James L Gray, PhD
James Gray is a Research Chemist for the USGS Water Resources Mission Area.
Science and Products
Filter Total Items: 20
Per- and polyfluoroalkyl substances (PFAS) results in tapwater samples, in select areas within the United States, beginning 2023 (ver. 2.0, June 2025) Per- and polyfluoroalkyl substances (PFAS) results in tapwater samples, in select areas within the United States, beginning 2023 (ver. 2.0, June 2025)
This data release provides concentration results for per- and polyfluoroalkyl substances (PFAS) collected by volunteer community members, in tapwater samples from 83 private residences, in select areas within the United States. Samples were collected July 1, 2023, through November 10, 2023. Samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory (NWQL) in...
Target-Chemical Concentrations for Assessment of Mixed-Organic/Inorganic Chemical and Biological Exposures in Private-Well Tapwater at Campbell, Wisconsin, 2021 Target-Chemical Concentrations for Assessment of Mixed-Organic/Inorganic Chemical and Biological Exposures in Private-Well Tapwater at Campbell, Wisconsin, 2021
Tapwater samples were obtained from groundwater sources on French Island, in the town of Campbell, Wisconsin. Samples from three locations were collected multiple times over a period of three days to assess temporal variations in water quality. Samples from an additional eight locations, were collected one time, spatially distributed around Campbell. Due to privacy concerns, the exact...
Target-chemical concentrations and microbiological results in surface water and tapwater, Montana, 2022 Target-chemical concentrations and microbiological results in surface water and tapwater, Montana, 2022
This data release contains the concentration and quality-assurance results for inorganic constituents, as well as organic compounds (volatile organic compounds [VOC], per- and polyfluoroalkyl substances [PFAS], pesticides and disinfection byproducts [DBP]) and microbiological results collected in the Little Big Horn River and residential or commercial tapwater locations in Montana...
Concentrations of per- and polyfluoroalkyl substances (PFAS) in tapwater collected throughout the United States, 2021-22 Concentrations of per- and polyfluoroalkyl substances (PFAS) in tapwater collected throughout the United States, 2021-22
This dataset contains the concentration and quality assurance results for 34 per- and polyfluoroalkyl substances (PFAS). 409 residential and commercial tapwater samples were collected once between May 2021 and May 2022, in the contiguous U.S., Alaska, Hawaii, Puerto Rico, and U.S. Virgin Islands. Of these samples 252 were from publicly supplied tapwater locations, and 155 were sourced...
Chemical Concentrations and Microbiological Results for Assessment of Mixed-Organic/Inorganic Chemical Exposures in Tapwater in Mead, Nebraska, June 2022 and January 2023 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...
State-Wide Reconnaissance of Per- and Polyfluoroalkyl Substances, N-(1,3-Dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD), and 6PPD-Quinone in Iowa Streams, 2022-2023 State-Wide Reconnaissance of Per- and Polyfluoroalkyl Substances, N-(1,3-Dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD), and 6PPD-Quinone in Iowa Streams, 2022-2023
Water-quality samples were collected at 49 surface water sites covering a range of land uses across the state of Iowa starting the summer of 2022 and continuing into the spring of 2023 by staff from the U.S. Geological Survey Central Midwest Water Science Center. Samples were submitted to the National Water Quality Laboratory in Denver, Colorado, and were analyzed for 32 per- and...
Filter Total Items: 49
Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications
Drinking-water quality is a rising concern in the United States (US), emphasizing the need to broadly assess exposures and potential health effects at the point-of-use. Drinking-water exposures to per- and poly-fluoroalkyl substances (PFAS) are a national concern, however, there is limited information on PFAS in residential tapwater at the point-of-use, especially from private-wells. We...
Authors
Kelly L. Smalling, Kristin Romanok, Paul Bradley, Matthew Morriss, James L. Gray, Leslie Kanagy, Stephanie Gordon, Brianna Williams, Sara Breitmeyer, Daniel Jones, Laura DeCicco, Collin A. Eagles-Smith, Tyler Wagner
By
Ecosystems Mission Area, Water Resources Mission Area, Cooperative Research Units, Forest and Rangeland Ecosystem Science Center, New Jersey Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center, Utah Water Science Center
Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA
Continued improvements in drinking-water quality characterization and treatment/distribution infrastructure are required to address the expanding number of documented environmental contaminants. To better understand the variability in contaminant exposures from the drinking water resource (surface and groundwater), through the distribution process, to the point-of-use (tapwater), in 2019...
