bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of Cd and Zn toxicity forFolsomia candidaWillem (Collembola: Isotomidae) in relation to bioavailability in soil
Authors: Van Gestel Cornelis A M , Hensbergen Paul J
Published: March 2010

The use of toxicity tests in which each chemical is tested separately is inadequate for assessing the potential risk of complex mixtures of chemicals for soil ecosystems. In the present study, the effects of Cd and Zn, alone or in combination, on the survival, growth, and reproduction of the collembolan Folsomia candida were determined after 2, 4, and 6 weeks of exposure in an artificial soil. The water solubility of Cd in the soil was significantly increased by the presence of Zn, whereas Cd did not affect the water solubility of Zn. In spite of this, uptake of Cd or Zn in the animals was not affected by the presence of the other metal, suggesting that water solubility does not determine the uptake of these metals in F. candida. For both Cd and Zn, reproduction was the most sensitive parameter, with 50% effective concentration (EC50) values of 51 and 683 μg/g dry soil, respectively, after 6 weeks. These values corresponded with internal concentrations of 44 μg Cd/g and 97 μg Zn/g dry body weight, respectively, while corresponding water-soluble EC50s were 0.13 μg Cd/g and 14 μg Zn/g dry soil, respectively. Although a proper comparison of the effects of mixtures of the metals with the effects of the individual metals was sometimes hampered by the nonsimilarity of dose-response relationships, it may be concluded that the effects of the mixture of Cd and Zn on the growth of F. candida are antagonistic (EC50 significantly greater than 1.0 toxic unit), while the effects on reproduction are additive (EC50 = 1.0 toxic unit). Similar conclusions could be drawn for EC50s expressed on the basis of total and water-soluble soil concentrations as well as on the basis of internal concentrations in the animals. Analysis of the combined effects of Cd and Zn at the 10% effective concentration level did not change these conclusions.
2,4-D dissipation in field soils after applications of 2,4-D dimethylamine salt and 2,4-D 2-ethylhexyl ester
Authors: Wilson Ronald D , Geronimo Joseph , Armbruster James A
Published: March 2010

2,4-Dichlorophenoxyacetic acid (2,4-D) was first registered in 1947 as an agricultural herbicide, and it is still the most widely used herbicide worldwide. End-use products, however, are generally formulated as inorganic or amine salts, or as esters. Because of the various forms available, there was concern that by testing only one form, the environmental profile generated might be insufficient to represent all forms. Therefore, as part of the 2,4-D reregistration process in the U.S., 30 soil dissipation studies were conducted with 2,4-D dimethylamine salt and 2,4-D 2-ethylhexyl ester over a 2-year period. Trials were located in seven states and included four cropping practices and bare soil. The results, averaged over all conditions, showed equivalent rates of 2,4-D dissipation in soil when applied as either the amine salt or ester forms. These results also confirm data from earlier field studies in Canada and Washington state showing equivalent 2,4-D dissipation in soil from applications of isooctyl ester, dimethylamine salt, and mixed amine salt forms. The data from the current and former studies show that ester and amine forms have little effect on the rate of dissipation of 2,4-D per se because they are converted rapidly to the same anionic form.
Toxic effects of linear alkylbenzene sulfonate, quaternary alkylammonium chloride and their complexes on Dunaliella sp. and Chlorella pyrenoidos
Authors: Utsunomiya Akiko , Watanuki Tomohiko , Matsushita Kazuhiro , Tomita Isao
Published: March 2010

The toxic effects of linear alkylbenzene sulfonate (LAS), quaternary alkylammonium chlorides (cationic surfactants[CS]), and their complexes (LAS-CS) were examined in Dunaliella sp. by proton nuclear magnetic resonance spectroscopic analysis of glycerol and in Chlorella pyrenoidosa by growth inhibition. The glycerol content decreased quantitatively with increased concentrations of LAS, CS, and LAS-CS complexes. The 24-h median effective concentration (EC50] values of LAS and CS in free form were 0.38 to 18 mg/L and the toxic effects were in the order alkyltrimethylammonium chloride (TM) > alkyldimethylbenzylam-monium chloride (BM) > LAS > dialkyldimethylammonium chloride (DM). The 24-h EC50 values of LAS-CS complexes at molar ratios of 1:1 and 2:1 were 1.3 to 13 and 5.6 to 9.6 mg/L as LAS-equivalent concentration, respectively. The order of toxic effects was LAS-TM > LAS = LAS-BM > 2LAS-BM > 2LAS-DM > 2LAS-TM > LAS-DM. The toxic effect of LAS was enhanced by equimolar complex formation with TM. The 96-h EC50 values of LAS and CS on the inhibition of growth in C. pyrenoidosa were 0.28 to 29 mg/L for the compounds in free form and their toxic effects were in the order TM > BM ≫ DM > LAS. The 96-h EC50 values of LAS-CS complexes at molar ratios of 1:1 and 2:1 were 1.4 to 59 and 11 to 86 mg/L, respectively, and the order of toxic effects was LAS-BM > LAS-TM > 2LAS-BM > 2LAS-TM > LAS > LAS-DM > 2LAS-DM. The toxic effects of LAS were also enhanced by the formation of complexes with TM or BM at molar ratio of 1:1 and 2:1. Thus, not only LAS but also its CS complexes might exert toxic effects on organisms in the environment.
Selenium toxicity to aquatic life: An argument for sediment-based water quality criteria
Authors: Canton Steven P , Van Derveer William D
Published: March 2010

