bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of three marine screening tests and four Oslo and Paris commission procedures to evaluate toxicity of offshore chemicals
Authors: Weideborg Mona , Vik Eilen Arctander , Øfjord Gro Daae , Kjønnø Ocelie
Published: March 2010

The results from the screening toxicity tests Artemia salina, Microtox®, and Mitochondria RET test were compared with those obtained from OSPAR (Oslo and Paris Commissions)-authorized procedures for testing of offshore chemicals (Skeletonema costatum, Acartia tonsa, Abra alba, and Corophium volutator). In this study 82 test substances (26 non-water soluble) were included. The Microtox test was found to be the most sensitive of the three screening tests. Microtox and Mitochondria RET test results showed good correlation with results from Acartia and Skeletonema testing, and it was concluded that the Microtox test was a suitable screening test as a base for assessment of further testing, especially regarding water-soluble chemicals. Sensitivity of Artemia salina to the tested chemicals was too low for it to be an appropriate bioassay organism for screening testing. A very good correlation was found between the results obtained with the Skeletonema and Acartia tests. The results indicated no need for more than one of the Skeletonema or Acartia tests if the Skeletonema median effective concentration or Acartia median lethal concentration was greater than 200 mg/L. The sediment-reworker tests (A. alba or C. volutator) for chemicals that are likely to end up in the sediments (non-water soluble or surfactants) should be performed, independent of results from screening tests and other OSPAR species.
A quasi-steady-state pollutant flux methodology for determining sediment quality criteria
Authors: Valsaraj Kalliat T , Thibodeaux Louis J , Reible Danny D
Published: March 2010

A methodology for estimating quasi-steady-state flux of pollutants from bed sediments to water and air is presented. This is illustrated using the example case of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a sediment bed. The rate of transport from the bed sediment was found to be important in determining the concentration of TCDD along its pathway from sediment to air. The concentration in the water column that leads to exposure to aquatic species was found to scale in proportion to the flux from the sediment and not to the pollutant concentration in the sediment. The sediment-side processes were found to provide the dominant resistance to mass transfer of pollutant. Both transport (rates) and thermodynamics (equilibrium partition constants) are shown to be important in setting sediment quality criteria. These should be incorporated in the next generation of sediment quality criteria.
A new method for simultaneous quantification of uncoupling and inhibitory activity of organic pollutants in energy-transducing membranes
Authors: Escher Beate I , Snozzi Mario , Häberli Katharina , Schwarzenbach René P
Published: March 2010

A new, mechanistically based approach is presented for the quantitative determination of the uncoupling and inhibitory activity of compounds interfering with energy transduction. Time-resolved spectroscopy of single-turnover events in the photosystem of the photosynthetic bacterium Rhodobacter sphaeroides can quantitatively distinguish uncoupling from inhibition. The decay kinetics of the membrane potential after a single turnover flash are used as a measure of uncoupling activity, and the redox kinetics of several components of the electron transfer chain are used as indicators of specific inhibition at various potential inhibitory sites. Results are presented for 21 nitrated and chlorinated phenols, some reference uncouplers, and some anisoles. Inhibition was exclusively detected at one specific quinone binding site, the quinone reductase site Qi. For most phenols, uncoupling was observed at lower concentrations than inhibition with the exception of alkylated 2,6-dinitrophenols and 2,4,6-trichlorophenol, where both effects occurred in the same concentration range. No direct correlation was observed between the uncoupling and inhibitory activity of a given compound. The data obtained with this new method correlate well with data from various bioassays on energy-transducing systems, indicating that this method may also be well suited as a screening tool for compounds suspected to interfere with energy transduction.
Effects of piperonyl butoxide and β-naphthoflavone on cytochrome P4501A expression and activity in Atlantic salmon (Salmo salarL.)
Authors: Grøsvik Bjørn Einar , Larsen Håvard E , Goksøyr Anders
Published: March 2010

The effects of piperonyl butoxide (PBO) and β-naphthoflavone (BNF) on cytochrome P4501A (CYP1A) expression and activity in juvenile Atlantic salmon (Salmo salar L.) with regard to time and temperature was investigated. The time exposure study was performed at 8 °C, and the results show that PBO, although acutely functioning as a CYP1A inhibitor, is able to induce CYP1A expression in salmon liver. Both PBO and BNF give highest induction of CYP1A mRNA 48 h after intraperitoneal injection (five- and 14-fold, respectively). The mRNA levels induced by PBO and BNF were sustained during the 8 d of the experiment (four- and 11-fold, respectively). The CYP1A protein content measured by enzyme-linked immunosorbent assay demonstrated the highest induction by PBO 8 d after exposure (eightfold) and by BNF 4 d after exposure (11-fold). Activity of CYP1A measured by ethoxyresorufin-O-deethylase (EROD) demonstrated inhibition after PBO treatment the first 24 h after exposure, followed by threefold induction from 48 h and to the end of the experiment (8 d). β-Naphthoflavone strongly induced EROD activity, with the highest levels occurring 4 d after treatment (56-fold) and 8 d after treatment (22-fold). In the temperature study, the results demonstrated temperature compensation, as salmon acclimated to 7°C for 3 weeks had a significantly higher EROD activity than those acclimated to 11 and 15°C. This was not reflected in significantly higher levels of reduced nicotinamide adenine dinucleotide phosphate cytochrome c reductase activity or CYP1A protein. The inductive properties of PBO and BNF on CYP1A expression was also demonstrated in primary cultures of salmon hepatocytes.
Reductive transformation and sorption of cis- and trans-1,2-dichloroethene in a metallic iron–water system
Authors: Allen-King Richelle M , Halket Richard M , Burris David R
Published: March 2010

