The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Beate I. Escher - One of the best experts on this subject based on the ideXlab platform.
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effect based trigger values for in vitro and in vivo Bioassays performed on surface water extracts supporting the environmental quality standards eqs of the european water framework directive
Science of The Total Environment, 2018Co-Authors: Beate I. Escher, Sebastian Buchinger, Selim Aїtaїssa, Peter A Behnisch, Sarah E Crawford, François Brion, Werner Brack, A Brouwer, David Du PasquierAbstract:Effect-based methods including cell-based Bioassays, reporter gene assays and whole-organism assays have been applied for decades in water quality monitoring and testing of enriched solid-phase extracts. There is no common EU-wide agreement on what level of Bioassay response in water extracts is acceptable. At present, Bioassay results are only benchmarked against each other but not against a consented measure of chemical water quality. The EU environmental quality standards (EQS) differentiate between acceptable and unacceptable surface water concentrations for individual chemicals but cannot capture the thousands of chemicals in water and their biological action as mixtures. We developed a method that reads across from existing EQS and includes additional mixture considerations with the goal that the derived effect-based trigger values (EBT) indicate acceptable risk for complex mixtures as they occur in surface water. Advantages and limitations of various approaches to read across from EQS are discussed and distilled to an algorithm that translates EQS into their corresponding bioanalytical equivalent concentrations (BEQ). The proposed EBT derivation method was applied to 48 in vitro Bioassays with 32 of them having sufficient information to yield preliminary EBTs. To assess the practicability and robustness of the proposed approach, we compared the tentative EBTs with observed environmental effects. The proposed method only gives guidance on how to derive EBTs but does not propose final EBTs for implementation. The EBTs for some Bioassays such as those for estrogenicity are already mature and could be implemented into regulation in the near future, while for others it will still take a few iterations until we can be confident of the power of the proposed EBTs to differentiate good from poor water quality with respect to chemical contamination.
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in vitro Bioassays to evaluate complex chemical mixtures in recycled water
Water Research, 2015Co-Authors: Bingfeng Dong, Erin M Snyder, Erik Prochazka, Frederic D.l. Leusch, Beate I. Escher, Janet Y. M. Tang, Shane A. SnyderAbstract:With burgeoning population and diminishing availability of freshwater resources, the world continues to expand the use of alternative water resources for drinking, and the quality of these sources has been a great concern for the public as well as public health professionals. In vitro Bioassays are increasingly being used to enable rapid, relatively inexpensive toxicity screening that can be used in conjunction with analytical chemistry data to evaluate water quality and the effectiveness of water treatment. In this study, a comprehensive Bioassay battery consisting of 36 Bioassays covering 18 biological endpoints was applied to screen the bioactivity of waters of varying qualities with parallel treatments. Samples include wastewater effluent, ultraviolet light (UV) and/or ozone advanced oxidation processed (AOP) recycled water, and infiltrated recycled groundwater. Based on assay sensitivity and detection frequency in the samples, several endpoints were highlighted in the battery, including assays for genotoxicity, mutagenicity, estrogenic activity, glucocorticoid activity, arylhydrocarbon receptor activity, oxidative stress response, and cytotoxicity. Attenuation of bioactivity was found to be dependent on the treatment process and Bioassay endpoint. For instance, ozone technology significantly removed oxidative stress activity, while UV based technologies were most efficient for the attenuation of glucocorticoid activity. Chlorination partially attenuated genotoxicity and greatly decreased herbicidal activity, while groundwater infiltration efficiently attenuated most of the evaluated bioactivity with the exception of genotoxicity. In some cases, bioactivity (e.g., mutagenicity, genotoxicity, and arylhydrocarbon receptor) increased following water treatment, indicating that transformation products of water treatment may be a concern. Furthermore, several types of Bioassays with the same endpoint were compared in this study, which could help guide the selection of optimized methods in future studies. Overall, this research indicates that a battery of Bioassays can be used to support decision-making on the application of advanced water treatment processes for removal of bioactivity.
Shane A. Snyder - One of the best experts on this subject based on the ideXlab platform.
