (measured concentrations). Interstitial water cadmium (IWcd) and sediment concentrations of SEMcd and AVS were monitored periodically and by depth during the exposure. When sediment SEMcd/AVS ratios were ≤1.55, mean IWcd concentrations were less than the 96-h water-only cadmium LC50 for juvenile and subadult L. plumulosus, and mortality, growth, and reproduction were not affected. When SEMcd/AVS ratios were ≥2.23, IWcd concentrations were more than 100 times greater than the 96-h water-only cadmium LC50, and all amphipods died. These results are consistent with predictions of metal bioavailability from acute tests with metal-spiked sediments, i.e., that sediments with SEMcd/AVS ratios <1 are not toxic, while sediments with SEMcd/AVS ratios >1 may be toxic.
TCDD-Like activity of 2,3,6,7-tetrachloroxanthene in rainbow trout early life stages and in a rainbow trout gonadal cell line (RTG-2)
Authors: Zabel Erik W. , Peterson Richard E.
Published: March 2010

Fish in many areas are contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and biphenyl (PCB) congeners. Other chemicals may also be present that act through the same mechanism. 2,3,6,7-Tetrachloroxanthene (TCX) has been found to be an interference in PCDD and PCDF analyses and may occur in sediments near pulp and paper mills. However, the toxicology of TCX has not been studied in any species. This study sought to determine whether TCX causes TCDD-like effects in two fish systems, rainbow trout early life stages and rainbow trout gonadal cells (RTG-2) in culture. 2,3,6,7-Tetrachloroxanthene caused rainbow trout sac fry mortality secondary to blue sac syndrome, identical to that caused by TCDD, and was similar in potency to TCDD for causing cytochrome P4501A mRNA induction in RTG-2 cells and sac fry mortality in rainbow trout, with toxic equivalency factors of 1.09 to 2.29. These results suggest that TCX may pose a risk to feral fish in contaminated areas even at low concentrations.
Comparative evaluation of soil toxicity using lettuce seeds and soil ciliates
Authors: Bowers Nancy , Pratt James R , Beeson David , Lewis Mark
Published: March 2010

The toxicity of elutriates from 25 putatively contaminated soils was evaluated using the standard seed (Lactuca sativa) germination test and a recently developed soil ciliate (Colpoda inflata) growth test. Correspondence in the identification of presence or absence of toxicity in the 25 soil elutriates between the two tests was 60% and concordance in ranking of toxicity between the two tests was significant (p < 0.05) using Spearman's rank correlation test (rs = 0.3831). Stepwise multiple regression analysis of toxicity results against soil elutriate chemistry indicated that pH explained the greatest amount of variation in response in both tests, despite high concentrations of several metals in the elutriates. For the germination test, a multiple regression model that included pH and cadmium explained 58.5% of response variation, whereas over 83% of response variation in the ciliate growth test could be explained by pH, copper, and cadmium. Differences in the response of the plant and protozoan models appeared to be due primarily to differences in their sensitivity to elutriate pH. In addition to better correspondence between elutriate chemistry and ciliate response compared to the seed germination test, lower response variability associated with the measure of ciliate growth compared with seed germination provided greater statistical sensitivity for detecting toxic effects.
Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on development of anuran amphibians
Authors: Jung Robin E , Walker Mary K
Published: March 2010

We exposed anuran eggs and tadpoles to vehicle control (0.7% acetone) or waterborne [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 24 h (American toad, 0.003-30 μg/L; leopard frog, 3 μg/L; green frog, 0.3-100 μg/L) and subsequently raised them in clean water. Neither American toads nor green frogs exhibited TCDD-related mortality, but leopard frogs showed significantly increased (10%) mortality over controls. Eggs and tadpoles eliminated TCDD relatively quickly compared with published data for other vertebrates, with t1/2 of 1 to 5 d (American toad), 2 to 7 d (leopard frog), and 4 to 6 d (green frog). Elimination rates were slowest for tadpoles fed nothing, fastest for those fed a low-fat diet, and intermediate for those fed a high-fat diet. Although not significant, American toads exposed to ⩾0.03 μg TCDD/L appeared to metamorphose earlier, and those exposed to higher TCDD treatments appeared to metamorphose at a larger body mass than controls. Comparisons of these results with studies of fish early life stages suggest that anuran eggs and tadpoles eliminate TCDD more rapidly and are 100- to 1,000-fold less sensitive to its deleterious effects during development. These differences may be related to differences in metabolic rate, patterns of lipid storage and utilization, and aryl hydrocarbon receptor binding and signal transduction.
Ecotoxicological assessment of aquatic sediments withCaenorhabditis elegans(nematoda) — a method for testing liquid medium and whole-sediment samples
Authors: Traunspurger Walter , Haitzer Markus , Höss Sebastian , Beier Stefanie , Ahlf Wolfgang , Steinberg Christian
Published: March 2010

