Michelle L Hladik, PhD
(She/her)I am an environmental organic chemist whose current research focuses on the fate and transport of current-use pesticides and other organic contaminants in aquatic and terrestrial environments.
Much of my research is focused on pesticides but also includes other organic contaminants. I direct a research laboratory that is focused on developing new methods to measure pesticides and their degradates in water, sediment, and biota. My laboratory specializes in small samples sizes, complex matrices, and non-standard procedues. Additionally, I also work on developing methods and measuring disinfection by-products in treated water (especially those that are not-currently regulated and are understudied) with a focus on wastewater discharges.
Professional Experience
Research Chemist, USGS, California Water Science Center, Sacramento, 2006 to present
Chemist, USGS, California Water Science Center, Sacramento, 2005-2006
Graduate Fellow/Research and Teaching Assistant, Deparment of Geography and Environmental Engineering, Johns Hopkins University, 1999-2005
Undergraduate Research Summer Institute, Department of Chemistry, Vassar College, 1997,1998
Undergraduate Research and Teaching Assistant, Department of Chemistry, Vassar College ,1997,1998
Education and Certifications
Ph.D. 2005, Environmental Engineering and Chemistry, Johns Hopkins University, Baltimore, Maryland
B.A. 1999, Chemistry, Vassar College, Poughkeepsie, New York
Science and Products
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)
Pesticide detections in streams throughout the foothills of the Sierra Nevada range using passive samplers from 2017 to 2019
Insecticide and fungicide concentrations in irrigation runoff and soils from a lettuce field in the Salinas Valley, California, 2019 and 2020
Pesticide concentrations in surface waters of the Sacramento Valley rice-growing regions, 2010
Pesticides in pollinator tissue collected from margins near agricultural fields in Conservation Areas of Missouri
Partitioning of six pyrethroid insecticides at varying salinities
Fungicides in nectar and pollen collected by bumble bees in a cherry orchard
Assessment of Endocrine Disruption in the Shenandoah River Watershed - Chemical and Biological Data from Mobile Laboratory Fish Exposures and Other Experiments Conducted during 2014, 2015, and 2016
Uptake and toxicity of clothianidin to monarch butterflies from milkweed consumption (ver. 2.0, January 2020)
Absorption, distribution, metabolism, and elimination of seed-treatment pesticides following the dosing of Japanese quail (Coturnix japonica)
Current-use pesticides and emerging amphibian pathogens in natural ponds, excavated ponds, and stormwater basins from 24 sites varying in land-use classifications throughout the New Jersey Pinelands, 2014-2016
Nitrapyrin, 6-CPA, and herbicide concentrations in agricultural soils, subsurface drains, and corresponding streams in the Midwestern US
Tapwater exposures, effects potential, and residential risk management in Northern Plains Nations
Potential health effects of contaminant mixtures from point and nonpoint sources on fish and frogs in the New Jersey Pinelands
Measured efficacy, bioaccumulation, and leaching of a transfluthrin-based insecticidal paint: A case study with a nuisance, nonbiting aquatic insect
Exposure to crop production alters cecal prokaryotic microbiota, inflates virulome and resistome in wild prairie grouse
Pesticide exposure of wild bees and honey bees foraging from field border flowers in intensively managed agriculture areas
Site- and individual-level contaminations affect infection prevalence of an emerging infectious disease of amphibians
Watershed-scale risk to aquatic organisms from complex chemical mixtures in the Shenandoah River
Juvenile African clawed frogs (Xenopus laevis) express growth, metamorphosis, mortality, gene expression, and metabolic changes when exposed to thiamethoxam and clothianidin
The silence of the clams: Forestry registered pesticides as multiple stressors on soft-shell clams
Assessing the ecological functionality and integrity of natural ponds, excavated ponds and stormwater basins for conserving amphibian diversity
Evaluation of ELISA for the analysis of imidacloprid in biological matrices: Cross-reactivities, matrix interferences, and comparison to LC-MS/MS
