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Fu Y, Yu J, Fan F, Wang B, Cao Z. Elucidating the Enzymatic Mechanism of Dihydrocoumarin Degradation: Insight into the Functional Evolution of Methyl-Parathion Hydrolase from QM/MM and MM MD Simulations. J Phys Chem B 2024; 128:5567-5575. [PMID: 38814729 DOI: 10.1021/acs.jpcb.4c00970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Methyl-parathion hydrolase (MPH), which evolved from dihydrocoumarin hydrolase, offers one of the most efficient enzymes for the hydrolysis of methyl-parathion. Interestingly, the substrate preference of MPH shifts from the methyl-parathion to the lactone dihydrocoumarin (DHC) after its mutation of five specific residues (R72L, L273F, L258H, T271I, and S193Δ, m5-MPH). Here, extensive QM/MM calculations and MM MD simulations have been used to delve into the structure-function relationship of MPH enzymes and plausible mechanisms for the chemical and nonchemical steps, including the transportation and binding of the substrate DHC to the active site, the hydrolysis reaction, and the product release. The results reveal that the five mutations remodel the active pocket and reposition DHC within the active site, leading to stronger enzyme-substrate interactions. The MM/GBSA-estimated binding free energies are about -20.7 kcal/mol for m5-MPH and -17.1 kcal/mol for wild-type MPH. Furthermore, this conformational adjustment of the protein may facilitate the chemical step of DHC hydrolysis and the product release, although there is a certain influence on the substrate transport. The hydrolytic reaction begins with the nucleophilic attack of the bridging OH- with the energy barriers of 22.0 and 18.0 kcal/mol for the wild-type and m5-MPH enzymes, respectively, which is rate-determining for the entire process. Unraveling these mechanistic intricacies may help in the understanding of the natural evolution of enzymes for diverse substrates and establish the enzyme structure-function relationship.
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Affiliation(s)
- Yuzhuang Fu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jun Yu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Fangfang Fan
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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Landis WG, Mitchell CJ, Hader JD, Nathan R, Sharpe EE. Incorporation of climate change into a multiple stressor risk assessment for the Chinook salmon (Oncorhynchus tshawytscha) population in the Yakima River, Washington, USA. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2024; 20:419-432. [PMID: 38062648 DOI: 10.1002/ieam.4878] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 02/09/2024]
Abstract
One outcome of the 2022 Society of Environmental Toxicology and Chemistry Pellston Workshop on incorporating climate change predictions into ecological risk assessments was the key question of how to integrate ecological risk assessments that focus on contaminants with the environmental alterations from climate projections. This article summarizes the results of integrating selected direct and indirect effects of climate change into an existing Bayesian network previously used for ecological risk assessment. The existing Bayesian Network Relative Risk Model integrated the effects of two organophosphate pesticides (malathion and diazinon), water temperature, and dissolved oxygen levels on the Chinook salmon population in the Yakima River Basin (YRB), Washington, USA. The endpoint was defined as the entity, Yakima River metapopulation, and the attribute was defined as no decline to a subpopulation or the overall metapopulation. In this manner, we addressed the management objective of no net loss of Chinook salmon, an iconic and protected species. Climate change-induced changes in water quality parameters (temperature and dissolved oxygen levels) used models based on projected climatic conditions in the 2050s and 2080s by the use of a probabilistic model. Pesticide concentrations in the original model were modified assuming different scenarios of pest control strategies in the future, because climate change may alter pest numbers and species. Our results predict that future direct and indirect changes to the YRB will result in a greater probability that the salmon population will continue to fail to meet the management objective of no net loss. As indicated by the sensitivity analysis, the key driver in salmon population risk was found to be current and future changes in temperature and dissolved oxygen, with pesticide concentrations being not as important. Integr Environ Assess Manag 2024;20:419-432. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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Affiliation(s)
- Wayne G Landis
- Institute of Environmental Toxicology and Chemistry, Western Washington University, Bellingham, Washington, USA
| | | | - John D Hader
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Rory Nathan
- Department of Infrastructure Engineering, University of Melbourne Faculty of Veterinary and Agricultural Sciences, Parkville, Victoria, Australia
| | - Emma E Sharpe
- Institute of Environmental Toxicology and Chemistry, Western Washington University, Bellingham, Washington, USA
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Malathion alters the transcription of target genes of the tumour suppressor tp53 and cancerous processes in Colossoma macropomum: Mechanisms of DNA damage response, oxidative stress and apoptosis. Chem Biol Interact 2023; 374:110405. [PMID: 36796534 DOI: 10.1016/j.cbi.2023.110405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 02/11/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
Different classes of pesticides such as fungicides, herbicides, and insecticides, can induce differential expression of genes that are involved in tumorigenesis events in fish, including the expression of tumor suppressor tp53. The degree and duration of the stressful condition is decisive in defining which tp53-dependent pathway will be activated. Herein we evaluate the target genes expression that participates in the regulation pathway of the tumor suppressor tp53 and in the cancerous processes in tambaqui after exposure to malathion. Our hypothesis is that malathion promotes a gene response that is differentially regulated over time, with positive regulation of tp53 target genes related to the apoptotic pathway and a negative regulation of genes that promote antioxidant responses. The fish were exposed to a sublethal concentration of the insecticide for 6 and 48 h. Liver samples were used to analyze the expression of 11 genes using real-time PCR. Overall, the malathion promoted over time increases in tp53 expression and differential expression of tp53 related genes. The exposure resulted in the activation of damage response related genes, caused a positive expression of atm/atr genes. The pro-apoptotic gene bax was up-regulated and the anti-apoptotic bcl2 was down-regulated. Increased expression of mdm2 and sesn1 in the first hours of exposure and no effect on the antioxidant genes sod2 and gpx1 were also observed. We also witnessed an increase in the expression of the hif-1α gene, with no effect on ras proto-oncogene. The extension of this stressful condition accentuated tp53 transcription, and minimized the levels of mdm2, sens1 and bax; however, it down regulated the levels of bcl2 and the bcl2/bax ratio, which indicates the maintenance of the apoptotic response to the detriment of an antioxidant response.
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Hong X, Cholko T, Chang CEA, Wheeldon I. Multiscale simulation-guided design of enzyme bioconjugates with enhanced catalysis. CHEM CATALYSIS 2022; 2:2691-2703. [PMID: 36569428 PMCID: PMC9784400 DOI: 10.1016/j.checat.2022.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Biopolymer-scaffold modification is widely used to enhance enzyme catalysis. A central challenge is predicting the effects of scaffold position on enzyme properties. Here, we use a computational-experimental approach to develop a model for the effects of DNA scaffold position on enzyme kinetics. Using phosphotriesterase modified with a 20bp dsDNA, we demonstrate that conjugation position is as important as the scaffold's chemistry and structure. Multiscale simulations predict the effective substrate concentration increases close to the scaffold, which has μM-strength binding to the substrate. Kinetic analysis shows that the effective concentration that the scaffold provides is best utilized when positioned next to, but not blocking, the active site. At ~5Å distance between scaffold and active site a 7-fold increase in k cat /K M was achieved. A model that accounts for the substrate concentration as well PTE-DNA geometry accurately captures the kinetic enhancements, enabling prediction of the effect across a range of DNA positions.
