Michael S Gross (Former Employee)
Science and Products
Organic Chemistry Research Core Technology Team
About the Research The Organic Chemistry Research Laboratory Core Technology Team (CTT) as part of the Environmental Health Program focuses on the identification and quantitation of trace level organic contaminants (with a special focus on pesticides) in a wide array of environmental media (water, sediment/soil, plants, biota, etc.).
A National Assessment of Pesticide, PFAS, Microplastic, and Antibiotic Resistance Gene Exposures in White-Tailed Deer
Research has documented exposures and consequential environmental health effects of pesticides, PFAS, microplastics, and antibiotic resistance genes in environmental biota. Little is known, however, regarding such effects in white-tailed deer ( Odocoileus virginianus ).
Wild Prairie Grouse Diet and Microbiomes Vary Between Cropland and Grassland Habitats
Wild prairie grouse residing in croplands had altered diets and gut microbiome imbalances characterized by a greater abundance of pathogenic bacteria and antibiotic-resistance genes in comparison to those residing in grasslands. Similar gut microbiome imbalances are rarely associated with lethal outcomes, but rather linked to sublethal health effects including growth, development, behavior, immune...
Dysbiosis, immunomodulation, and health effects of agricultural pesticides in wild prairie grouse
Agrochemical pollution poses a severe threat to biodiversity. Agrochemicals can detrimentally affect wildlife growth, development, survival, reproduction, and immune responses, which facilitates emergence and spread of infectious diseases that may cause unusually high mortality. Animal microbiota plays a fundamental role in host’s food detoxification and defense against pathogens, regulates...
Pesticide Fate Research Group (PFRG)
Pesticides are used in both agricultural and urban settings to manage unwanted plants, insects, fungi, and other pests. However, these substances and their breakdown products can move beyond their intended application sites through various means, ending up in areas where they weren't meant to be. This movement can happen via the air, through water (both surface and groundwater), and by sticking to...
Pesticides in small volume plasma samples
Pesticides are widely applied and can enter the environment, potentially effecting non-target organisms. To better evaluate pesticide exposure using non-lethal techniques, a method was developed for the extraction of pesticides and their degradates from small (100 µL) volume plasma samples. Solid phase extraction was used for lipid removal after plasma samples were protein precipitated. Samples we
Analysis of Polyphenols in Water Primrose (Ludwigia hexapetala) Plants from the Sacramento-San Joaquin Delta of California
Water primrose (Ludwigia hexapetala) is an invasive aquatic plant that has rapidly increased in coverage throughout the Sacramento-San Joaquin Delta. Water primrose has invaded wetlands and may contribute towards mortality of tules (Schoenoplectus spp.) and cattails (Typha spp.). Little research has been completed on the mechanisms responsible for marsh loss, but previous studies have suggested th
Current-use pesticides in tree swallow (Tachycineta bicolor) prey
Analysis of biological tissues or direct sources of food may better characterize exposure of non-target organisms to current-use pesticides. Food boluses were collected from tree swallow (Tachycineta bicolor) nestlings using a non-lethal, ligature method and were composited based on nest. The ligatures, which prevented the bolus from being swallowed, were placed on nestlings for 1 h until samples
Chemical Concentrations and Microbiological Results for Assessment of Mixed-Organic/Inorganic Chemical Exposures in Tapwater in Mead, Nebraska, June 2022 and January 2023
In the United States and globally, the lack of data on contaminant exposure from unregulated private-well point-of-use (POU) tapwater (TW) is a recognized public health data gap and an obstacle to risk management and homeowner decision making. Mead, Nebraska, is an agricultural community about 30 miles west of Omaha. To help address the lack of data on broad contaminant exposures in TW sourced fro
Pesticide Concentrations Measured in Zooplankton Samples Collected from the Sacramento River and Yolo Bypass, California, 2021
Zooplankton samples were collected at one site upstream of the Yolo Bypass in Northern California, three sites within the Bypass, and at a comparison site on the Sacramento River below the city of Sacramento and analyzed for a large suite of current-use pesticides and degradates. Samples were collected every two weeks from early August 2021 to mid-October 2021. Samples were collected by towing a 1
Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive extraction with analysis by gas and liquid chromatography tandem mass spectroscopy
A multiresidue method for solids (i.e., soil, sediment, sludge) was developed and evaluated for the analysis of pesticides and pesticide degradates. Initially, a well characterized soil was used to determine the recovery of target compounds using an Energized Dispersive Guided Extraction (EDGE) system with two extraction solvents, acetonitrile and 1:1 (v/v) hexane:acetone. Extracts were cleaned us
Characterizing microbiota, virulome, and resistome of wild prairie grouse in crop producing and uncultivated areas of Nebraska
Chart listing the geographic locations, NCBI numbers, voucher numbers, and microbiome characteristics of specimens collected for publication
Evaluation of ELISA for the Analysis of Imidacloprid in Plasma, Liver, and Fecal Matter
Neonicotinoids have become the most widely used insecticides in world with rapid growth in applications as seed coatings. Nontarget organisms are exposed to concentrated levels of pesticidal active ingredients through ingestion of treated seeds. To better understand pesticide fate, analytical methods are necessary to rapidly screen and accurately quantitate contaminants in environmental and biolog
A Multiresidue Method for the Analysis of Pesticides in Water using Solid-Phase Extraction with Gas and Liquid Chromatography-Tandem Mass Spectrometry (ver. 2.0, April 2023)
Applications of pesticides in agricultural and urban settings play an essential role in increasing crop yields, preserving food and materials, reducing pest-borne diseases, and eradicating or deterring pests. Pesticides are transported from their point of application to environmental media, including surface water. To better understand the fate of fate and transport of pesticides in the environmen
Absorption, distribution, metabolism, and elimination of seed-treatment pesticides following the dosing of Japanese quail (Coturnix japonica)
Japanese quail (Coturnix japonica) were orally dosed with pesticide-treated or control-untreated wheat seeds. Pesticide treated wheat seeds were analytically verified for active ingredients of imidacloprid, metalaxyl, tebuconazole, and fludioxonil. Pesticide and metabolite residues were measured in plasma, liver, brain, kidney, muscle, and excreta of exposed and control birds. Samples were extract
In situ allelopathic expression by the invasive amphibious plant, Ludwigia hexapetala (water primrose) across habitat types, seasons, and salinities
Broad infestations of invasive, non-native vegetation have transformed wetlands around the world. Ludwigia hexapetala is a widespread, amphibious invasive plant with a creeping growth habit in open water and an erect growth habit in terrestrial habitats. In the upper San Francisco Estuary of California, L. hexapetala is increasingly terrestrializing into marshes and this expansion may be facilitat
Authors
Judith Z. Drexler, Michael Gross, Michelle Hladik, Bailey Morrison, Erin Hestir
Pesticide concentrations of surface water and suspended sediment in Yolo By-Pass and Cache Slough Complex, California, 2019–2021
Managed flow pulses in the north Sacramento-San Joaquin Delta are an adaptive management tool used in efforts to enhance food availability in delta smelt (Hypomesus transpacificus) habitat as part of the North Delta Food Subsidies Action. The California Department of Water Resources (DWR) monitors non-managed seasonal and local flow pulses and managed flow pulses from agricultural drainage or main
Authors
Matthew Uychutin, James L. Orlando, Michelle L. Hladik, Corey J. Sanders, Michael S. Gross, Matthew D. De Parsia, Elisabeth M. LaBarbera, Laura Twardochleb, Brittany E. Davis
Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme
Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark-eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse and
Authors
Allison J. Byrd, Katherine M. Talbott, Tara M. Smiley, Taylor B. Verrett, Michael S. Gross, Michelle Hladik, Ellen D. Ketterson, Daniel J. Becker
Pesticides in small volume plasma samples: Method development and application to smallmouth bass (Micropterus dolomieu) from the Chesapeake Bay watershed, USA