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in vitro Bioassays to evaluate complex chemical mixtures in recycled water
Water Research, 2015Co-Authors: Bingfeng Dong, Erin M Snyder, Erik Prochazka, Frederic D.l. Leusch, Beate I. Escher, Janet Y. M. Tang, Shane A. SnyderAbstract:With burgeoning population and diminishing availability of freshwater resources, the world continues to expand the use of alternative water resources for drinking, and the quality of these sources has been a great concern for the public as well as public health professionals. In vitro Bioassays are increasingly being used to enable rapid, relatively inexpensive toxicity screening that can be used in conjunction with analytical chemistry data to evaluate water quality and the effectiveness of water treatment. In this study, a comprehensive Bioassay battery consisting of 36 Bioassays covering 18 biological endpoints was applied to screen the bioactivity of waters of varying qualities with parallel treatments. Samples include wastewater effluent, ultraviolet light (UV) and/or ozone advanced oxidation processed (AOP) recycled water, and infiltrated recycled groundwater. Based on assay sensitivity and detection frequency in the samples, several endpoints were highlighted in the battery, including assays for genotoxicity, mutagenicity, estrogenic activity, glucocorticoid activity, arylhydrocarbon receptor activity, oxidative stress response, and cytotoxicity. Attenuation of bioactivity was found to be dependent on the treatment process and Bioassay endpoint. For instance, ozone technology significantly removed oxidative stress activity, while UV based technologies were most efficient for the attenuation of glucocorticoid activity. Chlorination partially attenuated genotoxicity and greatly decreased herbicidal activity, while groundwater infiltration efficiently attenuated most of the evaluated bioactivity with the exception of genotoxicity. In some cases, bioactivity (e.g., mutagenicity, genotoxicity, and arylhydrocarbon receptor) increased following water treatment, indicating that transformation products of water treatment may be a concern. Furthermore, several types of Bioassays with the same endpoint were compared in this study, which could help guide the selection of optimized methods in future studies. Overall, this research indicates that a battery of Bioassays can be used to support decision-making on the application of advanced water treatment processes for removal of bioactivity.
Crawford W Revie - One of the best experts on this subject based on the ideXlab platform.
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a fixed dose approach to conducting emamectin benzoate tolerance assessments on field collected sea lice lepeophtheirus salmonis
Journal of Fish Diseases, 2013Co-Authors: Shona K Whyte, J D Westcott, Ahmed M Elmoslemany, K L Hammell, Crawford W RevieAbstract:In New Brunswick, Canada, the sea louse, Lepeophtheirus salmonis, poses an on-going management challenge to the health and productivity of commercially cultured Atlantic salmon, Salmo salar. While the in-feed medication, emamectin benzoate (SLICE®; Merck), has been highly effective for many years, evidence of increased tolerance has been observed in the field since late 2008. Although Bioassays on motile stages are a common tool to monitor sea lice sensitivity to emamectin benzoate in field-collected sea lice, they require the collection of large numbers of sea lice due to inherent natural variability in the gender and stage response to chemotherapeutants. In addition, sensitive instruments such as EC50 analysis may be unnecessarily complex to characterize susceptibility subsequent to a significant observed decline in efficacy. This study proposes an adaptation of the traditional, dose-response format Bioassay to a fixed-dose method. Analysis of 657 Bioassays on preadult and adult stages of sea lice over the period 2008-2011 indicated a population of sea lice in New Brunswick with varying degrees of susceptibility to emamectin benzoate. A seasonal and spatial effect was observed in the robustness of genders and stages of sea lice, which suggest that mixing different genders and stages of lice within a single Bioassay may result in pertinent information being overlooked. Poor survival of adult female lice in Bioassays, particularly during May/June, indicates it may be prudent to consider excluding this stage from Bioassays conducted at certain times of the year. This work demonstrates that fixed-dose Bioassays can be a valuable technique in detecting reduced sensitivity in sea lice populations with varying degrees of susceptibility to emamectin benzoate treatments.
J D Westcott - One of the best experts on this subject based on the ideXlab platform.
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a fixed dose approach to conducting emamectin benzoate tolerance assessments on field collected sea lice lepeophtheirus salmonis
Journal of Fish Diseases, 2013Co-Authors: Shona K Whyte, J D Westcott, Ahmed M Elmoslemany, K L Hammell, Crawford W RevieAbstract:In New Brunswick, Canada, the sea louse, Lepeophtheirus salmonis, poses an on-going management challenge to the health and productivity of commercially cultured Atlantic salmon, Salmo salar. While the in-feed medication, emamectin benzoate (SLICE®; Merck), has been highly effective for many years, evidence of increased tolerance has been observed in the field since late 2008. Although Bioassays on motile stages are a common tool to monitor sea lice sensitivity to emamectin benzoate in field-collected sea lice, they require the collection of large numbers of sea lice due to inherent natural variability in the gender and stage response to chemotherapeutants. In addition, sensitive instruments such as EC50 analysis may be unnecessarily complex to characterize susceptibility subsequent to a significant observed decline in efficacy. This study proposes an adaptation of the traditional, dose-response format Bioassay to a fixed-dose method. Analysis of 657 Bioassays on preadult and adult stages of sea lice over the period 2008-2011 indicated a population of sea lice in New Brunswick with varying degrees of susceptibility to emamectin benzoate. A seasonal and spatial effect was observed in the robustness of genders and stages of sea lice, which suggest that mixing different genders and stages of lice within a single Bioassay may result in pertinent information being overlooked. Poor survival of adult female lice in Bioassays, particularly during May/June, indicates it may be prudent to consider excluding this stage from Bioassays conducted at certain times of the year. This work demonstrates that fixed-dose Bioassays can be a valuable technique in detecting reduced sensitivity in sea lice populations with varying degrees of susceptibility to emamectin benzoate treatments.