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Affiliation(s)
- Xiao Hong
- Department of Biochemistry, University of California-Riverside, Riverside, CA, 92521
| | - Timothy Cholko
- Department of Chemistry, University of California-Riverside, Riverside, CA, 92521
| | - Chia-en A. Chang
- Department of Chemistry, University of California-Riverside, Riverside, CA, 92521
| | - Ian Wheeldon
- Department of Chemical and Environmental Engineering, University of California-Riverside, Riverside, CA, 92521
- Center for Industrial Biotechnology, University of California-Riverside, Riverside, CA, 92521
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Fu Y, Fan F, Wang B, Cao Z. Water-Regulated Mechanisms for Degradation of Pesticides Paraoxon and Parathion by Phosphotriesterase: Insight from QM/MM and MD Simulations. Chem Asian J 2022; 17:e202200439. [PMID: 35586954 DOI: 10.1002/asia.202200439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/12/2022] [Indexed: 11/06/2022]
Abstract
The enzymatic degradation of pesticides paraoxon (PON) and parathion (PIN) by phosphotriesterase (PTE) has been investigated by QM/MM calculations and MD simulations. In the PTE-PON complex, Zn α and Zn β in the active site are five- and six-coordinated, respectively, while both zinc ions are six coordinated with the Zn α -bound water molecule (WT1) for the PTE-PIN system. The hydrolytic reactions for PON and PIN are respectively driven by the nucleophilic attack of the bridging-OH - and the Zn α -bound water molecule on the phosphorus center of substrate, and the two-step hydrolytic process is predicted to be the rate-limiting step with the energy spans of 13.8 and 14.4 kcal/mol for PON and PIN, respectively. The computational studies reveal that the presence of the Zn α -bound water molecule depends on the structural feature of substrates characterized by P=O and P=S, which determines the hydrolytic mechanism and efficiency for the degradation of organophosphorus pesticides by PTE.
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Affiliation(s)
- Yuzhuang Fu
- Xiamen University, Department of Chemistry, CHINA
| | - Fangfang Fan
- Zhejiang University of Science and Technology, School of Biological and Chemical Engineering, CHINA
| | - Binju Wang
- Xiamen University, Department of Chemistry, CHINA
| | - Zexing Cao
- Xiamen University, Department of Chemistry, Si Ming Nan Lu, 361005, Xiamen, CHINA
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Fu Y, Zhang Y, Fan F, Wang B, Cao Z. Degradation of pesticides diazinon and diazoxon by phosphotriesterase: insight into divergent mechanisms from QM/MM and MD simulations. Phys Chem Chem Phys 2022; 24:687-696. [PMID: 34927643 DOI: 10.1039/d1cp05034f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Enzymatic hydrolysis by phosphotriesterase (PTE) is one of the most effective ways of degrading organophosphorus pesticides, but the catalytic efficiency depends on the structural features of substrates. Here the enzymatic degradation of diazinon (DIN) and diazoxon (DON), characterized by PS and PO, respectively, have been investigated by QM/MM calculations and MM MD simulations. Our calculations demonstrate that the hydrolysis of DON (with PO) is inevitably initiated by the nucleophilic attack of the bridging-OH- on the phosphorus center, while for DIN (with PS), we proposed a new degradation mechanism, initiated by the nucleophilic attack of the Znα-bound water molecule, for its low-energy pathway. For both DIN and DON, the hydrolytic reaction is predicted to be the rate-limiting step, with energy barriers of 18.5 and 17.7 kcal mol-1, respectively. The transportation of substrates to the active site, the release of the leaving group and the degraded product are generally verified to be favorable by MD simulations via umbrella sampling, both thermodynamically and dynamically. The side-chain residues Phe132, Leu271 and Tyr309 play the gate-switching role to manipulate substrate delivery and product release. In comparison with the DON-enzyme system, the degraded product of DIN is more easily released from the active site. These new findings will contribute to the comprehensive understanding of the enzymatic degradation of toxic organophosphorus compounds by PTE.
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Affiliation(s)
- Yuzhuang Fu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Yuwei Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Fangfang Fan
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, 310023, China.
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
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Arora S, Kumar A. Mixture toxicity assessment of selected insecticides to silver perch fingerling, Bidyanus bidyanus. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 226:112790. [PMID: 34653840 DOI: 10.1016/j.ecoenv.2021.112790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/08/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
The organophosphorus (OP) and carbamate (CB) insecticides are responsible for inhibition of the Acetylcholinesterase (AChE) enzyme. The AChE activity, therefore, has been demonstrated to be a potent biomarker for these insecticides in terrestrial and aquatic environments. The objective of this study was to investigate the response of AChE in the brain of four-week old fingerlings of silver perch, Bidyanus bidyanus exposed to OP and CB insecticides. The fish fingeling were exposed to three OPs and one CB insecticide as individual and their binary mixtures for 48 h. The OP insecticides with oxon (PO) as well as thion (PS) group gets oxidized to oxon analogs in biological systems. The 50% AChE inhibition (48 h EC50) in fingerling exposed to chlorpyrifos (CPF) and triazophos (TRZ) was evident at 2.3 and 6.7 µg/L, respectively. The toxicological interaction of three OPs and one CB insecticide was evaluated using the toxic unit method. A strong synergism was observed for binary combination of CPF with profenofos (PRF), and CPF with TAZ. In contrast, the mixture of TAZ with PRF and carbofuran (CBF) with CPF and PRF showed antagonistic behavior. Although OP and CB insecticides can break down rapidly in the environment, this study suggests that non-target aquatic biota may be exposed to mixtures of ChE-inhibiting insecticides for a period of several months, in agricultural regions where insecticides are applied for extended periods of the year. And at environmentally relevant concentrations such mixtures may lead to deleterious effects in non-target organisms.