Reductive transformation kinetic and sorption coefficients were determined for both cis- and trans-1,2-dichlo-roethene (DCE) in batch systems with zero-valent iron and water. Sorption quasi-equilibrium occurred rapidly (<1.1 h) for both compounds. Freundlich-type isotherms adequately described sorption over the measured concentration range. The magnitude of sorption was greater for trans-1,2-DCE than for the more soluble cis-1,2-DCE, indicating a possible influence of hydrophobicity. The trans-isomer was more reactive than the cis-isomer. The reaction order (95% confidence intervals) for trans-1,2-DCE was 1.22 (0.97–1.48), and for cis-1,2-DCE was 1.77 (0.92–2.63) and 1.64 (1.05–2.23) in relatively high and low initial concentration experiments, respectively. The fact that the reaction order for the cis-isomer could not be reduced to unity by assuming that the bulk of observed sorption was to nonreactive sorption sites suggests that either the assumption may not be valid or that a more complex process exists for this isomer. Chloride was produced by the transformation reaction and chlorine mass balances for the batch systems were 80 to 85%. Other products observed were acetylene, ethene, ethane, C3-C5 alkanes, and vinyl chloride.
Distribution of polycyclic aromatic hydrocarbons in southern Chesapeake Bay surface water: Evaluation of three methods for determining freely dissolved water concentrations
Authors: Gustafson Kurt E , Dickhut Rebecca M
Published: March 2010

Gas sparging, semipermeable-membrane devices (SPMDs), and filtration with sorption of dissolved polycyclic aromatic hydrocarbons (PAHs) to XAD-2 resin were evaluated for determining the concentrations of freely dissolved PAHs in estuarine waters of southern Chesapeake Bay at sites ranging from rural to urban and highly industrialized. Gas sparging had significant sampling artifacts due to particle scavenging by rising bubbles, and SPMDs were kinetically limited for four-ring and larger PAHs relative to short-term temporal changes in water concentrations. Filtration with sorption of the dissolved contaminant fraction to XAD-2 resin was found to be the most accurate and feasible method for determining concentrations of freely dissolved PAHs in estuarine water. Concentrations and distribution coefficients of dissolved and particulate PAHs were measured using the filtration/ XAD-2 method. Concentrations of PAHs in surface waters of southern Chesapeake Bay were higher than those reported for the northern bay; concentrations in the Elizabeth River were elevated relative to all other sites. A gradient for particulate PAHs was observed from urban to remote sites. No seasonal trends were observed in dissolved or particle-bound PAH fractions at any site. Distributions of dissolved and particulate PAHs in surface waters of the Chesapeake Bay are near equilibrium at all locations and during all seasons.
Aerobic biodegradation of (14C)-sarafloxacin hydrochloride in soil
Authors: Marengo Jose R , Kok Rebecca A , O'Brien Kelly , Velagaleti Ranga R , Stamm John M
Published: March 2010

The aerobic biodegradation of sarafloxacin hydrochloride, a fluoroquinolone antibiotic registered for use against poultry diseases, was tested in three soils: loam, silt loam, and sandy loam. Sarafloxacin treatment demonstrated mineralization to 14CO2 amounting to 0.58%, 0.49%, and 0.57% in loam, silt loam, and sandy loam soils, respectively, at the termination of the test. The extractability of sarafloxacin from soil in acetonitrile and water (ACN:H2O, 1:1, v/v) was less than 1% of the applied radioactivity. This was followed by extraction with pipemidic acid (a quinolone with structural similarity to sarafloxacin) and KOH (PIP:KOH), which resulted in ∼25% extractability in loam, ∼73% in silt loam, and ∼80% in sandy loam soils, with extractability increasing with decreasing organic matter content (5.8%, 2.5%, and 1.3%, respectively, for the three soils). The high-performance liquid chromatography (HPLC) analysis of ACN:H2O extractable radioactivity showed several components, all of which were less than 1% of the applied radioactivity. Hence, no attempt was made to characterize these components. The HPLC analysis of PIP:KOH extracts demonstrated two major components, one with a retention time of ∼4 to 5 min (designated polar component), the other component, sarafloxacin, with a retention time of ∼35 min. The components present in ACN:H2O or PIP:KOH extracts were not significantly different at day zero or at termination, prompting experiments that resulted in the following observations. Sarafloxacin standard exposed to extraction solvents (PIP:KOH and ACN:H2O) showed no degradation, suggesting stability of the test article in extraction solvents. Component profiles in sterile soils were similar to those in nonsterile soils, suggesting that the formation of the polar degradate component of sarafloxacin is an abiotic phenomenon. Experiments conducted with sand spiked with sarafloxacin showed very little or no transformation, suggesting that the degradation is a soil-related phenomenon. The polar component was converted to sarafloxacin when the extracts were subjected to acid hydrolysis.
Contaminants in white sturgeon (Acipenser transmontanus) from the upper Fraser River, British Columbia, Canada
Authors: MacDonald Donald D , Ikonomou Michael G , Rantalaine Anna-Lea , Rogers I Hal , Sutherland David , Van Oostdam Jay
Published: March 2010

