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Christopher G. Ingersoll - One of the best experts on this subject based on the ideXlab platform.

  • Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters.
    Environmental toxicology and chemistry, 2016
    Co-Authors: Chris D. Ivey, Christopher G. Ingersoll
    Abstract:

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response of H. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L. Environ Toxicol Chem 2016;35:2425-2429. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

  • Evaluation of toxicity: Whole‐sediment versus overlying‐water exposures with amphipod Hyalella azteca
    Environmental Toxicology and Chemistry, 2000
    Co-Authors: Christopher G. Ingersoll, Eric L. Brunson, Chris D. Ivey, Doug K. Hardesty, Nile E. Kemble
    Abstract:

    A laboratory study was conducted to evaluate the toxicity of whole-sediment versus overlying-water exposures to the amphipod Hyalella azteca using field-collected sediments. Severe toxic effects (5–63% survival) were observed with amphipods exposed for 10 d in direct contact with sediment. In contrast, amphipods exposed only to overlying water in these sediment exposures did not exhibit any toxic effects.

  • Interlaboratory study of precision: Hyalella azteca and Chironomus tentans freshwater sediment toxicity assays
    Environmental Toxicology and Chemistry, 1996
    Co-Authors: G. Allen Burton, Gerald T. Ankley, Teresa J. Norberg-king, Duane A. Benoit, Parley V. Winger, Jody A. Kubitz, James M. Lazorchak, Mark E. Smith, Daniel J. Call, Christopher G. Ingersoll
    Abstract:

    Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod Hyalella azteca and the midge Chironomus tentans. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in H. azteca and C. tentans median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. Hyalella azteca and C. tentans tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for C. tentans growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the H. azteca survival tests. No samples exceeded the intralaboratory precision limit for H. azteca or C. tentans survival tests. However, intralaboratory variability limits for C. tentans growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for C. tentans survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.

  • Evaluation of reproduction as an endpoint in chronic toxicity tests with the amphipod Hyalella azteca
    1995
    Co-Authors: Eric L. Brunson, F. J. Dwyer, Christopher G. Ingersoll
    Abstract:

    In 1994, USEPA published ``Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates`` (EPA/600/R-94/024). Within that document a Hyalella azteca 10-d survival test for sediments is described. The 10-d survival test provides a measure of acute toxicity from moderately to highly contaminated sediments. In addition to survival, growth during the 10-d test can be measured and could be a more sensitive endpoint. However, the ecological significance of reduced growth is questionable. Reproduction may be a more sensitive endpoint than growth or survival and its ecological importance is not questionable. The objective of this research is to develop a Hyalella azteca sediment toxicity test with a reproductive endpoint. The reproductive test will closely resemble the 10-d test but will be longer in duration and may require isolation of amphipods from the sediment for reproduction. Presently, reproductive effects of different diets and water types have been evaluated. A preliminary test protocol has been developed and is being tested and refined. This presentation will provide the most current results of this ongoing research. This study will be used to develop standard methods for measuring chronic toxicity in sediments using Hyalella azteca.

  • Recovery of known‐age Hyalella azteca (amphipoda) from sediment toxicity tests
    Environmental Toxicology and Chemistry, 1995
    Co-Authors: Michael J. Tomasovic, F. James Dwyer, Ivan E. Greer, Christopher G. Ingersoll
    Abstract:

    Recovery of 1-, 7-, 14-, or 21-d-old Hyalella azteca from sediment was evaluated. Recovery of 1- and 7-d-old amphipods was below an acceptability criterion of 80% survival for sediment tests. Another important aspect to consider when conduction sediment tests with H. azteca is defining mortality. A second study was conducted to evaluate the decomposition rate of dead amphipods in sediment. Regardless of sediment type, {ge}90% of the amphipods started to break apart within 12h of death; specifically, the head separates from the body. Therefore, if an immobile amphipod with its head and body intact is recovered in sieved material, it was probably alive within 12 h of the end of the test (an amphipod may be alive before sieving but may die during the sieving process). However, immobile amphipods removed from the sediment surface before sieving are known to be dead.