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optimization and field use of a Bioassay to monitor sea lice lepeophtheirus salmonis sensitivity to emamectin benzoate
Diseases of Aquatic Organisms, 2008Co-Authors: J D Westcott, John F Burka, Henrik Stryhn, Larry K HammellAbstract:A Bioassay for sea lice Lepeophtheirus salmonis sensitivity towards emamectin ben- zoate (EMB) was validated for field use. A probit regression model with natural responsiveness was used for the number of affected (moribund or dead) sea lice in Bioassays involving different concen- trations of EMB. Bioassay optimization included an evaluation of the inter-rater reliability of sea lice responsiveness to EMB and an evaluation of gender-related differences in susceptibility. Adoption of a set of Bioassay response criteria improved the concordance (evaluated using the concordance cor- relation coefficient) between raters' assessments and the model estimation of EC50 values (the 'effec- tive concentration' leading to a response of 50% of the lice not prone to natural response). An evalu- ation of gender-related differences in EMB susceptibility indicated that preadult stage female sea lice exhibited a significantly larger sensitivity towards EMB in 12 of 19 Bioassays compared to preadult males. In order to evaluate sea lice sensitivity to EMB in eastern Canada, the intensive salmon farm- ing area in the Bay of Fundy in southwestern New Brunswick was divided into 4 distinct regions based on industry health management practices and hydrographics. A total of 38 Bioassays were completed from 2002 to 2005 using populations of preadult stage sea lice collected from Atlantic salmon Salmo salar farms within the 4 described regions. There was no significant overall effect of region or year on EC50 values; however, analysis of variance indicated a significant effect of time of year on EC50 values in 2002 and a potential effect in 2004 to 2005. Although the range of EC50 values obtained in this 3 yr study did not appear sufficient to affect current clinical success in the control of sea lice, the results suggest a seasonal- or temperature-associated variation in sensitivity to EMB. This will need to be considered if changes in EMB efficacy occur in the future.
Shona K Whyte - One of the best experts on this subject based on the ideXlab platform.
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a fixed dose approach to conducting emamectin benzoate tolerance assessments on field collected sea lice lepeophtheirus salmonis
Journal of Fish Diseases, 2013Co-Authors: Shona K Whyte, J D Westcott, Ahmed M Elmoslemany, K L Hammell, Crawford W RevieAbstract:In New Brunswick, Canada, the sea louse, Lepeophtheirus salmonis, poses an on-going management challenge to the health and productivity of commercially cultured Atlantic salmon, Salmo salar. While the in-feed medication, emamectin benzoate (SLICE®; Merck), has been highly effective for many years, evidence of increased tolerance has been observed in the field since late 2008. Although Bioassays on motile stages are a common tool to monitor sea lice sensitivity to emamectin benzoate in field-collected sea lice, they require the collection of large numbers of sea lice due to inherent natural variability in the gender and stage response to chemotherapeutants. In addition, sensitive instruments such as EC50 analysis may be unnecessarily complex to characterize susceptibility subsequent to a significant observed decline in efficacy. This study proposes an adaptation of the traditional, dose-response format Bioassay to a fixed-dose method. Analysis of 657 Bioassays on preadult and adult stages of sea lice over the period 2008-2011 indicated a population of sea lice in New Brunswick with varying degrees of susceptibility to emamectin benzoate. A seasonal and spatial effect was observed in the robustness of genders and stages of sea lice, which suggest that mixing different genders and stages of lice within a single Bioassay may result in pertinent information being overlooked. Poor survival of adult female lice in Bioassays, particularly during May/June, indicates it may be prudent to consider excluding this stage from Bioassays conducted at certain times of the year. This work demonstrates that fixed-dose Bioassays can be a valuable technique in detecting reduced sensitivity in sea lice populations with varying degrees of susceptibility to emamectin benzoate treatments.