We present a method using the free-living nematode Caenorhabditis elegans (Maupas, 1899) to assess toxicity in liquid medium and whole-sediment setups. Test duration is 72 h; endpoints are body length, number of eggs inside worms, percentage of gravid worms, and number of offspring per worm. The effect of CdCl2 on C. elegans in liquid-phase exposures is described as an example. Results from a field study with polluted sediments from the River Elbe (Germany) suggest that nematodes may be useful organisms in assessing toxicity of sediments in the whole phase.
Effects of exposure to an organophosphate pesticide on behavior and acetylcholinesterase activity in the common shrew, Sorex araneus
Authors: Dell'Omo Giacomo , Bryenton Rachel , Shore Richard F
Published: March 2010

The behavioral and physiological effects of exposure to dimethoate, an organophosphate (OP) pesticide, were examined in common shrews, Sorex araneus, under laboratory conditions. Shrews were given either saline or an acute sublethal dose (50 mg/kg intraperitoneal) of dimethoate, and a time course of behavior was recorded in five 10-min open field tests spaced over a 12-h period. Parallel measurements of brain acetylcholinesterase (AChE) activity were carried out to monitor the onset of brain AChE inhibition and its subsequent recovery. Dimethoate produced a significant depression of locomotor activity for approx. 6 h. Rearing, exploring, and sniffing activities were also significantly inhibited. The observed behavioral effects coincided with the maximal inhibition of AChE and disappeared before the brain AChE level had recovered. Statistically significant correlations were observed between the reduced frequencies of exploring, rearing, and crossings (a measure of locomotor activity) and the severity of inhibition of brain AChE activity, suggesting that brain AChE activity, the biomaker of exposure, could be used as a predictor of the severity of OP-induced effects on behavior.
The significance of growth inChironomus tentanssediment toxicity tests: Relationship to reproduction and demographic endpoints
Authors: Sibley Paul K , Benoit Duane A , Ankley Gerald T
Published: March 2010

In the Chironomus tentans 10-d growth test, changes in larval growth relative to sediment contamination are often ascribed ecological relevance by assuming that such changes become manifest at the population level through effects on reproductive output even though the relationship between growth and reproduction is poorly understood. The objective of this study was to evaluate the relationship between growth and reproduction in C. tentans and to use these data in a demographic model to predict the growth and size of a theoretical population. Growth was manipulated by varying food supply (0.29, 0.33, 0.38, 0.42, 0.46, and 0.5 mg/individual per d). The test was initiated with 12 newly hatched larvae per replicate and carried through one complete generation. Larval growth and survival were determined at 20 d, and reproduction was monitored daily during emergence. Food supply did not significantly affect survivorship at any life stage; survival of larvae at 20 d, pupae, and adults exceeded 83%, while survival of larvae in the reproduction replicates exceeded 65%. Both larval and adult dry weight declined significantly with a reduction in food supply. Total emergence was reduced at the lowest feeding level only, whereas the rate of emergence declined at food supplies below 0.42 mg/individual per d. Based on the relationship between larval and adult dry weight, a minimum larval tissue mass of between 0.5 and 0.6 mg dry weight/individual appears to be necessary before emergence can take place. The number of eggs/female declined significantly with a decrease in food supply below 0.42 mg/individual per d. Above this level (corresponding to larval dry weight of ∼ 1.5 mg/individual), the addition of more food had no effect on reproductive output. Fecundity (number of daughters/female) and expected number of progeny declined linearly with reduced food supply. Application of the data in a demographic model showed that the growth and predicted size of a population would decline significantly with a decline in larval growth and reproductive output. These results demonstrate that changes in growth, positive or negative, can be used to make meaningful predictions regarding reproduction and population dynamics in the midge C. tentans.
A method for evaluating the toxicity of industrial solvent mixtures
Authors: Kononen Douglas W , Gorski Robert A
Published: March 2010

