The Experts below are selected from a list of 5253 Experts worldwide ranked by ideXlab platform
Michael J. Lydy - One of the best experts on this subject based on the ideXlab platform.
-
bioaccumulation potential of chlorpyrifos in resistant hyalella Azteca implications for evolutionary toxicology
Environmental Pollution, 2021Co-Authors: Nadhirah Johanif, Richard E. Connon, Michael J. Lydy, Kara Huff E Hartz, Donald P Weston, Alexandra E Figueroa, Devon Lee, Helen C. PoyntonAbstract:Abstract Given extensive use of pesticides in agriculture, there is concern for unintended consequences to non-target species. The non-target freshwater amphipod, Hyalella Azteca has been found to show resistance to the organophosphate (OP) pesticide, chlorpyrifos, resulting from an amino acid substitution in acetylcholinesterase (AChE), suggesting a selective pressure of unintended pesticide exposure. Since resistant organisms can survive in contaminated habitats, there is potential for them to accumulate higher concentrations of insecticides, increasing the risk for trophic transfer. In the present study, we estimated the uptake and elimination of chlorpyrifos in non-resistant US Lab, and resistant Ulatis Creek (ULC Resistant), H. Azteca populations by conducting 24-h uptake and 48-h elimination toxicokinetic experiments with 14C-chlorpyrifos. Our results indicated that non-resistant H. Azteca had a larger uptake clearance coefficient (1467 mL g−1 h−1) than resistant animals (557 mL g−1 h−1). The half-life derived from the toxicokinetic models also estimated that steady state conditions were reached at 13.5 and 32.5 h for US Lab and ULC, respectively. Bioaccumulation was compared between non-resistant and resistant H. Azteca by exposing animals to six different environmentally relevant concentrations for 28 h. Detection of chlorpyrifos in animal tissues indicated that resistant animals exposed to high concentrations of chlorpyrifos were capable of accumulating the insecticide up to 10-fold higher compared to non-resistant animals. Metabolite analysis from the 28-h concentration experiments showed that between 20 and 50 % parent compound was detected in H. Azteca. These results imply that bioaccumulation potential can be more significant in chlorpyrifos resistant H. Azteca and may be an essential factor in assessing the full impacts of toxicants on critical food webs, especially in the face of increasing pesticide and chemical runoff.
-
Pyrethroid bioaccumulation in field-collected insecticide-resistant Hyalella Azteca
Ecotoxicology, 2021Co-Authors: Kara E. Huff Hartz, Richard E. Connon, Donald P Weston, Nadhirah Johanif, Helen C. Poynton, Michael J. LydyAbstract:Wild-type Hyalella Azteca are highly sensitive to pyrethroid insecticides and typically do not survive exposure; however, pyrethroid bioaccumulation by insecticide-resistant H. Azteca is an important potential risk factor for the transfer of pyrethroids to higher trophic species in aquatic systems. In the current study, four populations of pyrethroid-resistant H. Azteca with corresponding sediment samples were sampled throughout the year, and nine-current use pyrethroids (tefluthrin, fenpropathrin, bifenthrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, esfenvalerate and deltamethrin) were measured. Bifenthrin was detected in every pyrethroid-resistant H. Azteca tissue sample, up to 813 ng/g lipid, while cyhalothrin and permethrin were detected in fewer (18 and 28%, respectively) samples. Concurrent sampling of the sediment showed total pyrethroid concentrations exceeding toxic unit thresholds for non-resistant H. Azteca survival, and confirmed the ubiquitous presence of bifenthrin at each site and sampling event. Bifenthrin concentrations in H. Azteca tended to be higher in samples collected in winter months, and seasonal factors, such as temperature and rainfall, may have contributed to the noted differences in bioaccumulation. Finally, the bifenthrin and permethrin biota-sediment accumulation factors (BSAF) for pyrethroid-resistant H. Azteca were similar to the BSAF values for less sensitive invertebrates, and therefore the development of resistance may enable an additional pathway for trophic transfer of pyrethroids in species that would otherwise be too sensitive to survive the exposure.
-
Fitness costs of pesticide resistance in Hyalella Azteca under future climate change scenarios.