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Affiliation(s)
- Sumitra Arora
- ICAR-National Research Centre for Integrated Pest Management, PUSA New Delhi-12, India.
| | - Anu Kumar
- Land and Water, CSIRO, Waite Campus, Urrbrae, South Australia 5064, Australia
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Santana MS, Sandrini-Neto L, Di Domenico M, Prodocimo MM. Pesticide effects on fish cholinesterase variability and mean activity: A meta-analytic review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 757:143829. [PMID: 33248758 DOI: 10.1016/j.scitotenv.2020.143829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 06/12/2023]
Abstract
Fish cholinesterases (ChEs) - like acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) - are common biomarkers of environmental contamination due to their sensitivity to a variety of toxicants. To understand pesticide effects on fish ChEs mean activity and variability, we conducted a systematic review and meta-analyses. Our goal was to verify (i) if brain and muscle ChEs responded differently to pesticide exposure; (ii) how fish size and life stage (i.e., juvenile and adult) influence ChEs variability and mean activity; (iii) what type of pesticides (i.e., herbicide, insecticide, and fungicide) has the strongest effect, and if the analytical-grade compounds differ from commercial formulations; (iv) if increasing concentrations combined with prolonged exposure leads to stronger ChEs inhibition; and (v) how each class of pesticide affects these enzymes. We validated ChEs reliability as biomarkers and identified factors influencing their response. Regardless of tissue, BChE response was more variable than AChE, and no difference between their average activity was detected. The size of juvenile fish is an important factor affecting ChEs mean activity and variability, whereas pesticide had no significant effect on adult fish ChEs. Insecticides were stronger inhibitors compared to herbicides and fungicides. Analytical-grade compounds decreased ChEs mean activity to a higher degree than commercial formulations. The combined effect of concentration and time was only significant for fungicides and insecticides. Among classes, organophosphorus insecticides had the strongest effect on ChEs, followed by carbamates, organochlorines, and pyrethroids. Organophosphorus herbicides and oxazolidinones were the only herbicides to decrease ChEs mean activity significantly, and their effects were similar from those of pyrethroids and organochlorines. Additionally, our results identified research gaps, such as the small number of studies on fungicides, neonicotinoids and other relevant pesticides. These findings suggest future directions, which might help researchers identify robust cause-effect relationships between fish ChEs and pesticides.
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Affiliation(s)
- Manuela S Santana
- Departamento de Biologia Celular, Setor de Ciências Biológicas, Universidade Federal do Paraná, CEP 81.531-980 Curitiba, Paraná, Brazil; Centro de Estudos do Mar, Universidade Federal do Paraná, CEP 83255-976 Pontal do Paraná, Paraná, Brazil.
| | - Leonardo Sandrini-Neto
- Centro de Estudos do Mar, Universidade Federal do Paraná, CEP 83255-976 Pontal do Paraná, Paraná, Brazil
| | - Maikon Di Domenico
- Centro de Estudos do Mar, Universidade Federal do Paraná, CEP 83255-976 Pontal do Paraná, Paraná, Brazil
| | - Maritana Mela Prodocimo
- Departamento de Biologia Celular, Setor de Ciências Biológicas, Universidade Federal do Paraná, CEP 81.531-980 Curitiba, Paraná, Brazil
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9
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Mitchell CJ, Lawrence E, Chu VR, Harris MJ, Landis WG, von Stackelberg KE, Stark JD. Integrating Metapopulation Dynamics into a Bayesian Network Relative Risk Model: Assessing Risk of Pesticides to Chinook Salmon (Oncorhynchus tshawytscha) in an Ecological Context. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2021; 17:95-109. [PMID: 33064347 DOI: 10.1002/ieam.4357] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/15/2020] [Accepted: 10/06/2020] [Indexed: 05/20/2023]
Abstract
The population level is often the biological endpoint addressed in ecological risk assessments (ERAs). However, ERAs tend to ignore the metapopulation structure, which precludes an understanding of how population viability is affected by multiple stressors (e.g., toxicants and environmental conditions) at large spatial scales. Here we integrate metapopulation model simulations into a regional-scale, multiple stressors risk assessment (Bayesian network relative risk model [BN-RRM]) of organophosphate (OP) exposure, water temperature, and DO impacts on Chinook salmon (Oncorhynchus tshawytscha). A matrix metapopulation model was developed for spring Chinook salmon in the Yakima River Basin (YRB), Washington, USA, including 3 locally adapted subpopulations and hatchery fish that interact with those subpopulations. Three metapopulation models (an exponential model, a ceiling density-dependent model, and an exponential model without dispersal) were integrated into the BN-RRM to evaluate the effects of population model assumptions on risk calculations. Risk was defined as the percent probability that the abundance of a subpopulation would decline from their initial abundance (500 000). This definition of risk reflects the Puget Sound Partnership's management goal of achieving "no net loss" of Chinook abundance. The BN-RRM model results for projection year 20 showed that risk (in % probability) from OPs and environmental stressors was higher for the wild subpopulations-the American River (50.9%-97.7%) and Naches (39.8%-84.4%) spring Chinook-than for the hatchery population (CESRF 18.5%-46.5%) and the Upper Yakima subpopulation (21.5%-68.7%). Metapopulation risk was higher in summer (58.1%-68.7%) than in winter (33.6%-53.2%), and this seasonal risk pattern was conserved at the subpopulation level. To reach the management goal in the American River spring Chinook subpopulation, the water temperature conditions in the Lower Yakima River would need to decrease. We demonstrate that 1) relative risk can vary across a metapopulation's spatial range, 2) dispersal among patches impacts subpopulation abundance and risk, and 3) local adaptation within a salmon metapopulation can profoundly impact subpopulation responses to equivalent stressors. Integr Environ Assess Manag 2021;17:95-109. © 2020 SETAC.
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Affiliation(s)
| | - Eric Lawrence
- Institute of Environmental Toxicology, Huxley College of the Environment, Western Washington University, Bellingham, Washington, USA
| | - Valerie R Chu
- Institute of Environmental Toxicology, Huxley College of the Environment, Western Washington University, Bellingham, Washington, USA
| | | | - Wayne G Landis
- Institute of Environmental Toxicology, Huxley College of the Environment, Western Washington University, Bellingham, Washington, USA
| | | | - John D Stark
- Washington State University, Puyallup, Washington, USA
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Laetz CA, Baldwin DH, Scholz NL. Sublethal neurotoxicity of organophosphate insecticides to juvenile coho salmon. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 221:105424. [PMID: 32058876 DOI: 10.1016/j.aquatox.2020.105424] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 01/08/2020] [Accepted: 01/26/2020] [Indexed: 06/10/2023]
Abstract
For decades, organophosphate (OP) insecticides have been used as chemical control agents in watersheds that support at-risk populations of Pacific salmon throughout western North America. Spray drift, runoff, and other processes transport OPs to critical surface water habitats for migratory salmonids. While most OPs share a common mechanism of action (i.e., inhibition of neuronal acetylcholinesterase, or AChE), they typically vary in toxic potency. Moreover, dose-response relationships for exposure and sublethal neurotoxicity (e.g., brain AChE inhibition) in salmonids have not been defined for many OPs. Here we exposed juvenile coho salmon (Oncorhynchus kisutch) to five common anticholinesterase insecticides (dimethoate, ethoprop, naled, phorate and phosmet) that are widely used on agricultural, commercial, residential, and public lands. Each of the five pesticides produced a concentration-dependent inhibition of AChE enzyme activity. The effective concentration for 50 % AChE inhibition (96-hr EC50) indicated the highest toxicity for phorate (EC50 = 0.57 μg/L) followed by phosmet (3.3 μg/L), naled (7.8 μg/L), ethoprop (90.6 μg/L) and dimethoate (273 μg/L). These findings can inform 1) relative hazard analyses for OP use near sensitive aquatic habitats, 2) predictions of sublethal OP mixture toxicity, and 3) ecological risk assessments for threatened or endangered species of Pacific salmon.
