Past CHEEC Research:

Funded Research and Data Management Projects
Cooperative Research Projects

Funded Research and Data Management Projects

Nitrates, Nitrites and Nitrosatable Drugs and the Risk for Selected Birth Defects
Collaborators: Texas A&M University, University of Iowa (CHEEC, Iowa Registry for Congenital and Inherited Disorders), National Birth Defects Prevention Study Centers.
Funding Agency: National Institute for Environmental Health Sciences
Project period: 2007 – 2012

Congenital defects are the greatest contributor to infant mortality in the U.S., but the causes for the majority of these defects are either unknown or poorly understood. Amine- and amide-containing (nitrosatable) drugs and other compounds react with nitrite in the stomach to form N-nitroso compounds, which have been found to induce a variety of congenital malformations in animal studies. Previous epidemiologic studies have focused on the separate effects of nitrates, nitrites, and nitrosatable drugs on risk of congenital malformations without consideration of their interaction in the formation of N-nitroso compounds. This study is examining the separate and joint effects of prenatal exposures to nitrates, nitrites, and nitrosatable drugs on the risk for neural tube defects, limb malformations, oral clefts, and heart defects. Cases and controls were obtained from the National Birth Defects Prevention Study (NBDPS), a CDC-funded study that covers populations in 10 different states. Subjects' usual intake of dietary nitrates, nitrites, and nitrosamines was calculated from a food frequency survey. The subject survey will also have information on medications taken one month pre-conception and during the first trimester; these will be classified as to their likelihood of nitrosatability based on the literature and chemical structure. Addresses of Iowa and Texas participants are being linked to community water systems and water nitrate sampling results. The separate and joint effects of nitrosatable precursors on risk of selected malformations will be analyzed. The effects of vitamins C and E (inhibitors of nitrosation) on the relations between nitrate/nitrite intake and nitrosatable drugs and risk of congenital malformations will also be examined. Use of over-the-counter medications is fairly common during pregnancy; several over-the-counter preparations contain nitrosatable compounds as active ingredients. This study will help us understand whether pregnant women who take nitrosatable drugs and also consume greater amounts of nitrates and nitrites are at increased risk of having offspring with birth defects. Exposure Assessment Protocol.

Comprehensive Assessment of Rural Health in Iowa: the Carroll County Well Water Study 
Collaborators: Carroll County (IA) Environmental Health Department, CHEEC, Iowa Department of Public Health, University Hygienic Laboratory 
Funding Agency: Iowa Department of Public Health, National Center for Environmental Health 
Project period: 2007 – 2008

Intensive private drinking water well sampling in Carroll County, Iowa, will be conducted in 2007 – 2008 as part of the Comprehensive Assessment of Rural Health in Iowa (CARHI) project. This sampling will be a cooperative effort with the ongoing Iowa Statewide Rural Well Water Survey Phase 2 (SWRL2), a three year project (2006-08) conducted by CHEEC in collaboration with the Iowa County Health Departments and County sanitarians, the Iowa Departments of Public Health and Natural Resources, and other agencies. The intensive sampling effort in Carroll County will include 50 wells for the entire suite of SWRL2 compounds (nutrients, bacteria, metals, pesticides and herbicide degradates). Research questions of interest for this set of wells include are there seasonal variation for certain analytes in a confined geographic area (county), and what are the risk factors related to well characteristics/proximate sources of contaminants for poor water quality? An additional 100 wells will sampled and analyzed for total coliform bacteria, E. coli, enterococci, somatic coliphage, and chloride, as part of a special microbial monitoring study conducted by the University Hygienic Laboratory. The research objectives of the microbial monitoring study are to determine the incidence of enterovirus in private drinking water wells, to determine the occurrence of traditional and non-traditional fecal indicators in groundwater (e.g. somatic coliphage, chloride, and enterococci), and to determine whether the source of fecal pollution is human (by utilizing a human specific molecular marker).

CHEEC provided database support and applications development for the Muscular Dystrophy Surveillance Tracking and Research Network (MDSTARNet). The study is a multi-center multi-state research, tracking and surveillance effort that is identifying all people with childhood-onset Duchenne and Becker muscular dystrophies (DBMD). Collaborators are the Centers for Disease Control and Prevention (CDC), and researchers from Arizona, Colorado, Georgia, and New York. At the University of Iowa, the Iowa Registry for Congenital and Inherited Disorders is coordinating research efforts with assistance from the Iowa Department of Public Health.