Leobardo Manuel Gómez-oliván - One of the best experts on this subject based on the ideXlab platform.

  • Oxidative stress induced in Hyalella azteca by an effluent from a NSAID-manufacturing plant in Mexico
    Ecotoxicology, 2016
    Co-Authors: Karen Adriana Novoa-luna, Rubí Romero-romero, Reyna Natividad-rangel, Catalina Martínez-vieyra, Nadia Neri-cruz, Nely Sanjuan-reyes, Marcela Galar-martínez, Sandra García-medina, Leobardo Manuel Gómez-oliván
    Abstract:

    Production in the pharmaceutical industry has increased and along with it, the amount of wastewater of various characteristics and contaminant concentrations. The main chemicals in these effluents are solvents, detergents, disinfectants—such as sodium hypochlorite (NaClO)—and pharmaceutical products, all of which are potentially ecotoxic. Therefore, this study aimed to evaluate the oxidative stress induced in the amphipod Hyalella azteca by the effluent from a nonsteroidal anti-inflammatory drug (NSAID)-manufacturing plant. The median lethal concentration (72 h-LC_50) was determined and H. azteca were exposed to the lowest observed adverse effect level (0.0732 %) for 12, 24, 48 and 72 h, and biomarkers of oxidative stress were evaluated [hydroperoxide content (HPC), lipid peroxidation (LPX), protein carbonyl content (PCC), and the activity of the superoxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)]. Statistically significant increases with respect to the control group ( P  

  • Assessing the Oxidative Stress Induced by Paracetamol Spiked in Artificial Sediment on Hyalella azteca
    Water Air & Soil Pollution, 2012
    Co-Authors: Leobardo Manuel Gómez-oliván, Nadia Neri-cruz, Marcela Galar-martínez, Sandra García-medina, Celene Razo-estrada, Patricia Vieyra-reyes, Octavio Dublán-garcía, Alba Yadira Corral-avitia
    Abstract:

    Paracetamol is an antipyretic analgesic widely used globally. It has been recurrently found in water bodies and is known to elicit toxic effects in aquatic species; however, its potential ability to induce oxidative stress in sentinel species remains unknown The objective was to establish a methodology to evaluate the toxicity elicited on the sentinel species Hyalella azteca by paracetamol-enriched sediment using oxidative stress tests. Concentrations used in assays were determined using the previously obtained median lethal concentration (72 h LC50). The following oxidative stress biomarkers were evaluated: lipid peroxidation (LPO), protein carbonyl content (PCC) in order to determine oxidized protein content, and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). LPO and PCC increased significantly while SOD, CAT, and GPX decreased significantly (p < 0.05) with respect to controls. Paracetamol induces oxidative stress on H. azteca, and the set of tests employed is helpful in evaluating the toxicity of this group of pharmaceuticals on aquatic species.

  • Diclofenac-enriched artificial sediment induces oxidative stress in Hyalella azteca.
    Environmental toxicology and pharmacology, 2009
    Co-Authors: Dennis Gloria Carolina Oviedo-gómez, Marcela Galar-martínez, Sandra García-medina, Celene Razo-estrada, Leobardo Manuel Gómez-oliván
    Abstract:

    Diclofenac is a nonsteroidal anti-inflammatory drug widely used in Mexico where it is sold over the counter. It enters water bodies through municipal and industrial discharges, posing a risk to water systems and aquatic organisms. Diclofenac-enriched artificial sediment was used to evaluate the toxicity of this pharmaceutical on the sentinel species Hyalella azteca, using oxidative stress biomarkers in order to determine if the set of tests used in this study is a suitable early damage biomarker. The median lethal concentration (72-h LC50) was determined and oxidative stress was evaluated using lipid peroxidation, protein carbonyl content to evaluate oxidized protein content, and the activity of superoxide dismutase, catalase, and glutathione peroxidase. All biomarkers were significantly altered. Diclofenac induces oxidative stress in H. azteca and the set of tests used (lipid peroxidation, protein carbonyl content, antioxidant enzyme activities) constitutes an adequate early damage biomarker for evaluating the toxicity of this pharmaceutical group in aquatic species.