Authors
Kelly L. Smalling, Paul M. Bradley, Kristin M. Romanok, Sarah Elliott, Jane de Lambert, Michael Focazio, Stephanie Gordon, James L. Gray, Leslie Kanagy, Michelle Hladik, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Mary Cardon, Nicola Evans, Christopher P. Weis
Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa
In the United States and globally, contaminant exposure in unregulated private-well point-of-use tapwater (TW) is a recognized public-health data gap and an obstacle to both risk-management and homeowner decision making. To help address the lack of data on broad contaminant exposures in private-well TW from hydrologically-vulnerable (alluvial, karst) aquifers in agriculturally-intensive...
Authors
Paul M. Bradley, Dana W. Kolpin, Darrin Thompson, Kristin M. Romanok, Kelly L. Smalling, Sara Breitmeyer, Mary Cardon, David Cwiertny, Nicola Evans, R. Field, Michael Focazio, Laura Freeman, Carrie Givens, James Gray, Gordon Hager, Michelle Hladik, Jonathan Hoffman, Rena Jones, Leslie Kanagy, Rachael Lane, R. Blaine McCleskey, Danielle Medgyesi, Elizabeth Medlock-Kakaley, Shannon M. Meppelink, Michael T. Meyer, Diana Stavreva, Mary Ward
Contaminant exposure and transport from three potential reuse waters within a single watershed Contaminant exposure and transport from three potential reuse waters within a single watershed
Global demand for safe and sustainable water supplies necessitates a better understanding of contaminant exposures in potential reuse waters. In this study, we compared exposures and load contributions to surface water from the discharge of three reuse waters (wastewater effluent, urban stormwater, and agricultural runoff). Results document substantial and varying organic-chemical...
Authors
Jason Masoner, Dana W. Kolpin, Isabelle Cozzarelli, Paul M. Bradley, Brian Arnall, Kenneth Forshay, James L. Gray, Justin Groves, Michelle Hladik, Laura Hubbard, Luke R. Iwanowicz, Jeanne Jaeschke, Rachael Lane, R. Blaine McCleskey, Bridgette Polite, David Roth, Michael Pettijohn, Michaelah Wilson
By
Water Resources Mission Area, Environmental Health Program, Central Plains Water Science Center, Eastern Ecological Science Center, Colorado Water Science Center, California Water Science Center, Central Midwest Water Science Center, Geology, Energy & Minerals Science Center, Kansas Water Science Center, Oklahoma-Texas Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Water Science Center, Reston Biogeochemical Processes in Groundwater Laboratory
Bottled water contaminant exposures and potential human effects Bottled water contaminant exposures and potential human effects
Bottled water (BW) consumption in the United States and globally has increased amidst heightened concern about environmental contaminant exposures and health risks in drinking water supplies, despite a paucity of directly comparable, environmentally-relevant contaminant exposure data for BW. This study provides insight into exposures and cumulative risks to human health from inorganic...
Authors
Paul M. Bradley, Kristin M. Romanok, Kelly L. Smalling, Michael Focazio, Nicola Evans, Suzanne Fitzpatrick, Carrie Givens, Stephanie Gordon, James L. Gray, Emily Green, Dale Griffin, Michelle Hladik, Leslie Kanagy, John Lisle, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Ana Navas-Acien, David Roth, Paul South, Christopher Weis
Tapwater exposures, effects potential, and residential risk management in Northern Plains Nations 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...
Authors
Paul M. Bradley, Kristin M. Romanok, Kelly L. Smalling, Michael Focazio, Robert Charboneau, Christine George, Ana Navas-Acien, Marcia O’Leary, Reno Red Cloud, Tracy Zacher, Sara Breitmeyer, Mary Cardon, Christa Cuny, Guthrie Ducheneaux, Kendra Enright, Nicola Evans, James L. Gray, David Harvey, Michelle Hladik, Leslie Kanagy, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Shannon Meppelink, Joshua F. Valder, Christopher Weis
Non-USGS Publications**
Kolodziej, E. P., Gray, J. L., & Sedlak, D. L. (2003). Quantification Of Steroid Hormones With Pheromonal Properties In Municipal Wastewater Effluent. Environmental Toxicology and Chemistry, 22(11), 2622. doi:10.1897/03-42
Sedlak, D. L., Pinkston, K. E., Gray, J. L., & Kolodziej, E. P. (2003). Approaches for Quantifying the Attenuation of Wastewater-Derived Contaminants in the Aquatic Environment. CHIMIA International Journal for Chemistry, 57(9), 567-569. doi:10.2533/000942903777679055
Sedlak, D. L., Gray, J. L., & Pinkston, K. E. (2000). Peer Reviewed: Understanding Microcontaminants in Recycled Water. Environmental Science & Technology, 34(23). doi:10.1021/es003513e
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 20
Per- and polyfluoroalkyl substances (PFAS) results in tapwater samples, in select areas within the United States, beginning 2023 (ver. 2.0, June 2025) Per- and polyfluoroalkyl substances (PFAS) results in tapwater samples, in select areas within the United States, beginning 2023 (ver. 2.0, June 2025)
This data release provides concentration results for per- and polyfluoroalkyl substances (PFAS) collected by volunteer community members, in tapwater samples from 83 private residences, in select areas within the United States. Samples were collected July 1, 2023, through November 10, 2023. Samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory (NWQL) in...