Go to the CDC website for further information:

Download a pdf brochure: mdstarnet.pdf

Research and database management on the Comprehensive Assessment of Rural Health in Iowa (CARHI) in collaboration with the UI Departments of Geography, Occupational and Environmental Health, and Family Medicine. Funding is provided by the CDC.

Comprehensive Assessment of Rural Health in Iowa (CARHI)—NCEH is funding and providing technical oversight to a 2- to 3-year cooperative surveillance activity that is generating baseline health data for selected rural communities in Iowa. With input from a CARHI committee of stakeholders, the Iowa Department of Public Health (IDPH) is linking environmental and health data from a rural community to allow investigation of health effects possibly associated with the environment, such as effects associated with agricultural exposures. The CARHI committee is developing a tool and process for collecting data and a CARHI database. The committee also is recruiting communities and health care practitioners to participate in the CARHI project. Public health officials will use CARHI data to monitor communities’ health, identify existing or emerging health problems that warrant further investigation, enhance or guide environmental sampling, conduct comprehensive health studies, or target important public health programs such as smoking cessation and safe farming practices.

Agricultural Health Study 
CHEEC Data Management Center staff provided full computer support including database design and administration, system services and applications programming for the Agricultural Health Study for the first 13 years to this study. This study is funded by National Cancer Institute (NCI), the Environmental Protection Agency (EPA) and the National Institute of Environmental Health Sciences (NIEHS)has enrolled more than 60,000 people in Iowa. The University of Iowa College of Public Health is the lead investigator in Iowa. This large cohort will be followed for many year obtain detailed information on agricultural exposures, diet, and other factors which may be related to the development of cancer and other diseases. Information gathered will provide data on agricultural practices that can be helpful to farmers nationwide. For more information on the Agricultural Health Study, visit

Naturally Occurring Ammonia in Drinking Water Wells 
The (UHL) and the University of Iowa Center for Health Effects of Environmental Contamination (CHEEC), in collaboration with the Iowa Department of Natural Resources (DNR) Drinking Water Section, used existing databases and special monitoring efforts to conduct a statewide assessment of ground water quality and its relationship to certain public health outcomes. The study looked at the occurrence of ammonia, nitrite, nitrate and nitrifying bacteria in selected public water supplies. The study also included the linkage of analytical data maintained by the UHL and CHEEC, IDNR and health outcome data maintained by the Iowa Registry for Congenital and Inherited Disorders and the State Health Registry of Iowa. The study examined exposure to certain water contaminants and the incidence of various health outcomes at the community level. The study goal was to provide the State of Iowa with an ecological assessment of the occurrence and concentration of ammonia, nitrite, and nitrate-nitrogen in community water supplies and the risk for adverse health outcomes including, low birthweight, certain birth defects and certain cancers. Results of the investigation showed that systems with elevated ammonia concentrations in their source water had elevated nitrite and nitrate concentrations in their distributions systems. The results also indicated that bacterial growth, even with chlorination, was sufficient to lead to the reduction of ammonia and thus contribute to nitrite and nitrate concentrations in the distribution system. No adverse health outcomes, associated with the contaminants of concern, were identified in the study because of an insufficient study population. The report made several recommendations related to monitoring for ammonia and nitrite, as well as control of scaling and biofilms in water supply distribution systems.

Portions of the report submitted to the Iowa Department of Natural Resources are available at Microsoft Office document iconammonia_report.DOC (Note: this report is a Microsoft Word Document).

Residential Radon and Lung Cancer Case-Control Study
Please visit information regarding this study and radon at

Mammography Surveillance Pilot Studies
CHEEC provided data support for the Mammography Surveillance Pilot Study conducted in Scott County, Iowa. The study evaluated the feasibility of performing population-based mammography surveillance by identifying and linking Scott County patients receiving screening and diagnostic mammograms with their breast tissue pathology reports and breast cancer experience. 1993 is the study year. Specific aims of the study are: (1) Assess use and effectiveness of breast cancer mammography in Scott County for 1993, (2) Determine the need for changes in the practice of screening and in the workup of women with positive screening tests, and (3) Evaluate the feasibility of performing studies of biologic characteristics of screen-detected breast cancers and non-screen detected breast cancers. The Mammography Surveillance Pilot Study is participating in a consortium of similar surveillance studies. The consortium is committed to sharing common protocol, study design, and research objectives as well as comparable data collection procedures.

