U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2019–5019

Prepared in cooperation with the City of Dallas, Dallas Water Utilities

Compounds of Emerging Concern Detected in Water Samples 

from Potable Water and Wastewater Treatment Plants and 

Detected in Water and Bed-Sediment Samples from Sites on 

the Trinity River, Dallas, Texas, 2009–13
Cover photograph: Dallas skyline at twilight, March 2017. Photograph courtesy of Teddie Bridget Proctor, 

licensed under Creative Commons BY-ND 2.0. 
Compounds of Emerging Concern Detected 

in Water Samples from Potable Water 

and Wastewater Treatment Plants and 

Detected in Water and Bed-Sediment 

Samples from Sites on the Trinity River, 

Dallas, Texas, 2009–13

By Christopher J. Churchill, Stanley Baldys III, Cathina L. Gunn, Craig A. Mobley, 

and Daniel P. Quigley 

Prepared in cooperation with the City of Dallas, Dallas Water Utilities

Scientific Investigations Report 2019–5019

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

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Suggested citation:

Churchill, C.J., Baldys, S., III, Gunn, C.L., Mobley, C.A., and Quigley, D.P., 2020, Compounds of emerging concern 

detected in water samples from potable water and wastewater treatment plants and detected in water and 

bed-sediment samples from sites on the Trinity River, Dallas, Texas, 2009–13: U.S. Geological Survey Scientific 

Investigations Report 2019–5019, 57 p., https://doi.org/10.3133/sir20195019.

Associated data for this publication: 

Null, M.L., Treviño, J.M., and Churchill, C.J., 2019, Detections and concentrations of compounds of emerging concern 

at water treatment plants and in the Trinity River in or near Dallas, Texas, 2009–13: U.S. Geological Survey data 

release, https://doi.org/10.5066/P9QUPBZK.

ISSN 2328-0328 (online)
iii

Contents

Abstract ..........................................................................................................................................................1

Introduction ....................................................................................................................................................2

Purpose and Scope .............................................................................................................................3

Description of Study Area ..................................................................................................................4

Potable Water Treatment Plants ..............................................................................................4

Wastewater Treatment Plants ..................................................................................................7

Trinity River Study Sites .............................................................................................................7

Methods ..........................................................................................................................................................7

Sample-Collection Methods ..............................................................................................................7

Sample Collection at Potable Water Treatment Plants ........................................................8

Sample Collection at Wastewater Treatment Plants ............................................................8

Sample Collection at Trinity River Sites ..................................................................................8

Laboratory Analysis .............................................................................................................................8

Human-Health Pharmaceuticals in Water Samples .............................................................9

Antibiotics in Water Samples ...................................................................................................9

Steroidal Hormones, Stanols, and Sterols in Water Samples ...........................................10

Wastewater Compounds in Water Samples ........................................................................10

Wastewater Compounds in Bed-Sediment Samples ..........................................................10

Duplicate Analyses of Selected Compounds .......................................................................11

Quality Control ....................................................................................................................................11

Blank Samples ...........................................................................................................................13

Replicate Samples ....................................................................................................................13

Matrix-Spike Samples ..............................................................................................................16

Surrogate Data ..........................................................................................................................16

Statistical Analyses ...........................................................................................................................16

Detections, Concentrations, and Distributions of Compounds of Emerging Concern ....................21

Compounds of Emerging Concern in Water Samples Collected at Potable Water 

Treatment Plants ...................................................................................................................21

Compound Detections ..............................................................................................................21

Compound Concentrations ......................................................................................................21

Compounds of Emerging Concern in Water Samples Collected at Wastewater 

Treatment Plants ...................................................................................................................23

Human-Health Pharmaceuticals and Antibiotics ................................................................23

Steroidal Hormones, Stanols, and Sterols ............................................................................26

Detergents, Personal-Use Products, and Pesticides .........................................................30

Industrial Wastewater and Disinfection Compounds and Polycyclic Aromatic 

Hydrocarbons ..............................................................................................................32

Flame Retardants and Plasticizers ........................................................................................32

Observations Regarding Compounds of Emerging Concern Detected in Water 

Samples Collected at Potable Water and Wastewater Treatment Plants ..................32

Compounds of Emerging Concern in Stream-Water and Bed-Sediment Samples 

Collected at Study Sites on the Trinity River ....................................................................35

Compounds of Emerging Concern in Stream-Water Samples ..........................................35

Compounds of Emerging Concern in Bed-Sediment Samples ..........................................39

Summary .......................................................................................................................................................41

References Cited .........................................................................................................................................42
iv

Figures

1. Map showing locations of potable water and wastewater treatment plants and 

U.S. Geological Survey water-quality monitoring stations on the Trinity River in 

or near Dallas, Texas, where samples were collected during 2009–13 .............................5

2. Graph showing detection frequencies of selected compounds in raw- and 

finished-water samples collected at potable water treatment plants in or near 

Dallas, Texas, 2009–13 ...............................................................................................................22

3. Graph showing detection frequencies of human-health pharmaceuticals and 

antibiotic compounds in untreated-influent and treated-effluent water samples 

collected at wastewater treatment plants in or near Dallas, Texas, 2009–13 .................24

4. Graph showing concentrations of selected human-health pharmaceuticals and 

antibiotics in untreated-influent and treated-effluent water samples collected at 

wastewater treatment plants in or near Dallas, Texas, 2009−13 .......................................25

5. Graph showing detection frequencies of steroidal hormones, stanols, sterols, 

and other wastewater compounds measured in untreated-influent and treatedeffluent water samples collected at wastewater treatment plants in or near 

Dallas, Texas, 2009–13 ...............................................................................................................27

6. Graph showing concentrations of steroidal hormones, stanols, sterols, and 

wastewater compounds detected in untreated-influent and treated-effluent 

water samples collected at wastewater treatment plants in or near Dallas, 

Texas, 2009−13 ............................................................................................................................29

7. Graph showing detection frequencies of detergents and detergent metabolites, 

personal-use products (flavors and fragrances), and pesticides and repellents in 

untreated-influent and treated-effluent water samples collected at wastewater 

treatment plants in or near Dallas, Texas, 2009–13 ..............................................................31

8. Graph showing detection frequencies of industrial wastewater and disinfection 

compounds and polycyclic aromatic hydrocarbons in untreated-influent and 

treated-effluent water samples collected at wastewater treatment plants in or 

near Dallas, Texas, 2009–13 .....................................................................................................33

9. Graph showing detection frequencies of flame retardants and plasticizers in 

untreated-influent and treated-effluent water samples collected at wastewater 

treatment plants in or near Dallas, Texas, 2009–13 ..............................................................34

10. Graph showing detection frequencies of human-health pharmaceuticals, 

antibiotics, steroidal hormones, stanols, and sterols in seven stream-water 

samples collected at study sites on the Trinity River in or near Dallas, Texas, 

2009–13 ........................................................................................................................................36

11. Graph showing detection frequencies of personal-use products (fragrances), 

pesticides, industrial wastewater compounds, and flame retardants and 

plasticizers in seven stream-water samples collected at study sites on the Trinity 

River in or near Dallas, Texas, 2009–13 ..................................................................................38

12. Graph showing detection frequencies of stanols and sterols, personal-use 

products and fragrances, disinfectants, polycyclic aromatic hydrocarbons, and 

plasticizers in seven bed-sediment samples collected at study sites on the 

Trinity River in or near Dallas, Texas, 2009–13 ......................................................................40
v

Tables

1. Water-quality study sites in or near Dallas, Texas, 2009–13 ................................................6

2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, 

sterols, and wastewater compounds analyzed in water and bed-sediment 

samples collected at study sites in or near Dallas, Texas, 2009–13 ..................................47

3. Compounds analyzed by using more than one laboratory method in water 

samples collected at study sites in or near Dallas, Texas, 2009–13 ..................................12

