Michelle L Hladik

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 has focused on pesticides but has expanded to include other organic contaminants. I oversee a research laboratory that is focused on developing new methods to measure pesticides and their degradates in water, sediment and biota. 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. 

I have a B.A. in Chemistry from Vassar College (1999) and a Ph.D. in Environmental Engineering from Johns Hopkins University (2005).


Klarich Wong, K.L., Webb, D.T., Nagorzanski, M.R., Kolpin, D.W., Hladik, M.L., Cwiertny, D.M., LeFevre, G.J., 2019, Chlorinated byproducts of neonicotinoids and their metabolites: An unrecognized human exposure potential? Environ. Sci. Technol. Lett., v. 6, pp. 98-105.

Bradley, P.M., Kolpin, D.W., Romanok, K.M, Focazio, M.J., Brown, J.B., Cardon, M.C,, Carpenter, K.D., Corsi, S.R., De Cicco, L.A., Dietze, J.E., Evans, N., Furlong, E.T., Givens, C.E., Gray, J.L., Griffin, D.W., Higgins, C.P., Hladik, M.L., Iwanowicz, L.R., Journey, C.A., Kuivila, K.M., Masoner, J.R., McDonough, C.A., Meyer, M.T., Orlando, J.L., Smalling, K.L., Strynar, M.J., Weis, C.P., Wilson, V.S., 2019, Reconnaissance of mixed organic and inorganic chemicals in private and public supply tapwaters at selected residential and workplace sites in the United States, Environ. Sci. Technol., published online November 23, 2018.

Romanok, K.M., Kolpin, D.W., Meppelink, S.M., Argos, M., Brown, J.B., DeVito, M.J., Dietze, J.E., Givens, C.E., Gray, J.L., Higgins, C.P., Hladik, M.L., Iwanowicz, L.R., Loftin, K.A., McCleskey, R.B., McDonough, C.A., Meyer, M.T., Strynar, M.J., Weis, C.P., Wilson, V.S., and Bradley, P.M., 2018, Methods used for the collection and analysis of chemical and biological data for the Tapwater Exposure Study, United States, 2016–17: U.S. Geological Survey Open-File Report 2018–1098, 79 p.

Woodward, E.E., Kolpin, D.W., Zheng, W., Holm, N.L., Meppelink, S.M., Terrio, P.J., Hladik, M.L., 2019, Fate and transport of nitrapyrin in agroecosystems: occurrence in agricultural soils, subsurface drains, and receiving streams in the Midwestern US, Sci. Tot. Environ., v. 650 pp. 2830-2841.

Orlando, J.L., Stout, S.M., McWayne, M.M., Sanders, C.J., Hladik, M.L., 2018, Dissolved pesticide concentrations in the lower Sacramento River and its source waters, California, 2016: U.S. Geological Survey Open-File Report 2018-1153, 24 p.

Smalling, K.L., Bunnell, J.F., Cohl, J., Romanok, K.M., Hazard, L., Monsen, K., Akob, D.M., Hansen, A., Hladik, M.L., Abdallah, N., Ahmed, Q., Assan, A., De Parsia, M., Griggs, A., McWayne-Holmes, M., Patel, N., Sanders, C., Shrestha, Y., Stout, S., and Williams, B., 2018, An initial comparison of pesticides and amphibian pathogens between natural and created wetlands in the New Jersey Pinelands, 2014–16: U.S. Geological Survey Open-File Report 2018–1077, 18 p.

Sanders, C.J., Orlando, J.L., Hladik, M.L., 2018, Detections of Current-Use Pesticides at 12 Surface Water Sites in California During a 2-Year Period Beginning in 2015, USGS Data Series 1088, 40 p.

De Parsia, M.D., Orlando, J.L., McWayne, M.M., Hladik, M.L., 2018, Pesticide Inputs to the Sacramento-San Joaquin Delta, 2015-16: Results from the Delta Regional Monitoring Program, USGS Data Series 1089, 49 p.