Four white sturgeon were collected from the upper Fraser River near Prince George, British Columbia, Canada, in the fall of 1991 and 1992. Two additional fish were taken from the Fraser River near Williams Lake, some 250 km downstream of Prince George. Samples of white muscle, red muscle, liver, and roe were analyzed for metals, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non-ortho and mono–ortho polychlorinated biphenyls (PCBs), and chlorophenols to determine whether the tissues of this species were acceptable for human consumption. The concentrations of mercury in the white muscle and liver of several fish from the upper Fraser River exceeded the provincial tissue residue criteria for people who consumed low quantities of fish (i.e., 210 g wet weight/week). The concentrations of PCDDs, PCDFs, and coplanar PCBs (expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents) in red muscle and liver of these fish exceeded the Health Canada working guidelines for the protection of human health. By comparison, white sturgeon collected in the lower Fraser River had much lower concentrations of metals and organic contaminants. The differences in contaminant burdens in fish from the two widely separated reaches of the river reflect their proximity to or distance from known contaminant sources.
PCBS, DDE, DDT, and TCDD-EQ in two species of albatross on Sand Island, Midway Atoll, North Pacific Ocean
Authors: Auman Heidi J , Ludwig James P , Summer Cheryl L , Verbrugge David A , Froese Kenneth L , Colborn Theo , Giesy John P
Published: March 2010

Concentrations of total polychlorinated biphenyls (PCBs) and organochlorine insecticides, including the 1 1,1-trichloro-2, 2′-bis-p-chlorophenyl-ethane (DDT) complex, were measured in the plasma of chicks and adults and in eggs of Laysan albatrosses (Diomedea immutabilis) and black-footed albatrosses (Diomedea nigripes) in a remote area of the central North Pacific Ocean. Significant differences in total concentrations of PCBs, DDT, and 1,1-dichloro-2,2′-bis-p-chlorophenyl-ethylene (DDE) in the plasma were detected between species and among sampling periods. Current concentrations of DDE in eggs of Laysan albatrosses are well below the threshold for eggshell thinning, based on the sensitivities of other fish-eating birds, whereas concentrations of DDE in eggs of black-footed albatrosses were approximately one-half of the threshold concentrations necessary for eggshell thinning. The shells of Laysan and black-footed albatross eggs are not currently exhibiting significant thinning that is resulting in population-level effects. Current concentrations of PCBs are near those that could be having subtle population-level effects in the black-footed albatross, but not in the Laysan albatross. The hazard posed to the albatrosses by current concentrations of PCBs was assessed by calculating a hazard quotient (HQ), based on composite dose–response relationships for other species. Dioxin equivalents (TEq) based on mammalian toxic equivalency factors resulted in the greatest HQ, which was near the concentration when embryo lethality and deformities are observed in fish-eating colonial waterbirds of the North American Great Lakes. Current concentrations of both PCBs and the DDT complex were similar to those in some species of piscivorous birds of the North American Great Lakes region.
Cryoalgotox: Use of cryopreserved alga in a semistatic microplate test
Authors: Benhra Ali , Radetski Claudemir Marcos , Férard Jean-François
Published: March 2010

Use of cryopreserved alga Selenastrum capricornutum has been evaluated as a simple and cost-efficient procedure in a new semistatic algal ecotoxicity test. Experiments have been conducted to compare performance criteria of this method, named Cryoalgotox, versus the classic microplate test using fresh algae. Cryoalgotox 72-h 50% effective concentrations (EC50s) determined with Cd2+, Cu2+, Cr6+, and atrazine were more sensitive, repeatable (low coefficients of variation), and reproducible (low time effect) than the results obtained with the classical microplate tests. The effect of storage time at −80°C on the sensitivity of the algae was assessed using cadmium as a toxic reference; it was shown that algae stored at −80°C over a 3-month period gave comparable toxicity results to those found with fresh algae.
Evaluation of the water-effect ratio procedure for metals in a riverine system
Authors: Diamond Jerome M , Koplish Daniel E , McMahon Joe , Rost Robert
Published: March 2010