Eric L. Brunson - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of toxicity: Whole‐sediment versus overlying‐water exposures with amphipod Hyalella azteca
    Environmental Toxicology and Chemistry, 2000
    Co-Authors: Christopher G. Ingersoll, Eric L. Brunson, Chris D. Ivey, Doug K. Hardesty, Nile E. Kemble
    Abstract:

    A laboratory study was conducted to evaluate the toxicity of whole-sediment versus overlying-water exposures to the amphipod Hyalella azteca using field-collected sediments. Severe toxic effects (5–63% survival) were observed with amphipods exposed for 10 d in direct contact with sediment. In contrast, amphipods exposed only to overlying water in these sediment exposures did not exhibit any toxic effects.

  • Evaluation of reproduction as an endpoint in chronic toxicity tests with the amphipod Hyalella azteca
    1995
    Co-Authors: Eric L. Brunson, F. J. Dwyer, Christopher G. Ingersoll
    Abstract:

    In 1994, USEPA published ``Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates`` (EPA/600/R-94/024). Within that document a Hyalella azteca 10-d survival test for sediments is described. The 10-d survival test provides a measure of acute toxicity from moderately to highly contaminated sediments. In addition to survival, growth during the 10-d test can be measured and could be a more sensitive endpoint. However, the ecological significance of reduced growth is questionable. Reproduction may be a more sensitive endpoint than growth or survival and its ecological importance is not questionable. The objective of this research is to develop a Hyalella azteca sediment toxicity test with a reproductive endpoint. The reproductive test will closely resemble the 10-d test but will be longer in duration and may require isolation of amphipods from the sediment for reproduction. Presently, reproductive effects of different diets and water types have been evaluated. A preliminary test protocol has been developed and is being tested and refined. This presentation will provide the most current results of this ongoing research. This study will be used to develop standard methods for measuring chronic toxicity in sediments using Hyalella azteca.

  • Postembryonic growth and development of Hyalella azteca in laboratory cultures and contaminated sediments
    Chemosphere, 1995
    Co-Authors: M.k. Nelson, Eric L. Brunson
    Abstract:

    The environmental, biological, and ecological requirements of but a few species used in testing sediments are known and well understood. The present investigation was designed to provide fundamental information on the postembryonic growth and development of Hyalella azteca (Amphipoda) that can be used as sublethal indicators of contaminated sediments, and the influence growth characteristics may have on interpretation of sediment toxicity test results. The biological endpoints for measuring H. azteca growth and development included sexual maturation, molt frequency, intermolt duration, body length, antennal segment addition, and the relation between total body length and antennal segment addition. To use growth and development of H. azteca as sublethal indicators of contaminated sediments, tests of up to 28 days duration should begin with immature amphipods (less than two weeks old) that will begin the adult stage at the end of the test. Sexual maturation begins at the sixth instar (about 24 days at 20°C) and can be used as a sublethal indicator of development effects. The presence of an enlarged propodus is a reliable indicator of sexual maturation in H. azteca which easily distinguishes the immature (first five instars) from the juvenile (instars 6 and 7) stage.