The toxicity of a mixture of toluene and mixed xylenes was studied with the frog embryo teratogenesis assay—Xenopus (FETAX). Single compound experiments with either toluene or mixed xylenes show that growth inhibition, not mortality or malformation, is the most sensitive toxic endpoint in the FETAX system (i.e., growth is inhibited at lower exposure concentrations than those resulting in malformations and mortality). A multiple logistic regression analysis model described mortality and malformation as functions of exposure concentrations of toluene and mixed xylenes. The results indicate that toluene and mixed xylenes are additive in their effects on mortality in the FETAX system. Further experimentation is necessary to validate the model's ability to describe malformation as a function of coexposure to toluene and mixed xylenes.
Do mosquito control treatments of wetlands affect red-winged blackbird (Agelaius phoeniceus) growth, reproduction, or behavior?
Authors: Hanowski JoAnn M , Niemi Gerald J , Lima Ann R , Regal Ronald R
Published: March 2010

We found no convincing evidence that reproduction, growth, or foraging behavior of red-winged blackbirds (Agelaius phoeniceus) were negatively impacted by treatments of wetlands with either Bacillus thuringiensis israelensis (Bti, applied as Vectobac-G granules) or methoprene (applied as Altosid sand granules). Most red-winged blackbird parameters examined varied annually and some differences were found before treatments began. In all cases, differences found before treatments were either found again during the treatment years or no patterns existed to suggest impacts of mosquito control treatments. Only 1 of the 22 variables examined indicated a significant difference between a treatment group and the controls; males in Bti-treated sites were larger than males in control sites during the treatment years. Clutch size indicated a significant treatment-by-year interaction and was higher in control areas as compared with Bti-treated areas in 3 of the 6 years of study; 2 years occurred before any treatments were applied. Data from benthic aquatic insect studies showed that aquatic insects were depressed in wetlands treated with both methoprene and Bti in July and August. However, it is unlikely that food available to avian species in these wetlands was lower during the breeding season (May and June). Other portions of the avian life cycle that may be affected include the dispersal of young birds within or to these sites and individuals that use wetlands during migration. Impacts on these aspects of the avian community and landscape-level effects of treatments were not addressed.
Risk of ammonia toxicity during sediment bioassays with the estuarine amphipodLeptocheirus plumulosus
Authors: Moore David W , Bridges Todd S , Gray Brian R , Duke B Maurice
Published: March 2010

High levels of ammonia in sediment toxicity tests can potentially confound test results. At issue is whether the observed toxicity is due to elevated ammonia or the presence of more persistent anthropogenic contaminants. To evaluate the risk of ammonia toxicity, information on (1) the exposure–response relationship and (2) the probability of exposure are needed. Preliminary exposure–response data were obtained for two different sieved size classes of the estuarine amphipod Leptocheirus plumulosus representing juveniles (425–600 μm) and subadults (not reproductively active) (600–1,000 μm) in 4-d water-only exposures with ammonia (NH4Cl). Resulting LC50 values were 44 (juvenile) and 89 mg NH3-N/L (subadult). Results from 4-d tests were used to establish exposure concentrations for two spiked-sediment studies: (1) a 10-d static exposure starting with subadults measuring survival and growth and (2) a 28-d exposure with daily renewal of overlying water starting with juveniles and measuring survival, growth, and reproduction. Risk of ammonia toxicity to L. plumulosus during sediment toxicity tests was characterized via a Monte Carlo simulation using the exposure–response curves from laboratory spiked-sediment studies and published porewater ammonia values for 322 marine sediments. Results indicate a significant potential for ammonia induced interference in the 10-d test (e.g., 2–18% probability of significant mortality due to ammonia alone). Risk in 28-d tests appears to be minimal due to rapid dissipation of ammonia via renewal of overlying water.
Structure-activity relationships for Pimephales and Tetrahymena: A mechanism of action approach
Authors: Bearden Anna P , Schultz T Wayne
Published: March 2010