A number of streams in Colorado were found to contain waterborne selenium concentrations that consistently exceeded the current U.S. EPA chronic criterion of 5 μg/L and often exceeded the acute criterion of 20 μg/L. Despite these elevated concentrations, no biological impact was observed. These findings led to a review of selenium exposure pathways in freshwater. The literature strongly indicates that chronic selenium toxicity can result from accumulation of selenium in the sediment, movement into the food chain, and resulting dietary uptake. Chronic toxicity does not appear to be strictly a result of waterborne selenium concentrations. In fact, dissolved selenium concentrations are a poor predictor of potential chronic toxicity to freshwater organisms, when evaluated with Hill's criteria for causal association. To develop a more reliable chronic waterborne criterion, a sediment-based method is needed to describe accurately potential chronic toxicity of selenium on a site-specific basis.
Toxicity and bioaccumulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin in long-term tests with the freshwater benthic invertebratesChironomus tentansandLumbriculus variegatus
Authors: West Corlis W , Ankley Gerald T , Nichols John W , Elonen Gregory E , Nessa David E
Published: March 2010

Two species of freshwater benthic invertebrates, Chironomus tentans and Lumbriculus variegatus, were exposed to three dietary concentrations of 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD), and toxicity and bioaccumulation were determined. No toxic effects were observed in full life cycle tests with either species at tissue residue concentrations up to 9,533 ng TCDD/g lipid. The observed lack of sensitivity of the two species to TCDD was consistent with a presumed absence of the aryl hydrocarbon receptor in aquatic invertebrates. Predictions of lipid-normalized tissue concentrations were made based on lipid-normalized TCDD concentrations in the food and were within 15% of targeted concentrations in both species. Depuration studies indicated that TCDD elimination followed first-order kinetics, with elimination rate constants of 0.0014 to 0.0022 h−1 for L. variegatus and 0.0070 to 0.0099 h−1 for C. tentans. Half-lives ranged from 315 to 495 h in L. variegatus and from 70 to 99 h in C. tentans. The ability of invertebrates to accumulate relatively high concentrations of TCDD in the absence of toxic effects may be relevant to the transfer of contaminants through aquatic food webs to potentially sensitive vertebrate species.
Revised approach to toxicity test acceptability criteria using a statistical performance assessment
Authors: Thursby Glen B , Heltshe James , Scott K John
Published: March 2010

Current acceptability requirements for toxicity tests are often more restrictive than necessary. They focus primarily on response in a control and generally ignore what a test was “designed” to detect as a significant difference from that control. An approach is presented that takes into account the performance of an entire test and the magnitude of the deviation from the current acceptability requirements. The procedure is based on analyzing the past statistical performance of a test method (i.e., what kind of difference from the control was the test designed to detect). It takes into account traditional control acceptance criteria, but adds a requirement for selecting a difference from the control desired to be detected as statistically significant (a threshold value). Choice of statistical procedure is not relevant to the approach. The proposed method allows a sliding scale of acceptance. The greater the deviation of mean control response below current requirements, the less likely a test is to be accepted. An example is presented using data from a 10-d sediment test using the marine amphipod Ampelisca abdita. Use of the proposed acceptability criterion will reduce the frequency of required retesting without sacrificing defensibility of data. Using the old acceptability criterion, 19% of the samples in the amphipod data set would require retesting. The proposed criterion reduces the potential percentage of retests to 9%.
Does cadmium pollution change trophic interactions in rockpool food webs?
Authors: Koivisto Sanna , Arnér Marie , Kautsky Nils
Published: March 2010

We studied the regulation of phytoplankton and zooplankton biomass in rockpool food webs under chronic cadmium pollution. Experimental food webs with two and three trophic levels were composed of phytoplankton, small-bodied zooplankton (Chydorus sphaericus, Cyclops sp., and rotifers), Daphnia magna, and Notonecta sp., a zooplanktivorous predator. Every food web received a control and cadmium treatment allowing a separate study of cadmium and predation effects. After a 3-week stabilization period, cadmium and Notonecta were added and changes in primary productivity, chlorophyll, zooplankton species composition, and biomass were followed during 8 weeks. The results showed that phytoplankton and Daphnia were consumer regulated in both control and cadmium treatments, although resource availability ultimately determined the biomass at each trophic level. Daphnia was the only zooplankton species that reduced phytoplankton and also the only species that was eliminated by Notonecta predation. Notonecta had an indirect positive impact on phytoplankton biomass that increased after the extinction of Daphnia. Cadmium significantly reduced phytoplankton and Daphnia but did not change the trophic interactions between them, i.e., Daphnia and chlorophyll were significantly negatively correlated both in the control and cadmium treatments. Cadmium did not affect the relationship between Daphnia and Notonecta.
Analytical evaluation of laboratories wishing to perform environmental characterization studies
Authors: Lauenstein Gunnar G , Cantillo Adriana Y
Published: March 2010