Cyprosulfamide: Analysis of the herbicide safener and two of its degradates in surface water and groundwater from the Midwestern United States
Science and Products
- Science
Filter Total Items: 17
- Data
Filter Total Items: 39
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 environmenPesticide detections in streams throughout the foothills of the Sierra Nevada range using passive samplers from 2017 to 2019
This dataset was produced from analyzing Affinisep SDB-RPS, Affinisep HLB, and Restek Resprep C18 disks that were deployed with the use of Chemcatcher� passive sampling devices. Silicone bands were also deployed and used for exploring economical methods of sampling for pesticides in surface water. Sampling assemblies were deployed in streams throughout the foothills of the Sierra Nevada range andInsecticide and fungicide concentrations in irrigation runoff and soils from a lettuce field in the Salinas Valley, California, 2019 and 2020
Irrigation runoff and soil samples were collected from a lettuce field located at the USDA-ARS Spence Research farm in the Salinas Valley, California to measure neonicotinoid insecticides (clothianidin and imidacloprid) and a fungicide (azoxystrobin) applied via coated seed and drench treatments. The field trial was designed to evaluate four treatments with replication: 1) control, untreated seed,Pesticide concentrations in surface waters of the Sacramento Valley rice-growing regions, 2010
Surface water samples were collected from four stream/agricultural drain sites in the Sacramento Valley of California to measure pesticides commonly applied to rice. Samples were collected weekly from May through August 2010 to capture the rice pesticide application season. Water samples were filtered (0.7 ?m) and extracted via solid-phase extraction. Additionally, the filter paper was solvent extPesticides in pollinator tissue collected from margins near agricultural fields in Conservation Areas of Missouri
Wild bee and butterfly samples were collected from the margins of agricultural fields located on five Conservation Areas in Missouri. In 2016 and 2017, samples were collected and composited by genera for a total of 90 samples. Samples were extracted via pressurized liquid extraction and solid phase extraction cleanup. Samples were analyzed for 168 pesticides and degradates using both gas and liquiPartitioning of six pyrethroid insecticides at varying salinities
To determine aqueous pyrethroid partitioning across a salinity gradient 20 mL Pyrex beakers were filled with 8 mL of deionized water at varying salinities (0, 0.5, 2, 6 ppt). Salinity was adjusted using a 10 ppt stock solution (made by diluting Instant Ocean into deionized water). The water samples were spiked with pyrethroids (bifenthrin, cyhalothrin, cyfluthrin, cypermethrin, deltamethrin, esfenFungicides in nectar and pollen collected by bumble bees in a cherry orchard
Lab-reared colonies of Bombus huntii (Hunt bumble bee) were deployed in a commercial cherry orchard in the spring of 2016. A fungicide formulation containing boscalid (25.2%) and pyraclostrobin (12.8%) was applied one time at the recommended label rate. Nectar and pollen were collected daily, beginning two days before spray application and continuing for ten days following. Nectar samples were extAssessment of Endocrine Disruption in the Shenandoah River Watershed - Chemical and Biological Data from Mobile Laboratory Fish Exposures and Other Experiments Conducted during 2014, 2015, and 2016
This data release presents chemical and biological results from investigations of water quality, fish endocrine disruption, and emergent insects in the Shenandoah River Watershed (Virginia and West Virginia, USA) conducted during 2014, 2015, and 2016. Multiple sampling campaigns were conducted at sites located throughout the Shenandoah River Watershed (Table 1). The complex inorganic and organic cUptake and toxicity of clothianidin to monarch butterflies from milkweed consumption (ver. 2.0, January 2020)
Recent concern for the adverse effects from neonicotinoid insecticides has centered on risk for insect pollinators in general and bees specifically. However, natural resource managers are also concerned about the risk of neonicotinoids to conservation efforts for the monarch butterfly (Danaus plexippus) and need a tool to estimate risk for wild monarch butterflies exposed to clothianidin. In the pAbsorption, 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 extractCurrent-use pesticides and emerging amphibian pathogens in natural ponds, excavated ponds, and stormwater basins from 24 sites varying in land-use classifications throughout the New Jersey Pinelands, 2014-2016