The Science of the total environment, 2020Co-Authors: Corie A. Fulton, Richard E. Connon, Kara E. Huff Hartz, Neil W. Fuller, Logan N. Kent, Sara E. Anzalone, Tristin M. Miller, Helen P. Poynton, Michael J. LydyAbstract:Abstract Global climate change continues to cause alterations in environmental conditions which can be detrimental to aquatic ecosystem health. The development of pesticide resistance in organisms such as Hyalella Azteca can lead to increased susceptibility to environmental change. This research provides a robust assessment of the effects of alterations in salinity on the fitness of H. Azteca. Full-life cycle bioassays were conducted with non-resistant and pyrethroid-resistant H. Azteca cultured under two salinity conditions representing a rise from freshwater control (0.2 psu) to increased salinity due to salt-water intrusion, reduced snowpack and evaporative enrichment (6.0 psu). Additionally, the upper thermal tolerance was defined for each population at each salinity. Pyrethroid-resistant H. Azteca exhibited reduced thermal tolerance; however, they produced more offspring per female than non-resistant animals. Compared to the low salinity water, both non-resistant and pyrethroid-resistant H. Azteca produced more offspring, grew larger (based on dry mass), and produced larger offspring in elevated salinity, although pyrethroid-resistant animals had lower survival and lipid levels. This study provides fundamental information about the fitness potential of H. Azteca in a changing climate, suggesting advantages for non-resistant animals under future climate scenarios. In addition, this research further supports the need to consider the effects of global climate change when conducting risk assessment of contaminants of concern, as well as the contribution of contaminants when investigating climate change impacts on populations, as exposure may contribute to niche contraction.
-
the g119s ace 1 mutation confers adaptive organophosphate resistance in a nontarget amphipod
Evolutionary Applications, 2020Co-Authors: Kaley M Major, Michael J. Lydy, Kara Huff E Hartz, Donald P Weston, Gary A Wellborn, Austin R Manny, Helen C. PoyntonAbstract:Organophosphate (OP) and carbamate (CM) insecticides are widely used in the United States and share the same mode of toxic action. Both classes are frequently documented in aquatic ecosystems, sometimes at levels that exceed aquatic life benchmarks. We previously identified a population of the nontarget amphipod, Hyalella Azteca, thriving in an agricultural creek with high sediment levels of the OP chlorpyrifos, suggesting the population may have acquired genetic resistance to the pesticide. In the present study, we surveyed 17 populations of H. Azteca in California to screen for phenotypic resistance to chlorpyrifos as well as genetic signatures of resistance in the acetylcholinesterase (ace-1) gene. We found no phenotypic chlorpyrifos resistance in populations from areas with little or no pesticide use. However, there was ~3- to 1,000-fold resistance in H. Azteca populations from agricultural and/or urban areas, with resistance levels in agriculture being far higher than urban areas due to greater ongoing use of OP and CM pesticides. In every case of resistance in H. Azteca, we identified a glycine-to-serine amino acid substitution (G119S) that has been shown to confer OP and CM resistance in mosquitoes and has been associated with resistance in other insects. We found that the G119S mutation was always present in a heterozygous state. Further, we provide tentative evidence of an ace-1 gene duplication in H. Azteca that may play a role in chlorpyrifos resistance in some populations. The detection of a genetically based, adaptive OP and CM resistance in some of the same populations of H. Azteca previously shown to harbor a genetically based adaptive pyrethroid resistance indicates that these nontarget amphipod populations have become resistant to many of the insecticides now in common use. The terrestrial application of pesticides has provided strong selective pressures to drive evolution in a nontarget, aquatic species.