Laboratories competing to analyze bivalve mollusks under contract to the National Oceanic and Atmospheric Administration's Mussel Watch Project were required to undergo analytical tests of their ability to quantify environmental contaminants as part of the contract evaluation process. During the 1989 selection process laboratories that appeared to qualify on the basis of their written proposals were provided a gravimetrically prepared solution with “unknown” quantities of an undefined number of organic contaminants that are regularly quantified for the Mussel Watch Project. In 1994, competing laboratories were once again tested but this time using matrix materials for the quantification of both trace elements and organic contaminants. Three laboratory groups participated in the exercises. For the 1989 gravimetrically prepared solutions, all participating laboratories were able to identify the contaminants present and in all but two cases were able to report values to within ±25% of the known values. In 1994, all laboratories were within the acceptance criteria for the quantification of trace elements in the homogenate sample. Analytical laboratory testing is an important first step to ensure that environmental characterization studies are successful.
Toxic effects of some benzamines on the growth of Azotobacter vinelandii and other bacteria
Authors: Chung King-Thom , Chen Ssu-Ching , Zhu You-Yan , Wong Tit Yee , Stevens S Edward
Published: March 2010

Benzamines are the major aromatic amines used in industry and can also be released from azo dyes, which are widely used in the textile, paper-making, and food industries. The toxicity of 10 benzamines was tested by the well diffusion assay technique against 18 common bacterial species including the nitrogen-fixing bacterium Azotobacter vinelandii.  p-Phenylenediamine was found to be inhibitory to the growth of Aeromonas hydrophila and Pseudomonas fluorescens.  o-Phenylenediamine was inhibitory to Escherichia coli, Klebsiella pnemoniae, Salmonella enteritidis, and Shigella sonnei. 2,5-Diaminotoluene was inhibitory to the growth of P. fluorescens and Streptococcus mitis. The growth of A. vinelandii was inhibited by p-phenylenediamine and 2,5-diaminotoluene in the well diffusion assay. p-Nitroaniline was also found to be inhibitory to the growth of A. vinelandii in Burk's nitrogen-free medium. The nitrogenase activity of A. vinelandii was inhibited by p-phenylenediamine, 2,5-diaminotoluene, p-nitroaniline, 2-nitro-p-phenylenediamine, 3-nitro-o-phenylenediamine, and 4-nitro-o-phenylenediamine. Because many of these organisms are common soil and aquatic bacteria, the accumulation of these benzamine compounds in the environment may have an adverse impact on soil biochemical activities.
Acute toxicity of fire-retardant and foam-suppressant chemicals to Hyalella azteca (Saussure)
Authors: McDonald Susan F , Hamilton Steven J , Buhl Kevin J , Heisinger James F
Published: March 2010

Acute toxicity tests were conducted with Hyalella azteca Saussure (an amphipod) exposed in soft and hard waters to three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two foam suppressants (Phos-Chek WD-881 and Silv-Ex). The chemicals were slightly to moderately toxic to amphipods. The most toxic chemical to amphipods in soft and hard water was Phos-Chek WD-881 (96-h mean lethal concentration [LC50] equal to 10 mg/L and 22 mg/L, respectively), and the least toxic chemical to amphipods in soft water was Fire-Trol GTS-R (96-h LC50 equal to 127 mg/L) and in hard water was Fire-Trol LCG-R (96-h LC50 equal to 535 mg/L). Concentrations of ammonia in tests with the three fire retardants and both water types were greater than reported LC50 values and probably were the major toxic component. Estimated un-ionized ammonia concentrations near the LC50 were frequently less than the reported LC50 ammonia concentrations for amphipods. The three fire retardants were more toxic in soft water than in hard water even though ammonia and un-ionized ammonia concentrations were higher in hard water tests than in soft water tests. The accidental entry of fire-fighting chemicals into aquatic environments could adversely affect aquatic invertebrates, thereby disrupting ecosystem function.
Separation of 2,3,3′,4′,6-pentachlorobiphenyl (IUPAC 110) from 3,3′,4,4′-tetrachlorobiphenyl (IUPAC 77) using high-performance liquid chromatography
Authors: Qi Min , Anderson Michael
Published: March 2010

A double forward–reverse (DFR) flow high-performance liquid chromatography (HPLC) technique was developed for the separation of coplanar chlorobiphenyl (CB) congener 77 and nonplanar CB congener 110. The DFR separated these two congeners into different HPLC fractions; each fraction was analyzed using gas chromatography–electron capture detection. The method was successfully applied in the analysis of Aroclor mixtures and fish samples.
Phytotoxicity of floodplain soils contaminated with trace metals along the Clark Fork River, Grant-Kohrs Ranch National Historic Site, Deer Lodge, Montana, USA
Authors: Rader Brian R , Nimmo Del Wayne R , Chapman Phillip L
Published: March 2010

Concentrations of metals in sediments and soils deposited along the floodplain of the Clark Fork River, within the Grant–Kohrs Ranch National Historic Site, Deer Lodge, Montana, USA, have exceeded maximum background concentrations in the United States for most metals tested. As a result of mining and smelting activities, portions of the Deer Lodge Valley, including the Grant–Kohrs Ranch, have received National Priority List Designation under the Comprehensive Environmental Response, Compensation and Liability Act. Using a series of plant germination tests, pH measurements, and metal analyses, this study investigated the toxicity of soils from floodplain “slicken” areas, bare spots devoid of vegetation, along the Clark Fork River. The slicken soils collected from the Grant–Kohrs Ranch were toxic to all four plant species tested. The most sensitive endpoint in the germination tests was root length and the least sensitive was emergence. Considering emergence, the most sensitive species was the resident grass species Agrostis gigantea. The sensitivities were reversed when root lengths were examined, with Echinochloa crusgalli showing the greatest sensitivity. Both elevated concentrations of metals and low pH were necessary to produce an acutely phytotoxic response in laboratory seed germination tests using slicken soils. Moreover, pH values on the Grant–Kohrs Ranch appear to be a better predictor of acutely phytotoxic conditions than total metal levels.
Comparison of azinphosmethyl toxicity to juvenile red drum (Sciaenops ocellatus) and the mummichog (Fundulus heteroclitus)
Authors: Van Dolah Robert F , Maier Philip P , Fulton Michael H , Scott Geoffrey I
Published: March 2010