The toxicity data of 74 chemicals tested in both the 96-h fathead minnow (Pimephales promelas) mortality assay and the 2-d Tetrahymena pyriformis (a protozoan) growth inhibition assay were evaluated using quantitative structure-activity relationships (QSARs). Each chemical was a priori assigned a mechanism of acute toxic action from either nonpolar narcosis, polar narcosis, weak acid respiratory uncoupling, soft electrophilicity, or proelectrophilicity. The polar narcotics were further split into a phenol group and an aniline group. The relationship between bioreactivity and the importance of penetration to the site of action in both systems was studied. Bioreactivity showed a trend to be inversely proportional to the value of the hydrophobicity term. The data were examined to investigate how different molecular descriptors modeled the mechanisms of action. Models were produced for nonpolar narcotics and anilines for both species with the 1-octanol/water partition coefficient (log Kow) alone. Soft electrophiles were best predicted by the average acceptor superdelocalizability (Snav), whereas proelectrophiles were modeled by log Kow and Snav. The weak acid uncouplers modeled with either log Kow or log Kow plus the ionization constant (pKa) for Pimephales and Tetrahymena, respectively. Phenols yielded predictive models using a either a combination of log Kow with Snav or lowest unoccupied molecular orbital, for fathead minnow and protozoan, respectively.
Effect of hybrid poplar trees on microbial populations important to hazardous waste bioremediation
Authors: Jordahl James L , Foster Lesley , Schnoor Jerald L , Alvarez Pedro J J
Published: March 2010

Microbial concentrations of denitrifiers, pseudomonads, and monoaromatic petroleum hydrocarbon (BTX) degraders were significantly higher (p < 0.1) in soil samples from the rhizosphere of poplar trees than in adjacent agricultural soils, and atrazine degraders were found only in one rhizosphere sample. The relative abundance of these phenotypes (as a fraction of total heterotrophs) was not significantly different between rhizosphere and surrounding soils. Therefore, the poplar rhizosphere enhanced the growth of microbial populations that participate in natural bioremediation without exerting selective pressure for them.
Hepatic ethoxyresorufin-O-deethylase activity and inducibility in wild populations of double-crested cormorants (Phalacrocorax auritus)
Authors: Davis Jay A , Fry D Michael , Wilson Barry W
Published: March 2010

Microplate fluorometric techniques were used to measure ethoxyresorufin O-deethylase (EROD) activity in hepatic microsomes and primary hepatocyte cultures from individual wild double-crested cormorant (Phalacrocorax auritus) embryos. Embryos were collected in 1993 and 1994 from Humboldt Bay and San Francisco Bay (CA, USA) and a reference site in coastal Oregon (USA). Median microsomal EROD activities in embryos collected from San Francisco Bay (in both 1993 and 1994) and from Humboldt Bay (1994) were four- to eightfold higher than the reference site median (Kruskal–Wallis, p < 0.05). This degree of induction suggests that cormorant embryos in the two California locations were exposed to concentrations of dioxinlike compounds that are at the threshold for toxic effects in this species. Substantial variation in the EROD response in cultured hepatocytes was observed between individuals, populations, and the two bird species tested (cormorants and chickens [Gallus gallus]). Although most of the cormorant individuals displayed a consistent dose–response profile, a few individuals were uninducible, showing no appreciable increase over basal activity with increasing dose of inducer. Composite dose–response curves for two cormorant colonies appeared to be divergent in spite of small sample sizes, indicating that inducibility can also vary at the population level. These observations suggest that considerable variability in pollutant metabolism and sensitivity associated with single enzyme systems may exist within wild populations and species.
Biomagnification of polychlorinated biphenyls through a riverine food web
Authors: Zaranko Danuta T , Griffiths Ronald W , Kaushik Narinder K
Published: March 2010

From 1989 to 1993, biota collected from Pottersburg Creek, London, ON, Canada were analyzed for total polychlorinated biphenyls (PCBs) and lipids. Data were analyzed by analysis of covariance (ANCOVA) with lipid as the covariate, to investigate station, time, and trophic effects on PCB accumulation in aquatic organisms. All three variables were highly significant (p < 0.0001). PCB concentrations in biota decreased along the length of the creek away from the point source. PCB concentrations in biota collected in July 1993 were not significantly different from concentrations in biota collected in July 1990 (p > 0.16), suggesting that sources into the creek have not been alleviated. The relationship between PCBs and lipid for biota from Pottersburg Creek suggests that organisms accumulate PCBs relative to their position in the food web (p < 0.0001). Fish and leeches occupying the top of the food web accumulated more PCBs than organisms occupying a lower trophic position (crayfish and oligochaetes/chironomids), indicating that biomagnification through trophic transfer (i.e., the uptake of a chemical through ingestion) is the primary mechanism governing contaminant levels in biota and not bioconcentration (i.e., the uptake of a chemical from water).
The calux (chemical-activated luciferase expression) assay adapted and validated for measuring TCDD equivalents in blood plasma
Authors: Murk Albertinka J , Leonards Pim E G , Bulder Astrid S , Jonas Arjen S , Rozemeijer Marcel J C , Denison Michael S , Koeman Jan H , Brouwer Abraham
Published: March 2010