Nontarget organisms are exposed to pesticides following applications in agricultural and urban settings, potentially resulting in deleterious effects. Direct measurements of pesticides in biological tissues may aid in characterizing exposure, accumulation, and potential toxicity versus analyses in environmental media alone (e.g., water, soil, and air). Plasma represents a nonlethal sampling medium
Authors
Michael S. Gross, Vicki S. Blazer, Michelle Hladik
Methods of analysis—Determination of pesticides in filtered water and suspended sediment using liquid chromatography- and gas chromatography-tandem mass spectrometry
The widespread application of pesticides in agricultural and urban areas leads to their presence in surface waters. Presence of these biologically active chemicals in environmental waters potentially has adverse effects on nontarget organisms. To better understand the environmental fate of these contaminants, a robust method to capture chemicals with wide-ranging physicochemical properties has bee
Authors
Michael S. Gross, Corey J. Sanders, Matthew D. De Parsia, Michelle L. Hladik
Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive guided extraction with analysis by gas and liquid chromatography tandem mass spectroscopy
The development of sample processing techniques that recover a broad suite of pesticides from solid matrices, while mitigating coextracted matrix interferences, and reducing processing time is beneficial for high throughput analyses. The objective of this study was to evaluate the effectiveness of an automated extraction system for pesticide analyses in solid environmental samples. An Energized Di
Authors
Gabrielle Pecora Black, Emily Woodward, Corey Sanders, Michael S. Gross, Michelle Hladik
Exposure to crop production alters cecal prokaryotic microbiota, inflates virulome and resistome in wild prairie grouse
Chemically intensive crop production depletes wildlife food resources, hinders animal development, health, survival, and reproduction, and it suppresses wildlife immune systems, facilitating emergence of infectious diseases with excessive mortality rates. Gut microbiota is crucial for wildlife's response to environmental stressors. Its composition and functionality are sensitive to diet changes an
Authors
Serguei Vyacheslavovich Drovetski, Brian K. Schmidt, Jonas Ethan Lai, Michael S. Gross, Michelle Hladik, Kenan Oguz Matterson, Natalie K. Karouna-Renier
Evaluation of ELISA for the analysis of imidacloprid in biological matrices: Cross-reactivities, matrix interferences, and comparison to LC-MS/MS
Imidacloprid is among the most used pesticides worldwide and there are toxicity concerns for nontarget organisms. Accurate and sensitive methods are necessary to quantitate imidacloprid concentrations in biological matrices to better understand their fate and effects. Here we evaluated an enzyme-linked immunosorbent assay (ELISA) kit for the analysis of imidacloprid in biological samples. Followin
Authors
Michael S. Gross, Emily Woodward, Michelle Hladik
Uptake, metabolism, and elimination of fungicides from coated wheat seeds in Japanese quail (Coturnix japonica)
Pesticides coated to the seed surface potentially pose an ecological risk to granivorous birds that consume incompletely buried or spilled seeds. To assess the toxicokinetics of seeds treated with current-use fungicides, Japanese quail (Coturnix japonica) were orally dosed with commercially coated wheat seeds. Quail were exposed to metalaxyl, tebuconazole, and fludioxonil at either a low (0.07, 0.
Authors
Michael S. Gross, Thomas G. Bean, Michelle Hladik, Barnett A. Rattner, Kathryn Kuivila
Toxicokinetics of imidacloprid-coated wheat seeds in Japanese quail (Coturnix japonica) and an evaluation of hazard
Birds are potentially exposed to neonicotinoid insecticides by ingestion of coated seeds during crop planting. Adult male Japanese quail were orally dosed with wheat seeds coated with an imidacloprid (IMI) formulation at either 0.9 mg/kg body weight (BW) or 2.7 mg/kg BW (~3 and 9% of IMI LD50 for Japanese quail, respectively) for 1 or 10 days. Quail were euthanized between 1 and 24 h post-exposure
Authors
Thomas G. Bean, Michael S. Gross, Natalie K. Karouna-Renier, Paula F. P. Henry, Sandra L. Schultz, Michelle Hladik, Kathryn Kuivila, Barnett A. Rattner
Science and Products
Organic Chemistry Research Core Technology Team
About the Research The Organic Chemistry Research Laboratory Core Technology Team (CTT) as part of the Environmental Health Program focuses on the identification and quantitation of trace level organic contaminants (with a special focus on pesticides) in a wide array of environmental media (water, sediment/soil, plants, biota, etc.).