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Affiliation(s)
- Cathy A Laetz
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, USA.
| | - David H Baldwin
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, USA
| | - Nathaniel L Scholz
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, USA
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Alavinia SJ, Mirvaghefi A, Farahmand H, Rafiee G, Alavinia SJ, Shiry N, Moodi S. DNA damage, acetylcholinesterase activity, and hematological responses in rainbow trout exposed to the organophosphate malathion. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 182:109311. [PMID: 31272021 DOI: 10.1016/j.ecoenv.2019.05.081] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 05/27/2019] [Accepted: 05/30/2019] [Indexed: 06/09/2023]
Abstract
Effects of sub-lethal concentrations (0 (control), 0.009, 0.014, and 0.023 ppm) of the organophosphate insecticide "malathion" to rainbow trout (Oncorhynchus mykiss) after the determination of LC50-96 h value (0.093 ppm) were evaluated. Changes in biomarkers of neurotoxicity (acetylcholinesterase (AChE) activity), genotoxicity (DNA damage), and hematological parameters (red (RBC) and white (WBC) blood cell count, hemoglobin (Hb), hematocrit (Hct), mean cell hemoglobin (MCH), mean cell volume (MCV), and mean cell hemoglobin concentration (MCHC)) were assessed for a 15-day exposure. A significant time- and dose-dependent reduction in AChE activities of gill, muscle, brain, and liver tissues was found. However, the AChE activity was less affected by malathion concentration than by exposure time. DNA damage of erythrocytes at different malathion concentrations increased by increasing the experimental time up to the fourth day. A decrease in the count of WBC, RBC, and Hct and an increase in the number of MCH and MCV were observed by increasing malathion exposure dose and time (p < 0.05). An increase in the malathion concentration and exposure time significantly resulted in a decrease in Hb and an increase in MCHC. A significant improvement in AChE activity; DNA damage; and RBC, Hb, Hct, MCV, and MCH indices was detected during a 30-day recovery period, but the WBC count changed insignificantly. The recovery pattern based on 100% water exchange with clean water could be a successful strategy to improve the biomarker responses of rainbow trout habituating in contaminated aquatic environments.
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Affiliation(s)
- Seyed Jalil Alavinia
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Iran.
| | - Alireza Mirvaghefi
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Iran
| | - Hamid Farahmand
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Iran
| | - Gholamreza Rafiee
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Iran
| | | | - Nima Shiry
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Iran
| | - Saeed Moodi
- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Iran
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Pham B, Miranda A, Allinson G, Nugegoda D. Assessing interactive mixture toxicity of carbamate and organophosphorus insecticides in the yabby (Cherax destructor). ECOTOXICOLOGY (LONDON, ENGLAND) 2018; 27:1217-1224. [PMID: 30187357 DOI: 10.1007/s10646-018-1973-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/21/2018] [Indexed: 06/08/2023]
Abstract
Carbamate (CB) and organophosphorus (OP) pesticides are commonly detected in aquatic ecosystems and predominantly occur as mixtures of varying complexity. These pesticides inhibit the activity of total cholinesterase (ChE) and thus have the potential to interfere with behaviours that may be essential for the survival of aquatic species. Although the effects of individual ChE insecticides on aquatic species have been reported for decades, the neurotoxicity of mixtures is still poorly understood. This study examined the chronic toxicities of two OP insecticides (chlorpyrifos (CPF) and malathion (MAL)) and one carbamate insecticide (methomyl (METH)) in binary and ternary mixtures on the ChE activity of the yabby (C. destructor). Using the concentration addition approach to estimate mixture toxicity, the observed inhibition of ChE activity caused by all binary mixtures of CPF plus MAL, CPF plus METH and MAL plus METH was additive. In ternary mixtures, all combinations of CPF, MAL and METH were either additive or antagonistic depending on the relative ratios of these chemicals in the mixtures. The effect of mixtures of these three insecticides on C. destructor has not previously been assessed, and the data suggest that individual chemical risk assessments are likely to incorrectly estimate the effect of these insecticides on C. destructor in the aquatic environment where combinations of such chemicals occur.
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Affiliation(s)
- Ben Pham
- School of Science, RMIT University, Bundoora West Campus, Victoria, 3083, Australia.
| | - Ana Miranda
- School of Science, RMIT University, Bundoora West Campus, Victoria, 3083, Australia
| | - Graeme Allinson
- School of Science, RMIT University, City Campus, Melbourne, Victoria, 3001, Australia
| | - Dayanthi Nugegoda
- School of Science, RMIT University, Bundoora West Campus, Victoria, 3083, Australia
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Cacciatore LC, Verrengia Guerrero NR, Cochón AC. Toxicokinetic and toxicodynamic studies of carbaryl alone or in binary mixtures with azinphos methyl in the freshwater gastropod Planorbarius corneus. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 199:276-284. [PMID: 29689476 DOI: 10.1016/j.aquatox.2018.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 12/27/2017] [Accepted: 04/10/2018] [Indexed: 06/08/2023]
Abstract
Carbamate insecticides such as carbaryl and organophosphates such as azinphos-methyl share the ability to inhibit the activity of B-esterases. This study aimed to (1) assess the inhibitory effects of carbaryl on B-esterase activity in soft tissues and hemolymph of Planorbarius corneus; (2) establish whether binary mixtures of carbaryl and azinphos-methyl depart or not from a model of concentration addition on the inhibition of cholinesterase activity; (3) determine the bioconcentration and elimination of the pesticides. The results showed that exposure of gastropods to increasing concentrations of carbaryl (0.1-5 mg L-1) for 48 h inhibited cholinesterase activity in a concentration-dependent manner, with an EC50 of 1.4 ± 0.3 mg L-1 and 1.2 ± 0.1 mg L-1 for soft tissue and hemolymph, respectively. Carboxylesterase activity, measured with the substrates p-nitrophenyl butyrate and p-nitrophenyl acetate, was between 2.3 and 25 times more sensitive to carbaryl inhibition than cholinesterase activity. Binary mixtures corresponding to 0.5 EC50 carbaryl + 0.5 EC50 azinphos-methyl and 0.75 EC50 carbaryl + 0.75 EC50 azinphos-methyl produced inhibitions of cholinesterase activity similar to those of individual pesticides, following a model of concentration addition. Bioconcentration was analyzed using a one-compartment model. The absorption kinetics (k1) for both pesticides alone (1.4 mg L-1 of carbaryl or 1.8 mg L-1 of azinphos-methyl) or mixed (1.4 mg L-1 of carbaryl + 1.8 mg L-1 of azinphos-methyl) were similar. The elimination kinetics ratio (k2) estimated for the pesticides alone or in the mixtures showed that carbaryl was eliminated 3.5 times faster than azinphos-methyl. These results suggest that exposure of Planorbarius corneus to binary mixtures of carbaryl and azinphos-methyl for 48 h follow a concentration addition model on inhibition of cholinesterase activity and that the pesticide mixtures do not change the toxicokinetic parameters of the parent compounds.