Site-specific metal standards were determined for a part of the lower Lehigh River using the U.S. Environmental Protection Agency's water-effect ratio (WER) procedure. The WERs were based on laboratory and site water (collected downstream of the City of Allentown Publicly Owned Treatment Works) testing of the species Ceriodaphnia dubia and Pimephales promelas (fathead minnow) and five metals (copper, cadmium, lead, silver, and zinc) during four different months. Both species generally exhibited similar patterns in WERs. The greatest variability between the two species was observed for copper, silver, and lead. Ceriodaphnia yielded a lower mean WER than the fathead minnow for lead and zinc and WERs similar to those of the fathead minnow for copper, cadmium, and silver. The species more sensitive to a given metal did not always exhibit a higher WER, as had been previously assumed. A comparison of final WER calculations indicated that the geometric mean WER (1983 method) was typically higher than the final WER obtained using the 1994 guidance. For most metals, site water toxicity was reduced due to nonacutely toxic dissolved metal. Copper yielded the highest final WER regardless of the calculation method used. Regression analyses indicated that the copper WER was directly related, and the cadmium WER inversely related, to effluent concentration. Copper, lead, and silver WERs were related to site water pH. Cadmium and lead WERs were related to pH and dissolved solids. Zinc WERs were unrelated to any of the water quality variables measured and were similar among site water samples. Our results suggest it is prudent to use two species in WER testing and different site water samples to derive a final WER, particularly at sites that are not effluent dominated.
Evaluation of prairie grass species as bioindicators of halogenated aromatics in soil
Authors: Siciliano Steven D , Germida James J , Headley John V
Published: March 2010

The purpose of this study was to assess the potential of prairie grasses as bioindicators of toxicants in soil and to investigate the effect different soil types and organisms have upon the germination of plant bioindicators. As a model compound, we used 2-chlorobenzoic acid (2CBA), a hydrophilic, polar compound present in the degradation pathways of halogenated aromatics. The germination response of prairie grasses to Aroclor™ 1260-contaminated soil, with concentrations ranging from 13 to 133 μg kg−1 total polychlorinated biphenyls, was also investigated. The grasses responded to a wide range of contamination levels, with a 12- and 10-fold difference in the sensitivity of grass species to 2CBA and Aroclor, respectively. Canada blue grass (Poa compressa) and slender wheatgrass (Agropyron trachycaulum) were selected for further study of the effects of soil type and biological treatments on bioindicator response to 2CBA. Canada blue grass response in three of four soils was characterized by Y = 110 — 26 × ln(X), while in the fourth soil it was Y = 94 — 1.6 × X, where Y equals percent germination and × the 2CBA concentration. Slender wheatgrass response was Y = 140 — 23 × ln(X), with no significant difference between soil types. Previous biological treatments of soil significantly affected the response of slender wheatgrass as a bioindicator. Growing plants or plants inoculated with bacteria in noncontaminated soil before slender wheatgrass was planted inhibited emergence, changing the logarithmic relationship between germination and 2CBA concentrations to Y = 100 — 0.28 × X. Prairie grasses are potentially useful bioindicators of chlorinated aromatics in soil, but biological interactions may alter the bioindicator response.
Estrogenic activity in five United Kingdom rivers detected by measurement of vitellogenesis in caged male trout
Authors: Harries Jule E , Sheahan David A , Jobling Susan , Matthiessen Peter , Neall Paula , Sumpter John P , Tylor Tina , Zaman Nicholas
Published: March 2010

It was recently demonstrated that most, if not all, effluents of sewage-treatment works (STWs) in the United Kingdom are estrogenic to fish. As many STWs discharge into rivers, it is possible that some stretches of rivers downstream of where the effluent enters might also be estrogenic. To assess this possibility, the induction of vitellogenin synthesis in caged male trout placed at various distances downstream of the effluent entry point was used as a biomarker of estrogen exposure. Individual discharges into five rivers in England were studied. In four cases, fish placed in the neat effluent, or close to where it entered a river, showed very marked and rapid increases in their plasma vitellogenin concentrations, demonstrating that the effluent was estrogenic. In two of these four cases, none of the downstream sites were estrogenic, whereas in one of the four, fish placed at a site 1.5 km downstream did respond by synthesizing appreciable amounts of vitellogenin, although sites further downstream were not estrogenic. The situation in the fourth river was quite different; not only was the effluent extremely estrogenic (a maximum vitellogenin response in the mg/ml range was attained), but so were all the other study sites on the river, the last of which was 5 km downstream of where the effluent entered. This particular river receives trade effluent from wool-scouring mills, which contains much higher concentrations of alkylphenolic chemicals than any of the other discharges studied. It is suggested that these chemicals probably account for the estrogenic activity of this river. The final (fifth) river showed no estrogenic activity, not even in the neat effluent. This discharge comes from a very small STW, which receives no trade waste, and one or both of these factors may account for why the effluent (and hence the river) was not estrogenic.
An in vitro rainbow trout cell bioassay for aryl hydrocarbon receptor-mediated toxins
Authors: Richter Catherine A , Tieber Virginia L , Denison Michael S , Giesy John P
Published: March 2010

Halogenated aromatic hydrocarbons (HAHs) and other chemicals that act as aryl hydrocarbon (Ah) receptor (AhR) agonists cause a variety of toxic effects. In sac fry of many fish species, these effects include blue-sac disease and mortality. Because HAHs occur in complex mixtures, their toxicity in the environment is difficult to predict. A bioassay useful in predicting AhR-mediated toxicity to fish was developed using the RTH-149 rainbow trout hepatoma cell line. Stable transfection of this cell line with the pGudLuc1.1 plasmid, which contains a firefly luciferase reporter gene under the transcriptional regulation of dioxin responsive enhancers, has produced a recombinant cell line designated Remodulated Lightning Trout (RLT 2.0). The RLT 2.0 bioassay method detection limit for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is 4 pM. The responses of the RLT 2.0 bioassay to TCDD and several HAH congeners closely matched the responses observed in vivo in fish. The RLT 2.0 bioassay can provide an integrative measure of the total AhR-mediated toxic activity of complex mixtures to fish. The assay will be useful in screening environmental extracts, guiding chemical analysis, and interpreting the AhR-mediated mechanism of toxicity.
Identification of acute toxicants in new bedford harbor sediments
Authors: Ho Kay T , McKinney Richard A , Kuhn Anne , Pelletier Marguerite C , Burgess Robert M
Published: March 2010