A National Assessment of Pesticide, PFAS, Microplastic, and Antibiotic Resistance Gene Exposures in White-Tailed Deer
Research has documented exposures and consequential environmental health effects of pesticides, PFAS, microplastics, and antibiotic resistance genes in environmental biota. Little is known, however, regarding such effects in white-tailed deer ( Odocoileus virginianus ).
Wild Prairie Grouse Diet and Microbiomes Vary Between Cropland and Grassland Habitats
Wild prairie grouse residing in croplands had altered diets and gut microbiome imbalances characterized by a greater abundance of pathogenic bacteria and antibiotic-resistance genes in comparison to those residing in grasslands. Similar gut microbiome imbalances are rarely associated with lethal outcomes, but rather linked to sublethal health effects including growth, development, behavior, immune...
Dysbiosis, immunomodulation, and health effects of agricultural pesticides in wild prairie grouse
Agrochemical pollution poses a severe threat to biodiversity. Agrochemicals can detrimentally affect wildlife growth, development, survival, reproduction, and immune responses, which facilitates emergence and spread of infectious diseases that may cause unusually high mortality. Animal microbiota plays a fundamental role in host’s food detoxification and defense against pathogens, regulates...
Pesticide Fate Research Group (PFRG)
Pesticides are used in both agricultural and urban settings to manage unwanted plants, insects, fungi, and other pests. However, these substances and their breakdown products can move beyond their intended application sites through various means, ending up in areas where they weren't meant to be. This movement can happen via the air, through water (both surface and groundwater), and by sticking to...
Pesticides in small volume plasma samples
Pesticides are widely applied and can enter the environment, potentially effecting non-target organisms. To better evaluate pesticide exposure using non-lethal techniques, a method was developed for the extraction of pesticides and their degradates from small (100 µL) volume plasma samples. Solid phase extraction was used for lipid removal after plasma samples were protein precipitated. Samples we
Analysis of Polyphenols in Water Primrose (Ludwigia hexapetala) Plants from the Sacramento-San Joaquin Delta of California
Water primrose (Ludwigia hexapetala) is an invasive aquatic plant that has rapidly increased in coverage throughout the Sacramento-San Joaquin Delta. Water primrose has invaded wetlands and may contribute towards mortality of tules (Schoenoplectus spp.) and cattails (Typha spp.). Little research has been completed on the mechanisms responsible for marsh loss, but previous studies have suggested th
Current-use pesticides in tree swallow (Tachycineta bicolor) prey
Analysis of biological tissues or direct sources of food may better characterize exposure of non-target organisms to current-use pesticides. Food boluses were collected from tree swallow (Tachycineta bicolor) nestlings using a non-lethal, ligature method and were composited based on nest. The ligatures, which prevented the bolus from being swallowed, were placed on nestlings for 1 h until samples
Chemical Concentrations and Microbiological Results for Assessment of Mixed-Organic/Inorganic Chemical Exposures in Tapwater in Mead, Nebraska, June 2022 and January 2023
In the United States and globally, the lack of data on contaminant exposure from unregulated private-well point-of-use (POU) tapwater (TW) is a recognized public health data gap and an obstacle to risk management and homeowner decision making. Mead, Nebraska, is an agricultural community about 30 miles west of Omaha. To help address the lack of data on broad contaminant exposures in TW sourced fro
Pesticide Concentrations Measured in Zooplankton Samples Collected from the Sacramento River and Yolo Bypass, California, 2021
Zooplankton samples were collected at one site upstream of the Yolo Bypass in Northern California, three sites within the Bypass, and at a comparison site on the Sacramento River below the city of Sacramento and analyzed for a large suite of current-use pesticides and degradates. Samples were collected every two weeks from early August 2021 to mid-October 2021. Samples were collected by towing a 1
Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive extraction with analysis by gas and liquid chromatography tandem mass spectroscopy
A multiresidue method for solids (i.e., soil, sediment, sludge) was developed and evaluated for the analysis of pesticides and pesticide degradates. Initially, a well characterized soil was used to determine the recovery of target compounds using an Energized Dispersive Guided Extraction (EDGE) system with two extraction solvents, acetonitrile and 1:1 (v/v) hexane:acetone. Extracts were cleaned us
Characterizing microbiota, virulome, and resistome of wild prairie grouse in crop producing and uncultivated areas of Nebraska
Chart listing the geographic locations, NCBI numbers, voucher numbers, and microbiome characteristics of specimens collected for publication
Evaluation of ELISA for the Analysis of Imidacloprid in Plasma, Liver, and Fecal Matter
Neonicotinoids have become the most widely used insecticides in world with rapid growth in applications as seed coatings. Nontarget organisms are exposed to concentrated levels of pesticidal active ingredients through ingestion of treated seeds. To better understand pesticide fate, analytical methods are necessary to rapidly screen and accurately quantitate contaminants in environmental and biolog
A Multiresidue Method for the Analysis of Pesticides in Water using Solid-Phase Extraction with Gas and Liquid Chromatography-Tandem Mass Spectrometry (ver. 2.0, April 2023)
Applications of pesticides in agricultural and urban settings play an essential role in increasing crop yields, preserving food and materials, reducing pest-borne diseases, and eradicating or deterring pests. Pesticides are transported from their point of application to environmental media, including surface water. To better understand the fate of fate and transport of pesticides in the environmen
Absorption, distribution, metabolism, and elimination of seed-treatment pesticides following the dosing of Japanese quail (Coturnix japonica)
Japanese quail (Coturnix japonica) were orally dosed with pesticide-treated or control-untreated wheat seeds. Pesticide treated wheat seeds were analytically verified for active ingredients of imidacloprid, metalaxyl, tebuconazole, and fludioxonil. Pesticide and metabolite residues were measured in plasma, liver, brain, kidney, muscle, and excreta of exposed and control birds. Samples were extract
In situ allelopathic expression by the invasive amphibious plant, Ludwigia hexapetala (water primrose) across habitat types, seasons, and salinities
Broad infestations of invasive, non-native vegetation have transformed wetlands around the world. Ludwigia hexapetala is a widespread, amphibious invasive plant with a creeping growth habit in open water and an erect growth habit in terrestrial habitats. In the upper San Francisco Estuary of California, L. hexapetala is increasingly terrestrializing into marshes and this expansion may be facilitat
Authors
Judith Z. Drexler, Michael Gross, Michelle Hladik, Bailey Morrison, Erin Hestir
Pesticide concentrations of surface water and suspended sediment in Yolo By-Pass and Cache Slough Complex, California, 2019–2021
Managed flow pulses in the north Sacramento-San Joaquin Delta are an adaptive management tool used in efforts to enhance food availability in delta smelt (Hypomesus transpacificus) habitat as part of the North Delta Food Subsidies Action. The California Department of Water Resources (DWR) monitors non-managed seasonal and local flow pulses and managed flow pulses from agricultural drainage or main
Authors
Matthew Uychutin, James L. Orlando, Michelle L. Hladik, Corey J. Sanders, Michael S. Gross, Matthew D. De Parsia, Elisabeth M. LaBarbera, Laura Twardochleb, Brittany E. Davis
Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme
Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark-eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse and
Authors
Allison J. Byrd, Katherine M. Talbott, Tara M. Smiley, Taylor B. Verrett, Michael S. Gross, Michelle Hladik, Ellen D. Ketterson, Daniel J. Becker
Pesticides in small volume plasma samples: Method development and application to smallmouth bass (Micropterus dolomieu) from the Chesapeake Bay watershed, USA