  • Calculation of sediment effect concentrations (SECs) for Hyalella azteca and Chironomus riparius
    1994
    Co-Authors: Christopher G. Ingersoll, Eric L. Brunson, P.s. Haveriand, Nile E. Kemble, F. J. Dwyer, C. E. Henke, Timothy J. Canfield, David R. Mount
    Abstract:

    A data base for sediment toxicity and chemistry was generated with field-collected sediments using 10 to 32 d tests with the amphipod Hyalella azteca and the midge Chironomus riparius. Physical characterizations of sediment included organic carbon, percentage water, and particle size. Chemical characterizations of sediment included total metals, butyltins, methyl-mercury, acid volatile sulfide, (AVS) and simultaneously extracted metals, chlorinated pesticides, total polychlorinated biphenyls (PCBs), polychlorinated dioxins and furans, or polycyclic aromatic hydrocarbons (PAHs). Samples which significantly reduced survival, length, or maturation of test organisms relative to the control were classified as ``toxic``. A 10-fold difference in concentration for at least one chemical among the samples at each site was checked. If the concentration of a chemical measured in a toxic sample was less than or equal to the mean concentration of the chemical in the non-toxic samples at a site, then the chemical in this toxic sample was classified as ``no concordance`` (and then designated as a non-toxic in the calculations of SECs). The authors will discuss how the data base was created and the criteria used to calculate SECs (three types of SECs were calculated: (1) ERL and MM, (2) TEL and PEL, and (3) AET).

  • Calculation of sediment effect concentrations (SECs) for Hyalella azteca and Chironomus riparius
    1994
    Co-Authors: Christopher G. Ingersoll, Eric L. Brunson, P.s. Haveriand, Nile E. Kemble, F. J. Dwyer, C. E. Henke, Timothy J. Canfield, David R. Mount
    Abstract:

    A data base for sediment toxicity and chemistry was generated with field-collected sediments using 10 to 32 d tests with the amphipod Hyalella azteca and the midge Chironomus riparius. Physical characterizations of sediment included organic carbon, percentage water, and particle size. Chemical characterizations of sediment included total metals, butyltins, methyl-mercury, acid volatile sulfide, (AVS) and simultaneously extracted metals, chlorinated pesticides, total polychlorinated biphenyls (PCBs), polychlorinated dioxins and furans, or polycyclic aromatic hydrocarbons (PAHs). Samples which significantly reduced survival, length, or maturation of test organisms relative to the control were classified as ``toxic``. A 10-fold difference in concentration for at least one chemical among the samples at each site was checked. If the concentration of a chemical measured in a toxic sample was less than or equal to the mean concentration of the chemical in the non-toxic samples at a site, then the chemical in this toxic sample was classified as ``no concordance`` (and then designated as a non-toxic in the calculations of SECs). The authors will discuss how the data base was created and the criteria used to calculate SECs (three types of SECs were calculated: (1) ERL and MM, (2) TEL and PEL, and (3) AET).

Uwe Borgmann - One of the best experts on this subject based on the ideXlab platform.

  • Models of Cadmium Accumulation and Toxicity to Hyalella azteca during 7- and 28-Day Exposures
    Human and Ecological Risk Assessment: An International Journal, 2010
    Co-Authors: Uwe Borgmann, J. E. Schroeder, Lisa A. Golding, D.g. Dixon
    Abstract:

    ABSTRACT The inhibition of Cd accumulation by Ca in the amphipod Hyalella azteca in short-term (7-d) exposures appears to follow anti-competitive, rather than competitive, inhibition. Increasing Ca reduces Cd accumulation more at high than at low Cd concentrations. Cadmium accumulation and toxicity in chronic exposures can be predicted using the 7-d model to which the effects of acclimation, Cd inhibition of acclimation, and growth dilution are added. The resultant model is complex and species-specific, making it unwieldy for direct application in water quality guideline or criteria development. However, it does demonstrate that a mechanistic explanation of the relationship between short- and long-term accumulation and toxicity is possible, as well as suggest why the acute-to-chronic ratio changes with water chemistry. It is not, therefore, appropriate to estimate chronic Cd toxicity to H. azteca from acute toxicity assuming a constant acute-to-chronic ratio. The standard Biotic Ligand Model (BLM) can als...