A method was developed to isolate lipophilic compounds efficiently from small aliquots of blood plasma and test these for total dioxin-like toxic potency using recombinant rat (H4IIE) and mouse (Hepa1c1c7) hepatoma cell lines, containing the firefly (Photinus pyralis) luciferase gene under trans-activational control of the aryl hydrocarbon receptor (AhR). For this experiment, blood plasma was used originating from eider ducks (Somateria mollissima) that had been dosed with 3,3′,4,4′-tetrachlorobiphenyl (PCB-77) or with the technical PCB-mixture Clophen A50. For each sample the CALUX (chemical-activated luciferase expression) response of both the fat-containing organic extract and the fat-free, cleaned extract were compared with data from chemical analyses of these samples. The CALUX responses for the extracts were converted into so-called CALUX TEQs (TCDD equivalents), using a 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) standard curve. The CALUX TEQs in both fatty and cleaned extracts correlated significantly with PCB-77 or PCB-153 levels (depending on the dosage group) determined in blood plasma using gas chromatography–mass spectrometry (GC-MS). For PCB-77 a toxic equivalency factor (TEF) of 1.5 × 10−3 was calculated based on these correlations. In addition, PCB-118 and PCB-156 levels in abdominal fat (assessed with GC with electron capture detection) and hepatic ethoxyresorufin O-deethylase activities correlated well with the CALUX TEQs in both fatty and cleaned blood plasma extracts, suggesting the TEQ levels in blood offer a good measure for internal dose. Plasma cholesterol and triglyceride levels were determined as a measure of lipid content, in 10-μl aliquots of blood plasma using enzymatic spectrophotometric determination. In conclusion, we have demonstrated that the CALUX assay is a rapid, sensitive assay for assessing the toxic potency of (mixtures of) AhR-active compounds in small aliquots of blood plasma. The limit of detection for the CALUX assay is currently less than 0.1 fmol (32 fg) TEQ, which corresponds with the amount of TEQs present in 0.1 to 1 ml of blood plasma in environmentally exposed species or man.
Cereal aphid and parasitoid survival in a logarithmically diluted deltamethrin spray transect in winter wheat: Field-based risk assessment
Authors: Longley Martin , Jepson Paul C
Published: March 2010

Dose rates of the pyrethroid insecticide deltamethrin were optimized for aphid control and the conservation of beneficial parasitoids in winter wheat. A logarithmic dose sprayer was used to apply concentrations ranging from twice the recommended field rate to a concentration representing one-fiftieth of the field rate. Volumetric analysis of colored dye deposits quantified the partitioning of pesticide through the crop canopy and was used to calculate direct exposure rates of aphid colonies and residue concentration on different plant structures contacted by foraging parasitoids. Aphid parasitoids, from the genus Aphidius, were found to be more at risk from exposure to insecticide residues than were their aphid hosts under the given bioassay conditions. However, the toxicity of deltamethrin residues on flag leaves was found to dissipate over a 5-d period after application. Deltamethrin provided significant aphid control at dose rates greater than 1 g a.i./ha (or at approximately one-sixth of the recommended field rate). At low concentrations of deltamethrin, aphids survived in the lower crop strata within low toxicity refuges. The implications of these refugia and the spatial redistribution of prey and host populations following spray application for the success of biological control agents are discussed.
Temporal biomarker responses in wild passerine birds exposed to pesticide spray drift
Authors: Cordi Britt , Fossi Cristina , Depledge Michael
Published: March 2010