New Bedford Harbor (NBH) is a marine Superfund site contaminated with high concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and metals. Experiments were conducted to determine the causal toxic agent(s) in pore waters from New Bedford Harbor sediments to amphipods and mysid shrimp. Chemical manipulations to characterize toxicity revealed that pore-water toxicity was organic in nature. Fractionation and subsequent mass spectral identification of peaks in the toxic fraction indicated that PCBs, PAHs, and unknown compounds were present. Comparisons of PAH LC50s and PAH concentrations in this fraction indicated that the toxicity was not due to PAHs because the PAH concentrations were much lower than the reported PAH LC50s. One unknown peak was positively identified as bis(2-ethylhexyl) phthalate, and the other tentatively identified as pyrazole. Toxicity tests and comparison of toxicity in the blank and toxic fractions eliminated the two “unknowns” as toxic causal agents. We determined the range of PCB LC50s to fall between 10 and 110 ppb for Mysidopsis bahia and Ampelisca abdita. Concentrations of PCBs for the toxic fractions ranged from 12 to 27 ppb. This range falls within our observed PCB LC50s for M. bahia and A. abdita. Based upon these PCB concentrations, we concluded that PCBs were the acute toxic agents in NBH pore waters. Other compounds in the toxic fractions, or compounds that coeluted and were undistinguished from PCBs had minor contributions to the measured toxicity.
Immunotoxicity of environmentally relevant mixtures of polychlorinated aromatic hydrocarbons with methyl mercury on rat lymphocytes in vitro
Authors: Omara Felix Olima , Brochu Charles , Flipo Denis , Denizeau Francine , Fournier Michel
Published: March 2010

The immunosuppressive effects of methyl mercury (MH), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) are well established at high exposure levels but unclear at low exposure levels. We exposed Fischer 344 rat splenocytes, thymocytes, and peripheral blood lymphocytes in vitro for 72 h to MHg (0.1, 2 μg/ml), PCDD/PCDF mixtures (1, 15 pg/ml) of three PCDDs (2,3,7,8-tetrachlorodibenzo-p-dioxin, 1,2,3,7,8-pentachlorodibenzo-p-dioxin, and 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin) and two PCDFs (2,3,7,8-tetrachlorodibenzofuran and 1,2,3,7,8-pentachlorodibenzo-furan), three Aroclor® (1242, 1254, 1260), PCB mixtures (0.01, 0.5 μg/ml), or combinations of MHg/PCB/PCDD/PCDF mixtures Mitogenic responses of lymphocytes to concanavalin A, phytohemagglutinin, or lipopolysaccharide/dextran sulfate were determined by 3H-thymidine uptake; cytotoxicity and intracellular Ca2+ were determined by flow cytometry. Methylmercury (2 μg/ml and PCB/ PCDD/PCDF mixtures with 2 μg/ml MHg decreased the viability of splenocytes to 57 and 40% at 4 and 24 h, respectively. Basal intracellular calcium ion levels were unaffected by the treatments. Methylmercury suppressed the responses of lymphocytes to T and B cell mitogens. All combinations of MHg/PCB/PCDD/PCDF mixtures decreased mitogenic responses to levels similar to those to MHg alone. In contrast, PCB and PCDD/PCDF mixtures did not suppress but augmented responses of splenocytes and peripheral blood lymphocytes to T cell mitogens. Overall, no interactive toxicity was observed with MHg/PCB/PCDD/PCDF mixtures on cytotoxicity and lymphocyte mitogenic responses. Therefore, MHg may pose a greater threat than organochlorines to the mammalian immune system.
Persistence and toxicological effects of pesticides in topsoil: Use of the equilibrium partitioning theory
Authors: Ronday Rob , Van Kammen-Polman Annie M M , Dekker Abraham , Houx Norbert W H , Leistra Minze
Published: March 2010

Three parameters for indicating toxicologic risk of pesticides to soil organisms were compared: the traditional total content parameter, the equilibrium partitioning approach, and the pore-water concentration parameter. The relevance of each parameter was tested using different soil types and prolonged chemical–soil contact time by relating the results to bioavailability as measured in toxicity tests. The pesticide concentration measured in the soil pore water could be shown to correspond strongly with toxicologic effects on the soil organism Folsomia candida, irrespective of soil type and chemical–soil contact time. This relationship is predicted by the equilibrium partitioning theory and so this aspect of the theory could be validated in this study for pesticides in soil. However, the theory's assumption of equilibrium (which implies that the bioavailable fraction of the chemical is constant with time and can be calculated using one particular soil to pore-water partition coefficient) could not be justified in this study. Although organic matter normalization reduced soil-to-soil differences, it did not account for the time-related decrease in bioavailability that was found in two of the four soil–chemical combinations investigated. As a consequence, pore-water concentrations calculated from chemical content measurements in soil and a partition coefficient obtained in short-term laboratory experiments may not be a good estimate for sorption or toxicologic effects on a longer term. The suggestion is made to measure the concentration of chemical in pore water directly and to use water-only toxicity values as a basis for soil quality criteria.
Effect of oxygen status on pesticide transformation and sorption in undisturbed soil and lake sediment
Authors: Vink Jos P M , van der Zee Sjoerd E A T M
Published: March 2010