The acute and sublethal responses of juvenile red drum (Sciaenops ocellatus) and mummichogs (Fundulus heteroclitus) were evaluated to determine the relative effects of exposure to azinphosmethyl (APM). Acute responses were based on 96-h static-renewal bioassays at salinities of 5 and 20‰. Sublethal responses were based on inhibition of brain acetylcholinesterase (AChE) activity after 24-h exposures at each salinity and by measuring behavioral and stamina (swimming ability) responses of each species. The acute toxicity tests indicated that juvenile red drum were significantly more sensitive to APM than were mummichogs (mean lethal concentration [LC50] = 6.3–7.1 μg/L versus 65–84 μg/L). No significant differences were noted in the LC50 response of either species at reduced salinities. In contrast, mummichogs were more sensitive to APM-induced inhibition of brain AChE activity than juvenile red drum (mean effective concentration [EC50] < 1.0 μg/L in mummichogs and >5.0 μg/L in red drum). Behavioral response tests indicated that neither species avoided pesticide-laden water, which may increase their vulnerability to APM runoff. Stamina assays indicated that juvenile red drum experienced a decreased ability to swim after a 6-h exposure to 12 μg/L APM. Mummichogs were less sensitive with respect to the effects of APM on swimming ability at concentrations as high as 24 μg/L APM (p < 0.1).
Bioaccumulation of polychlorinated dibenzo-p-dioxins in sediment by oligochaetes: Influence of exposure pathway and contact time
Authors: Loonen Hélène , Muir Derek C G , Parsons John R , Govers Harry A J
Published: March 2010

Oligochaetes (Lumbriculus variegatus) were exposed simultaneously to radiolabeled [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and [14C]octachlorodibenzo-p-dioxin (OCDD) in sediment for 28 d, in order to study accumulation processes of hydrophobic substances. Elimination was studied for a further 20 d. The uptake and elimination rate constants and the bioaccumulation factors (BAFs) were determined for TCDD and OCDD in the presence and absence of sediment (overlying water). Steady-state concentrations in oligochaetes were achieved for TCDD but not for OCDD over the 28-d exposure. Biota-sediment accumulation factors (BSAFs) after a 28-d exposure were 1.6 ± 0.27 for TCDD and 0.07 ± 0.02 for OCDD. Steady-state log BAF values (lipid based) for TCDD and OCDD in oligochaetes in the overlying water were 5.9 and 5.5 L/kg, respectively. The effect of incubation time between sediment and contaminants was investigated by repeating the accumulation study after a contact period of 21 months. BSAFs of sediment-sorbed TCDD and OCDD were 1.5 to 2-fold lower for the long contact time sediment. Based on comparison of predicted accumulation from pore water and observed accumulation by sediment-exposed oligochaetes, it was concluded that 1.4-fold greater accumulation occurred due to assimilation of TCDD and OCDD from ingested sediment. This additional accumulation in the presence of sediment, not accounted for by uptake only from pore waters, was consistent with literature data for other hydrophobic organochlorines.
Subchronic effects of five di-orthoPCB congeners on survival, growth and reproduction in the fathead minnowPimephales promelas
Authors: Suedel Burton C , Dillon Tom M , Benson William H
Published: March 2010

The effects of five di-ortho polychlorinated biphenyl (PCB) congeners (International Union of Pure and Applied Chemists numbers 52, 101, 138, 153, 180) on survival, growth, and reproduction in the fathead minnow, Pimephales promelas, were determined. Fish were exposed to one of two nominal concentrations (2.5 μg/L [low] and 25.0 μg/L [high]) of each congener for a total of 13 weeks (7-week prespawning period plus 6-week spawning period) under flow-through conditions using methanol as a carrier solvent. At termination, P. promelas survival was high (92.6–100%) in all PCB congener treatments. PCB congeners had no significant (p < 0.05) sublethal effects on reproductive success within the concentration range examined. The total number of eggs, clutch size, number of clutches, percent hatchability, and presence of terata in offspring were not significantly affected. Reproductive success was slightly but not significantly enhanced in the solvent control and high (25 μg/L) treatment concentrations for congeners 52, 101, 138, and 153. Growth expressed as wet weight was not affected for both adult males or females. Male lengths were not significantly affected but female lengths were significantly reduced when exposed to congeners 101, 138, 153, and 180. Pimephales promelas accumulated substantial amounts of all PCBs, with tissue concentrations ranging from 13 to 183 mg/kg wet weight at termination in PCB-exposed fish. These tissue residues are one to several orders of magnitude greater than those reported for these congeners in aquatic biota previously collected in industrial waterways of the Great Lakes. Several di-ortho PCB congeners frequently found in aquatic biota showed minimal adverse effects on fathead minnow survival, growth, and reproduction even though bioaccumulation of these congeners was substantial.
2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in extracts of Baltic white-tailed sea eagles
Authors: Koistinen Janna , Koivusaari Juhani , Nuuja Ismo , Vuorinen Pekka J , Paasivirta Jaakko , Giesy John P
Published: March 2010

Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin-(TCDD) equivalents were measured in extracts of Baltic white-tailed sea eagle tissues. Extracts of salmon, ringed seal, and grey seal were analyzed as other predatory species of the same area. Concentrations in eagle and seal tissues were greater than those in salmon. Concentrations of TCDD equivalents (TCDD-EQs) determined by the H4IIE bioassay were compared with toxic equivalents (TEQs) derived from instrumental chemical analyses in fractions containing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) or coplanar polychlorinated biphenyls (PCBs). Toxic equivalents were calculated by use of an additive model in which the product of the concentrations of instrumentally measured individual congeners were multiplied by their TCDD equivalency factors and were summed to give a total concentration of TEQs. The TCDD-EQs were compared with TEQs to develop a mass balance to determine whether all the TCDD-like activity was accounted for. For example, the concentration of TCDD-EQs in the coplanar PCB fraction of the most contaminated eagle was 980 pg/g fresh weight (fw), and that of the PCDD/PCDF fraction was 240 pg/g fw. The TEQs determined by chemical analyses for coplanar PCBs was 770 pg/g fw, and that of PCDD/PCDFs was 270 pg/g fw in this eagle. Thus, concentrations of TCDD-EQs were approx. 20% greater than those of TEQs. The true difference in activities is probably greater because of lower recoveries and infra-additivities among congeners in the bioassay. This indicates that there are compounds present in the extracts that can contribute to the total concentrations of TCDD-EQs that were not accounted for by TEQs. The hazard quotient, calculated as the ratio of current concentrations of TCDD-EQs in white-tailed sea eagle eggs to the no-observable-adverse-effect concentration, ranged from 7.3 to 141 (mean = 52.7, SD = 43). This indicates that current concentrations of TCDD-EQs in these eggs are likely causing adverse effects in the Baltic populations of white-tailed sea eagles. This study indicated that the H4IIE bioassay is useful for monitoring the presence and biological activity of TCDD-like compounds in environmental samples like white-tailed sea eagles.
Evaluation of a first-order model for the prediction of the bioaccumulation of PCBS and DDT from sediment into the marine deposit-feeding clamMacoma nasuta
Authors: Boese Bruce L , Lee Henry , Echols Scott
Published: March 2010

A first-order model for predicting contaminant bioaccumulation from sediments into benthic invertebrates was validated using a marine deposit-feeding clam, Macoma nasuta, exposed to polychlorobiphenyl (PCB)-spiked and dichlorodiphenyltrichloroethane (DDT)-contaminated sediments. Contaminant uptake and depuration were analyzed following short-term and long-term sediment exposures. Uptake and depuration rates were used to predict steady-state bioaccumulation factors (BAFs) and exposure times needed to attain steady state. These predictions were compared to observed steady-state BAFs. Estimating elimination and uptake rates from depuration and short-term uptake experiments was an accurate means of predicting BAFs for some PCBs (log octanol-water partition coefficient, Kow, <7) but was not as accurate for predicting DDT BAFs. The exposure time need to attain steady state was poorly predicted by the model. The results demonstrated that a standard 28-d bioaccumulation test estimated steady-state tissue residues within two-fold and was a better predictor than the model for the BAFs of superlipophilic PCBs (log Kow >7). Differences in contaminant bioavailability were noted between field-contaminated (DDT) and laboratory-spiked (PCB) sediments.
Estimating inhibition concentrations for different response scales using generalized linear models
Authors: Bailer A John , Oris James T
Published: March 2010

Legal mandates exist for the protection of aquatic life and human health from the impacts of toxins released into receiving waters. To accomplish this objective, numeric environmental quality criteria are set. Data utilized commonly in the development of such criteria include no-observed-effect concentrations (NOECs), lowest-observed-effect concentrations (LOECs) and effective concentrations (ECs). The NOEC and LOEC are design-sensitive indices and are open to strong criticism. The EC indices are often estimated through the inversion of a fitted parametric regression model. One criticism leveled against the EC estimation routines has been that one model cannot be appropriate for the variety of different biological endpoints that are studied in aquatic toxicology. These biological endpoints include survival (dichotomous response), fecundity (counts), and biomass/growth (continuous response). In the present study, generalized linear models (GLiMs) are shown to provide a general model for data commonly encountered in aquatic toxicology. The proposed EC estimator, labeled a relative inhibition or RI estimator, is derived in this GLiM framework. This estimator represents the concentration, or more generally, the exposure level to some hazard, associated with a specified level of change in the response relative to the control response. Along with the construction of this estimator, standard errors and confidence intervals are presented. This RI estimator is then applied to dichotomous, count, and continuous responses to illustrate its use.
Initial sorption of aromatic amines to surface soils
Authors: Lee Linda S , Nyman Arto K , Li Hui , Nyman Marianne C , Jafvert Chad
Published: March 2010