One Time Testing of Iowa Regulated Drinking Water Supplies 
In 1986 the Iowa General Assembly passed House File 2303. This legislation mandated that the Iowa Department of Natural Resources (IDNR) must develop and implement a one-time analytical testing of the finished water from Iowa's publicly and privately owned water systems for 35 pesticide compounds and 35 volatile organic contaminants (VOC). The University Hygienic Laboratory (UHL) provided all analytical services to this program which ran from November 1986 to November 1987.

Eight hundred and fifty-six public water systems were tested. One hundred and twenty-five tested positive for one or more pesticides. Five hundred and fifty tested positive for one or more synthetic organic compounds. No measurable concentrations of pesticides or volatile organic chemicals were found in 279 systems. A few water systems had pesticides or volatile organic chemical levels that exceeded U.S. Environmental Protection Agency health advisories or maximum contaminant levels, but contaminant levels high enough to cause an acute health risk were not observed in this study.

The pesticides most commonly found were atrazine, cyanazine (Bladex), alachlor (Lasso), metolachlor (Dual), and 2,4-D. The most frequently found volatile organic chemicals belong to a group called trihalomethanes (THMs). THMs are formed during disinfection when chlorine reacts with organic matter in the water. Para- and meta-xylene, measured as a single compound, was the second most abundant VOC observed.

The following are the most significant findings of this one time testing:

  • Surface water systems have the greatest potential for pesticide contamination.
  • The shallower ground water sources have a greater potential for contamination by pesticides and VOCs.
  • A seasonal trend in pesticide occurrences in water sources was not observed, with the exception of 2,4-D found at low levels.
  • The frequency of appearance and concentration of trihalomethanes in ground water systems serving small municipalities was unexpected.

For a copy of this report, contact the University Hygienic Laboratory at (319) 335-4500.


Cooperative Research Projects

Naturally-occurring radioactivity in private drinking water in Iowa: Understanding the potential for increased cancer risks to Iowans (2016)                                                                                                                                                                     Investigators: Michael Schultz, UI Department of Radiology; Michael Wichman, Dustin May, State Hygienic Laboratory at the University of Iowa                                                                                                                                                                   Cooperators: UI Department of Radiology, State Hygienic Laboratory at the University of Iowa                                Naturally-occurring radioactive material can be a substantial source of radiation exposure to the public, especially in ground-derived drinking water. Two radionuclides from the uranium decay series (lead-210; Pb-210 and polonium-210; Po-210) are of particular concern because their characteristic properties combine to present potential carcinogenic risks to human. These radionuclides are present in subsurface geological deposits where a great deal of drinking water in the state of Iowa is derived. While the potential carcinogenicities are known, concentrations of Pb-210 and Po-210 are not well characterized in Iowa aquifers. This study proposes to determine the concentrations of Pb-210 and Po-210 in 50 privately-owned wells across the state to develop an understanding of the potential contribution to increased lifetime cancer risk to Iowans.It is expected that success in these studies will result in a more detailed understanding of the biogeochemical relationship of increased levels of Po-210 and Pb-210 to other natural radionuclides found in Iowa's well water, and will provide preliminary data for understanding potential risk of natural radioactivity in Iowa's well water.

Development of novel, composite nanomaterials for water filtration (2014)
Investigators: Sarah Larsen, UI Department of Chemistry; David Cwiertny, Gene Parkin, UI Department of Civil and Environmental Engineering
Cooperators: Savannah River National Laboratory (SRNL) funds to support GRA; EPA funds (via Cwiertny/Parkin Labs) for lab equipment and supplies                                                                                                                                               
Approximately 1/3 of the world’s population lacks access to safe drinking water. Human exposures to drinking water contaminants, such as arsenic, have been linked to cancer, neurological, cardiovascular and pulmonary health problems. In a recent survey of private wells in Iowa, 48% were found to contain arsenic and 8% were determined to have arsenic levels greater than the EPA’s drinking water standard of 10 ppb. It is critical, both globally and locally, to develop improved methods for removing groundwater contaminants. Investigators in this study will design, fabricate and evaluate mesoporous silica-coated electrospun iron oxide nanofibers for arsenic adsorption from water. The Larsen Lab is developing functionalized mesoporous silica materials for adsorption of radioactive contaminants; these materials are also promising for application as arsenic adsorbents. The Cwiertny/Parkin Lab is developing electrospun nanofibers for use as chemically active filtration materials. CHEEC funds will allow the two Labs to work collaboratively to develop and evaluate these novel composite adsorbents.