-
are there fitness costs of adaptive pyrethroid resistance in the amphipod hyalella Azteca
Environmental Pollution, 2018Co-Authors: Jennifer R Heim, Kara Huff E Hartz, Donald P Weston, Helen C. Poynton, Kaley M Major, Michael J. LydyAbstract:Abstract Pyrethroid-resistant Hyalella Azteca with voltage-gated sodium channel mutations have been identified at multiple locations throughout California. In December 2013, H. Azteca were collected from Mosher Slough in Stockton, CA, USA, a site with reported pyrethroid (primarily bifenthrin and cyfluthrin) sediment concentrations approximately twice the 10-d LC50 for laboratory-cultured H. Azteca. These H. Azteca were shipped to Southern Illinois University Carbondale and have been maintained in pyrethroid-free culture since collection. Even after 22 months in culture, resistant animals had approximately 53 times higher tolerance to permethrin than non-resistant laboratory-cultured H. Azteca . Resistant animals held in culture also lacked the wild-type allele at the L925 locus, and had non-synonymous substitutions that resulted in either a leucine-isoleucine or leucine-valine substitution. Additionally, animals collected from the same site nearly three years later were again resistant to the pyrethroid permethrin. When resistant animals were compared to non-resistant animals, they showed lower reproductive capacity, lower upper thermal tolerance, and the data suggested greater sensitivity to, 4, 4′-dichlorodiphenyltrichloroethane (DDT), copper (II) sulfate, and sodium chloride. Further testing of the greater heat and sodium chloride sensitivity of the resistant animals showed these effects to be unrelated to clade association. Fitness costs associated with resistance to pyrethroids are well documented in pest species (including mosquitoes, peach-potato aphids, and codling moths) and we believe that H. Azteca collected from Mosher Slough also have fitness costs associated with the developed resistance.
Christian Schlechtriem - One of the best experts on this subject based on the ideXlab platform.
-
bioconcentration metabolism and spatial distribution of 14c labeled laurate in the freshwater amphipod hyalella Azteca
Environmental Toxicology and Chemistry, 2020Co-Authors: Johannes Raths, Sebastian Kuehr, Christian SchlechtriemAbstract:Regulatory assessment of the bioaccumulation from water is commonly based on bioconcentration factors (BCFs) derived from fish flow-through tests. Such experiments require many laboratory animals and are time-consuming and costly. An alternative test setup for organic, neutral compounds using the amphipod Hyalella Azteca was recently suggested, resulting in BCF values which show a strong correlation with fish BCF data. In the present study, the bioconcentration potential of the ionic compound laurate was elucidated in H. Azteca. The sodium salt of 1-14 C laurate was applied to H. Azteca in a flow-through and a semistatic approach. Because of rapid biodegradation, a semistatic approach with frequent medium replacements was required to ensure a stable medium concentration. Laurate was also rapidly metabolized by H. Azteca. A large proportion of the total radioactivity measured in the amphipod tissue was not extractable, suggesting that mineralized laurate was accumulated in the calcified exoskeleton of H. Azteca. This was confirmed in a further study using carbonate [14 C]. A lipid-normalized (5.0%) Hyalella BCF of 8.9 was calculated for laurate, measured as free fatty acids. The results of the bioconcentration studies with H. Azteca confirm the low bioaccumulation potential of the test item previously observed in fish. However, more organic ionic compounds with various properties need to be tested to assess whether a general correlation between fish and Hyalella BCF data exists. Environ Toxicol Chem 2020;39:310-322. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
-
bioconcentration metabolism and spatial distribution of 14 c labeled laurate in the freshwater amphipod hyalella Azteca
Environmental Toxicology and Chemistry, 2020Co-Authors: Johannes Raths, Sebastian Kuehr, Christian SchlechtriemAbstract:Regulatory assessment of the bioaccumulation from water is commonly based on bioconcentration factors (BCFs) derived from fish flow-through tests. Such experiments require many laboratory animals and are time-consuming and costly. An alternative test setup for organic, neutral compounds using the amphipod Hyalella Azteca was recently suggested, resulting in BCF values which show a strong correlation with fish BCF data. In the present study, the bioconcentration potential of the ionic compound laurate was elucidated in H. Azteca. The sodium salt of 1-14 C laurate was applied to H. Azteca in a flow-through and a semistatic approach. Because of rapid biodegradation, a semistatic approach with frequent medium replacements was required to ensure a stable medium concentration. Laurate was also rapidly metabolized by H. Azteca. A large proportion of the total radioactivity measured in the amphipod tissue was not extractable, suggesting that mineralized laurate was accumulated in the calcified exoskeleton of H. Azteca. This was confirmed in a further study using carbonate [14 C]. A lipid-normalized (5.0%) Hyalella BCF of 8.9 was calculated for laurate, measured as free fatty acids. The results of the bioconcentration studies with H. Azteca confirm the low bioaccumulation potential of the test item previously observed in fish. However, more organic ionic compounds with various properties need to be tested to assess whether a general correlation between fish and Hyalella BCF data exists. Environ Toxicol Chem 2020;39:310-322. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
Paul K. Sibley - One of the best experts on this subject based on the ideXlab platform.