Sorption of aniline, α-naphthylamine, and benzidine to three silty clay loams was measured from CaCl, electrolyte solutions in single and binary solute systems after a 1-d residence time. Soils varied in pH (4.4–7.2), cation-exchange capacity (CEC, 10–30 cmolc/kg), and organic carbon content (OC, 1–3%). Plots of sorbed amine concentrations versus aqueous amine concentrations exhibited nonlinearity in the concentration range investigated. Sorption increased with decreasing soil-solution pH for all solutes. Decreases in sorption with increasing CaCl2 concentrations were greatest at low pH. In binary solute experiments, α-naphthylamine depressed the sorption of aniline and this depression increased with decreasing pH. Normalizing sorption to the cation-exchange capacity of the protonated species compensated for most of the differences observed between soils at different pH values suggesting that cation exchange is the primary process occurring during initial contact times. In selected experiments, sorbed aromatic amines were extracted from soils with different solvents after a 1-d incubation. At low initial concentrations (<0.01 mM) only a few percent of each amine was extractable; whereas 85% to 98% was recoverable at higher initial concentrations (1 mM). Although initial sorption appears to be to cation-exchange sites, the inability to recover all of the sorbed amine suggests early covalent bond formation on highly reactive sites and/or sorption to high-energy sites on clays or other soil constituents.
An automated HPLC method for the fractionation of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans in fish tissue on a porous graphitic carbon column
Authors: Echols Kathy , Gale Robert , Tillitt Donald , Schwartz Ted , O'Laughlin Jerome
Published: March 2010

The Ah (aryl-hydrocarbon) hydroxylase-receptor active polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were fractionated by an automated high-performance liquid chromatography (HPLC) system using the Hypercarb™ porous graphitic carbon (PGC) column. This commercially available column was used to fractionate the di-, mono-, and non-ortho PCBs into three fractions for gas chromatography (GC)/electron capture detection analysis, and a fourth fraction containing the PCDDs/PCDFs for GC/mass spectrometry analysis. The recoveries of the PCBs ranged from 68 to 96%, and recoveries of the PCDDs/PCDFs ranged from 74 to 123%. The PGC column has the advantage of faster separations (110 min versus 446 min) and less solvent use (275 ml versus 1,100 ml) compared with automated fractionation of these compounds on activated carbon (PX-21), while still affording good separation of the classes. The PGC column may have an advantage over the pyrenyl-based HPLC method because it has a greater loading capacity (400 μg total PCBs versus 250 μg). Overall, the PGC is a standard column that provides reproducible fractionation of PCDD/PCDFs and PCBs for analytical measurement in environmental samples.
A review of concurrent ambient water column and sediment toxicity testing in the Chesapeake Bay watershed: 1990–1994
Authors: Hall Lenwood W , Alden Raymond W
Published: March 2010

The objectives of this study were to identify toxic ambient areas in the Chesapeake Bay watershed by using a battery of water column and sediment toxicity tests. Twenty-five ambient stations in nine river/harbors were tested during 1990 through 1994. Seasonal and annual comparisons were conducted at selected stations. Inorganic and organic contaminants were evaluated in ambient water and sediment concurrently with water column and sediment tests to assess possible causes of toxicity, although absolute causality cannot be established. Multivariate statistical analysis was used to develop a TOX-INDEX at each station for both water column and sediment toxicity data. Water column tests from the 5-year testing period showed that 43% of the time, some degree of toxicity was reported. The most toxic sites based on water column results were located in urbanized areas such as the Elizabeth River, Baltimore Harbor, and the Middle River. Water quality criteria for copper, lead, mercury, nickel, and zinc were exceeded at one or more of these sites. Some degree of sediment toxicity was reported from 70% of the tests conducted during the 5-year period. The Elizabeth River and Baltimore Harbor stations were reported as the most toxic areas based on sediment results. Sediment toxicity guidelines (Long and Morgan effects range median [ER-M] values) were exceeded for one or more of the following metals at these two locations: arsenic, cadmium, chromium, copper, lead, nickel, and zinc. At the Elizabeth River stations 9 of 16 semivolatile organics and 2 of 7 pesticides measured exceeded the ER-M values. Various semivolatile organics exceeded the ER-M values at a number of Baltimore Harbor sites; pyrene and dibenzo (a,h) anthracene were particularly high at one of the stations (Northwest Harbor).
The influence of worm age, duration of exposure and endpoint selection on bioassay sensitivity for Neanthes arenaceodentata (Annelida: Polychaeta)
Authors: Bridges Todd S , Farrar J Daniel
Published: March 2010

The influence of worm age, duration of exposure, and endpoint selection on bioassay sensitivity were evaluated for Neanthes arenaceodentata. Worms were exposed to contaminated sediment collected from Black Rock Harbor (BRH) near Bridgeport, Connecticut, USA. This sediment was diluted with clean control sediment to result in five experimental treatments: 0, 25, 50, 75, and 100% BRH. Three exposure scenarios were employed: (1) a 4-week exposure beginning with newly emerged juveniles (EJ–4w), (2) a 7-week exposure beginning with newly emerged juveniles (EJ–7w), and (3) a 4-week exposure beginning with 3-week-old juveniles (3WO–4w). Six measures of worm size were recorded at the conclusion of each exposure to evaluate differences among measurement endpoints. Survival was significantly reduced at the 25% BRH level for the EJ–7w scenario and at the 100% BRH level for the EJ–4w and 3WO–4w scenarios. Growth was significantly reduced at the 25% BRH level in each exposure scenario. Estimates based on the calculated minimum detectable difference indicated that considerably lower concentrations of BRH (6–10%) should be distinguishable by measuring effects on Neanthes growth. Worm size measured in terms of projected area, dry weight, and ash-free dry weight provided the most sensitive measures of effects. Increasing the length of exposure from 4 to 7 weeks and initiating exposures with emergent juveniles rather than 3-week-old worms increased the sensitivity of the bioassay. The results of this study demonstrate that N. arenaceodentata is sensitive to the presence of sediment-associated contaminants and that test animal age, duration of exposure, and choice of endpoint can have a large effect on the magnitude of the toxic response observed.
Functional responses inLeptoxis praerosato increasing metal concentration and exposure duration
Authors: Reed-Judkins Donna K , Farris Jerry L , Cherry Donald S , Heath Alan G , Cairns John
Published: March 2010