Nontarget organisms are exposed to pesticides following applications in agricultural and urban settings, potentially resulting in deleterious effects. Direct measurements of pesticides in biological tissues may aid in characterizing exposure, accumulation, and potential toxicity versus analyses in environmental media alone (e.g., water, soil, and air). Plasma represents a nonlethal sampling medium
Authors
Michael S. Gross, Vicki S. Blazer, Michelle Hladik
Methods of analysis—Determination of pesticides in filtered water and suspended sediment using liquid chromatography- and gas chromatography-tandem mass spectrometry
The widespread application of pesticides in agricultural and urban areas leads to their presence in surface waters. Presence of these biologically active chemicals in environmental waters potentially has adverse effects on nontarget organisms. To better understand the environmental fate of these contaminants, a robust method to capture chemicals with wide-ranging physicochemical properties has bee
Authors
Michael S. Gross, Corey J. Sanders, Matthew D. De Parsia, Michelle L. Hladik
Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive guided extraction with analysis by gas and liquid chromatography tandem mass spectroscopy
The development of sample processing techniques that recover a broad suite of pesticides from solid matrices, while mitigating coextracted matrix interferences, and reducing processing time is beneficial for high throughput analyses. The objective of this study was to evaluate the effectiveness of an automated extraction system for pesticide analyses in solid environmental samples. An Energized Di
Authors
Gabrielle Pecora Black, Emily Woodward, Corey Sanders, Michael S. Gross, Michelle Hladik
Exposure to crop production alters cecal prokaryotic microbiota, inflates virulome and resistome in wild prairie grouse
Chemically intensive crop production depletes wildlife food resources, hinders animal development, health, survival, and reproduction, and it suppresses wildlife immune systems, facilitating emergence of infectious diseases with excessive mortality rates. Gut microbiota is crucial for wildlife's response to environmental stressors. Its composition and functionality are sensitive to diet changes an
Authors
Serguei Vyacheslavovich Drovetski, Brian K. Schmidt, Jonas Ethan Lai, Michael S. Gross, Michelle Hladik, Kenan Oguz Matterson, Natalie K. Karouna-Renier
Evaluation of ELISA for the analysis of imidacloprid in biological matrices: Cross-reactivities, matrix interferences, and comparison to LC-MS/MS
Imidacloprid is among the most used pesticides worldwide and there are toxicity concerns for nontarget organisms. Accurate and sensitive methods are necessary to quantitate imidacloprid concentrations in biological matrices to better understand their fate and effects. Here we evaluated an enzyme-linked immunosorbent assay (ELISA) kit for the analysis of imidacloprid in biological samples. Followin
Authors
Michael S. Gross, Emily Woodward, Michelle Hladik
Uptake, metabolism, and elimination of fungicides from coated wheat seeds in Japanese quail (Coturnix japonica)
Pesticides coated to the seed surface potentially pose an ecological risk to granivorous birds that consume incompletely buried or spilled seeds. To assess the toxicokinetics of seeds treated with current-use fungicides, Japanese quail (Coturnix japonica) were orally dosed with commercially coated wheat seeds. Quail were exposed to metalaxyl, tebuconazole, and fludioxonil at either a low (0.07, 0.
Authors
Michael S. Gross, Thomas G. Bean, Michelle Hladik, Barnett A. Rattner, Kathryn Kuivila
Toxicokinetics of imidacloprid-coated wheat seeds in Japanese quail (Coturnix japonica) and an evaluation of hazard
Birds are potentially exposed to neonicotinoid insecticides by ingestion of coated seeds during crop planting. Adult male Japanese quail were orally dosed with wheat seeds coated with an imidacloprid (IMI) formulation at either 0.9 mg/kg body weight (BW) or 2.7 mg/kg BW (~3 and 9% of IMI LD50 for Japanese quail, respectively) for 1 or 10 days. Quail were euthanized between 1 and 24 h post-exposure
Authors
Thomas G. Bean, Michael S. Gross, Natalie K. Karouna-Renier, Paula F. P. Henry, Sandra L. Schultz, Michelle Hladik, Kathryn Kuivila, Barnett A. Rattner