-
Bioaccumulation of the synthetic hormone 17a-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella Azteca
2020Co-Authors: B Dussault, Uwe Borgmann, Keith R. Solomon, Vimal K. Balakrishnan, Paul K. SibleyAbstract:a b s t r a c t The present study investigated the bioaccumulation of the synthetic hormone 17a-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella Azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS-MS, while biota extracts were analyzed using both LC/MS-MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. Azteca in the water-only assays (p ¼ 0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1 mg/L, C. tentans had a greater body burden than H. Azteca (p ¼ 0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.270.14 vs. 0.570.05 mg/g dw, n ¼ 4). Measurements in H. Azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. Azteca (31 vs. 142, respectively; po0.0001). In contrast, the sediment bioaccumulation factor (BSAF) of C. tentans was larger than that of H. Azteca (0.8 vs. 0.3; po0.0001). Extracts of the exposed animals caused a response in a recombinant yeast estrogen receptor assay, thus confirming the estrogenic activity of the samples, presumably from EE2 and its estrogenic metabolites. The results of the present study suggest that consumption of invertebrate food items could provide an additional source of exposure to estrogenic substances in vertebrate predators
-
Bioaccumulation of the synthetic hormone 17α-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella Azteca
Ecotoxicology and environmental safety, 2009Co-Authors: Ève B. Dussault, Uwe Borgmann, Keith R. Solomon, Vimal K. Balakrishnan, Paul K. SibleyAbstract:Abstract The present study investigated the bioaccumulation of the synthetic hormone 17α-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella Azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS–MS, while biota extracts were analyzed using both LC/MS–MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. Azteca in the water-only assays (p=0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1 mg/L, C. tentans had a greater body burden than H. Azteca (p=0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.2±0.14 vs. 0.5±0.05 μg/g dw, n=4). Measurements in H. Azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. Azteca (31 vs. 142, respectively; p
-
chronic toxicity of the synthetic hormone 17α ethinylestradiol to chironomus tentans and hyalella Azteca
Environmental Toxicology and Chemistry, 2008Co-Authors: Keith R. Solomon, Ève B. Dussault, Vimal K. Balakrishnan, Paul K. SibleyAbstract:The chronic toxicity of the synthetic hormone 17α-ethinylestradiol (EE2) was investigated in two benthic invertebrates, the midge Chironomus tentans and the freshwater amphipod Hyalella Azteca, in life-cycle water-only assays. In C. tentans, a 50% decrease in emergence was observed at a concentration of 1.5 mg/L; emergence was a more sensitive endpoint than survival, growth, or biomass. Reproduction was not significantly affected by EE2 exposure until a concentration of 3.1 mg/L, where emergence, and therefore reproduction, did not occur. In contrast, reproduction was the most sensitive endpoint in H. Azteca (50% decrease in reproduction observed at a concentration of 0.36 mg/L). The sensitivity of the F1 generation to EE2 was also investigated with H. Azteca, but was not different from the F0 generation. The data from the present study were combined with those from previous 10-d toxicity assays, to derive acute to chronic toxicity ratios (ACRs) for EE2. The ACRs calculated for EE2 were 13 for C. tentans and 16 for H. Azteca, indicating that the application factors currently used in ecological risk assessment for the derivation of chronic toxicity are protective and conservative for these organisms. The results of the present study suggest that chronic toxicity was not mediated by disruption of endocrine pathways. Using a hazard quotient approach, the risk associated with sublethal exposure to EE2 was << 1 for H. Azteca and C. tentans, indicating that adverse effects are not expected, and that environmental exposure to EE2 likely poses a low risk to benthic invertebrates.
Ève B. Dussault - One of the best experts on this subject based on the ideXlab platform.