Swanson, J.E., Muths, E., Pierce, C.L., Dinsmore, S.J., Vandever, M.W., Hladik, M.L., Smalling, K.L., 2018, Exploring the amphibian exposome in an agricultural landscape using telemetry and passive sampling, Sci. Rep., v. 8, 10045.

Hladik, M.L., Main, A.R., Goulson, D., 2018, Environmental risks and challenges associated with neonicotinoid insecticides, Feature for Environ. Sci. Technol., v. 52, pp. 3329-3335.

Hladik, M.L., Corsi, S.R., Kolpin, D.W., Baldwin, A.K., Blackwell, B.R., Cavallin, J.E., 2018, Year-round presence of neonicotinoid insecticides in tributaries to the Great Lakes, USA, Environ., Pollut., v. 235, pp. 1022-1029.

Smalling, K.L., Hladik, M.L., Sanders, C.J., Kuivila, K.M., 2018, Leaching and sorption of neonicotinoid insecticides and fungicides from seed coatings, J. Environ. Sci. Health B, v. 53, pp. 176-183.

Woodward, E.E., Hladik, M.L., Kolpin, D.W., 2018, Occurrence of dichloroacetamide herbicide safeners and co-applied herbicides in Midwestern US streams, Environ. Sci. Technol. Lett., v. 5, pp. 3-8.

Nowell, L. H., Moran, P.W., Schmidt, T.S., Norman, J.E., Nakagaki, N., Shoda, M.E., Mahler, B.J., Van Metre, P.C., Stone, W.W., Sandstrom, M.W., Hladik, M.L., 2018, Complex mixtures of dissolved pesticides show potential aquatic toxicity in a synoptic study of Midwestern U.S. streams, Sci. Tot. Environ., v. 613-614, pp. 1469-1488.

Ginsberg, H.S., Bargar, T.A., Hladik, M.L., Lubelczyk, C., 2017, Management of arthropod pathogen vectors in North America: minimizing adverse effects on pollinators, J. Med. Entomol., v. 54, pp. 1463-1475.

Bradley, P.M., Battaglin, W.A., Clark, J.M. , Henning, F.,  Hladik, M.L., Iwanowicz, M.L.,  Journey, C.A., Riley, J., Romanok, K.M. 2017, Widespread Occurrence and Potential for Biodegradation of Bioactive Contaminants in Protected Wilderness of Congaree National Park, USA,  Environ. Toxciol. Chem., v. 36, pp. 3045-3056.

Hubbard, L.E., Kolpin, D.W., Fields, C., Hladik, M.L., Iwanowicz, L.R., 2017, Response to the 2015 avian influenza outbreak in the Midwestern United States: study design, lessons learned, and select results, Environ. Res., v. 158, pp. 212-224.

Klarich, K.L., Pflug, N.C., DeWald, E.M., Hladik, M.L., Kolpin, D.W., Cwiertny, D.M., LeFevre, G.H., 2017, Occurrence of neonicotinoid insecticides in finished drinking water and persistence during drinking water treatment, Environ. Sci. Technol. Lett., v. 4, pp. 168-173.

Bradley, P.M., Journey, C.A., Romanok, K.M., Barber, L.B., Buxton, H.T., Foreman, W.T., Furlong, E.T., Glassmeyer, S.T., Hladik, M.L., Iwanowicz, L.R., Jones, D.K., Kolpin, D.W., Kuivila, K.M., Loftin, K.A., Mills, M.A., Meyer, M.T., Orlando, J.L., Reilly, T.J., Smalling, K.L., Villeneuve, D.L., 2017, Expanded target-chemical analysis reveals extensive mixed-organic-contaminant exposure in USA streams, Environ. Sci. Technol., v. 51, pp 4792-4802.