The behavior of four chemically distinctly different pesticides (aldicarb, simazine, mecoprop, and phenoxic acid [MCPA] was investigated under simulated redox conditions that occur at the terrestrial–aqueous interface. Sorption was measured in soil and lake sediment and in pure and combined pesticide solutions to study effects of competition. Transformation was investigated in undisturbed soil microcolumns and in anaerobic lake sediment. Using an air-tight nitrogen incubator, oxygen concentrations were varied from 20.8% (ambient) to less then 0.01 % v/v O2, while redox potentials varied from +330 to —120 mV. Aldicarb was transformed more rapidly under anaerobic than under aerobic conditions. Under low oxygen conditions, both reductive and oxidative metabolites were formed. Simazine showed some reductive transformation, but the overall transformation rate decreased with decreasing O2 concentrations. A pronounced redox effect was shown for both mecoprop and MCPA. With decreasing oxygen concentrations, transformation rates decreased from 0.173 to less than 0.001 d−, monitored over 200 d. These compounds, which are considered improbable leachers based on their short aerobic half lifes, appear to be more persistent in low-oxygenous conditions. It is shown that a period of oxygen inhibition could be survived by the responsible soil microorganisms and was followed by accelerated transformation of the compound when oxygen became abundant again. No relationship was observed between sorption affinity and transformation rate. The effect of redox conditions that occur along the pesticide's emission route appears to be an important screening parameter to assess environmental risks.
A multi-laboratory evaluation of analytical methods for estimating bioconcentratable contaminants in effluents, tissues and sediments
Authors: Wong Diana C L , van Compernolle Remi , Chai Eric Y , Fitzpatrick Richard D , Bover W James
Published: March 2010

The U.S. Environmental Protection Agency has developed draft guidance for the assessment and control of bioconcentratable contaminants in surface waters that are not covered by water quality criteria. The guidance document contains analytical procedures for identification and quantification of bioconcentratable contaminants in effluents, sediments, and tissues. These analytical procedures were the subject of a multilaboratory round-robin study in 1992. The results reported in this article are from five of the 12 laboratories that completed the round-robin study. Analyses of data from the five laboratories show that analytical variance explains the large observed intralaboratory variability in surrogate recoveries. Sample variance is minor relative to analytical and laboratory variances. All five laboratories isolated and positively identified only three of eight spiked compounds at >50% frequency using the proposed analytical procedures and gas chromatography–mass spectrometry library search method. The inability of the library search method to detect some of the reference spike chemicals is a concern because the methods are intended to detect unknown bioconcentratable chemicals. In general, the multistep procedure for each matrix was complex, prone to analyte loss, time intensive, and analytically demanding. Specific procedural problems and alternative methods are discussed, and recommendations for improvement are presented.
Survival and ecological effects of genetically engineered Erwinia carotovora in soil and aquatic microcosms
Authors: Palmer Sarah , Scanferlato Vjera S , Orvos David R , Lacy George H , Cairns John
Published: March 2010

The release of genetically engineered organisms into the environment has raised concerns about their potential ecological impact. In this study, genetically engineered Erwinia carotovora strains expressing varying levels of reduced phytopathogenicity and wildtype E. carotovora strains were used in aquatic and soil microcosms to assess the survival, intraspecific competition, and effects upon specific groups of indigenous bacteria. In aquatic microcosms, the densities of Erwinia genetically engineered organisms (GEMs) and wildtype strains declined and fell below the detectable limit of plate counts 15 d after the microcosms were inoculated. In aquatic microcosms, engineered E. carotovora did not exhibit a competitive advantage over the wildtype. The effect of engineered and wildtype E. carotovora on densities of total and selected bacteria was not significantly different. Treatment with engineered E. carotovora did not change biomass values of the receiving community but did cause a transitory increase in metabolic activity. In aquatic microcosms, the inability of genetically engineered E. carotovora to persist, displace resident species, or affect the metabolic activity of aquatic communities indicates the low risk of adverse ecological consequences in aquatic ecosystems. Unlike previous investigations involving soil microcosms, densities of both the genetically engineered and wildtype E. carotovora remained at detectable levels over 60 d in both agricultural clay and forest loam soils. The type of soil significantly affected the survival of the GEM and the wildtype. The sorptive properties of clay particles, as well as low concentrations of soil nutrients and organic matter, may have contributed to the unexpected patterns of GEM and wildtype survival.
Polynuclear aromatic hydrocarbon metabolism in soils: Relationship to soil characteristics and preexposure
Authors: Carmichael Lisa M , Pfaender Frederic K
Published: March 2010