4. Detected compounds and range of concentrations in laboratory-grade 

organic-free water in nine blank samples analyzed in conjunction with waterquality sampling in or near Dallas, Texas, 2009–13 ..............................................................14

5. Relative percent differences of compounds detected in 11 replicate samples 

collected at water-quality study sites in or near Dallas, Texas, 2009–13 .........................15

6. Spike report for treated-effluent water samples collected at water-quality 

study sites in or near Dallas, Texas, 2009–13 ........................................................................17

7. Relative percent differences for field and laboratory spikes of treated-effluent 

water samples collected November 23, 2009, at WWTP-2 near Dallas, Texas ...............19

8. Surrogate percent recoveries for environmental samples collected at study 

sites in or near Dallas, Texas, 2009–13 ...................................................................................20

9. Results of Wilcoxon rank-sum tests for selected compounds detected in water 

samples collected at potable water treatment plants in or near Dallas, Texas, 

2009–13 ........................................................................................................................................23

10. Results of Wilcoxon signed-rank tests for selected human-health 

pharmaceuticals and antibiotic compounds detected in water samples collected 

at wastewater treatment plants in or near Dallas, Texas, 2009–13 ...................................26

11. Results of Wilcoxon signed-rank tests for selected hormones, stanols, sterols, 

and wastewater compounds detected in water samples collected at wastewater 

treatment plants in or near Dallas, Texas, 2009–13 ..............................................................28
vi

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Volume

gallon (gal) 3.785 liter (L) 

million gallons (Mgal) 3,785 cubic meter (m3)

cubic foot (ft3) 0.02832 cubic meter (m3) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

gallon per day (gal/d) 0.003785 cubic meter per day (m3/d)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

Datum

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Supplemental Information

Concentrations of chemical compounds in water are given in micrograms per liter (μg/L). 

Micrograms per liter is a unit expressing the concentration of chemical compounds in solution 

as weight of solute (micrograms) per unit volume (liter) of water.

Concentrations of chemical compounds in sediment are given in micrograms per kilogram 

(μg/kg).
vii

Abbreviations

AHTN acetyl-hexamethyl-tetrahydronaphthalene

ANOVA analysis of variance

BPA bisphenol A

CAFO concentrated animal feeding operation

CECs compounds of emerging concern

DEET N,N-diethyl-m-toluamide

E estimated

EDC endocrine disrupting compound

EPA U.S. Environmental Protection Agency

HHCB hexahydro-hexamethyl-cyclopenta-benzopyran

LCAB OGRL analysis for antibiotics by use of liquid chromatography/mass spectrometry

LRL laboratory reporting level

LT-MDL long-term method detection level

NWQL U.S. Geological Survey National Water Quality Laboratory

OGRL U.S. Geological Survey Organic Geochemistry Research Laboratory

PAH polycyclic aromatic hydrocarbon

PWTP potable water treatment plant

RPD relative percent difference

SH laboratory analyses for a group of compounds

SPE solid-phase extraction

USGS U.S. Geological Survey

WWTP wastewater treatment plant

Compounds of Emerging Concern Detected in Water 

Samples from Potable Water and Wastewater Treatment 

Plants and Detected in Water and Bed-Sediment Samples 

from Sites on the Trinity River, Dallas, Texas, 2009–13

By Christopher J. Churchill, Stanley Baldys III, Cathina L. Gunn, Craig A. Mobley, and Daniel P. Quigley 

Abstract

The population in the Dallas-Fort Worth metropolitan 

area in northern Texas is rapidly growing, resulting in a rapid 

increase in the demand for potable water and an increase 

in the discharge of wastewater treatment plant effluent. An 

assessment of compounds of emerging concern (CECs) in 

samples collected at potable water and wastewater treatment 

plants in Dallas and downstream from Dallas in the Trinity 

River was completed by the U.S. Geological Survey in 

cooperation with the City of Dallas, Dallas Water Utilities. 

CECs are synthetic or naturally occurring chemicals that are 

not commonly monitored in the environment but can enter the 

environment and cause known or suspected adverse ecological 

or human health effects. CECs can enter the environment 

through nonpoint sources (for example, runoff) and point 

sources (for example, concentrated animal feeding operations 

and treated-effluent discharge from wastewater treatment 

plants), which can increase concentrations of CECs especially 

in highly populated areas. CECs include pharmaceuticals 

(prescription and nonprescription), steroidal hormones, 

stanols, sterols, detergents and detergent metabolites 

(hereinafter referred to as “detergents”), personal-use products, 

pesticides, polycyclic aromatic hydrocarbons (PAHs), 

flame retardants, plasticizers, and other organic compounds 

used in everyday domestic, agricultural, and industrial 

applications. The release of CECs to the environment went 

largely unrecognized until relatively recently. Increased 

loading of certain CECs to the environment, combined with 

advancements in laboratory analysis methods that resulted in 

appreciably lower detection levels, brought greater attention to 

the release of CECs. In addition, synthesis of new chemicals 

or changes in use and disposal of existing chemicals can create 

new sources of CECs. Some CECs are endocrine disrupting 

compounds (EDCs), which can elicit adverse effects on 

development, behavior, and reproduction of wildlife and can 

cause dysfunction of human and wildlife endocrine (hormone) 

systems.

Results of studies in the United States and Europe 

indicate that CECs, their metabolites, and industrial, 

agricultural, and household wastewater products are present 

in the aquatic environment, water treatment plants, and septic 

systems. CECs, especially pharmaceuticals, are of interest 

because of their persistence, widespread use, and potential to 

cause adverse effects in humans and nontargeted organisms. 

There is also concern that some CECs and EDCs resist 

degradation of water treatment processes at potable water 

treatment plants (PWTPs) and wastewater treatment plants 

(WWTPs) and that treated-effluent discharge could contain 

compounds that negatively affect biota living in receiving 

waters. Therefore, CECs and EDCs are more likely to be 

detected in environmental samples collected near areas of high 

population density where treated effluent from WWTPs can 

contribute substantially to receiving waters.

The U.S. Geological Survey, in cooperation with the City 

of Dallas, Dallas Water Utilities, evaluated the occurrence 

and concentrations of selected CECs in samples collected 

at PWTPs and WWTPs in Dallas and downstream from the 

Dallas-Fort Worth metropolitan area in the Trinity River, 

Texas, from August 2009 to December 2013. Water samples 

were collected at three PWTP sites, two WWTP sites, and five 

study sites on the Trinity River; all sites where samples were 

collected were in or downstream from Dallas. These water 

samples were analyzed for 120 CECs, including humanhealth pharmaceuticals (prescription and nonprescription), 

antibiotics, steroidal hormones, stanols, sterols, detergents, 

personal-use products (flavors and fragrances), pesticides and 

repellents, industrial wastewater compounds, disinfection 

compounds, PAHs, flame retardants, and plasticizers. 

Additionally, bed-sediment samples were collected at each of 

the five Trinity River sites. The bed-sediment samples were 

analyzed for 57 CECs.

In general, the water treatment processes at PWTPs 

and WWTPs were effective at reducing detections and 

concentrations of CECs to undetectable levels or transforming 

the compounds into degradates that were not analyzed. There 

were 14 and 73 CECs detected in raw water and in untreatedinfluent water at PWTPs and WWTPs, respectively. Of these, 

11 of the 14 CECs detected in raw-water samples and 44 of 

the 73 CECs detected in untreated-influent samples were not 
2 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

detected in finished water or in treated-effluent water samples, 

respectively, indicating that these compounds were removed or 

degraded to compounds that were not analyzed. Some CECs, 

however, are resistant to degradation and were detected in 

untreated and treated water at PWTPs and at WWTPs. The 

three CECs detected at PWTPs in raw-water and finishedwater samples were tris(dichloroisopropyl)phosphate, 

benzophenone, and methyl salicylate. At WWTPs, 29 CECs 

were detected, including carbamazepine, sulfamethoxazole, 

4-androstene-3,17-dione, 3-beta-coprostanol, acetylhexamethyl-tetrahydronaphthalene (AHTN), hexahydrohexamethyl-cyclopenta-benzopyran (HHCB), 

1,4-dichlorobenzene, tribromomethane, benzophenone, and 

tris(dichloroisopropyl)phosphate, in untreated and treated 

water, indicating that treatment processes likely did not 

remove or degrade these compounds.