Target-Chemical Concentrations for Assessment of Mixed-Organic/Inorganic Chemical and Biological Exposures in Private-Well Tapwater at Campbell, Wisconsin, 2021 Target-Chemical Concentrations for Assessment of Mixed-Organic/Inorganic Chemical and Biological Exposures in Private-Well Tapwater at Campbell, Wisconsin, 2021
Tapwater samples were obtained from groundwater sources on French Island, in the town of Campbell, Wisconsin. Samples from three locations were collected multiple times over a period of three days to assess temporal variations in water quality. Samples from an additional eight locations, were collected one time, spatially distributed around Campbell. Due to privacy concerns, the exact...
Target-chemical concentrations and microbiological results in surface water and tapwater, Montana, 2022 Target-chemical concentrations and microbiological results in surface water and tapwater, Montana, 2022
This data release contains the concentration and quality-assurance results for inorganic constituents, as well as organic compounds (volatile organic compounds [VOC], per- and polyfluoroalkyl substances [PFAS], pesticides and disinfection byproducts [DBP]) and microbiological results collected in the Little Big Horn River and residential or commercial tapwater locations in Montana...
Concentrations of per- and polyfluoroalkyl substances (PFAS) in tapwater collected throughout the United States, 2021-22 Concentrations of per- and polyfluoroalkyl substances (PFAS) in tapwater collected throughout the United States, 2021-22
This dataset contains the concentration and quality assurance results for 34 per- and polyfluoroalkyl substances (PFAS). 409 residential and commercial tapwater samples were collected once between May 2021 and May 2022, in the contiguous U.S., Alaska, Hawaii, Puerto Rico, and U.S. Virgin Islands. Of these samples 252 were from publicly supplied tapwater locations, and 155 were sourced...
Chemical Concentrations and Microbiological Results for Assessment of Mixed-Organic/Inorganic Chemical Exposures in Tapwater in Mead, Nebraska, June 2022 and January 2023 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...
State-Wide Reconnaissance of Per- and Polyfluoroalkyl Substances, N-(1,3-Dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD), and 6PPD-Quinone in Iowa Streams, 2022-2023 State-Wide Reconnaissance of Per- and Polyfluoroalkyl Substances, N-(1,3-Dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD), and 6PPD-Quinone in Iowa Streams, 2022-2023
Water-quality samples were collected at 49 surface water sites covering a range of land uses across the state of Iowa starting the summer of 2022 and continuing into the spring of 2023 by staff from the U.S. Geological Survey Central Midwest Water Science Center. Samples were submitted to the National Water Quality Laboratory in Denver, Colorado, and were analyzed for 32 per- and...
Filter Total Items: 49
Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications
Drinking-water quality is a rising concern in the United States (US), emphasizing the need to broadly assess exposures and potential health effects at the point-of-use. Drinking-water exposures to per- and poly-fluoroalkyl substances (PFAS) are a national concern, however, there is limited information on PFAS in residential tapwater at the point-of-use, especially from private-wells. We...
Authors
Kelly L. Smalling, Kristin Romanok, Paul Bradley, Matthew Morriss, James L. Gray, Leslie Kanagy, Stephanie Gordon, Brianna Williams, Sara Breitmeyer, Daniel Jones, Laura DeCicco, Collin A. Eagles-Smith, Tyler Wagner
By
Ecosystems Mission Area, Water Resources Mission Area, Cooperative Research Units, Forest and Rangeland Ecosystem Science Center, New Jersey Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center, Utah Water Science Center
Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA
Continued improvements in drinking-water quality characterization and treatment/distribution infrastructure are required to address the expanding number of documented environmental contaminants. To better understand the variability in contaminant exposures from the drinking water resource (surface and groundwater), through the distribution process, to the point-of-use (tapwater), in 2019...