A field study was conducted to assess the degree of exposure experienced by nestling and adult great tits, (Parus major) to spray drift of pirimicarb and dimethoate. Nondestructive assays of serum esterases, serum butyrylcholinesterase (BChE), and carboxylesterase (CbE) were used as exposure biomarkers and measurements of weight gain and survival were made to assess adverse biological effects. Nest boxes were placed in hedgerows bordering fields sprayed with pesticides (either pirimicarb or dimethoate). One hedge was sprayed directly with pirimicarb to simulate maximum drift effect. Two hedges were left untreated to serve as control areas. The concentrations of the two insecticides were within the recommended dose for cereals. Significant inhibition of BChE activity was detected within 24 h in adult birds exposed to drift of dimethoate and in adult birds from the hedge sprayed directly with pirimicarb. Highly significant correlations were found between the weight of unexposed nestlings and BChE and CbE activity, indicating that a developmental increase in enzyme activities is correlated with the growth rate of the nestlings. Inhibition in nestling BChE activity was found in all treated hedges after 24 h. A tendency of reduced weight gain was found in nestlings both between 0 to 24 h and 24 to 48 h after treatment in all the treated hedges compared to nestlings from the control hedge (p > 0.07). These results indicate the potential of pesticide drift to reduce growth rate and survival of juvenile wild passerine birds.
Photoactivation and toxicity of mixtures of polycyclic aromatic hydrocarbon compounds in marine sediment
Authors: Swartz Richard C , Ferraro Steven P , Lamberson Janet O , Cole Faith A , Ozretich Robert J , Boese Bruce L , Schults Donald W , Behrenfeld Michael , Ankley Gerald T
Published: March 2010

The direct toxicity and photoinduced toxicity of sediment-associated acenaphthene, phenanthrene, fuoranthene, and pyrene were determined for the marine amphipod Rhepoxynius abronius. The four polycyclic aromatic hydrocarbons (PAHs) were spiked into sediment in a concentration series of either single compounds or as approximately equitoxic mixtures of all four compounds. Standard 10-d sediment toxicity tests were conducted under fluorescent lighting. After 10 d, survivors were exposed for 1 h to ultraviolet (UV) radiation in the absence of sediment and then tested for their ability to bury in uncontaminated sediment. The 10-d median lethal concentrations (LC50s) were 2.31 mg acenaphthene/g organic carbon (OC), 2.22 mg phenanthrene/g OC, 3.31 mg fluoranthene/g OC, and 2.81 mg pyrene/g OC These LC50s were used to calculate the sum of toxic units (ΣTU) of the four PAHs in the approximately equitoxic mixtures. The ΣTU LC50 was then calculated for the mixture treatments. If the toxicologic interaction of a mixture of contaminants is additive, ΣTU LC50 =1.0. The observed LC50 (1.55 ΣTU) was slightly, but significantly, greater than unity, indicating that the interaction of PAHs in the mixture was less than additive. Exposure to UV radiation enhanced the toxic effects of fluoranthene and pyrene, but did not affect the toxicity of acenaphthene and phenanthrene. Effects of UV radiation on the toxicity of the mixture of four PAHs could be explained by the photoactivation of fluoranthene and pyrene alone. These results are consistent with predictions based on photophysical properties of PAH compounds.
Biodegradation of organic compounds sequestered in organic solids or in nanopores within silica particles
Authors: Hatzinger Paul B , Alexander Martin
Published: March 2010

A study was conducted using model solids to determine whether the time-dependent decline in availability for biodegradation of organic pollutants in soil might result from the entrapment of these compounds in porous or nonporous solids. A strain of Pseudomonas mineralized phenanthrene in solid alkanes containing 18 to 32 carbons, three waxes, and low-molecular-weight polycaprolactone, polyethylene, and polypropylene. The rates were appreciably slower than when the substrate was not initially present within these nonporous solids. From 1.4 to 63.4% of the polycyclic aromatic hydrocarbon added to the solids was mineralized in 90 d. The rates and extents of partitioning of phenanthrene varied markedly among the solids. The rates of partitioning and biodegradation of phenanthrene initially present in the alkanes were positively correlated. The bacterium rapidly and extensively mineralized phenanthrene provided in calcium alginate beads containing varying amounts of soluble soil organic matter. The rates and extents of phenanthrene mineralization declined as the percentage of the substrate in the nanopores within silica particles increased, but the reductions in rate, extent, or both were less pronounced than with nonporous solids. The rate of 4-nitrophenol biodegradation also declined with increasing percentages of the compound in these nanopores. The data are consistent with hypotheses that the sequestration and consequent decrease in bioavailability of organic compounds that persist in soil result from their partitioning into organic matter or their presence within nanopores in soil.
Polychlorinated biphenyl congeners and selected organochlorines in lake superior fish, USA
Authors: Gerstenberger Shawn L , Gallinat Mike P , Dellinger John A
Published: March 2010