-
Bioaccumulation of the synthetic hormone 17α-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella Azteca
Ecotoxicology and environmental safety, 2009Co-Authors: Ève B. Dussault, Uwe Borgmann, Keith R. Solomon, Vimal K. Balakrishnan, Paul K. SibleyAbstract:Abstract The present study investigated the bioaccumulation of the synthetic hormone 17α-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella Azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS–MS, while biota extracts were analyzed using both LC/MS–MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. Azteca in the water-only assays (p=0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1 mg/L, C. tentans had a greater body burden than H. Azteca (p=0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.2±0.14 vs. 0.5±0.05 μg/g dw, n=4). Measurements in H. Azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. Azteca (31 vs. 142, respectively; p
-
chronic toxicity of the synthetic hormone 17α ethinylestradiol to chironomus tentans and hyalella Azteca
Environmental Toxicology and Chemistry, 2008Co-Authors: Keith R. Solomon, Ève B. Dussault, Vimal K. Balakrishnan, Paul K. SibleyAbstract:The chronic toxicity of the synthetic hormone 17α-ethinylestradiol (EE2) was investigated in two benthic invertebrates, the midge Chironomus tentans and the freshwater amphipod Hyalella Azteca, in life-cycle water-only assays. In C. tentans, a 50% decrease in emergence was observed at a concentration of 1.5 mg/L; emergence was a more sensitive endpoint than survival, growth, or biomass. Reproduction was not significantly affected by EE2 exposure until a concentration of 3.1 mg/L, where emergence, and therefore reproduction, did not occur. In contrast, reproduction was the most sensitive endpoint in H. Azteca (50% decrease in reproduction observed at a concentration of 0.36 mg/L). The sensitivity of the F1 generation to EE2 was also investigated with H. Azteca, but was not different from the F0 generation. The data from the present study were combined with those from previous 10-d toxicity assays, to derive acute to chronic toxicity ratios (ACRs) for EE2. The ACRs calculated for EE2 were 13 for C. tentans and 16 for H. Azteca, indicating that the application factors currently used in ecological risk assessment for the derivation of chronic toxicity are protective and conservative for these organisms. The results of the present study suggest that chronic toxicity was not mediated by disruption of endocrine pathways. Using a hazard quotient approach, the risk associated with sublethal exposure to EE2 was << 1 for H. Azteca and C. tentans, indicating that adverse effects are not expected, and that environmental exposure to EE2 likely poses a low risk to benthic invertebrates.
Vimal K. Balakrishnan - One of the best experts on this subject based on the ideXlab platform.
-
Bioaccumulation of the synthetic hormone 17a-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella Azteca
2020Co-Authors: B Dussault, Uwe Borgmann, Keith R. Solomon, Vimal K. Balakrishnan, Paul K. SibleyAbstract:a b s t r a c t The present study investigated the bioaccumulation of the synthetic hormone 17a-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella Azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS-MS, while biota extracts were analyzed using both LC/MS-MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. Azteca in the water-only assays (p ¼ 0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1 mg/L, C. tentans had a greater body burden than H. Azteca (p ¼ 0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.270.14 vs. 0.570.05 mg/g dw, n ¼ 4). Measurements in H. Azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. Azteca (31 vs. 142, respectively; po0.0001). In contrast, the sediment bioaccumulation factor (BSAF) of C. tentans was larger than that of H. Azteca (0.8 vs. 0.3; po0.0001). Extracts of the exposed animals caused a response in a recombinant yeast estrogen receptor assay, thus confirming the estrogenic activity of the samples, presumably from EE2 and its estrogenic metabolites. The results of the present study suggest that consumption of invertebrate food items could provide an additional source of exposure to estrogenic substances in vertebrate predators
-
variation in the toxicity of sediment associated substituted phenylamine antioxidants to an epibenthic hyalella Azteca and endobenthic tubifex tubifex invertebrate