Of the 23 CECs detected in stream-water samples 

collected at 5 sites on the Trinity River in or near Dallas, 

10 CECs (carbamazepine, sulfamethoxazole, caffeine, 

3-beta-coprostanol, cholesterol, HHCB, benzophenone, 

triethyl citrate, tributyl phosphate, and tris(dichloroisopropyl)

phosphate) were detected at all 5 sites. The 10 CECs detected 

in water samples collected at all 5 sites on the Trinity River 

were also detected in treated-effluent water at WWTPs. 

Eleven of the 57 targeted CECs were detected in bedsediment samples collected at study sites on the Trinity River. 

Of these 11 CECs, only 2 (beta-sitosterol and cholesterol) 

were detected in bed-sediment samples at all 5 sites on the 

Trinity River. Nine of these 11 CECs were not detected 

in any water-column sample, likely because of the strong 

hydrophobic characteristics of these compounds.

Results from water treatment plants indicate that the 

water treatment process is less effective for removing or 

degrading compounds that are engineered to be resistant to 

degradation. These results also indicate the presence of CECs 

and EDCs at locations upstream from PWTPs in Dallas. 

Results from Trinity River main-stem sites indicate that some 

compounds are naturally attenuated during transport, but a 

few are persistent throughout the study reach. Many CECs 

and EDCs are hydrophobic and were only detected in bed 

sediment, indicating multiple pathways through which CECs 

can persist in the environment. 

In general, concentrations of CECs in the Dallas-Fort 

Worth metropolitan area were similar to those found in 

metropolitan areas nationwide.

Introduction

Dallas is in the upper Trinity River Basin in northern 

Texas and is the largest city in the Dallas-Fort Worth 

metropolitan area (Dallas-Fort Worth) with an estimated 

population of 1.26 million in 2015 (U.S. Census Bureau, 

2015a). Dallas-Fort Worth includes 14 cities with populations 

greater than 100,000; the estimated population of the 

metropolitan area was 7.1 million in 2015 (U.S. Census 

Bureau, 2015b). Dallas-Fort Worth is projected to more than 

double in population to approximately 15 million by 2060 

(Texas Water Development Board, 2010). The burgeoning 

population of the Dallas-Fort Worth area creates an increased 

demand for potable water supplies, and the increasing 

urbanization associated with rapid population growth 

increases water-quality concerns. Water supplies for Dallas 

and nearby cities that are served by Dallas Water Utilities 

come from surface-water reservoirs in the Trinity River Basin 

and in neighboring river basins (the Red, Sabine, and Sulphur 

River Basins). Several of these reservoirs can contain water 

diverted from regions downstream from Dallas-Fort Worth 

through water reuse and transfer programs. For example, 

North Texas Municipal Water District diverts water from the 

East Fork Trinity River through an artificial wetland before 

pipelines transfer the water to Lavon Lake; Tarrant Regional 

Water District diverts water from the Trinity River into an 

artificial wetland and returns treated water to reservoirs in 

Dallas-Fort Worth (Texas Water Development Board, 2011). 

Drought conditions during 2011–14 reduced water levels in 

these regional reservoirs, which adversely affected potablewater supplies. Regional water supplies were further reduced 

because of the presence of zebra mussels in Lake Texoma 

in the Red River Basin (Churchill and Baldys, 2012). The 

presence of zebra mussels precluded interbasin transfer of 

water from Lake Texoma to Dallas-Fort Worth. Drought 

conditions during 2011–14 also led to increased scrutiny on 

the quality of source and treated municipal waters, including 

raw water, finished water, untreated-influent and treatedeffluent wastewater, and receiving waters of wastewater 

discharges.

The release of compounds of emerging concern (CECs) 

to the environment went largely unrecognized until the 1970s; 

laboratory analysis methods that resulted in appreciably 

lower detection levels and increased media coverage have 

brought increased attention to the issue of CECs in recent 

years (National Association of Clean Water Agencies, 2010). 

CECs have become a water-quality concern in many large 

urban areas such as Dallas-Fort Worth. CECs can be broadly 

defined as any synthetic or naturally occurring chemical 

that is not commonly monitored in the environment but 

has the potential to enter the environment and cause known 

or suspected adverse ecological or human health effects 

(U.S. Geological Survey [USGS], 2018a). CECs include 

pharmaceuticals (steroidal hormones and their metabolites 

and antibiotics), naturally occurring steroids, stanols, sterols, 

and other organic compounds used in everyday domestic, 

agricultural, and industrial applications. Releases of CECs to 

the environment were not widely recognized until laboratory 

analysis methods capable of detecting concentrations in the 

parts per billion range or sub parts per billion range were 

developed. In addition, synthesis and widespread use of new 

chemicals such as pharmaceuticals have increased the loading 

of CECs to the environment. Changes in use and disposal of 

existing chemicals can also create new sources of CECs. There 

is increasing interest in CECs, especially pharmaceuticals, 
Introduction 3

because of their persistence, widespread use, and potential to 

cause adverse effects in humans and nontargeted organisms 

(Daughton and Ternes, 1999; Kolpin and others, 2002; Kim 

and others, 2007; Brooks and others, 2009; Raghav and others, 

2013). Many pharmaceutical compounds are designed to resist 

physical, chemical, and biological degradation, resulting in 

as much as 90 percent of the ingested drug being excreted 

in its biologically active form (Jjemba, 2006). The use of 

pharmaceuticals has steadily increased in the United States. 

The number of Americans who took at least one prescription 

drug increased from 44 to 48 percent from 1999 to 2008, and 

those who took two or more prescription drugs increased 

from 25 to 31 percent. Moreover, from 1990 to 2008, those 

who took five or more drugs increased from 6 to 11 percent 

(Gu and others, 2010). The increase in prescription drug use 

can concomitantly increase the potential for larger amounts 

of pharmaceuticals to enter potable water supplies and 

wastewater effluent (Buxton and Kolpin, 2002).

Results of studies in the United States and Europe 

indicate that CECs, their metabolites, and industrial, 

agricultural, and household wastewater products are widely 

present in the aquatic environment and are found in the water 

in water treatment plants and septic systems (Stackelberg 

and others, 2004; Clara and others, 2005; Glassmeyer and 

others, 2005; Godfrey and others, 2007; Phillips and others, 

2010; Phillips and others, 2012). Buxton and Kolpin (2002) 

reported that several compounds, steroids, insect repellents, 

and nonprescription drugs were frequently detected in 

surface-water samples collected across the United States. 

Examples of recent reports documenting the presence of CECs 

in the aquatic environment in different parts of the United 

States include reports pertaining to the presence of CECs in 

North Carolina (Ferrell, 2009); Minnesota (Lee and others, 

2010); Pennsylvania (Reif and others, 2012); and Wisconsin 

(Tomasek and others, 2012). Opsahl and Lambert (2013) 

also reported on the presence of CECs in the San Antonio 

River Basin in south-central Texas, and evaluated detections, 

concentrations, and distribution patterns of selected CECs 

downstream from effluent discharge locations in San Antonio.