Evaluation of a web-based approach to data collection in molecular environmental epidemiological investigations of adverse pregnancy outcomes (2012)
Investigators: Paul Romitti, Kristin Caspers, UI Dept. of Epidemiology; Gabriele Ludewig, UI Dept. of Occupational and Environmental Health; Michael Wichman, State Hygienic Laboratory; Peter Weyer, CHEEC
Cooperators: Iowa Registry for Congenital and Inherited Disorders, UI Reproductive Molecular Epidemiology Research and Education Program                                                                                                                                               

Wireless telephone use, caller ID, and call blocking pose challenges to telephone-based data collection for epidemiological studies; smartphones, tablets, and increased access to the internet have removed both time and place demands of home-based communications. Telephone-based data collection in Iowa for the NBDPS has indicated a steady decline in participation rates. This case-control study will evaluate a web-based approach for molecular environmental epidemiological studies of adverse pregnancy outcomes. 240 infants with selected birth defects and 240 infants without defects will be selected and equally assigned to a web-based or a telephone-based group. They will be administered a questionnaire for maternal environmental exposures; mothers in the web-based group will electronically sign a consent form to use residual newborn bloodspots for biomonitoring; for the telephone-based group, the U.S. Postal Service will be used for hand-signed informed consents. Participation rates, sample representativeness, exposure reporting, and costs between the web-based and telephone-based groups will be compared. Investigators hypothesize that improved participation rates will be seen in the web-based group, which will permit increased generalization of study results and increased statistical power for studies.

Occurrence of viruses and unregulated contaminants in Iowa public water supply groundwater (2012)
Investigators: Robert Libra, Iowa Geological and Water Survey; Michael Wichman, State Hygienic Laboratory 
Cooperators: Iowa Department of Natural Resources, U.S. Geological Survey, UI Department of Geosciences, U.S. Department of Agriculture                                                                                                                               

Groundwater supplies drinking water to about 80% of Iowa’s population; most Iowans obtain water from public water supplies (PWS), which are required by EPA to monitor finished water for various chemical, physical, and biological contaminants; raw source water monitoring is infrequently required. EPA publishes a Drinking Water Contaminant Candidate List detailing contaminants that may require standards and monitoring in the future. A strategy to assess future drinking water regulatory needs, and to guide source water protection activities for both public and domestic wells is targeted sampling and analysis of raw PWS groundwater for currently unregulated contaminants with public health and environmental concerns. This project will sample 66 Iowa PWS wells with known construction and hydrogeologic vulnerability for a number of contaminants. Funding for this project comes from EPA and Iowa DNR Drinking Water and Source-Water Protection programs. CHEEC funds will be used for sampling and analysis of PWS wells for human enteric viruses. The upcoming federal Unregulated Contaminant Monitoring Rule will have an emphasis on groundwater contaminants; this project will complement the national plan and establish Iowa as a leader in monitoring groundwater quality for contaminants with public health implications.

Influence of Redox Fluctuations on Arsenic Dynamics in Iowa Aquifer Materials (2011)
Investigators: Michelle Scherer, Gene Parkin, Douglas Schnoebelen, Department of Civil and Environmental Engineering, UI; Peter Weyer, Center for Health Effects of Environmental Contamination, UI
Cooperator: Cerro Gordo County (IA) Department of Public Health

Arsenic is an emerging water quality issue in Iowa’s groundwater. According to the Iowa Department of Natural Resources, there are 69 public water supplies that utilize groundwater with arsenic concentrations greater than the recommended limit and in as recent survey of 473 private wells in Iowa, 48% were found to contain arsenic. This study will help address the issue of arsenic in groundwater by conducting laboratory experiments to better understand the geochemical processes controlling the release of arsenic from soils to groundwater. This project will build on previous work that developed analytical methods for measuring arsenic and investigating the reduction of arsenic by common soil minerals. The objectives of this study are to 1) determine the extent of arsenic incorporation and release from iron minerals commonly found in Iowa aquifers, and 2) measure the release of iron and arsenic from Iowa aquifer materials where arsenic has been identified in the groundwater.