The fate of radiolabeled ([14C]) phenanthrene, pyrene, benz[a]anthracene, chrysene, and benzo[a]pyrene was examined in five soils, four of which had previous exposure to polycyclic aromatic hydrocarbons (PAHs). The soils and [14C]PAHs studied represent a range of characteristics (fraction of soil organic carbon [foc] and PAH solubility) that can potentially impact contaminant fate. Fates of [14C]PAHs examined in slurry microcosms included mineralization, production of water-soluble metabolites and their polarity, cellular incorporation, and the association of [14C]PAHs with soils, all compared to an abiotic control. The soils all contained active heterotrophic communities and the contaminated soils had sizable populations of PAH-degrading microorganisms, measured by the [14C]-most probable number assay. All [14C]PAHs, except [14C]benzo[a]pyrene, were readily mineralized in most of the preexposed soils, whereas in the uncontaminated soil, less than 5% of each [14C]PAH was mineralized. In the adapted soils, mineralization, after 8 weeks of incubation, accounted for 30 to 60% of [14C]phenanthrene, 10 to 55% of [14C]pyrene, 5 to 40% of [14C]benz[a]anthracene, 10 to 50% of [14C]chrysene, and 2 to 9% of [14C]benzo[a]pyrene added to the microcosms. Metabolite production and cellular incorporation usually accounted for less than 10% of the added [14C]PAH. The fate of PAHs was usually not related to measurements of microbial community size, characteristics of the PAH (water solubility and Kow), and many characteristics of soils (soil foc and PAH concentration). The fraction of silt and clay in the soils for each soil–PAH combination, however, was negatively related to the extent of added [14C]PAH mineralized and the amount solvent extractable from the soil, and positively related to the amount of [14C]PAH remaining in soils after extraction.
Effects of sublethal copper exposure on muscle energy metabolism of common carp, measured by 31P-nuclear magnetic resonance spectroscopy
Authors: De Boeck Gudrun , Borger Robert , Van der Linden Annemie , Blust Ronny
Published: March 2010

The effects of shock and subchronic exposure(1 week) to 0.36 ± 0.08 and 1.31 ± 0.22 μM of copper on the energy metabolism of common carp (Cyprinus carpio) were studied by means of in vivo 31P-nuclear magnetic resonance spectroscopy (31P-NMRS). During the experiments, fish were submitted to an additional hypoxic challenge and recovery from this challenge was followed for 6 hs. During all experiments adenosine triphosphate (ATP) levels remained stable. Under control conditions, levels of phosphocreatine (PCr) and inorganic phosphate (Pi) recovered rapidly after the hypoxic challenge; however, full recovery was not observed after shock copper exposure. Also, intracellular pH (pHi) did not recover from the hypoxic challenge after shock exposure. After 1 week of exposure the fish had clearly developed an increased tolerance to copper. At both copper concentrations, PCr and Pi levels returned to resting levels after the hypoxic challenge, but at the highest copper concentration PCr to Pi ratios were significantly lower than PCr to Pi ratios in the control group and levels of PCr and Pi were very unstable. At the high copper concentration, pHi was clearly decreased compared to the control group even before the hypoxic challenge.
Effect of feeding in 30-day bioaccumulation assays usingHyalella aztecain fluoranthene-dosed sediment
Authors: Harkey Gail A , Driscoll Susan Kane , Landrum Peter F
Published: March 2010

Current protocols for conducting freshwater sediment bioaccumulation tests recommend that food not be added to exposures, whereas toxicity tests require food addition. To determine effects of adding food on exposure, 30-d sediment exposures were conducted with Hyalella azteca to sediment dosed with four fluoranthene concentrations (trace level to 897 nmol/g dry weight). Accumulation was significantly greater in fed versus nonfed animals at all dose levels after 96 h of exposure and continued to be greater after 30 d in the low dose levels. At sediment concentrations above 478 nmol/g dry weight, survival of unfed animals dropped to 34% after 30 d. After 30 d of exposure, growth and reproduction were observed in fed animals exposed to sediment concentrations 20 to 90 times the expected median lethal concentration (LC50) values for fluoranthene in sediment, according to 10-d studies reported in the literature using sediment with comparable organic carbon concentrations. Samples of sediment in exposure beakers taken from the sediment–water interface (flocculant layer) and 1 to 2 cm below the interface had large differences in fluoranthene and organic carbon concentrations. The concentration of fluoranthene was 2 to 10 times greater in the flocculant layer, the area inhabited by H. azteca, compared to the deeper sediment. These data raise questions concerning the interpretation of standard toxicity and bioaccumulation tests when food is routinely added.
Sediment contaminants and biological effects in southern California: Use of a multivariate statistical approach to assess biological impact
Authors: Maxon Cynda L , Barnett Arthur M , Diener Douglas R
Published: March 2010