Some CECs are endocrine disrupting compounds 

(EDCs), which can elicit adverse effects on development, 

behavior, and reproduction of wildlife and can cause 

dysfunction of human and wildlife endocrine (hormone) 

systems. Although adverse effects of EDCs on human health 

are not clearly understood and can be difficult to predict 

(Kolpin and others, 2002; Brooks and others, 2009), several 

studies have documented the effects of EDCs on ecological 

health. For example, Crain and Guillette (1997) found that 

EDCs can cause feminization in alligators, and Kirk and 

others (2003) found that EDCs are estrogenic in fish, birds, 

and mammals. To further study the effect that EDCs have 

on endocrine systems, the U.S. Environmental Protection 

Agency (EPA) instituted the Endocrine Disruptor Screening 

Program in 2014 that superseded the original comprehensive 

management plan issued in June 2012 with targeted objectives 

for 2014–19 (EPA, 2014).

CECs and EDCs are more likely to be detected in 

environmental samples collected near areas of high population 

density where treated effluent from wastewater treatment 

facilities can contribute substantially to receiving waters 

(Clara and others, 2005). An additional source of CECs can be 

from concentrated animal feeding operations (CAFOs), such 

as cattle or chicken feedlots, because of the widespread use 

of pharmaceutical compounds in animal feed (Campagnolo 

and others, 2002). Several poultry and cattle CAFOs are in the 

Trinity River Basin upstream from Dallas. Although most of 

the Trinity River Basin is serviced by enclosed sewer systems, 

rural systems can contribute CECs to tributaries of the Trinity 

River through rainfall runoff. Land application of biosolids 

has also been identified as a potential way for CECs to enter 

the environment (Reif and others, 2012; Raghav and others, 

2013). The Trinity River Authority of Texas and the City of 

Fort Worth use biosolid application programs in the Trinity 

River Basin (City of Fort Worth, 2018; Trinity River Authority 

of Texas, 2018).

Some CECs are known to resist degradation during water 

treatment processes at wastewater treatment plants (WWTPs) 

(Venkatesan and Halden, 2014). If treated effluent discharged 

from WWTPs to the Trinity River contains CECs that were not 

degraded during treatment, these compounds could negatively 

affect the receiving waters of the Trinity River by causing 

adverse ecological or human health effects. Stream-water and 

bed-sediment data obtained from samples collected from the 

Trinity River could yield information regarding the transport, 

attenuation, and fate of CECs in this effluent-dominated river. 

To date, the occurrence, concentrations, and distributions 

of CECs in waters of the Trinity River Basin have not been 

studied. Therefore, the USGS, in cooperation with the City 

of Dallas, Dallas Water Utilities, assessed the occurrence, 

concentrations, and distributions of CECs in raw water and 

finished water at the City’s potable water treatment plants 

(PWTPs), in untreated-influent and treated-effluent water at 

the City’s WWTPs, and in water and bed sediment at five sites 

in the receiving waters of the Trinity River between Dallas and 

Trinidad, Tex.

Purpose and Scope

This report summarizes detections, concentrations, and 

distributions of CECs in raw- and finished-water samples 

collected at three PWTPs and in untreated-influent and 

treated-effluent water samples collected at two WWTPs in 

Dallas, Tex., and in stream-water and bed-sediment samples 

collected at five study sites on the main stem of the Trinity 

River during 2009–2013. The analyzed CECs were humanhealth prescription and nonprescription pharmaceuticals 

(14 compounds); antibiotics (30 compounds); steroidal 

hormones and their metabolites, stanols, and sterols 

(21 compounds); and organic compounds found in domestic 

and industrial wastewater (55 compounds). In addition to 

quality-control samples, seven environmental water samples 

were collected at the raw-water intake (inflow to plant) and 
4 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

from the finished water (outflow from plant) of three PWTPs 

and at the untreated-influent intake and from treated effluent 

of two WWTPs. Environmental samples collected at each of 

the five study sites on the Trinity River consisted of seven 

width- and depth-integrated stream-water samples and seven 

bed-sediment samples. A total of 129 total samples were 

analyzed during the study; of these 129 samples, 105 were 

environmental samples, and 24 were quality-control samples. 

Results from the quality-control samples were used to help 

interpret and provide context for the results obtained from the 

environmental samples.

Description of Study Area

The Trinity River extends approximately 710 miles and 

flows generally southeast from near the Oklahoma border 

to Galveston Bay near Houston, Tex. (fig. 1). The river’s 

headwaters are composed of the West Fork Trinity River 

(West Fork), Clear Fork Trinity River (Clear Fork), Elm Fork 

Trinity River (Elm Fork), and East Fork Trinity River (East 

Fork) in north-central Texas. Downstream from where Clear 

Fork flows into West Fork, the main stem of the Trinity River 

begins west of downtown Dallas at the confluence of West 

Fork and Elm Fork. The confluence of East Fork with the 

main stem is 12 miles southeast of Dallas and downstream 

from the treated-effluent discharge from WWTP-2, but 

upstream from USGS station 08062500 Trinity River near 

Rosser, Tex. (hereinafter referred to as the Trinity River 

Rosser site) and USGS station 08062700 Trinity River at 

Trinidad, Tex. (hereinafter referred to as the Trinity River 

Trinidad site). Streamflow upstream from the confluence of 

West Fork and Elm Fork is regulated by reservoirs that are 

mostly in the Dallas-Fort Worth area. These reservoirs include 

Benbrook Lake, Lake Bridgeport, Eagle Mountain Lake, Ray 

Roberts Lake, Lake Lewisville, Grapevine Lake, Lavon Lake, 

and Ray Hubbard Lake. Reservoirs in or near the Dallas-Fort 

Worth area store most of the potable water supply for DallasFort Worth and are sustained by natural inflows and inter- and 

intrabasin diversions. The Trinity River downstream from 

Dallas-Fort Worth flows unregulated until it is impounded by 

Lake Livingston near Houston.

Of the 339 permitted WWTPs in the Trinity River 

Basin, 192 are upstream from the Trinity River Trinidad 

site (J.R. Lueg, Texas Commission on Environmental 

Quality, written commun., 2014). WWTPs with the capacity 

to discharge the largest amounts of treated effluent are in 

Dallas-Fort Worth between source-water reservoirs and the 

confluence of the East Fork Trinity River. Because of the 

large amount of treated-effluent discharges from the WWTPs 

in Dallas-Fort Worth, the Trinity River can be a wastewaterdominated system, especially during base-flow conditions.

The City of Dallas operates three PWTPs and two 

WWTPs (table 1). Raw-water intakes for the three PWTPs 

are upstream from the discharge points for the two WWTPs. 

Other WWTPs discharge into the tributaries of the Trinity 

River upstream from Dallas WWTP discharge points (Trinity 

River Authority of Texas, 2014). Treated effluent from other 

WWTPs that are upstream from the potable water-supply 

reservoirs were not sampled as part of this study but could 

be potential point sources for CECs in the influent waters of 

Dallas’ PWTPs.

Potable Water Treatment Plants

The three PWTPs receive water for treatment from the 

following regional reservoirs: Grapevine Lake, Lake Fork 

Reservoir, Lake Lewisville, Lake Tawakoni, Ray Hubbard 

Lake, and Ray Roberts Lake (fig. 1). The combined treatment 

capacity of the three PWTPs is 900 million gallons per day 

(Mgal/d) with a record single-day water use of 789.6 million 

gallons on September 4, 2000 (Dallas Water Utilities, 2018). 