Fate of Endocrine Disruptors, Antibiotics and Pharmaceuticals in Wastewater Treatment Plants (2004)
Investigators: Gene Parkin, Craig Just, Department of Civil and Environmental Engineering, The University of Iowa
Cooperator: Iowa Department of Natural Resources (IDNR)

Biosolids are generally defined as the end-product of production and treatment of sludges generated during wastewater treatment. Beneficial uses of biosolids (e.g., land application, landfill covers, etc.) are expected to increase in the coming years. Wastewaters from domestic and industrial sources are known to contain relatively low concentrations of endocrine disruptors, antibiotics and pharmaceuticals. Most of what is known about the fate of these compounds comes from measurements taken before and after treatment of the liquid component of the wastewater. Very little is known about the fate of these compounds during processing of the solids generated during wastewater treatment. Many of these compounds are likely to partition onto particulate matter due to their hydrophobic nature. Thus, it is important to understand the fate of these compounds during the production and use of biosolids. Aqueous samples collected at points throughout a wastewater treatment plant were processed and analyzed for acetaminophen, caffeine, cotinine, ibuprofen, 4-nonylphenol, sulfamethoxazole, triclosan, and trimethoprim. Most aqueous phase removal occurred during primary clarification and/or activated sludge treatment while little or no aqueous phase removal resulted from secondary clarification or chlorination/dechlorination. Sorption isotherms determined for each compound on biosolids from the plant indicated compound specific sorption behavior. Caffeine, cotinine and acetaminophen were significantly removed from the aqueous phase during activated sludge treatment. This implicates biotransformation as a primary removal process given the low sorption potential of these chemicals. Sulfamethoxazole and trimethoprim also have low sorption potential, but are more chemically stabile such that only a small quantity of each was removed during activated sludge treatment. Ibuprofen, 4-nonylphenol and triclosan were significantly removed from the aqueous phase during activated sludge treatment, likely as a result of sorption processes as evidenced by high log Kow values and high concentrations of triclosan and 4-nonylphenol in analyzed biosolids.

Urinary Pesticide Metabolite Levels and Reproductive Effects: A Prospective, Pilot Study of Partners of Pregnant Women in Iowa (2003)
Investigators: Paul Romitti, Department of Epidemiology, and Amy Sparks, Department of Obstetrics/Gynecology and Urology, The University of Iowa
Cooperator: Study for Future Families

This study hypothesized that the variance in semen quality between geographic locations may be related to recent exposure to environmental toxins, particularly agricultural chemicals. Prospective, multi-center studies have demonstrated geographical variations in semen quality. A recent study of semen quality in four US cities found male partners of pregnant women a rural center (MO) to have significantly lower sperm counts and motility than men recruited from urban centers (NY, MN and CA). A small study of men from this population residing in MO demonstrated an association between semen quality and levels of urinary pesticide metabolites, while men in MN had few detectable levels. The study proposed to examine the relationship between semen quality and urinary pesticide metabolites in partners of pregnant women receiving obstetrical care at University of Iowa Hospitals and Clinics. 

Iowa Community Private Well Study (2002)
Investigators: Peter Weyer, David Riley: University of Iowa (UI) Center for Health Effects of Environmental Contamination, Jessica Ferrie, UI Dept. of Occupational and Environmental Health, UI College of Public Health, Michael Wichman, Lorelei Kurimski, Terence Cain, UI Hygienic Laboratory, David Osterberg: UI Environmental Health Sciences Research Center, Brent Parker, Iowa Department of Natural Resources, Douglas Schnoebelen: U.S. Geological Survey
Cooperators: The University of Iowa Hygienic Laboratory, the UI Center for Health Effects of Environmental Contamination (CHEEC), UI Environmental Health Sciences Research Center (EHSRC), the United States Geological Survey, the Iowa Department of Natural Resources, and County Environmental Health Specialists.

Conducted from June 2002-January 2003, the study aimed to achieve a better understanding of private drinking water wells in incorporated Iowa towns not served by a public water supply system. Water samples were analyzed by the University of Iowa Hygienic Laboratory (duplicate samples analyzed at USGS laboratories) for common use pesticides, nitrogen compounds, inorganics, bacteria, and VOCs. The study design contained a random and focused component. * Random Study Methodology: Approximately 103 drinking water wells from towns that did not have a public water supply were selected. A weighted distribution of households from US Census data was employed to select wells (i.e.- towns with a higher number of households stood a greater chance of having a well selected). County environmental health specialists visited these towns, located randomly generated points on maps, and found the nearest building to draw a water sample. Fifty distinct towns had one or more wells sampled. * Focus Study Methodology: The focus study employed the use of existing databases of potential contamination sources to intensively sample 15 communities. Selection criteria for these towns considered: towns utilizing private septic systems, existence of underground storage tanks, location of agricultural grain and chemical storage dealerships, regional hydrogeology, active and closed landfills, feedlots, railroad systems, industries in violation of wastewater permit applications (including stormwater permits), nearby uncontrolled sites identified by the Iowa Department of Natural Resources (IDNR), and Resource Conservation and Recovery Act (RCRA)/Superfund sites. 