Chemosphere, 2017Co-Authors: Ryan S Prosser, Adrienne J Bartlett, D Milani, E A M Holman, H Ikert, D Schissler, J Toito, Joanne L Parrott, Patricia L Gillis, Vimal K. BalakrishnanAbstract:Abstract Substituted phenylamine antioxidants (SPAs) are produced in relatively high volumes and used in a range of applications (e.g., rubber, polyurethane); however, little is known about their toxicity to aquatic biota. Therefore, current study examined the effects of chronic exposure (28 d) to four sediment-associated SPAs on epibenthic ( Hyalella Azteca ) and endobenthic ( Tubifex tubifex ) organisms. In addition, acute (96-h), water-only exposures were conducted with H. Azteca . Mortality, growth and biomass production were assessed in juvenile H. Azteca exposed to diphenylamine (DPA), N -phenyl-1-napthylamine (PNA), N -(1,3-dimethylbutyl)-N’-phenyl-1,4-phenylenediamine (DPPDA), or 4,4’-methylene-bis[ N - sec -butylaniline] (MBA). Mortality of adult T. tubifex and reproduction were assessed following exposure to the four SPAs. The 96-h LC50s for juvenile H. Azteca were 1443, 109, 250, and >22 μg/L and 28-d LC50s were 22, 99, 135, and >403 μg/g dry weight (dw) for DPA, PNA, DPPDA, and MBA, respectively. Reproductive endpoints for T. tubifex (EC50s for production of juveniles > 500 μm: 15, 9, 4, 3.6 μg/g dw, for DPA, PNA, DPPDA, and MBA, respectively) were an order of magnitude more sensitive than endpoints for juvenile H. Azteca and mortality of adult worms. The variation in toxicity across the four SPAs was likely related to the bioavailability of the sediment-associated chemicals, which was determined by the chemical properties of the SPAs (e.g., solubility in water, Koc). The variation in the sensitivity between the two species was likely due to differences in the magnitude of exposure, which is a function of the life histories of the epibenthic amphipod and the endobenthic worm. The data generated from this study will support effect characterization for ecological risk assessment.
-
Bioaccumulation of the synthetic hormone 17α-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella Azteca
Ecotoxicology and environmental safety, 2009Co-Authors: Ève B. Dussault, Uwe Borgmann, Keith R. Solomon, Vimal K. Balakrishnan, Paul K. SibleyAbstract:Abstract The present study investigated the bioaccumulation of the synthetic hormone 17α-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella Azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS–MS, while biota extracts were analyzed using both LC/MS–MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. Azteca in the water-only assays (p=0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1 mg/L, C. tentans had a greater body burden than H. Azteca (p=0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.2±0.14 vs. 0.5±0.05 μg/g dw, n=4). Measurements in H. Azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. Azteca (31 vs. 142, respectively; p
-
chronic toxicity of the synthetic hormone 17α ethinylestradiol to chironomus tentans and hyalella Azteca
Environmental Toxicology and Chemistry, 2008Co-Authors: Keith R. Solomon, Ève B. Dussault, Vimal K. Balakrishnan, Paul K. SibleyAbstract:The chronic toxicity of the synthetic hormone 17α-ethinylestradiol (EE2) was investigated in two benthic invertebrates, the midge Chironomus tentans and the freshwater amphipod Hyalella Azteca, in life-cycle water-only assays. In C. tentans, a 50% decrease in emergence was observed at a concentration of 1.5 mg/L; emergence was a more sensitive endpoint than survival, growth, or biomass. Reproduction was not significantly affected by EE2 exposure until a concentration of 3.1 mg/L, where emergence, and therefore reproduction, did not occur. In contrast, reproduction was the most sensitive endpoint in H. Azteca (50% decrease in reproduction observed at a concentration of 0.36 mg/L). The sensitivity of the F1 generation to EE2 was also investigated with H. Azteca, but was not different from the F0 generation. The data from the present study were combined with those from previous 10-d toxicity assays, to derive acute to chronic toxicity ratios (ACRs) for EE2. The ACRs calculated for EE2 were 13 for C. tentans and 16 for H. Azteca, indicating that the application factors currently used in ecological risk assessment for the derivation of chronic toxicity are protective and conservative for these organisms. The results of the present study suggest that chronic toxicity was not mediated by disruption of endocrine pathways. Using a hazard quotient approach, the risk associated with sublethal exposure to EE2 was << 1 for H. Azteca and C. tentans, indicating that adverse effects are not expected, and that environmental exposure to EE2 likely poses a low risk to benthic invertebrates.