The protectiveness of USEPA ambient water quality criteria for copper (Cu) and zinc (Zn) was tested using the snail Leptoxis praerosa in short- and long-term artificial stream tests. Acute criteria were tested in 96-h survival tests. Chronic criteria were tested by comparing cellulolytic enzyme activity impairment, bioconcentration, and survival in 14-, 20-, 30-, and 114-d exposures. Significant Cu bioconcentration occurred within 40 d at the chronic Cu criteria concentration, followed by significant cellulolytic enzyme activity impairment within 54 d. Significant bioconcentration and enzyme activity impairment occurred within 40 and 54 d, respectively, at the chronic Zn criteria concentration, but survival was much higher than in Cu-exposed snails. Approximate additive effects were seen in combination treatments of Cu and Zn. Similar patterns of effects were seen from both increased exposure duration and concentration. This research concluded that criteria based on abbreviated chronic tests may be underprotective for some sensitive taxa when exposures are prolonged.
In vivo testing of the functional integrity of the corticosterone-producing axis in mudpuppy (amphibia) exposed to chlorinated hydrocarbons in the wild
Authors: Gendron Andrée D , Bishop Christine A , Fortin Réjean , Hontela Alice
Published: March 2010

The functional integrity of the hypothalamo–pituitary–interrenal (HPI) axis was tested in an aquatic salamander, the mudpuppy (Necturus maculosus), exposed in the wild to HPI axis disrupters. The response to stress challenges was compared in mudpuppies sampled at nine sites of the St. Lawrence and Ottawa rivers during winter. Polychlorinated biphenyls and organochlorine pesticides measured in gonads indicated that the exposure was highly variable among sites. Females subjected to a standardized capture and confinement stress, a treatment that induces a surge of circulating corticosterone, had significantly lower levels of corticosterone at a number of contaminated sites compared to animals from the reference areas. Among-site differences could not be distinguished in males that had very low corticosterone levels overall. The reduced corticosterone response at contaminated sites was not associated with an atrophy of the interrenal corticosterone-releasing cells. A corticotrophin (adrenocorticotrophic hormone, ACTH) challenge imposed in situ after a 24-h postcapture recovery elicited a corticosterone surge significantly lower in contaminated females and males, pointing to disruptions along the HPI axis downstream of the pituitary ACTH-secreting cells. Corticosterone levels measured after recovery were higher at the contaminated site, suggesting an increase in resting levels. Liver glycogen, whose replenishment is partly mediated by corticosterone, was significantly depleted in salamanders collected at most contaminated sites. Our results suggest xenobiotic-induced disruptions within the HPI axis of an amphibian species, but the role of alternative factors is also discussed.
Mechanisms of photoinduced toxicity of photomodified anthracene to plants: Inhibition of photosynthesis in the aquatic higher plant Lemna gibba (duckweed)
Authors: Huang Xiao-Dong , McConkey Brendan J , Babu T Sudhakar , Greenberg Bruce M
Published: March 2010

Polycyclic aromatic hydrocarbon (PAH) toxicity is enhanced by light, especially ultraviolet (UV) radiation. To examine a potential mechanism(s) of photoinduced toxicity of PAHs to plants, the effects of anthracene and its photoproducts on photosynthesis were investigated using the aquatic higher plant Lemna gibba L. G-3 (duckweed). Photosynthetic activity was monitored both in vivo and in vitro by measuring chlorophyll a (Chl a) fluorescence, carbon fixation, and electron transport. In simulated solar radiation (a light source with a visible light: UV-A: UV-B ratio similar to sunlight), inhibition of photosynthesis was more rapid with photomodified anthracene than with intact anthracene, and intact anthracene appeared to only inhibit photosynthesis following its photomodification. The primary site of action of photomodified anthracene was found to be electron transport at or near photosystem I (PSI). This was followed by inhibition of photosystem II (PSII), probably due to excitation pressure on PSII once the downstream electron transport through PSI was blocked. Accordingly, higher chemical concentrations and/or longer exposures were required to inhibit PSII than PSI. Net photosynthesis (carbon fixation) was also inhibited, implying that the inhibition of electron transport in PSI by photomodified anthracene can lead to diminished primary productivity. A linkage between inhibition of photosynthesis and inhibition of plant growth was established in terms of the initial site of action (PSI) and primary productivity (carbon fixation), which suggested that Chl a fluorescence can be used as a bioindicator of PAH impacts on plants.
Exposure of male american plaice (Hippoglossoides platessoides) to contaminated marine sediments decreases the hatching success of their progeny
Authors: Nagler James J , Cyr Daniel G
Published: March 2010