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Affiliation(s)
- Luis Claudio Cacciatore
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Ciudad Universitaria, Nuñez, 1428, Buenos Aires, Argentina
| | - Noemí Rosario Verrengia Guerrero
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Ciudad Universitaria, Nuñez, 1428, Buenos Aires, Argentina
| | - Adriana Cristina Cochón
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Ciudad Universitaria, Nuñez, 1428, Buenos Aires, Argentina.
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14
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Tam NT, Berg H, Van Cong N. Evaluation of the joint toxicity of chlorpyrifos ethyl and fenobucarb on climbing perch (Anabas testudineus) from rice fields in the Mekong Delta, Vietnam. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:13226-13234. [PMID: 27250094 DOI: 10.1007/s11356-016-6980-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/25/2016] [Indexed: 06/05/2023]
Abstract
Organophosphates (e.g. chlorpyrifos ethyl) and carbamates (e.g. fenobucarb) are commonly used to control a wide range of pests in rice fields of the Mekong Delta in Vietnam. This study assesses the combined effect of chlorpyrifos ethyl (CPF) and fenobucarb (F), applied at concentrations used by rice farmers, on the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings from rice fields in the Mekong Delta. It also investigates if Pyridine-2-aldoxime methiodide (2-PAM) can be used to reactivate cholinesterase that has been blocked by CPF. Three days after spraying, the water concentrations of both insecticides decreased quickly below the detection levels. However, the brain AChE activity in fish was inhibited for more than 7 days. The results indicate a quicker but less prolonged inhibition of the brain AChE activity by the mixture than by only CPF. The inhibition levels were above 70 % only during the first 48 h, which could explain why all fish survived. 2-PAM resulted in a significant reactivation of the cholinesterase blocked by a combination of CPF and F, and it is proposed that the reactivation by 2-PAM could provide a way to assess the AChE inhibition levels in organisms, when no unexposed individuals are available as controls. The results indicate that the current use of CPF and F in rice farming in the Mekong Delta is likely to cause negative effects on non-target organisms. Many of these effects may be sub-lethal, and there is a need to develop biomarkers that are relevant, inexpensive and easy to apply. The results show that brain AChE in climbing perch fingerling is a relevant biomarker for monitoring of exposure to, and sub-lethal impacts from organophosphates and carbamates under tropical conditions in developing countries.
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Affiliation(s)
- Nguyen Thanh Tam
- Faculty of Fishery, Nong Lam University, Block 6, Linh Trung Ward, Thu Duc District, HCM City, Vietnam.
- Department of Physical Geography, Stockholm University, Stockholm, SE-106 91, Sweden.
| | - Håkan Berg
- Department of Physical Geography, Stockholm University, Stockholm, SE-106 91, Sweden
| | - Nguyen Van Cong
- College of Environment and Natural Resources, Can Tho University, 3/2 Street, Can Tho City, Vietnam
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15
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Binary combinations of organophosphorus and synthetic pyrethroids are more potent acetylcholinesterase inhibitors than organophosphorus and carbamate mixtures: An in vitro assessment. Toxicol Lett 2017; 268:8-16. [DOI: 10.1016/j.toxlet.2016.12.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 11/04/2016] [Accepted: 12/11/2016] [Indexed: 11/17/2022]
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16
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Shuman-Goodier ME, Propper CR. A meta-analysis synthesizing the effects of pesticides on swim speed and activity of aquatic vertebrates. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 565:758-766. [PMID: 27261557 DOI: 10.1016/j.scitotenv.2016.04.205] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 04/15/2023]
Abstract
Pesticide contaminants are ubiquitous in aquatic environments and pose a threat to biodiversity. Pesticides also have diverse mechanisms of action that make it difficult to identify impacts on exposed wildlife. Behavioral measures represent an important link between physiological and ecological processes, and are often used to generalize sub-lethal effects of pesticide exposure. In order to bridge the toxicological and behavioral literature, and identify chemical classes that denote the largest threat, we conducted a meta-analysis summarizing the effects of pesticides on swim speed and activity of aquatic vertebrates. We found that exposure to environmentally relevant concentrations of pesticides reduced the swim speed of exposed amphibians and fish by 35%, and reduced overall activity by 72%. There were also differences in the magnitude of this effect across chemical classes, which likely reflect underlying physiological processes. Pyrethroids, carbamates, and organophosphates all produced a large decrease in swim speed, where as phosphonoglycines and triazines showed no overall effect. Pyrethroids, carbamates, organophosphates, organochlorines, and organotins also produced a large decrease in activity, while phosphonoglycines had no overall effect, and triazines had the opposite effect of increasing activity. Our results indicate that even sub-lethal concentrations of pesticides have a strong effect on critical behaviors of aquatic vertebrates, which can affect fitness and alter species interactions. We expect our synthesis can be used to identify chemical classes producing the largest sub-lethal effects for further research and management.
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Affiliation(s)
- Molly E Shuman-Goodier
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86001, United States.
| | - Catherine R Propper
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86001, United States
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17
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Rodea-Palomares I, Gonzalez-Pleiter M, Gonzalo S, Rosal R, Leganes F, Sabater S, Casellas M, Muñoz-Carpena R, Fernández-Piñas F. Hidden drivers of low-dose pharmaceutical pollutant mixtures revealed by the novel GSA-QHTS screening method. SCIENCE ADVANCES 2016; 2:e1601272. [PMID: 27617294 PMCID: PMC5014467 DOI: 10.1126/sciadv.1601272] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/09/2016] [Indexed: 05/27/2023]
Abstract
The ecological impacts of emerging pollutants such as pharmaceuticals are not well understood. The lack of experimental approaches for the identification of pollutant effects in realistic settings (that is, low doses, complex mixtures, and variable environmental conditions) supports the widespread perception that these effects are often unpredictable. To address this, we developed a novel screening method (GSA-QHTS) that couples the computational power of global sensitivity analysis (GSA) with the experimental efficiency of quantitative high-throughput screening (QHTS). We present a case study where GSA-QHTS allowed for the identification of the main pharmaceutical pollutants (and their interactions), driving biological effects of low-dose complex mixtures at the microbial population level. The QHTS experiments involved the integrated analysis of nearly 2700 observations from an array of 180 unique low-dose mixtures, representing the most complex and data-rich experimental mixture effect assessment of main pharmaceutical pollutants to date. An ecological scaling-up experiment confirmed that this subset of pollutants also affects typical freshwater microbial community assemblages. Contrary to our expectations and challenging established scientific opinion, the bioactivity of the mixtures was not predicted by the null mixture models, and the main drivers that were identified by GSA-QHTS were overlooked by the current effect assessment scheme. Our results suggest that current chemical effect assessment methods overlook a substantial number of ecologically dangerous chemical pollutants and introduce a new operational framework for their systematic identification.