Romanok, K.M., Reilly, T.J., Barber, L.B., Buxton, H.T., Foreman, W.T., Furlong, E.T., Glassmeyer, S.T., Hladik, M.L., Iwanowicz, L.R., Jones, D.K., Journey, C.A., Kolpin, D.W., Kuivila, K.M., Loftin, K.A., Mills, M.A., Meyer, M.T., Orlando, J.L., Smalling, K.L., Villeneuve, D.L., Bradley, P.M., 2017, Methods used to characterize the chemical composition and biological activity of environmental waters throughout the United States, 2012–14. U.S. Geological Survey Open File Report 2017-1011, 115p. 

Hladik, M.L., Bradbury, S., Schulte, L.A., Helmers, M., Witte, C., Kolpin, D.W., Garrett, J.D., Harris, M., 2017, Neonicotinoid insecticide removal by prairie strips in row-cropped watersheds with historical seed coating use, Agric. Ecosyst. Environ., v. 241, pp. 160-167.

Orem, W., Varonka, M., Crosby, L., Haase, K., Loftin, K., Hladik, M., Akob, D.M., Tatu, C., Mumford, A., Jaeschke, J., Bates, A., Schell, T., Cozzarelli, I., 2017, Organic geochemistry and toxicology of a stream impacted by unconventional oil and gas wastewater disposal operations, Appl. Geochem., v. 80, pp. 155-167.

Goff, A.D., Saranjampour, P., Ryan, L.M., Hladik, M.L., Covi, J.A., Armbrust, K.L., Brander, S.M., 2017, The effects of fipronil and the photodegradation product fipronil desulfinyl on growth and gene expression in juvenile blue crabs, Callinectes sapidus, at different salinities, Aquat. Toxicol., v. 186, pp. 96-104.

Woodward, E.E., Hladik, M.L., Kolpin, D.W., 2016, Nitrapyrin in streams: The first study documenting off-field transport of a nitrogen stabilizer compound, Environ. Sci. Techol. Lett., v. 3, pp. 387-392.

Rogers, H.A., Schmidt, T.S., Dabney, B.L., Hladik, M.L., Mahler, B.J., Van Metre, P.C., 2016, Bifenthrin causes trophic cascades in aquatic food webs and alters subsidies to terrestrial food webs, Environ. Sci. Technol., v. 50, pp. 11974-11983.

Forister, M., Cousens, B., Harrison, J., Casner, K., Thorne, J., Waetjen, D., Nice, C., De Parsia, M., Hladik, M., Meese, R., van Vliet, H., Shaprio, A., 2016, Increasing neonicotinoid use and the declining butterfly fauna of lowland California, Biol. Lett., v. 12(8), 20160475

Carpenter, K.D., Kuivila, K.M., Hladik, M.L., Haluska, T., Cole, M.B., 2016, Storm-event-transport of urban-use pesticides to streams likely impairs invertebrate assemblages, Environ. Monit. Assess., v. 188, article 345.

Hladik, M.L., Hubbard, L.E., Kolpin, D.W., Focazio, M.J., 2016, Dairy-impacted wastewater is a source of iodinated disinfection byproducts in the environment, Environ. Sci. Technol. Lett., v. 3, pp. 190-193.

Elskus, A.A., Smalling, K.L., Hladik, M.L., Kuivila, K.M., 2016, Effects of two fungicide formulations on microbial and macroinvertebrate leaf decomposition under laboratory conditions, Environ. Toxciol. Chem., v. 35, pp, 2834-2844.

Hladik, M.L., Vandever, M., Smalling K.L., 2016, Expsoure of native bees foraging in an agricultural landscape to current-use pesticides, Sci. Tot. Environ., v. 542, pp. 469-477.

Hladik, M.L., Kolpin, D.W., 2016, First national-scale reconnaissance of neonicotinoid insecticides in streams across the U.S.A., Environ. Chem., v. 13, pp. 12-20.