  • The amphipod Hyalella azteca as a biomonitor in field deployment studies for metal mining.
    Environmental pollution (Barking Essex : 1987), 2008
    Co-Authors: Yves Couillard, Uwe Borgmann, L.c. Grapentine, Patrick J. Doyle, S. Masson
    Abstract:

    Abstract Specimens of the amphipod Hyalella azteca were deployed, in June–July 2003, along metal contamination gradients in two rivers affected by metal mining in the Abitibi – James Bay region, northwestern Quebec. The amphipods were placed along with natural food items in small, acrylic cages and left in six riverine sites for 17 days. Twelve metals (As, Cu, La, Mn, Ni, Sb, Se, Tl, U, V, Zn, and CrO 4 2− modelled by WHAM VI) in transplanted H. azteca varied along metal contamination gradients in a consistent manner, i.e., as a function of metal exposure. Bioaccumulation of As, Cr, La, Ni, Sb, Se, Tl, U and V, as defined by a field BCF, was significantly correlated with their chronic toxicity potential towards the amphipod. We conclude that H. azteca may be a useful field biomonitor for metal mining. In addition, our results suggest that such biomonitoring programs should include less studied elements such as Se in mining effluents.

  • Water–sediment interactions for Hyalella azteca exposed to uranium-spiked sediment
    Aquatic toxicology (Amsterdam Netherlands), 2008
    Co-Authors: L.c. Alves, Uwe Borgmann, D.g. Dixon
    Abstract:

    Abstract Data on the toxicity of uranium in sediments to Hyalella azteca and the effect of overlying water chemistry are limited. This study exposed H. azteca to sediments spiked with U (0–10,000 μg U/g dry weight) and five different overlying waters, which varied independently in hardness and alkalinity. Water pH had a major effect on U bioavailability and uptake by H. azteca . Uranium toxicity was higher when overlying water pH was low, while desorption of U into the overlying water increased with increasing pH. There appears to be little effect of Ca on U uptake, other than its influence on U speciation. Experiments with caged animals indicate that U accumulation and toxicity occur mainly through the dissolved phase rather than the solid phase. Uranium bioaccumulation is a more reliable indicator of U toxicity than U concentration in water or sediment. Uranium bioaccumulation in the H. azteca and U adsorption to sediment can be satisfactorily explained using saturation models.

  • Interactive effects of metals in mixtures on bioaccumulation in the amphipod Hyalella azteca.
    Aquatic Toxicology, 2007
    Co-Authors: W.p. Norwood, Uwe Borgmann, D.g. Dixon
    Abstract:

    Mixtures were produced of "equi-toxic" concentrations of 10 elements at the 4-week LC25 for Hyalella azteca. Bioaccumulation was determined in 1-week exposures. The first mixtures tested included seven elements; As, Cd, Co, Cr, Ni, Pb and Tl. Copper, Mn and Zn were not included in the initial tests due to potential confounding effects, such as regulation of Cu and Zn by H. azteca and the high concentrations of Mn required to be "equi-toxic", which might cause adsorption of metals to Mn hydroxides if these were formed. The second set of tests included the seven element mixture in combination with, Cu, Mn and Zn individually, the binary pairs, Cu-Mn, Cu-Zn and Mn-Zn; and the tertiary group Cu, Mn and Zn. Interaction factors (IF) were computed which quantified each element's impact on the bioaccumulation of the other nine. Cobalt, Cd and Ni bioaccumulation was significantly inhibited with increasing number of metals in the mixture. Arsenic bioaccumulation was enhanced with increasing number of metals in the mixture exposure. Lead bioaccumulation was enhanced by some mixture combinations. Bioaccumulation of Cr, Cu, Mn, Tl and Zn were not significantly affected by exposure to other metals.

  • Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca.
    Environmental pollution (Barking Essex : 1987), 2006
    Co-Authors: W.p. Norwood, Uwe Borgmann, D.g. Dixon
    Abstract:

    Abstract Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r2: 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g−1 appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment.