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Affiliation(s)
- Ismael Rodea-Palomares
- Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, USA
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Miguel Gonzalez-Pleiter
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Soledad Gonzalo
- Departamento de Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, 28871 Madrid, Spain
| | - Roberto Rosal
- Departamento de Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, 28871 Madrid, Spain
| | - Francisco Leganes
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Sergi Sabater
- Institut Català de Recerca de l’Aigua, Carrer d’Emili Grafhit, 101, 17003 Girona, Spain
- Instituto de Ecología Acuática, Universidad de Girona, Campus de Montilivi, 17071 Girona, Spain
| | - Maria Casellas
- Institut Català de Recerca de l’Aigua, Carrer d’Emili Grafhit, 101, 17003 Girona, Spain
| | - Rafael Muñoz-Carpena
- Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, USA
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18
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Hapke WB, Morace JL, Nilsen EB, Alvarez DA, Masterson K. Year-Round Monitoring of Contaminants in Neal and Rogers Creeks, Hood River Basin, Oregon, 2011-12, and Assessment of Risks to Salmonids. PLoS One 2016; 11:e0158175. [PMID: 27348521 PMCID: PMC4922572 DOI: 10.1371/journal.pone.0158175] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/10/2016] [Indexed: 01/25/2023] Open
Abstract
Pesticide presence in streams is a potential threat to Endangered Species Act listed salmonids in the Hood River basin, Oregon, a primarily forested and agricultural basin. Two types of passive samplers, polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs), were simultaneously deployed at four sites in the basin during Mar. 2011-Mar. 2012 to measure the presence of pesticides, polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs). The year-round use of passive samplers is a novel approach and offers several new insights. Currently used pesticides and legacy contaminants, including many chlorinated pesticides and PBDEs, were present throughout the year in the basin's streams. PCBs were not detected. Time-weighted average water concentrations for the 2-month deployment periods were estimated from concentrations of chemicals measured in the passive samplers. Currently used pesticide concentrations peaked during spring and were detected beyond their seasons of expected use. Summed concentrations of legacy contaminants in Neal Creek were highest during July-Sept., the period with the lowest streamflows. Endosulfan was the only pesticide detected in passive samplers at concentrations exceeding Oregon or U.S. Environmental Protection Agency water-quality thresholds. A Sensitive Pesticide Toxicity Index (SPTI) was used to estimate the relative acute potential toxicity among sample mixtures. The acute potential toxicity of the detected mixtures was likely greater for invertebrates than for fish and for all samples in Neal Creek compared to Rogers Creek, but the indices appear to be low overall (<0.1). Endosulfans and pyrethroid insecticides were the largest contributors to the SPTIs for both sites. SPTIs of some discrete (grab) samples from the basin that were used for comparison exceeded 0.1 when some insecticides (azinphos methyl, chlorpyrifos, malathion) were detected at concentrations near or exceeding acute water-quality thresholds. Early life stages and adults of several sensitive fish species, including salmonids, are present in surface waters of the basin throughout the year, including during periods of peak estimated potential toxicity. Based on these data, direct toxicity to salmonids from in-stream pesticide exposure is unlikely, but indirect impacts (reduced fitness due to cumulative exposures or negative impacts to invertebrate prey populations) are unknown.
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Affiliation(s)
- Whitney B. Hapke
- U.S. Geological Survey, Oregon Water Science Center, Portland, Oregon, United States of America
| | - Jennifer L. Morace
- U.S. Geological Survey, Oregon Water Science Center, Portland, Oregon, United States of America
| | - Elena B. Nilsen
- U.S. Geological Survey, Oregon Water Science Center, Portland, Oregon, United States of America
| | - David A. Alvarez
- U.S. Geological Survey, Columbia Environmental Research Center, Columbia, Missouri, United States of America
| | - Kevin Masterson
- Oregon Department of Environmental Quality, Bend, Oregon, United States of America
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19
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Wang L, Espinoza HM, MacDonald JW, Bammler TK, Williams CR, Yeh A, Louie KW, Marcinek DJ, Gallagher EP. Olfactory Transcriptional Analysis of Salmon Exposed to Mixtures of Chlorpyrifos and Malathion Reveal Novel Molecular Pathways of Neurobehavioral Injury. Toxicol Sci 2015; 149:145-57. [PMID: 26494550 DOI: 10.1093/toxsci/kfv223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pacific salmon exposed to sublethal concentrations of organophosphate pesticides (OP) have impaired olfactory function that can lead to loss of behaviors that are essential for survival. These exposures often involve mixtures and can occur at levels below those which inhibit acetylcholinesterase (AChE). In this study, juvenile Coho salmon were exposed for 24 h to either 0.1, 0.5, or 2.5 ppb chlorpyrifos (CPF), 2, 10, or 50 ppb malathion (MAL), or binary mixtures of 0.1 CPF:2 ppb MAL, 0.5 CPF:10 ppb MAL, or 2.5 CPF:10 ppb MAL to mimic single and binary environmental exposures. Microarray analysis of olfactory rosettes from pesticide-exposed salmon revealed differentially expressed genes involved in nervous system function and signaling, aryl hydrocarbon receptor signaling, xenobiotic metabolism, and mitochondrial dysfunction. Coho exposed to OP mixtures exhibited a more pronounced loss in detection of a predatory olfactory cue relative to those exposed to single compounds, whereas respirometry experiments demonstrated that exposure to OPs, individually and in mixtures, reduced maximum respiratory capacity of olfactory rosette mitochondria. The observed molecular, biochemical, and behavioral effects occurred largely in the absence of effects on brain AChE. In summary, our results provide new insights associated with the sublethal neurotoxic effects of OP mixtures relevant to environmental exposures involving molecular and cellular pathways of injury to the salmon olfactory system that underlie neurobehavioral injury.