Water, sediment, anuran food (leaf litter and detritus) and whole body larval amphibian composites were analyzed for over 100 current-use pesticides from 24 wetlands representing land-use gradients in the New Jersey Pinelands, USA during 2014-2016. Emerging amphibian pathogens, Ranavirus and Batrachochytrium dendrobatidis (Bd) were also assessed in individual larvae at the 24 wetlands. Tables in tNitrapyrin, 6-CPA, and herbicide concentrations in agricultural soils, subsurface drains, and corresponding streams in the Midwestern US
Nitrapyrin is a nitrification inhibitor that is co-applied with N-fertilizer in agroecosystems. Over the course of one year (March 2016 to June 2017), 192 water samples from seven streams across Iowa and Illinois were analyzed for nitrapyrin, its degradate 6-chloropicolinic acid (6-CPA), and three widely used herbicides acetochlor, atrazine, and metolachlor. Additional environmental samples were c - Multimedia
- Publications
Filter Total Items: 113
Tapwater exposures, effects potential, and residential risk management in Northern Plains Nations
In the United States (US), private-supply tapwater (TW) is rarely monitored. This data gap undermines individual/community risk-management decision-making, leading to an increased probability of unrecognized contaminant exposures in rural and remote locations that rely on private wells. We assessed point-of-use (POU) TW in three northern plains Tribal Nations, where ongoing TW arsenic (As) interveAuthorsPaul M. Bradley, Kristin M. Romanok, Kelly L. Smalling, Michael J. Focazio, Robert Charboneau, Christine Marie George, Ana Navas-Acien, Marcia O'Leary, Reno Red Cloud, Tracy Zacher, Sara E. Breitmeyer, Mary C. Cardon, Christa K. Cuny, Guthrie Ducheneaux, Kendra Enright, Nicola Evans, James L. Gray, David E. Harvey, Michelle Hladik, Leslie K. Kanagy, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Shannon M. Meppelink, Joshua F. Valder, Christopher P. WeisPotential health effects of contaminant mixtures from point and nonpoint sources on fish and frogs in the New Jersey Pinelands
Aquatic ecosystems convey complex contaminant mixtures from anthropogenic pollution on a global scale. Point (e.g., municipal wastewater) and nonpoint sources (e.g., stormwater runoff) are both drivers of contaminant mixtures in aquatic habitats. The objectives of this study were to identify the contaminant mixtures present in surface waters impacted by both point and nonpoint sources, to determinAuthorsSara E. Breitmeyer, Heather L. Walsh, Vicki S. Blazer, John F. Bunnell, Patrick M. Burritt, Jeff Dragon, Michelle Hladik, Paul M. Bradley, Kristin M. Romanok, Kelly L. SmallingMeasured efficacy, bioaccumulation, and leaching of a transfluthrin-based insecticidal paint: A case study with a nuisance, nonbiting aquatic insect
BACKGROUNDPest management professionals will require a diverse, adaptive abatement toolbox to combat advanced challenges from disease vector and nuisance insect populations. Designed for post-application longevity, insecticidal paints offer extended residual effects on targeted insect pest populations; a measured understanding of active ingredient bioavailability over time is valuable to fully assAuthorsMichael C. Cavallaro, Corey Sanders, Michelle HladikExposure 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 anAuthorsSerguei Vyacheslavovich Drovetski, Brian K. Schmidt, Jonas Ethan Lai, Michael S. Gross, Michelle Hladik, Kenan Oguz Matterson, Natalie K. Karouna-RenierPesticide exposure of wild bees and honey bees foraging from field border flowers in intensively managed agriculture areas
Bees are critical for food crop pollination, yet their populations are declining as agricultural practices intensify. Pollinator-attractive field border plantings (e.g. hedgerows and forb strips) can increase bee diversity and abundance in agricultural areas, however recent studies suggest these plants may contain pesticides. Pesticide exposure for wild bees in agricultural areas remains largely uAuthorsLaura T. Ward, Michelle Hladik, Aidee Guzman, Sara Winsemius, Ariana Bautista, Claire Kremen, Nicholas MillsSite- and individual-level contaminations affect infection prevalence of an emerging infectious disease of amphibians