Peter F. Landrum - One of the best experts on this subject based on the ideXlab platform.

  • Response spectrum of pentachlorobenzene and fluoranthene for Chironomus tentans and Hyalella azteca.
    Environmental toxicology and chemistry, 2007
    Co-Authors: Lance J. Schuler, Peter F. Landrum, Michael J. Lydy
    Abstract:

    The whole-body residues of pentachlorobenzene (PCBz) and fluoranthene (FLU) in Hyalella azteca and Chironomus tentans were determined for a variety of chronic sublethal effects. The endpoints evaluated for H. azteca included 28-d growth and survival and 42-d growth, survival, and reproduction. Adverse effects to C. tentans also were determined at multiple endpoints including 10-d growth, cumulative pupation and emergence, and reproduction. The lowest-observed-effect residue (LOER) based on whole-body residues associated with growth was consistent between compounds and species tested with concentrations ranging from 0.17 to 0.33 μmol/g. For H. azteca, the most sensitive endpoints were growth at 0.23 μmol/g and reproduction at 0.11 μmol/g for PCBz and FLU, respectively. For C. tentans, the most sensitive endpoints were emergence, development and reproduction at 0.02 μmol/g, and development and reproduction at 0.15 μmol/g for PCBz and FLU, respectively. Compared to residues associated with acute lethality, the most sensitive sublethal endpoints were approximately 4 and 60 times lower for PCBz and FLU, respectively. The relative consistency of the sublethal endpoints suggests that body residues can be a valuable tool to evaluate bioaccumulation data as part of a risk assessment to predict adverse effects to biota.

  • Time-dependent toxicity of dichlorodiphenyldichloroethylene to Hyalella azteca.
    Environmental toxicology and chemistry, 2005
    Co-Authors: Peter F. Landrum, Jeffery A. Steevens, Michael Mcelroy, Duane C. Gossiaux, Jocelyn S. Lewis, Sander D. Robinson
    Abstract:

    Temporal effects on body residues of dichlorodiphenyldichloroethylene (DDE) associated with mortality in the freshwater amphipod Hyalella azteca were evaluated. Toxicokinetics and body residues were determined from water-only exposures that varied from 4 to 28 d, and DDE concentrations ranging from 0.0013 to 0.045 μmol L−1. Uptake and elimination parameters were not affected significantly by the various temporal and concentration treatments. Uptake rate coefficients ranged from 134.3 to 586.7 ml g−1 h−1, and elimination rate coefficients ranged from 0.0011 to 0.0249 h−1. Toxicity metric values included body residue for 50% mortality at a fixed sample time (LR50) and mean lethal residue to produce 50% mortality from individual exposure concentrations (MLR50) for live organisms and dead organisms. A twofold increase occurred in the MLR50 values calculated using live organisms compared to MLR50 values using dead organisms. Toxicity and kinetic data were fit to a damage assessment model that allows for the time course for toxicokinetics and damage repair, demonstrating the time-dependence of body residues to toxicity. The DDE appeared to act through a nonpolar narcosis mode of action for both acute and chronic mortality in H. azteca. Furthermore, the temporal trend in the toxic response using body residue as the dose metric is steep and found to be similar to another chlorinated hydrocarbon, pentachlorobenzene, but was more potent than that found for polycyclic aromatic hydrocarbons (PAHs).