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Affiliation(s)
- Lu Wang
- *Department of Environmental and Occupational Health Sciences and
| | | | | | - Theo K Bammler
- *Department of Environmental and Occupational Health Sciences and
| | - Chase R Williams
- *Department of Environmental and Occupational Health Sciences and
| | - Andrew Yeh
- *Department of Environmental and Occupational Health Sciences and
| | - Ke'ale W Louie
- *Department of Environmental and Occupational Health Sciences and
| | - David J Marcinek
- Department of Radiology, University of Washington, Seattle, Washington
| | - Evan P Gallagher
- *Department of Environmental and Occupational Health Sciences and
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20
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Rodea-Palomares I, González-Pleiter M, Martín-Betancor K, Rosal R, Fernández-Piñas F. Additivity and Interactions in Ecotoxicity of Pollutant Mixtures: Some Patterns, Conclusions, and Open Questions. TOXICS 2015; 3:342-369. [PMID: 29051468 PMCID: PMC5606646 DOI: 10.3390/toxics3040342] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/09/2015] [Accepted: 09/23/2015] [Indexed: 11/16/2022]
Abstract
Understanding the effects of exposure to chemical mixtures is a common goal of pharmacology and ecotoxicology. In risk assessment-oriented ecotoxicology, defining the scope of application of additivity models has received utmost attention in the last 20 years, since they potentially allow one to predict the effect of any chemical mixture relying on individual chemical information only. The gold standard for additivity in ecotoxicology has demonstrated to be Loewe additivity which originated the so-called Concentration Addition (CA) additivity model. In pharmacology, the search for interactions or deviations from additivity (synergism and antagonism) has similarly captured the attention of researchers over the last 20 years and has resulted in the definition and application of the Combination Index (CI) Theorem. CI is based on Loewe additivity, but focused on the identification and quantification of synergism and antagonism. Despite additive models demonstrating a surprisingly good predictive power in chemical mixture risk assessment, concerns still exist due to the occurrence of unpredictable synergism or antagonism in certain experimental situations. In the present work, we summarize the parallel history of development of CA, IA, and CI models. We also summarize the applicability of these concepts in ecotoxicology and how their information may be integrated, as well as the possibility of prediction of synergism. Inside the box, the main question remaining is whether it is worthy to consider departures from additivity in mixture risk assessment and how to predict interactions among certain mixture components. Outside the box, the main question is whether the results observed under the experimental constraints imposed by fractional approaches are a de fide reflection of what it would be expected from chemical mixtures in real world circumstances.
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Affiliation(s)
- Ismael Rodea-Palomares
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid E-28049, Spain.
| | - Miguel González-Pleiter
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid E-28049, Spain.
| | - Keila Martín-Betancor
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid E-28049, Spain.
| | - Roberto Rosal
- Departamento de Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, Madrid E-28871, Spain.
| | - Francisca Fernández-Piñas
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid E-28049, Spain.
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21
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Curl CL, Beresford SAA, Fenske RA, Fitzpatrick AL, Lu C, Nettleton JA, Kaufman JD. Estimating pesticide exposure from dietary intake and organic food choices: the Multi-Ethnic Study of Atherosclerosis (MESA). ENVIRONMENTAL HEALTH PERSPECTIVES 2015; 123:475-83. [PMID: 25650532 PMCID: PMC4421765 DOI: 10.1289/ehp.1408197] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 01/23/2015] [Indexed: 05/19/2023]
Abstract
BACKGROUND Organophosphate pesticide (OP) exposure to the U.S. population is dominated by dietary intake. The magnitude of exposure from diet depends partly on personal decisions such as which foods to eat and whether to choose organic food. Most studies of OP exposure rely on urinary biomarkers, which are limited by short half-lives and often lack specificity to parent compounds. A reliable means of estimating long-term dietary exposure to individual OPs is needed to assess the potential relationship with adverse health effects. OBJECTIVES We assessed long-term dietary exposure to 14 OPs among 4,466 participants in the Multi-Ethnic Study of Atherosclerosis, and examined the influence of organic produce consumption on this exposure. METHODS Individual-level exposure was estimated by combining information on typical intake of specific food items with average OP residue levels on those items. In an analysis restricted to a subset of participants who reported rarely or never eating organic produce ("conventional consumers"), we assessed urinary dialkylphosphate (DAP) levels across tertiles of estimated exposure (n = 480). In a second analysis, we compared DAP levels across subgroups with differing self-reported organic produce consumption habits (n = 240). RESULTS Among conventional consumers, increasing tertile of estimated dietary OP exposure was associated with higher DAP concentrations (p < 0.05). DAP concentrations were also significantly lower in groups reporting more frequent consumption of organic produce (p < 0.02). CONCLUSIONS Long-term dietary exposure to OPs was estimated from dietary intake data, and estimates were consistent with DAP measurements. More frequent consumption of organic produce was associated with lower DAPs.
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Affiliation(s)
- Cynthia L Curl
- Department of Environmental and Occupational Health Sciences, and 2Department of Epidemiology, University of Washington, Seattle, Washington, USA
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22
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Arora S, Kumar A. Binary combinations of organophosphorus pesticides exhibit differential toxicity under oxidised and un-oxidised conditions. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 115:93-100. [PMID: 25682586 DOI: 10.1016/j.ecoenv.2015.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 01/04/2015] [Accepted: 01/07/2015] [Indexed: 06/04/2023]
Abstract
Acetylcholinesterase (AChE) inhibition has been demonstrated to be useful as a biomarker for exposure to organophosphorus (OP) insecticides in many environments. The objective of this study was to investigate the response of housefly (Musca domestica) head AChE (HF-AChE) exposed to five OPs as individual compounds and their binary mixtures under in vitro conditions. To examine the effects of oxidation on OP potency in the HF-AChE system, bromine water was used as an oxidisng agent. With oxidation, the sensitivity of HF-AChE to chlorpyrifos (CPF), malathion (MLT) and triazophos (TRZ) increased significantly. Monocrotophos (MCP) and profenofos (PRF) did not exhibit any significant differences in toxicity under oxidised and un-oxidised conditions. The toxicological interaction of five organophosphorus pesticides was evaluated using the concentration addition model, the combination index-isobologram equation and the toxic unit approach. All three models provided similar predictions for the 10 binary combinations of OPs under oxidised and un-oxidised conditions. In the present study, the antagonistic effects of the binary combination of OPs (CPF+PRF, CPF+MLT, MCP+MLT, PRF+MLT, MLT+TRZ and PRF+TRZ) were observed under oxidised conditions. This may be due to dispositional and/or receptor antagonism. Most of the binary combinations assayed under un-oxidised conditions exhibited synergistic responses. Triazophos showed very strong synergism in binary combinations with CPF, MCP and PRF un-oxidised conditions. In contrast, under oxidised conditions, only CPF+TRZ exhibited synergism. The results obtained indicate differential toxicity of binary combinations of OPs under oxidised and un-oxidised conditions. This information could be a valuable tool in understanding the mechanisms of OPs interactions and the interpretation of future in vivo studies with mixtures of OP insecticides.
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Affiliation(s)
- Sumitra Arora
- ICAR-National Centre for Integrated Pest Management, PUSA Campus, New Delhi 12, India; Land and Water, CSIRO, Waite Campus, Urrbrae, South Australia 5064, Australia.
| | - Anu Kumar
- Land and Water, CSIRO, Waite Campus, Urrbrae, South Australia 5064, Australia.