This study attempts to predict biological toxicity and benthic community impact in sediments collected from two southern California sites. Contaminant concentrations and grain size were evaluated as predictors using a two-step multivariate approach. The first step used principal component analysis (PCA) to describe contamination type and magnitude present at each site. Four dominant PC vectors, explaining 88% of the total variance, each corresponded to a unique physical and/or chemical signature. The four PC vectors, in decreasing order of importance, were: (1) high molecular weight polynuclear aromatic hydrocarbons (PAH), most likely from combusted or weathered petroleum; (2) low molecular weight alkylated PAH, primarily from weathered fuel product; (3) low molecular weight nonalkylated PAH, indicating a fresh petroleum-related origin; and (4) fine-grained sediments and metals. The second step used stepwise regression analysis to predict individual biological effects (dependent) variables using the four PC vectors as independent variables. Results showed that sediment grain size alone was the best predictor of amphipod mortality. Contaminant vectors showed discrete depositional areas independent of grain size. Neither contaminant concentrations nor PCA vectors were good predictors of biological effects, most likely due to the low concentrations in sediments.
Estimating low toxic effects
Authors: Moore Dwayne R J , Caux Pierre-Yves
Published: March 2010

The use of no-observed-effect levels (NOLs) and lowest-observed-effect levels (LOELs) assummary statistics for low toxic effects has been criticized recently. In this paper, we explore the regression-based approach for estimating low toxic effects. Key questions with this approach include: (1) is the approach practical with typical toxicity data sets, (2) can low toxic effects be estimated with confidence, (3) what models are appropriate for typical data sets and endpoints, and (4) how do point estimates of low toxic effects (e.g., EC10) compare with their corresponding LOELs and NOELs? Analyses of 198 toxicity data sets (all but 13 unpublished) revealed that: (1) even with a range of models to choose from (three models in the logistic family, probit model, Weibull model), >80% of the data sets did not produce a single adequate model fit; (2) estimates of low toxic effects were often model dependent when an extrapolation beyond the toxicity data was required; (3) confidence intervals can be quite large at 5% effect and lower; (4) of the five models, the three-parameter logistic equation with a steep slope parameter had the best model fit in the majority of the data sets; and (5) 76.9% of the NOELs and 100% of the LOELs were higher than their corresponding 10% effect point estimates from the best-fit model equations, suggesting that NOELs and LOELs are poor indicators of low toxic effects. We believe that the regression-based approach is a better tool than hypothesis testing for estimating low toxic effects. The approach, however, does not produce adequate model fits unless there is an obvious concentration–response relationship and several treatments with partial effects.
Comparison of contaminant accumulation in three species of marine invertebrates with different feeding habits
Authors: Kaag Nicholas H B M , Foekema Edwin M , Scholten Martin C Th , van Straalen Nico M
Published: March 2010

In order to assess the importance of the mode of feeding for the bioaccumulation of contaminants from sediments, three marine benthic invertebrates, with different feeding habits, were exposed to contaminated sediments in outdoor mesocosms. Residue analyses were carried out for several polychlorinated biphenyls and polycyclic aromatic hydrocarbons after exposure periods of 60 to 140 days. It was shown that sediment ingestion is a major uptake route for the sediment-feeding lugworm, Arenicola marina, and for the facultative deposit-feeding baltic tellin, Macoma balthica. Residues in the filter-feeding mussel, Mytilus edulis, appeared to be independent of contaminant concentrations in the sediment. The difference between deposit and filter-feeding bivalves was confirmed in experiments involving the baltic tellin, with differences in the food availability in the overlying water. A simple linear regression model was used to describe contaminant concentrations in sediment-feeding invertebrates as a function of concentrations in sediment. A correction for the accumulation from water was made by subtracting the concentrations in filter feeders. It was concluded that chemical equilibrium partitioning alone is not sufficient for the assessment of the risks of contaminated sediments to sediment-feeding invertebrates, but that feeding habits should also be considered.
Assessment of toxicological interactions of benzene and its primary degradation products (catechol and phenol) using a lux-modified bacterial bioassay
Authors: Boyd Elaine M , Meharg Andrew A , Wright Julian , Killham Ken
Published: March 2010

A bacterial bioassay has been developed to assess the relative toxicities of xenobiotics commonly found in contaminated soils, river waters, and ground waters. The assay utilized decline in luminescence of lux-marked Pseudomonas fluorescens on exposure to xenobiotics. Pseudomonas fluorescens is a common bacterium in the terrestrial environment, providing environmental relevance to soil, river, and ground water systems. Three principal environmental contaminants associated with benzene degradation were exposed to the luminescence-marked bacterial biosensor to assess their toxicity individually and in combination. Median effective concentration (EC50) values for decline in luminescence were determined for benzene, catechol, and phenol and were found to be 39.9, 0.77, and 458.6 mg/L, respectively. Catechol, a fungal and bacterial metabolite of benzene, was found to be significantly more toxic to the biosensor than was the parent compound benzene, showing that products of xenobiotic biodegradation may be more toxic than the parent compounds. Combinations of parent compounds and metabolites were found to be significantly more toxic to the bioassay than were the individual compounds themselves. Development of this bioassay has provided a rapid screening system suitable for assessing the toxicity of xenobiotics commonly found in contaminated soil, river, and ground-water environments. The assay can be utilized over a wide pH range and is therefore more applicable to such environmental systems than bioluminescence-based bioassays that utilize marine organisms and can only be applied over a limited pH and salinity range.