  • Time-dependent lethal body residues for the toxicity of pentachlorobenzene to Hyalella azteca.
    Environmental toxicology and chemistry, 2004
    Co-Authors: Peter F. Landrum, Jeffery A. Steevens, Michael Mcelroy, Duane C. Gossiaux, Sander D. Robinson, Linda J. Begnoche, Sergei M. Chernyak, James P. Hickey
    Abstract:

    The study examined the temporal response of Hyalella azteca to pentachlorobenzene (PCBZ) in water-only exposures. Toxicity was evaluated by calculating the body residue of PCBZ associated with survival. The concentration of PCBZ in the tissues of H. azteca associated with 50% mortality decreased from 3 to 0.5 micromol/g over the temporal range of 1 to 28 d, respectively. No significant difference was observed in the body residue calculated for 50% mortality when the value was determined using live or dead organisms. Metabolism of PCBZ was not responsible for the temporal response because no detectable PCBZ biotransformation occurred over an exposure period of 10 d. A damage assessment model was used to evaluate the impact and repair of damage by PCBZ on H. azteca. The toxicokinetics were determined so that the temporal toxicity data could be fit to a damage assessment model. The half-life calculated for the elimination of PCBZ averaged approximately 49 h, while the value determined for the half-life of damage repair from the damage assessment model was 33 h.

  • Toxicokinetics of organic contaminants in Hyalella azteca.
    Archives of environmental contamination and toxicology, 2003
    Co-Authors: Susanna Nuutinen, Peter F. Landrum, Lance J. Schuler, Jussi V. K. Kukkonen, Michael J. Lydy
    Abstract:

    Uptake, biotransformation, and elimination rates were determined for pentachlorophenol (PCP), methyl parathion (MP), fluoranthene (FU), and 2,2',4,4',5,5'-hexachlorobiphenyl (HCBP) using juvenile Hyalella azteca under water-only exposures. A two-compartment model that included biotransformation described the kinetics for each chemical. The uptake clearance coefficients (k(u)) were 25.7 +/- 2.9, 11.5 +/- 1.1, 184.4 +/- 9.3, and 251.7 +/- 9.0 (ml g(-1) h(-1)) for PCP, MP, FU, and HCBP, respectively. The elimination rate constant of the parent compound (k(ep)) for MP was almost an order of magnitude faster (0.403 +/- 0.070 h(-1)) than for PCP and FU (0.061 +/- 0.034 and 0.040 +/- 0.008 h(-1)). The elimination rate constants for FU and PCP metabolites (k(em)) were similar to the parent compound elimination 0.040 +/- 0.005 h(-1) and 0.076 +/- 0.012 h(-1), respectively. For MP, the metabolites were excreted much more slowly than the parent compound (0.021 +/- 0.001 h(-1)). For PCP, FU, and MP whose metabolites were measured, the biological half-life (t(1/2p)) of the parent compound was shorter than the half-life for metabolites (t(1/2m)) because the rate is driven both by elimination and biotransformation processes. Thus, H. azteca is capable of metabolizing compounds with varying chemical structures and modes of toxic action, which may complicate interpretation of toxicity and bioaccumulation results. This finding improves our understanding of H. azteca as a test organism, because most biomonitoring activities do not account for biotransformation and some metabolites can contribute significantly to the noted toxicity.

  • Toxicokinetics and time-dependent PAH toxicity in the amphipod Hyalella azteca.
    Environmental science & technology, 2002
    Co-Authors: Jong-hyeon Lee, Peter F. Landrum, Chul-hwan Koh
    Abstract:

    The relationship between toxicokinetics and time-dependent PAH toxicity to Hyalella azteca was examined to test the constant critical body residue (CBR) model. A constant CBR model is based on the assumption that the body residue for 50% mortality is constant for each PAH across exposure times. With a constant CBR, kinetic parameters determined through kinetic experiments would be similar to those estimated from time series toxicity data. Time-dependent toxicity was investigated using three types of data:  time series LC50 data, LT50(c), and CBR values measured at multiple exposure times for live and dead animals. Kinetic parameters were measured independently. The constant CBR model did not predict the PAH toxicity time course for H. azteca. Since a first-order kinetic model predicted the bioaccumulation of the parent PAH except for naphthalene, this result is not due to a failure to predict the internal dose (body residue). The influence of metabolites on toxicity was negligible except for naphthalene. ...