The largest PWTP, PWTP-1, receives source waters from 

Ray Hubbard Lake by direct intake and from Lake Tawakoni 

by interbasin transfer. The City of Dallas uses conventional 

treatment processes (such as partial softening) as the primary 

type of treatment at PWTP-2 and PWTP-3 (table 1). Partial 

softening alters the hardness of water to aid in the removal of 

heavy metals, radionuclides, and dissolved organics and the 

reduction of viruses and bacteria (Pontius, 1990). The City 

of Dallas also uses other processes including sedimentation, 

chlorination, lime softening, coagulation and flocculation, 

dual-media filtration using anthracite coal and sand, and postfilter corrosion control (Christopher Holmgren, Dallas Water 

Utilities, oral commun., 2014). PWTP-1 used partial softening 

as primary treatment until June 2012, when enhanced 

coagulation was started (Peter Stencel, Dallas Water Utilities, 

oral commun., 2014). Coagulation is a process that combines 

small particles into larger aggregates to facilitate their removal 

(Pontius, 1990). Enhanced coagulation is part of the process 

by which raw water is purified for human consumption; 

inorganic chemicals (ferric sulfate and polymers) are added 

to the water to cause suspended particles to bind together 

until flocculation occurs. Flocculation is a physical process 

that promotes interparticle contact and clumping of particles, 

which increase in size (Pontius, 1990). After flocculation 

occurs, large particles descend gravimetrically or are 

mechanically removed from suspension by using settling 

ponds or filtration. PWTPs use chlorination or ozonation 

as a disinfectant to treat finished water to the point where it 

is safe for human consumption. All PWTPs where samples 

were collected use chlorination and ozonation as primary and 

secondary disinfectants, respectively.
Introduction 5

Trinity River

Basin

Rosser

Dallas

Forney

Irving

Fort Worth

Rosser

Trinidad

Forney

Dallas Irving

Houston

Trinity River Basin

TEXAS

OKLAHOMA

TEXAS

OKLAHOMA

ARKANSASLOUISIANA

DENTON COUNTY

HUNT COUNTY

COLLIN COUNTY

ROCKWALL

COUNTY

KAUFMAN COUNTY

VAN ZANDT COUNTY

JOHNSON

COUNTY

HENDERSON COUNTY 

ELLIS COUNTY

DALLAS COUNTY

TARRANT

COUNTY

Area enlarged

Trinity River

Basin

GULF OF MEXICO

Grapevine

Lake

Lake

Lewisville

Ray Hubbard

Lake Lake

Elm Fork Tawakoni

Trinity River

Lavon Lake

Benbrook

Lake

Eagle Mountain Lake

Lake

Bridgeport

West Fork Trinity River

Clear Fork

Trinity River

Trinity River

East Fork

Trinity River

Galveston

Bay

Sulphur River

Sabine River

Red River

Ray Hubbard

Lake

Elm Fork

Trinity River

Lake Fork

Reservoir

Lake

Livingston

Ray Roberts

Lake

Lake

Livingston

Lake Texoma

Jim Chapman

Lake Lake

Lewisville Grapevine 

Lake

Lake

Tawakoni

Trinity River

West Fork Trinity River

East Fork

Trinity River

Base modified from U.S. Geological Survey 

1:1,000,000-scale digital data

Texas Centric Mapping System

Lambert Conformal Conic projection

North American Datum of 1983 

08057410

08062500

08057448

PWTP–1

PWTP–3

PWTP–2

WWTP–1

WWTP–2

08057070

08062700

0 30 60 MILES

0 30 60 KILOMETERS

EXPLANATION

River basin boundary

U.S. Geological Survey water-quality 

monitoring station (Trinity River site)

and station number (see table 1)

Potable water treatment plant and number

Wastewater treatment plant and number

08057448

PWTP–1

WWTP–1

96°

98°

34°

32°

30°

Figure 1. Locations of potable water and wastewater treatment plants and U.S. Geological Survey water-quality monitoring stations on 

the Trinity River in or near Dallas, Texas, where samples were collected during 2009–13.
6 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 1. Water-quality study sites in or near Dallas, Texas, 2009–13.

[--, not applicable; USGS, U.S. Geological Survey]

Map 

identifier 

(see fig. 1)

Description of 

study site

Primary source 

of water

Primary type 

of treatment

Disinfectants 

used

Trinity 

River mile

Potable water treatment plants

PWTP-1 Raw water Ray Hubbard Lake, Lake Tawakoni, 

and Lake Fork Reservoir

Partial softening/

enhanced coagulation1

-- --

Finished water -- -- Chlorine and ozone1 --

PWTP-2 Raw water Lake Lewisville, Grapevine Lake, 

and Ray Roberts Lake

Partial softening2 -- --

Finished water -- -- Chlorine and ozone2 --

PWTP-3 Raw water Lake Lewisville and Grapevine Lake Partial softening3 -- --

Finished water -- -- Chlorine and ozone3 --

Wastewater treatment plants

WWTP-1 Untreated-influent water 1 -- Activated sludge4 -- --

Untreated-influent water 2 -- Activated sludge4 -- --

Treated-effluent water -- -- Chlorine/sulphur 

dioxide

495.0

WWTP-2 Untreated-influent water -- Activated sludge and 

sludge digestion5

-- --

Treated-effluent water -- -- Chlorine/sulphur 

dioxide

481.0

Map 

identifier 

(see fig. 1)

USGS station name (and short name) Trinity 

River mile

USGS water-quality monitoring stations (Trinity River sites)

08057070 Trinity River at State Highway 310, Dallas, Tex. (Trinity River Highway 310 site) 494.6

08057410 Trinity River below Dallas, Tex. (Trinity River Dallas) 491.8

08057448 Trinity River near Wilmer, Tex. (Trinity River Wilmer) 478.4

08062500 Trinity River near Rosser, Tex. (Trinity River Rosser) 451.4

08062700 Trinity River near Trinidad, Tex. (Trinity River Trinidad) 391.2

1

Primary type of treatment changed from partial softening to enhanced coagulation starting in June 2012 (Peter Stencel, Dallas Water Utilities, oral commun., 

2014).

2

Jim Crowley, Dallas Water Utilities, oral commun., 2014.

3

Chaise Holmgren, Dallas Water Utilities, oral commun., 2014.

4

Daniel Halter, Dallas Water Utilities, oral commun., 2014.

5

Nosa Irenumaagho, Dallas Water Utilities, oral commun., 2014.
Methods 7

Wastewater Treatment Plants

The two WWTPs in Dallas receive wastewater from a 

wastewater system and from 11 wholesale water customers 

(Dallas Water Utilities, 2018). The two plants have a 

combined capacity of 260 Mgal/d and treated a combined 

mean of 72 Mgal/d during 2010–11 (52.8 billion gallons total) 

(Dallas Water Utilities, 2018). The sources of water to the two 

WWTPs are water that goes down drains (including water 

from toilet systems) in homes and businesses and wastewater 

that is delivered by pipeline from wholesale water customers. 

Stormwater is separated into another collection system that is 

not treated before it is released to the Trinity River. Generally, 

wastewater from the southern and southwestern areas of the 

city is treated at WWTP-2, and the remaining wastewater 

is treated at WWTP-1 (fig. 1). However, wastewater can 

be transferred to either plant as needed based on treatment 

demands and weather (Paul Sill, Dallas Water Utilities, 

oral commun., 2014). WWTP-1 had two different influent 

sampling locations at the time of sampling. Both sampling 

locations represented the same step in the water treatment 

process (untreated influent). Inflows to WWTP-1, regardless 

of sampling location within the plant, are considered to carry 

sewage from the same area of Dallas. WWTP-1 uses activated 

sludge as the primary method of treatment. Activated sludge 

treatment is a process for removing organic matter from 

sewage by saturating it with air and microorganisms that can 

break down the organic matter (EPA, 2004). WWTP-2 uses 

activated sludge followed by sludge digestion, during which 

the sludge is placed in tanks where volatile organic materials 

are decomposed by bacteria, resulting in partial gasification, 

liquefaction, and mineralization of volatile organic compounds 

(EPA, 2004). Sludge from WWTP-1 is pumped to WWTP-2 

for sludge digestion. Treated effluent is disinfected by 

chlorine, and then sulfur dioxide is added to remove residual 

chlorine (Daniel Halter, Dallas Water Utilities, oral commun., 

2014).