A fact sheet in PDF is available here:

Analysis of Environmental Exposures in Hoop Structures and Conventional Confinement Swine Barns (1999)
Investigators: Peter Thorne, Department of Environmental and Occupational Health, The University of Iowa, Dwaine Bundy, Department of Agriculture and Biosystems Engineering, Iowa State University
Cooperators: The Leopold Center for Sustainable Agriculture, Iowa State University, and The University of Iowa Office of Vice President for Research

A major health concern in swine farming is inhalation of toxicants, which may lead to significant morbidity among swine farmers. Exposures to hydrogen sulfide, ammonia, dust and endotoxin have been linked to a number of health problems in workers, including upper airway diseases, lower airway diseases and interstitial diseases. In addition, outdoor air quality in proximity to swine operations has become a major concern in recent years. Neighbor complaints have been increasing as swine units become larger and more densely located in the neighboring community. While health effects related to odors from livestock units are very difficult to determine, the public perception that odors contain toxic substances has resulted in reports of headaches, nausea and other health complaints in neighbors. In recent years, hoop structures have emerged as an alternative method of housing hogs, and appear to have environmental benefits (related to air and water quality) in comparison to conventional confinement facilities. The purposes of this study are to 1) quantify airborne contaminant concentrations and exposure duration in hoop barns and conventional confinement barns controlling for location, season, micrometeorological conditions, animal density and other factors, and 2) to compare the exposure of airborne contaminants around and downwind of hoop structures and conventional confinement structures. The study will be conducted utilizing a pork producing farm with 3-5 hoop barns and 3-5 confinement buildings on a nearby site. The 15-month project will be a joint effort of researchers from The University of Iowa and Iowa State University; field sampling will be coordinated between study staffs, and laboratory analyses will be conducted utilizing labs at both institutions (ISU Odor Laboratory, ISU Animal Science Department, UI Inhalation Toxicology Facility), which specialize in specific contaminant identification and quantification.
CHEEC, the Leopold Center for Sustainable Agriculture, and the UI Office of the Vice President for Research conducted a study titled 'Analysis of Environmental Exposures in Hoop Structures and Conventional Confinement Swine Barns' . The study was an effort to quantify and describe airborne compounds present in both both types of swine production facilities and potential exposures to workers and area contaminations. Research was completed 2000.

Antibiotics in Surface Water (1999)
Investigators: Peter Weyer, Center for Health Effects of Environmental Contamination, The University of Iowa; Dana Kolpin, United States Geological Survey, Water Resource Division, Iowa District 
Cooperator: United States Geological Survey

In 1999, CHEEC and the Iowa District of the United States Geological Survey (USGS) joined in a collaboratively funded project investigating the presence of antibiotics/antimicrobials in Iowa surface waters. The study objectives are to provide baseline data for types of antimicrobial compounds present, concentrations, and geographical distribution. Thirty sites from across the state were selected representing a cross section of large and small watersheds and stream flows. Of secondary importance of this study was for laboratory methods development for detection of these compounds. Thirty-one sites from across the state were sampled, representing large and small stream flows. Streams were sampled once during the first peak runoff event following snow melt in April 1999. These 15 distinct antibiotics were sampled: carbadox, spectinomycin, sulfamethoxazol, erythromycin, sulfamethazine, trimethoprin, erythromycin - H2O, sulfachloropyrizadine, tylosin, ivermectin, sulfadimethoxine, virginiamycin, lincomycin, sulfamerazine, and tetracyclines (total). Analytical results show that 16 of the 31 stream samples had positive detections for antibiotics. Sulfamethazine was detected in 10 samples, tetracycline (total) in 6, and lincomycin in 1. One stream had two detections of a single compound. All of the concentrations were below .5 micrograms/L (parts per billion). The results of this work were first presented at a 1999 USGS meeting titled Effects of Animal Feeding Operations on Hydrologic Resources and the Environment. Proceedings are available at

Findings from this initial reconnaissance laid the groundwork for the the Kolpin et al journal article in Environmental Science and Technology, titled Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999-2000: A National Reconnaissance; Environ. Sci. Technol., 36 (6), 1202 -1211, 2002

For a more thorough discussion of emerging contamination of water sources, see the USGS Toxic Substances Hydrology Program.