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23
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Jain C, Choudhary N, Nagar M, Seth G. Synthesis and Biological Activity of Organophosphates Phenoxy Derivatives Derived from 2-Mercapto Benzoxazole. PHOSPHORUS SULFUR 2014. [DOI: 10.1080/10426507.2014.887076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Chandni Jain
- Department of Chemistry, University of Rajasthan, Jaipur 302004, India
| | - Neeru Choudhary
- Department of Chemistry, University of Rajasthan, Jaipur 302004, India
| | - Meena Nagar
- Department of Chemistry, University of Rajasthan, Jaipur 302004, India
| | - Gita Seth
- Department of Chemistry, University of Rajasthan, Jaipur 302004, India
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24
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Dietrich JP, Van Gaest AL, Strickland SA, Arkoosh MR. The impact of temperature stress and pesticide exposure on mortality and disease susceptibility of endangered Pacific salmon. CHEMOSPHERE 2014; 108:353-9. [PMID: 24559935 DOI: 10.1016/j.chemosphere.2014.01.079] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/18/2014] [Accepted: 01/30/2014] [Indexed: 05/13/2023]
Abstract
Anthropogenic stressors, including chemical contamination and temperature stress, may contribute to increased disease susceptibility in aquatic animals. Specifically, the organophosphate pesticide malathion has been detected in surface waters inhabited by threatened and endangered salmon. In the presence of increasing water temperatures, malathion may increase susceptibility to disease and ultimately threaten salmon survival. This work examines the effect of acute and sublethal exposures to malathion on ocean-type subyearling Chinook salmon held under two temperature regimes. Chinook salmon were exposed to malathion at optimal (11 °C) or elevated (19 and 20 °C) temperatures. The influence of temperature on the acute toxicity of malathion was determined by generating 96-h lethal concentration (LC) curves. A disease challenge assay was also used to assess the effects of sublethal malathion exposure. The malathion concentration that resulted in 50% mortality (LC50; 274.1 μg L(-1)) of the Chinook salmon at 19 °C was significantly less than the LC50 at 11 °C (364.2 μg L(-1)). Mortality increased 11.2% in Chinook salmon exposed to malathion at the elevated temperature and challenged with Aeromonas salmonicida compared to fish held at the optimal temperature and exposed to malathion or the carrier control. No difference in disease challenge mortality was observed among malathion-exposed and unexposed fish at the optimal temperature. The interaction of co-occurring stressors may have a greater impact on salmon than if they occur in isolation. Ecological risk assessments considering the effects of an individual stressor on threatened and endangered salmon may underestimate risk when additional stressors are present in the environment.
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Affiliation(s)
- Joseph P Dietrich
- Environmental & Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2032 SE OSU Drive, Newport, OR 97365, USA.
| | - Ahna L Van Gaest
- Environmental & Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2032 SE OSU Drive, Newport, OR 97365, USA.
| | - Stacy A Strickland
- Environmental & Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2032 SE OSU Drive, Newport, OR 97365, USA.
| | - Mary R Arkoosh
- Environmental & Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2032 SE OSU Drive, Newport, OR 97365, USA.
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Macneale KH, Spromberg JA, Baldwin DH, Scholz NL. A modeled comparison of direct and food web-mediated impacts of common pesticides on Pacific salmon. PLoS One 2014; 9:e92436. [PMID: 24686837 PMCID: PMC3970969 DOI: 10.1371/journal.pone.0092436] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 02/21/2014] [Indexed: 11/18/2022] Open
Abstract
In the western United States, pesticides used in agricultural and urban areas are often detected in streams and rivers that support threatened and endangered Pacific salmon. Although concentrations are rarely high enough to cause direct salmon mortality, they can reach levels sufficient to impair juvenile feeding behavior and limit macroinvertebrate prey abundance. This raises the possibility of direct adverse effects on juvenile salmon health in tandem with indirect effects on salmon growth as a consequence of reduced prey abundance. We modeled the growth of ocean-type Chinook salmon (Oncorhynchus tshawytscha) at the individual and population scales, investigating insecticides that differ in how long they impair salmon feeding behavior and in how toxic they are to salmon compared to macroinvertebrates. The relative importance of these direct vs. indirect effects depends both on how quickly salmon can recover and on the relative toxicity of an insecticide to salmon and their prey. Model simulations indicate that when exposed to a long-acting organophosphate insecticide that is highly toxic to salmon and invertebrates (e.g., chlorpyrifos), the long-lasting effect on salmon feeding behavior drives the reduction in salmon population growth with reductions in prey abundance having little additional impact. When exposed to short-acting carbamate insecticides at concentrations that salmon recover from quickly but are lethal to invertebrates (e.g., carbaryl), the impacts on salmon populations are due primarily to reductions in their prey. For pesticides like carbaryl, prey sensitivity and how quickly the prey community can recover are particularly important in determining the magnitude of impact on their predators. In considering both indirect and direct effects, we develop a better understanding of potential impacts of a chemical stressor on an endangered species and identify data gaps (e.g., prey recovery rates) that contribute uncertainty to these assessments.
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Affiliation(s)
- Kate H. Macneale
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
| | - Julann A. Spromberg
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
| | - David H. Baldwin
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
| | - Nathaniel L. Scholz
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
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Laetz CA, Baldwin DH, Hebert VR, Stark JD, Scholz NL. Elevated temperatures increase the toxicity of pesticide mixtures to juvenile coho salmon. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 146:38-44. [PMID: 24270668 DOI: 10.1016/j.aquatox.2013.10.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/21/2013] [Accepted: 10/23/2013] [Indexed: 06/02/2023]
Abstract
Pesticide mixtures and elevated temperatures are parallel freshwater habitat stressors for Pacific salmon in the western United States. Certain combinations of organophosphate (OP) insecticides are known to synergistically increase neurotoxicity in juvenile salmon. The chemicals interact to potentiate the inhibition of brain acetylcholinesterase (AChE) and disrupt swimming behavior. The metabolic activation and detoxification of OPs involve temperature-sensitive enzymatic processes. Salmon are ectothermic, and thus the degree of synergism may vary with ambient temperature in streams, rivers, and lakes. Here we assess the influence of water temperature (12-21°C) on the toxicity of ethoprop and malathion, alone and in combination, to juvenile coho salmon (Oncorhynchus kisutch). A mixture of ethoprop (0.9 μg/L) and malathion (0.75 μg/L) produced synergistic AChE inhibition at 12°C, and the degree of neurotoxicity approximately doubled with a modest temperature increase to 18°C. Slightly lower concentrations of ethoprop (0.5 μg/L) combined with malathion (0.4 μg/L) did not inhibit brain AChE activity but did produce a temperature-dependent reduction in liver carboxylesterase (CaE). The activity of CaE was very sensitive to the inhibitory effects of ethoprop alone and both ethoprop-malathion combinations across all temperatures. Our findings are an example of how non-chemical habitat attributes can increase the relative toxicity of OP mixtures. Surface temperatures currently exceed water quality criteria in many western river segments, and summer thermal extremes are expected to become more frequent in a changing climate. These trends reinforce the importance of pollution reduction strategies to enhance ongoing salmon conservation and recovery efforts.
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Affiliation(s)
- Cathy A Laetz
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, United States
| | - David H Baldwin
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, United States
| | - Vincent R Hebert
- Food and Environmental Laboratory, Washington State University-TriCities, 2710 Crimson Way, Richland, WA 99354, United States
| | - John D Stark
- Department of Entomology, Ecotoxicology Program, Puyallup Research and Extension Center, Washington State University, 7612 Pioneer Way E., Puyallup, WA 98371, United States
| | - Nathaniel L Scholz
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E., Seattle, WA 98112, United States.
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