There is increasing concern over the effect environmental contaminants may be having on male vertebrate reproduction, particularly persistent organics. This study sought to determine the effects of marine sediments, contaminated with organic compounds, on the reproductive performance of male American plaice (Hippoglossoides platessoides). Maturing fish were exposed to contaminated sediments, in the laboratory, for a 5-month period leading up to spawning. Sediments were obtained from three known environmentally contaminated sites, in which site 1 was the most toxic, followed by site 2, with site 3 relatively uncontaminated (i.e., control). Semen collected from all males with motile sperm were used to fertilize eggs from a single nonsediment-exposed female. Eggs fertilized with sperm from males exposed to sediments from site 1 produced 48% fewer larvae (p < 0.05), compared to the control group (i.e., site 3). Similarly, males exposed to site 2 produced 35% fewer larvae, relative to the control. There were no differences between groups with respect to sperm number, seminal sodium and potassium concentrations, and gonadosomatic index. The levels of liver cytochrome P450 1A1 (CYP1A1) mRNA, used as a biomarker for exposure to organics, were threefold higher in fish exposed to site 1 sediments, and twofold higher in fish exposed to site 2 sediments, relative to the site 3-exposed controls, at the end of the experiment. A significant negative correlation (r = −0.65, n = 16, p < 0.007) exists between male CYP1A1 levels and hatch success, with increasing CYP1A1 levels corresponding to decreased numbers of hatched larvae. These data indicate that long-term exposure of male American plaice to marine sediments contaminated with organics can result in a reduction in the number of eggs hatched, which correlates with increased levels of hepatic CYP1A1.
Polychlorinated biphenyls in a terrestrial predator, the pine marten (Martes martes L.)
Authors: Bremle Gudrun , Larsson Per , Helldin Jan Olof
Published: March 2010

A terrestrial predator population, the pine marten ( Martes martes, L.), inhabiting an area in mid-Sweden was investigated for polychlorinated biphenyls, p,p′-DDE, lindane, and hexachlorobenzene. The condition of the animals, as shown by intestine fat amounts or fat content of muscle tissue, showed negative relationships with concentration of persistent pollutants. The relationship resulted in a higher concentration of pollutants as intestinal fat amounts or muscle fat content decreased and lower levels of pollutants as these indexes of condition improved. The results indicate that terrestrial predators show changes in pollutant concentration due to condition, caused by food availability and starvation. No differences in pollutant concentration were recorded between males and females and no relationship was found for levels of pollutants and age or reproduction (females). The latter results are in contrast to those found for aquatic predatory mammals.
The selective dietary accumulation of planar polychlorinated biphenyls in the otter (Lutra lutra)
Authors: Leonards Pim E G , Zierikzee Yolanda , Brinkman Udo A Th , Cofino Wim P , van Straalen Nico M , van Hattum Bert
Published: March 2010

The decline of the populations of otters in Western Europe is assumed to be related to the accumulation of polychlorinated biphenyls (PCBs) in this species. A study was conducted to investigate the trophic transfer of non-ortho, mono-ortho-, and di-ortho-substituted PCBs in the food web of the otter (Lutra lutra) in the Oude Venen lake system in the Netherlands, with relatively low PCB contamination. This area was one of the last strongholds of otters in the Netherlands and the species is considered to be virtually extinct since 1988. A marked increase in concentration of chlorinated biphenyls (CBs) was observed with successive trophic levels of the aquatic food web. Mean concentrations of the sum of 28 CB congeners (ΣCB) increased from 142 ng CB/g (organic carbon basis) in sediment and particulate matter to 588 ng CB/g (lipid weight basis) in invertebrates, to 2,450 ng CB/g (lipid weight) in fish, and 70,940 ng CB/g (lipid weight) in otter. A diet-specific biomagnification factor (BMF) of 14 was calculated from fish to otter based on ΣCB; however, on the basis of toxic equivalent concentrations (ΣTEQ), a BMF of 41 was found. This higher BMF on TEQ basis was mainly due to the enrichment of non-ortho-substituted CB 126 in otter, compared to fish. In fish CB 126 contributed 30 to 50% to ΣTEQ, while this congener contributed 60 to 80% in otters. A shift in the CB patterns was found from relatively high concentrations of lowly chlorinated CBs in the abiotic compartments to the higher chlorinated CBs (five to seven chlorine atoms) at the highest trophic level. The relatively low concentrations of CB 77 and CBs with vicinal H-atoms at the meta-para position in otter compared to fish indicates that otters can metabolize these CBs and have P4501A-like and P4502B-like enzyme systems. It appears that even in an ecosystem with relatively low CB contamination, concentrations of CBs can be relatively high in aquatic top predators. The non-ortho-substituted CBs seem to be the most important toxic threat for otters, firstly because of the relatively high BMFs of CB 126 and CB 169 and secondly because of the formation of metabolites of CB 77.
Structure–biodegradability study and computer-automated prediction of aerobic biodegradation of chemicals
Authors: Klopman Gilles , Tu Meihua
Published: March 2010

It is shown that a combination of two programs, MultiCASE and META, can help assess the biodegradability of industrial organic materials in the ecosystem. MultiCASE is an artificial intelligence computer program that had been trained to identify molecular substructures believed to cause or inhibit biodegradation and META is an expert system trained to predict the aerobic biodegradation products of organic molecules. These two programs can be used to help evaluate the fate of disposed chemicals by estimating their biodegradability and the nature of their biodegradation products under conditions that may model the environment.