Emerging infectious disease outbreaks are one of multiple stressors responsible for amphibian declines globally. In the northeastern United States, ranaviral diseases are prevalent in amphibians and other ectothermic species, but there is still uncertainty as to whether their presence is leading to population level effects. Further, there is also uncertainty surrounding the potential interactionsAuthorsKelly L. Smalling, Brittany A. Mosher, Luke R. Iwanowicz, Keith Loftin, Adam Boehlke, Michelle Hladik, Carly R. Muletz-Wolz, Nandadevi Córtes-Rodríguez, Robin Femmer, Evan H. Campbell GrantByEcosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center, California Water Science Center, Geology, Geophysics, and Geochemistry Science Center, Kansas Water Science Center, New Jersey Water Science CenterWatershed-scale risk to aquatic organisms from complex chemical mixtures in the Shenandoah River
River waters contain complex chemical mixtures derived from natural and anthropogenic sources. Aquatic organisms are exposed to the entire chemical composition of the water, resulting in potential effects at the organismal through ecosystem level. This study applied a holistic approach to assess landscape, hydrological, chemical, and biological variables. On-site mobile laboratory experiments wereAuthorsLarry Barber, Kaycee E. Faunce, David Bertolatus, Michelle Hladik, Jeramy Jasmann, Steffanie H. Keefe, Dana W. Kolpin, Michael T. Meyer, Jennifer L. Rapp, David A. Roth, Alan M. VajdaJuvenile African clawed frogs (Xenopus laevis) express growth, metamorphosis, mortality, gene expression, and metabolic changes when exposed to thiamethoxam and clothianidin
Neonicotinoids (NEO) represent the main class of insecticides currently in use, with thiamethoxam (THX) and clothianidin (CLO) primarily applied agriculturally. With few comprehensive studies having been performed with non-target amphibians, the aim was to investigate potential biomarker responses along an adverse outcome pathway of NEO exposure, whereby data were collected on multiple biologicalAuthorsJill Jenkins, Katherine R. Hartop, Ghadeer Bukhari, Debra E. Howton, Kelly L. Smalling, Scott Mize, Michelle Hladik, Darren Johnson, Rassa Dale, Bonnie L. BrownThe silence of the clams: Forestry registered pesticides as multiple stressors on soft-shell clams
Contaminants are ubiquitous in the environment, often reaching aquatic systems. Combinations of forestry use pesticides have been detected in both water and aquatic organism tissue samples in coastal systems. Yet, most toxicological studies focus on the effects of these pesticides individually, at high doses, and over acute time periods, which, while key for establishing toxicity and safe limits,AuthorsAlexandra G. Tissot, Elise F. Granek, Anne W Thompson, Michelle Hladik, Patrick W. Moran, Kaegen Scully-EngelmeyerAssessing the ecological functionality and integrity of natural ponds, excavated ponds and stormwater basins for conserving amphibian diversity
Wetlands provide ecological functionality by maintaining and promoting regional biodiversity supporting quality habitat for aquatic organisms. Globally, habitat loss, fragmentation and degradation due to increases in agricultural activities and urban development have reduced or altered geographically isolated wetlands, thus reducing biodiversity. The objective of this study was to assess the relatAuthorsKelly L. Smalling, Sara E. Breitmeyer, John F. Bunnell, Kim J Laidig, Patrick Burritt, Marilyn Sobel, Jonathan Cohl, Michelle Hladik, Kristin M. Romanok, Paul M. BradleyEvaluation 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. FollowinAuthorsMichael S. Gross, Emily Woodward, Michelle HladikCyprosulfamide: Analysis of the herbicide safener and two of its degradates in surface water and groundwater from the Midwestern United States
Herbicide safeners are commonly included in herbicide formulations to selectively protect crops from herbicide toxicity but are poorly understood in terms of their environmental occurrence and fate. This study established an analytical method for a newer safener, cyprosulfamide, and two of its degradates, cyprosulfamide desmethyl and N-cyclopropyl-4-sulfamoylbenzamide, in water via solid-phase extAuthorsMonica E McFadden, Michelle Hladik - News