Trinity River Study Sites

The five study sites on the Trinity River span more than 

100 river miles (table 1). In upstream to downstream order, 

the sites are as follows: (1) USGS station 08057070 Trinity 

River at State Highway 310, Dallas, Tex. (hereinafter referred 

to as the Trinity River Highway 310 site); (2) USGS station 

08057410 Trinity River below Dallas, Tex. (hereinafter 

referred to as the Trinity River Dallas site); (3) USGS station 

08057448 Trinity River near Wilmer, Tex. (hereinafter 

referred to as the Trinity River Wilmer site); (4) the Trinity 

River Rosser site; and (5) the Trinity River Trinidad site 

(fig. 1). The Trinity River Highway 310 site (river mile 494.6) 

is downstream from the treated-effluent discharge point 

for treated effluent from WWTP-1 (river mile 495.0) and 

downstream from discharge points for other WWTPs located 

upstream on the West Fork Trinity River. Large WWTPs on 

the West Fork Trinity River upstream from WWTP-1 include 

the Village Creek Water Reclamation Facility (166 Mgal/d) 

(City of Fort Worth, 2018) and the Trinity River Authority 

of Texas Central Regional Wastewater System (162 Mgal/d) 

(Trinity River Authority of Texas, 2018). The next site 

downstream from the Trinity River Highway 310 site is the 

Trinity River Dallas site. The Trinity River Highway 310 site 

and the Trinity River Dallas site are in a highly urbanized area 

of southeast Dallas, and there are no substantial inflows in the 

2.8-mile reach between these sites. Treated-effluent discharge 

from WWTP-2 enters the main stem of the Trinity River at 

river mile 481.0, which is between the Trinity River Dallas 

site and the Trinity River Wilmer site. Flow from the East 

Fork Trinity River enters the main stem of the Trinity River 

downstream from the Trinity River Wilmer site and upstream 

from the Trinity River Rosser site. The farthest downstream 

site is Trinity River Trinidad (river mile 391.2).

Methods

A total of 105 environmental samples were collected by 

the USGS from 2009 to 2013 in the Dallas-Fort Worth study 

area. In addition to the environmental samples, 24 qualitycontrol samples were collected, consisting of 11 replicate 

samples, 9 equipment blank samples, 4 matrix-spike samples 

(1 of which was split and analyzed in replicate). Replicate 

samples are “two or more water samples that are collected, 

prepared, and analyzed such that they are essentially identical 

in composition and analysis” (Mueller and others, 2015, 

p. 7). Equipment blanks “are samples that are intended to 

demonstrate that sample collection and processing equipment 

and equipment-cleaning procedures are not sources of 

contamination” (Mueller and others, 2015, p. 5). A spike 

sample is a “water sample fortified (spiked) with known 

concentrations of compounds and is defined by the location 

where the spike solution is added to the sample, either in 

the field or in the laboratory, and by the type of water that is 

spiked, either environmental (matrix) water or blank (reagent) 

water” (Mueller and others, 2015, p. 6). In conjunction with 

the collection of the environmental samples, selected waterquality field properties (water temperature, dissolved-oxygen 

concentration, pH, and specific conductance) were measured 

in the field at each study site by using methods described in 

the USGS National Field Manual for the Collection of WaterQuality Data (USGS, variously dated).

Sample-Collection Methods

Water samples collected for analysis of pharmaceuticals, 

antibiotics, steroidal hormones, stanols, sterols, and 

wastewater compounds are susceptible to contamination 

because many of the targeted compounds are ubiquitous in 

the environment. To ensure sample integrity, on the day of 

sampling activities, field personnel avoided contact with or 

consumption of products that contain targeted compounds 
8 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

following methods as outlined in Chapter A5, Section 5.6.1F 

of the USGS National Field Manual (USGS, variously dated). 

Efficiency of sample-collection methods and laboratory 

analyses was assessed by using quality-control samples, 

such as field blanks, which are used to test for bias from the 

introduction of contamination into environmental samples.

Sample-collection equipment, including sample 

containers, filters, and associated tubing, is a possible source 

of field contamination (contamination that occurs before the 

sample is sent to analyzing laboratories). Sample-collection 

and sample-processing equipment were prepared by using 

standard methods described in the USGS National Field 

Manual (USGS, variously dated). Specifically, these methods 

included cleaning sample-collection equipment by washing 

with detergent and rinsing with tap water, then distilled water, 

then methanol, then organic-free blank water, then air drying.

Sample Collection at Potable Water Treatment 

Plants

Raw-water and finished-water samples were collected 

inside PWTPs. Raw-water grab samples were collected prior 

to the addition of ozone intake structure settling basins at 

PWTP-1 and PWTP-3 by using weighted bottle samplers and 

Teflon sample bottles. Raw-water samples were collected 

from an intake pipe at PWTP-2. Finished-water samples 

were collected from a pipe containing finished water prior 

to the application of chlorine for disinfection purposes at all 

PWTPs; samples were collected from the spigots after field 

properties had stabilized. Finished water from a PWTP is 

defined as water that has been fully treated by the processes 

of a plant but has not been placed in a pipeline to be delivered 

for consumption (Sacramento State Office of Water Programs, 

2017). The time required to process a volume of water 

from start to finish (that is, residence time) in the PWTPs 

was not available. Raw- and finished-water samples were 

collected at the three PWTPs seven times during 2009–13. 

Seven environmental samples were collected from the intake 

(raw water) and outflow (finished water) from each of the 3 

PWTPs, for a total of 42 environmental samples. Samples 

were filtered into sample bottles provided by the respective 

analyzing laboratory (the USGS National Water Quality 

Laboratory [NWQL] in Lakewood, Colorado or the USGS 

Organic Geochemistry Research Laboratory [OGRL] in 

Lawrence, Kansas) and shipped rapidly to meet all specified 

holding times (Sandstrom, 1995).

Sample Collection at Wastewater Treatment 

Plants

Untreated-influent grab samples at the WWTPs were 

collected from basins that contain wastewater prior to the step 

of the treatment process when surface skimmers remove large 

solid materials. Treated-effluent samples at WWTPs were 

collected from a pipe located in a laboratory at each plant. 

Treated-effluent samples were collected from WWTPs after 

chlorination but before the application of sulfur dioxide for 

dechlorination. Treated effluent from a WWTP is defined as 

water that has been fully treated by the processes of a plant 

but has not been released into a conveyance channel to the 

receiving waters. Treated-effluent samples from WWTPs 

were filtered into bottles that contained dechlorination 

reagents (ascorbic acid and sodium sulfite) in the event 

residual chlorine was in the treated water. A residence time 

of 10–14 hours in WWTPs was estimated by plant operators 

(Richard Seely and Mark Evers, Dallas Water Utilities, oral 

commun., 2009). Collection times for untreated-influent 

and treated-effluent samples collected after August 2009 at 

each WWTP were based on residence times to ensure that 

each sample contained the same volume of water. Seven 

environmental samples were collected from the intake 

(untreated-influent water), and seven environmental samples 

were collected from the outflow (treated-effluent water) at 

each of the two WWTPs between 2009 and 2013, for a total of 

28 samples.

Sample Collection at Trinity River Sites

Seven width- and depth-integrated stream-water samples 

were collected during 2009–2013 at each of the five USGS 

water-quality monitoring stations on the main stem of the 

Trinity River. Samples represented periods of base flow except 

for one sampling event during December 11–26, 2009, when 

streamflow ranged from 1,450 to 2,800 cubic feet per second 

at the five sites (U.S. Geological Survey, 2018b). Streamwater samples were collected by using either equal-depth or 

equal-width integrated sampling techniques as described in 

the USGS National Field Manual (USGS, variously dated). 