Smalling, K.L., Reeves, R., Muths, E., Vandever, M., Battaglin, W.A., Hladik, M.L., Pierce, C., 2015, Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture, Sci. Tot. Environ., v. 502, pp. 80-90.

Barber, L.B., Hladik, M.L., Vajda, A.M., Fitzgerald, K.C., Douville, C., 2015, Impact of wastewater infrastructure upgrades on the urban water cycle: reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection, Sci. Total. Environ., v. 529, pp. 264-274

Hladik, M.L., Focazio, M.J., Engle, M., 2014, Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams, Sci. Tot. Environ., v. 466-467, pp. 1085-1093.

Hladik, M.L., Kolpin, D.W., Kuivila, K.M., 2014, Widespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region, USA, Environ. Poll., v. 193, pp. 189-196.

Romanok, K.M., Reilly, T.J., Lopez, A.R., Trainor, J.J., Hladik, M.L., Stanley, J.K., Farrar, D., 2014, Characterization of selected bed-sediment-bound organic and inorganic contaminants and toxicity, Barnegat Bay and major tributaries, New Jersey, 2012: U.S. Geological Survey Data Series 867, 51 p. [Link]

Orlando, J., McWayne, M., Sanders, C., Hladik, M., 2014, Dissolved Pesticide Concentrations Entering the Sacramento–San Joaquin Delta from the Sacramento and San Joaquin Rivers, California, 2012–13: U.S. Geological Survey Data Series 876, 28 p. [Link]

Orlando, J.L., McWayne, M., Sanders, C., Hladik, M., 2013, Dissolved pesticide concentrations in the Sacramento-San Joaquin Delta and Grizzly Bay, California, 2011–12: U.S. Geological Survey Data Series 779, 24 p. [Link]

Reilly, T.J., Smalling, K.L., Meyer, M.T., Sandstrom, M.W., Hladik M.L., Boehlke, A., Fishman, N.S., Battaglin, W.A., Kuivila, K.M., 2013, Occurrence of pesticides in groundwater and sediment and mineralogy of sediments and grain coatings underlying the Rutgers Agricultural Research and Extension Center, Upper Deerfield, New Jersey, 2007: U.S. Geological Survey Data Series 811, 53 p. [Link]

Kuivila, K.M., Hladik, M.L., Ingersoll, C.G., Kemble, N.E., Moran, P.W., Calhoun, D.L., Nowell, L.H., Gilliom, R.J., 2012, Occurrence and potential sources of pyrethroid insecticides in stream sediments from seven U.S. metropolitan areas. Environ. Sci. Technol. v. 46, pp. 4297-4303.

Hladik, M.L., Kuivila, K.M., 2012, Pyrethroid insecticides in bed sediments from urban and agricultural streams across the United States, J. Environ. Monit. v. 14, pp. 1838-1845.

Brander, S.M., Mosser, C.M., Geist, J., Hladik, M.L., Werner, I., 2012, Esfenvalerate toxicity to the cladoceran Ceriodaphnia dubia in the presence of green algae, Pseudokirchneriella subcapitata,Ecotoxicology v. 21, pp. 2409-2418.

Hladik, M.L., Calhoun, D.L., 2012, Analysis of the herbicide diuron, three diuron degradates, and six Neonicotinoid insecticides in water – method and application, USGS Scientific Investigations Report 2012-5206, 10 p. [Link]

Hladik, M.L., McWayne, M.M., 2012, Methods of analysis—determination of pesticides in sediment using gas chromatography/mass spectrometry, USGS Techniques and Methods Report 5-C3, 18 p.[Link]

Moran, P.W., Calhoun, D.L., Nowell, L.H., Kemble, N.E., Ingersoll, C.G., Hladik, M.L., Kuivila, K.M., Falcone, J.A., Gilliom, R.J., 2012, Contaminants in stream sediments from seven U.S. metropolitan areas--Data summary of a national pilot study: U.S. Geological Survey Scientific Investigations Report 2011-5092, 66 p. [Link]

Domagalski, J.L., Weston, D.P., Zhang, M.H., Hladik, M.L., 2010, Pyrethroid insecticide concentrations and toxicity in streambed sediments and loads in surface waters of the San Joaquin Valley, California, USA, Environ. Toxicol. Chem., v. 29, pp. 813-823.