Authors
Kelly L. Smalling, Paul M. Bradley, Kristin M. Romanok, Sarah Elliott, Jane de Lambert, Michael Focazio, Stephanie Gordon, James L. Gray, Leslie Kanagy, Michelle Hladik, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Mary Cardon, Nicola Evans, Christopher P. Weis
Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa
In the United States and globally, contaminant exposure in unregulated private-well point-of-use tapwater (TW) is a recognized public-health data gap and an obstacle to both risk-management and homeowner decision making. To help address the lack of data on broad contaminant exposures in private-well TW from hydrologically-vulnerable (alluvial, karst) aquifers in agriculturally-intensive...
Authors
Paul M. Bradley, Dana W. Kolpin, Darrin Thompson, Kristin M. Romanok, Kelly L. Smalling, Sara Breitmeyer, Mary Cardon, David Cwiertny, Nicola Evans, R. Field, Michael Focazio, Laura Freeman, Carrie Givens, James Gray, Gordon Hager, Michelle Hladik, Jonathan Hoffman, Rena Jones, Leslie Kanagy, Rachael Lane, R. Blaine McCleskey, Danielle Medgyesi, Elizabeth Medlock-Kakaley, Shannon M. Meppelink, Michael T. Meyer, Diana Stavreva, Mary Ward
Contaminant exposure and transport from three potential reuse waters within a single watershed Contaminant exposure and transport from three potential reuse waters within a single watershed
Global demand for safe and sustainable water supplies necessitates a better understanding of contaminant exposures in potential reuse waters. In this study, we compared exposures and load contributions to surface water from the discharge of three reuse waters (wastewater effluent, urban stormwater, and agricultural runoff). Results document substantial and varying organic-chemical...
Authors
Jason Masoner, Dana W. Kolpin, Isabelle Cozzarelli, Paul M. Bradley, Brian Arnall, Kenneth Forshay, James L. Gray, Justin Groves, Michelle Hladik, Laura Hubbard, Luke R. Iwanowicz, Jeanne Jaeschke, Rachael Lane, R. Blaine McCleskey, Bridgette Polite, David Roth, Michael Pettijohn, Michaelah Wilson
By
Water Resources Mission Area, Environmental Health Program, Central Plains Water Science Center, Eastern Ecological Science Center, Colorado Water Science Center, California Water Science Center, Central Midwest Water Science Center, Geology, Energy & Minerals Science Center, Kansas Water Science Center, Oklahoma-Texas Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Water Science Center, Reston Biogeochemical Processes in Groundwater Laboratory
Bottled water contaminant exposures and potential human effects Bottled water contaminant exposures and potential human effects
Bottled water (BW) consumption in the United States and globally has increased amidst heightened concern about environmental contaminant exposures and health risks in drinking water supplies, despite a paucity of directly comparable, environmentally-relevant contaminant exposure data for BW. This study provides insight into exposures and cumulative risks to human health from inorganic...
Authors
Paul M. Bradley, Kristin M. Romanok, Kelly L. Smalling, Michael Focazio, Nicola Evans, Suzanne Fitzpatrick, Carrie Givens, Stephanie Gordon, James L. Gray, Emily Green, Dale Griffin, Michelle Hladik, Leslie Kanagy, John Lisle, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Ana Navas-Acien, David Roth, Paul South, Christopher Weis
Tapwater exposures, effects potential, and residential risk management in Northern Plains Nations 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...
Authors
Paul M. Bradley, Kristin M. Romanok, Kelly L. Smalling, Michael Focazio, Robert Charboneau, Christine George, Ana Navas-Acien, Marcia O’Leary, Reno Red Cloud, Tracy Zacher, Sara Breitmeyer, Mary Cardon, Christa Cuny, Guthrie Ducheneaux, Kendra Enright, Nicola Evans, James L. Gray, David Harvey, Michelle Hladik, Leslie Kanagy, Keith Loftin, R. Blaine McCleskey, Elizabeth Medlock-Kakaley, Shannon Meppelink, Joshua F. Valder, Christopher Weis
Non-USGS Publications**
Kolodziej, E. P., Gray, J. L., & Sedlak, D. L. (2003). Quantification Of Steroid Hormones With Pheromonal Properties In Municipal Wastewater Effluent. Environmental Toxicology and Chemistry, 22(11), 2622. doi:10.1897/03-42
Sedlak, D. L., Pinkston, K. E., Gray, J. L., & Kolodziej, E. P. (2003). Approaches for Quantifying the Attenuation of Wastewater-Derived Contaminants in the Aquatic Environment. CHIMIA International Journal for Chemistry, 57(9), 567-569. doi:10.2533/000942903777679055
Sedlak, D. L., Gray, J. L., & Pinkston, K. E. (2000). Peer Reviewed: Understanding Microcontaminants in Recycled Water. Environmental Science & Technology, 34(23). doi:10.1021/es003513e
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.