Samples were usually processed onsite in a mobile USGS 

laboratory and shipped from the USGS North Texas Program 

Office laboratory in Fort Worth to the respective analyzing 

laboratory (NWQL or OGRL) within 1–2 days after collection 

to meet holding times established for each laboratory analysis. 

Because the channel bed was armored with large rocks under 

the bridges where bed-sediment samples were collected from 

several sites on the Trinity River, standard bed-sampling 

equipment could not be used. In these cases, bed-sediment 

samples were collected by wading from the bank and scooping 

bed sediment into the sample container.

Laboratory Analysis

Four laboratory analysis schedules, each targeting a 

specific group of compounds, were used for water samples 

collected at the three types of study sites (PWTPs, WWTPs, 

and Trinity River sites) and one laboratory analysis schedule 

was used for bed-sediment samples collected at Trinity 

River sites. Water samples were sent to the NWQL for 

analysis by using one of three different laboratory schedules 

targeting a different group of compounds: (1) human-health 
Methods 9

pharmaceuticals (schedule SH2080); (2) steroidal hormones 

and metabolites (schedule SH2434); and (3) wastewater 

compounds: stanols, sterols, detergents and detergent 

metabolites, personal-use products, pesticides, disinfection 

compounds, flame retardants, and plasticizers (schedule 

SH1433) (table 2, at end of report). Part of each stream-water 

sample collected at the five Trinity River sites was sent to 

the OGRL for analysis of antibiotics by using their liquid 

chromatography/mass spectrometry antibiotics (LCAB) 

schedule (Meyer and others, 2007).

Analysis of wastewater compounds in bed-sediment 

samples collected at each stream site was done by the NWQL 

(schedule SH5433). About 120 compounds were analyzed in 

each bed-sediment sample; most of the same compounds were 

included in the different wastewater compound schedules for 

water. Methods for analyzing CECs in bed-sediment samples 

were developed in response to increasing concern about 

the effects of CECs in wastewater and wastewater-affected 

sediment on aquatic organisms (National Association of Clean 

Water Agencies, 2010). Occasionally, some compounds were 

not analyzed in a given sample for various reasons including 

internal laboratory quality-assurance data that identified 

compound concentrations that could not be determined 

because of nonspectroscopic interferences with the laboratory 

methods, referred to as matrix effects, that suppress or enhance 

the analytical signal or physically interfere with the analysis 

(Wolf and Adams, 2015).

Concentrations of compounds detected by the laboratory 

analysis schedules are reported with a numerical value (that 

is, a detection) if the value for the compound exceeds the 

laboratory reporting level (LRL). The analytical quantification 

procedure used by the NWQL for reporting results is based 

on the long-term method detection level (LT-MDL) and LRL. 

The LT-MDL is derived by determining the standard deviation 

of a minimum of 24 replicate spike-sample measurements 

near the previously reported LT-MDL over an extended period 

(typically 6 to 12 months) (Childress and others, 1999). The 

LT-MDL concentrations are defined as a censoring limit for 

most analytical methods at the NWQL, and their purpose is 

to limit false positives to less than or equal to 1 percent. A 

false positive measurement error occurs when a compound is 

incorrectly reported as present in the sample when it is not. 

The LRL is defined as twice the LT-MDL and is established to 

limit the occurrence of false negative detections to less than 

or equal to 1 percent. A false negative measurement error is 

the reporting of nondetection for a compound present in the 

sample (that is, not detecting a compound when it is present) 

(Childress and others, 1999). Generally, the probability of a 

false negative or false positive measurement error is predicted 

to be less than or equal to 1 percent when the compound 

concentration in the sample is equal to or less than the LRL 

(Childress and others, 1999). Values for several compounds 

were further censored to reduce the likelihood of reporting 

false positives for compound detections and are discussed in 

the “Blank Samples” section of this report. The LRL for some 

compounds varied during the study period (table 2). The use 

of variable LRLs by the laboratory increased the difficulty 

of computing detection frequencies because there was no 

single basis for detection when concentrations were reported 

as less than a maximum LRL. A constituent concentration 

was considered estimated by the laboratory when results 

were greater than the LT-MDL and less than the LRL; that 

is, a detection was considered likely, but quantification was 

considered questionable. These values were not considered 

detections. The remark code of “E” (estimated) was assigned 

by the laboratory for these results.

Human-Health Pharmaceuticals in Water 

Samples

Concentrations of human-health pharmaceutical 

compounds were determined at the NWQL by using 

laboratory schedule SH2080, except for ibuprofen, which 

was determined at the OGRL by using the LCAB schedule. 

Laboratory schedule SH2080, developed by the Methods 

Research and Development Program of the NWQL (Furlong 

and others, 2008), was used for analysis of 14 commonly used 

human-health pharmaceuticals by using solid-phase extraction 

(SPE) and high-performance liquid chromatography/mass 

spectrometry. For this study, human-health pharmaceuticals 

were separated into prescription and nonprescription 

pharmaceuticals (table 2). Concentrations for two compounds, 

the antibiotics sulfamethoxazole and trimethoprim, were 

determined by schedules SH2080 and LCAB, respectively, and 

are discussed in the “Antibiotics in Water Samples” section 

of this report. For the sample collected on November 15, 

2010, the results from the LCAB schedule were not complete 

because the concentrations for several antibiotic compounds 

were not determined. During statistical analyses of these 

missing values, the sample count was reduced by one for each 

missing value.

Antibiotics in Water Samples

The antibiotic schedule, LCAB, was developed at the 

OGRL and was modified from the liquid chromatography/

tandem mass spectrometry version of the online SPE method 

in Meyer and others (2007). Water samples were analyzed 

for 30 antibiotic compounds and their associated degradation 

products (6 quinolones, 6 macrolides, 5 sulfonamides, 

9 tetracycline antibiotics, and 4 other antibiotics: lincomycin, 

trimethoprim, chloramphenicol, and ormetoprim). In addition, 

ibuprofen, a nonprescription pharmaceutical, was determined 

by using the LCAB schedule. Samples were analyzed by 

using online SPE and ultra-pressure liquid chromatography/

tandem mass spectrometry with electrospray ionization with 

multiple reaction monitoring. Samples were analyzed in 

positive-ion mode except for chloramphenicol and ibuprofen, 

which were analyzed in negative-ion mode. Samples 

were extracted by using hydrophilic/lipophilic-balanced 

SPE cartridges (Waters Corp., Milford, Massachusetts). 
10 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Internal standards used are 13C3-15N-ciprofloxacin, 

clinafloxacin, 13C2-erythromycin, 13C2-erythromycinH2O, meclocycline, simatone, 13C6- sulfamethoxazole, 

13C3-trimethoprim, carbamazepine-d10, 13C3-ibuprofen, 

and 13C3- chloramphenicol. Surrogate standards included 

demeclocycline, nalidixic acid, oleandomycin, and 

13C6-sulfamethazine. A replicate sample, a matrix-spike 

sample, and a carryover blank sample were analyzed after 

every 10th sample. A check standard was analyzed after every 

20th sample. Also, two blank samples were interspersed for 

analysis between the environmental samples. All standard 

solutions, blanks, and matrix spikes were treated the same 

as the environmental water samples. LRLs ranged from 

0.005 to 0.010 microgram per liter (μg/L) for all antibiotics 

analyzed except chloramphenicol (0.10 μg/L) and ibuprofen 

(0.05 μg/L).

Steroidal Hormones, Stanols, and Sterols in 

Water Samples 

Concentrations of steroidal hormones, stanols, and 

sterols were determined primarily by laboratory schedule 

SH2434 (table 2). Laboratory schedule SH2434 was 

developed by the NWQL to detect a suite of 17 steroid 

hormones, 2 stanols, and 2 sterols by using SPE, derivatization 

(the conversion of compound into a different compound), 

and gas chromatography with tandem mass spectrometry 

(Foreman and others, 2012). Analysis is carried out by gas 

chromatography with tandem mass spectrometry by using 

calibration standards that are derivatized concurrently with 

the sample extracts (Li and others, 2017). Steroidal hormones 

were separated into categories of natural and synthetic 

estrogens, androgens, and progestins.