Hladik, M.L., Orlando, J.L., Kuivila, K.M., 2009, Collection of Pyrethroids in Water and Sediment Matrices: Development and Validation of a Standard Operating Procedure, USGS Scientific Investigations Report 2009-5012, 22 p. [Link]

Hladik, M.L., Smalling, K.L.. Kuivila, K.M., 2009, Methods of Analysis—Determination of Pyrethroid Insecticides in Water and Sediment Using Gas Chromatography/Mass Spectrometry, USGS Techniques and Methods Report 5-C2, 18 p. [Link]

Hladik, M.L., Kuivila, K.M., 2009, Assessing the occurrence and distribution of pyrethroids in water and suspended sediments, J. Agric. Food Chem., v. 57, pp. 9079-9085.

Hladik, M.L., Domagalski, J.L., Kuivila, K.M., 2009, Concentrations and loads of suspended sediment-associated pesticides in the San Joaquin River, California and tributaries during storm events, Sci. Tot. Enviorn., v. 408, pp. 356-364.

Hladik, M.L., Orlando, J.L., 2008, Level 1 water-quality inventory of baseline levels of pesticides in urban creeks: Golden Gate National Recreation Area and Presidio of San Francisco, USGS Data Series 338, 14p. [Link]

Hladik, M.L., Kuivila., K.M., 2008, Analysis of chlorothalonil and three degradates in sediment and soil, J. Agric. Food Chem., v. 56 (7), pp. 2310-2314.

Hladik, M.L., Smalling, K.L., Kuivila, K.M., 2008, A multi-residue method for the analysis of pesticides and pesticide degradates in water using HLB solid-phase extraction and gas chromatography-ion trap mass spectrometry, Bull. Environ. Contam. Toxicol. v. 80, pp.139-144.

Hladik, M. L., Bouwer, E.J., Roberts, A.L., 2008, Neutral chloroacetamide herbicide degradates and related compounds in Midwestern United States drinking water sources, Sci. Total. Environ., v. 390,pp. 155-165.

Hladik, M.L., Bouwer, E.J., Roberts, A.L., 2008, Neutral degradates of chloroacetamide herbicides: occurrence in drinking water and removal during conventional water treatment, Wat. Res., v. 42, pp. 4905-4914.

Kuivila, K.M., Hladik, M.L., 2008, Understanding the occurrence and transport of current-use pesticide in the San Francisco Estuary Watershed, San Francisco Estuary and Watershed Science, v. 6 (3), article 2.

Hladik, M.L., Kuivila K.M., 2008, Occurrence of pyrethroids in bed and suspended sediments in California. In Synthetic Pyrethroids: Occurrence and Behavior in Aquatic Environments, J. Gan, F. Spurlock, P. Hendley, D. Weston, Eds; ACS Symposium Series No. 991; American Chemical Society: Washington, DC; pp. 55-71.

Hladik, M. L., Roberts A.L., Bouwer, E.J., 2006, Chloroacetamide herbicides and their transformation products in drinking water. Report 91123; AWWA Research Foundation, Denver, CO, 108 pp.

Hladik, M.L., Bouwer, E.J., Roberts, A.L., 2005, Removal of neutral chloroacetamide herbicide degradates during simulated unit processes for drinking water treatment, Water Res., v. 39pp. 5033-5044.

Hladik, M.L., Hsiao, J.J., Roberts, A.L., 2005, Are neutral chloroacetamide herbicide degradates of potential environmental concern? Analysis and occurrence in the upper Chesapeake Bay, Environ. Sci. Technol., v. 39, pp. 6561-6574.