Walleye, whitefish and whitefish livers, lake trout, and siscowet lake trout were collected from the Apostle Islands Region of Lake Superior. Carp were obtained from a Lake Michigan tributary near Oshkosh, Wisconsin, USA. Each fish species was analyzed for 89 polychlorinated biphenyl congeners, 12 selected organochlorines, and total lipids. Congener profiles varied greatly between the fish species. Carp and whitefish contained tri- and tetra-chlorobiphenyl congeners, such as 28 + 31, 63, and 66+95 in the highest concentrations. Siscowet trout contained the more heavily chlorinated penta-, hexa-, and hepta-chlorobiphenyl congeners such as 153, 89, 138 + 163, 180, 182 + 187, and 170. In addition to the highly chlorinated PCB congeners routinely examined in Great Lakes fish, many lower chlorinated, ortho-substituted PCB congeners are also commonly found. These lower chlorinated congeners have known effects in laboratory animals but may be overlooked by analytical techniques in which Aroclor standards or mixtures of selected congeners are used for quantitation. A congener-specific approach including both the lower chlorinated ortho-substituted PCB congeners and the more highly chlorinated congeners should be implemented to better assess the interactions and toxicities of individual congeners and other persistent compounds.
Remobilization and export of cadmium from lake sediments by emerging insects
Authors: Currie Robert S , Fairchild Wayne L , Muir Derek C G
Published: March 2010

Emerging insects including, Diptera, Odonata, Ephemeroptera, and Trichoptera were collected from Lake 382(L382) in 1991 and 1992 to estimate quantitatively the export of Cd by aquatic insects from a natural system having elevated Cd concentrations in the water and sediment. L382 is a Canadian Shield lake, located within the Experimental Lakes Area in northwestern Ontario, that received experimental additions of Cd from 1987 to 1992. Emerging Diptera (mostly Chironomidae), Odonata, and Ephemeroptera had mean Cd concentrations of 1.41, 0.11, and 0.30 μg/g wet weight, respectively. An estimated 1.32 to 3.90 g of Cd per year were exported from the sediments of L382 depending on the estimate of production rates used for these groups of insects. Approximately 0.05 to 0.17% of the whole-lake Cd load in L382 sediments was exported annually or 0.12 to 0.39% of the epilimnion Cd sediment load. Insect emergence may have resulted in greater Cd export from L382 relative to losses via the outflow. Cadmium exported from the sediments by insects may be remobilized and become more available to aquatic organisms or enter the terrestrial ecosystem and become available to insectivores.
Acetylcholinesterase and ATPase activities in erythrocyte ghosts are not affected by 1,2,4-trichlorobenzene: Implications for toxicity by narcotic chemicals
Authors: van Wezel Annemarie P , Schmitz Marion G J , Tielens Aloysius G M
Published: March 2010

The membrane concentration at which 1 2,4-trichlorobenzene (1,2,4-triCBz) affects the functioning of diverse membrane proteins and the partition coefficient of 1,2,4-triCBz between ghosts and water were studied. Earlier studies showed that the fluidity of phospholipids is increased at concentrations of 20 to 60 mmol/kg lipid and that lethality by narcosis in an organism occurs at concentrations of 40 to 160 mmol/kg lipid, irrespective of the physicochemical properties of the nonpolar narcotic chemical. Concentrations in a horse erythrocyte membrane of 110 to 1,100 mmol/kg lipid did not affect the activity of the Na+/K+ ATPase and Mg2+ ATPase. Acetylcholinesterase functioning was not disturbed at membrane concentrations of 33 to 330 mmol/kg lipid. Therefore, disturbance of the membrane proteins studied is not the mechanism by which narcotic chemicals act. The functioning of these membrane proteins is not affected by the change in phospholipid fluidity that is known to occur in organisms that die due to exposure to narcotic chemicals. In vitro bioassays often contain a high concentration of lipids in the system. With hydrophobic test compounds, the concentration of the test compound in the exposure medium at the start of the experiment is much higher than the exposure concentration at equilibrium. Therefore, effects in in vitro bioassays should not be expressed in terms of the exposure concentration at the start of the experiment.