Wastewater Compounds in Water Samples

Laboratory schedule SH1433 was developed by the 

NWQL to determine concentrations of 57 compounds 

typically found in domestic and industrial wastewater, 

some of which could affect human health, by using 

polystyrene-divinylbenzene SPE and capillary-column gas 

chromatography/mass spectrometry (Zaugg and others, 

2007) (table 2). Analyzed compounds were divided into 

the following classes: (1) stanols and sterols; (2) detergents 

and detergent metabolites (hereinafter referred to as 

“detergents”); (3) personal-use products; (4) pesticides; 

(5) industrial wastewater compounds; (6) disinfection 

compounds; (7) polycyclic aromatic hydrocarbons (PAHs); 

and (8) flame retardants and plasticizers. When the analysis 

of data for this report began in 2009, pentachlorophenol 

(parameter code 34459), BPA (parameter code 62069), 

caffeine (parameter code 50305), and cotinine (parameter 

code 62005) were analyzed by schedule SH1433. By the 

completion of the study, they were not included in schedule 

SH1433. Pentachlorophenol was removed from schedule 

SH1433 shortly after sample collection began; because it 

was not included in another schedule, this compound is not 

mentioned further in this report. Concentrations of caffeine 

(parameter code 50305) were determined by schedule 

SH1433. Concentrations of cotinine (parameter code 62005) 

were determined by schedule SH2080. Concentrations for 

3-tert-butyl-4-hydroxyanisole (parameter code 62059) were 

reported for samples collected during the first round of 

sampling in 2009 and occasionally thereafter because of the 

highly variable nature of the compound when it was analyzed 

by schedule SH1433.

Wastewater Compounds in Bed-Sediment 

Samples

Laboratory schedule SH5433 uses methods developed 

by the NWQL for the detection of 57 compounds in 

environmental sediment and soil samples (table 2). Method 

development focused on the determination of many 

compounds that are targeted by schedule SH1433 but 

was designed for sediment-bound compounds by using 

pressurized solvent extraction, SPE, and capillary-column gas 

chromatography/mass spectrometry (Burkhardt and others, 

2006). Compounds are extracted from sediment and soil 

samples by using a pressurized solvent extraction system. 

Compounds of interest are extracted from interfering matrix 

components by using high-pressure water/isopropyl alcohol 

extraction. Compounds are isolated by using disposable 

SPE cartridges containing chemically modified polystyrenedivinylbenzene resin. Cartridges are dried with nitrogen gas, 

and sorbed compounds are eluted with methylene chloride 

(80 percent)-diethyl ether (20 percent) through the SPE 

cartridge. Concentrations are determined by capillary-column 

gas chromatography/mass spectrometry.

The lists of compounds analyzed by schedules 

SH5433 and SH1433 are similar, with 52 compounds 

in each schedule. Cotinine, 5-methyl-1H-benzotriazole, 

tribromomethane (bromoform), caffeine, carbaryl, triethyl 

citrate, tetrachloroethylene, metalaxyl, 4-nonylphenol, 

and methyl salicylate were analyzed by schedule SH1433 

or SH2080 but not by schedule SH5433. Compounds 

2,2',4,4'-tetrabromodiphenyl ether, 4-nonylphenol 

monoethoxylate, atrazine, bis(2-ethylhexyl) phthalate, and 

diethyl phthalate were analyzed by schedule SH5433, but not 

by schedule SH1433. Some of these compounds have LRLs 

that changed during the study. Human-health pharmaceuticals, 

antibiotics, and hormones were not targeted in bed-sediment 

sample analyses.
Methods 11

Duplicate Analyses of Selected Compounds

Concentrations were determined by using two separate 

analysis schedules for each sample for the following seven 

selected compounds: carbamazepine, sulfamethoxazole, 

trimethoprim, caffeine, cotinine, 3-beta-coprostanol, 

and cholesterol (table 3). Preference was given to values 

determined by methods where the associated qualitycontrol data support the decision to use one value instead 

of another (the process of determining which value used is 

explained further in the “Quality Control” section). A method 

comparison quality-control check was done by determining 

whether a detection reported by the preferred method with 

a concentration above the LRL of the other, nonpreferred 

method was reported as a detection by the nonpreferred 

method (table 3).

Research methods represented by the LCAB schedule 

provided lower LRLs for carbamazepine, sulfamethoxazole, 

and trimethoprim compared to the LRLs available for these 

compounds in the NWQL schedules. Concentrations of 

carbamazepine and sulfamethoxazole from schedule LCAB 

were selected as preferred values over values determined 

by schedule SH2080. Concentrations of carbamazepine in 

most samples were less than the LRL for schedule SH2080 

(0.06 μg/L) and, therefore, were not reported as detections 

(table 3). Concentrations of carbamazepine determined 

by schedule LCAB were often greater than the LRL 

(0.005 μg/L), therefore, values from schedule LCAB were 

used in the analyses for carbamazepine. Concentrations of 

sulfamethoxazole determined by schedule SH2080 (parameter 

code 62021) were less than the LRL (0.10 μg/L) in all 

samples. Concentrations of sulfamethoxazole determined by 

schedule LCAB (parameter code 62775) were often greater 

than the LRL (0.005 μg/L) and were used during analyses 

instead of those from schedule SH2080. By using the method 

comparison quality-control check, carbamazepine and 

sulfamethoxazole were frequently detected by schedule LCAB 

at concentrations that were greater than the LRL of schedule 

SH2080 for samples collected at WWTPs and in stream-water 

samples collected in the Trinity River main stem (table 3). 

These disparities could partially be caused by the higher LRLs 

for schedule SH2080 than for schedule LCAB. Although 

schedules SH2080 and LCAB performed similarly for 

trimethoprim, more historical laboratory quality-control data 

were available for schedule SH2080 compared to schedule 

LCAB. Therefore, trimethoprim concentrations determined 

by schedule SH2080 were preferred over those determined by 

schedule LCAB.

Caffeine and cotinine concentrations were determined 

by schedules SH1433 and SH2080; on both schedules, 

the parameter codes for caffeine and cotinine were 50305 

and 62005, respectively. Although the LRL for caffeine is 

0.06 μg/L on both schedules used by the NWQL, the percent

recovery for caffeine was slightly better when schedule 

SH1433 was used compared to the percent recovery when 

schedule SH2080 was used (Null and others, 2019). These 

percent recoveries apply to the analyses of caffeine in this 

report and for the analyses of caffeine reported as part of other 

studies nationwide during 2009–13. In addition, values for 

caffeine for schedule SH2080 were often assigned a remark 

code of “E” (estimated). Cotinine concentrations determined 

by schedule SH2080 were preferred over those determined by 

schedule SH1433 because the maximum LRL was lower for 

schedule SH2080 (0.04 μg/L) compared to the maximum LRL

for schedule SH1433 (0.80 μg/L). Schedule SH2080 also had

higher percent recoveries compared to schedule SH1433.

The CECs 3-beta-coprostanol and cholesterol are 

included in laboratory schedules SH2434 and SH1433. Results 

are separated by laboratory schedule because of methodspecific LRLs. Results for 3-beta-coprostanol determined by 

schedule SH2434 are reported under parameter code 64512 

(LRL 2.0 μg/L). Results determined for 3-beta-coprostanol

by SH1433 are reported under parameter code 62057 (LRL 

1.8 μg/L). Concentrations of 3-beta-coprostanol (parameter

code 64512) determined by schedule SH2434 were preferred 

over those determined by schedule SH1433 because schedule 

SH2434 had higher percent recoveries (Null and others, 2019). 

In addition, laboratory analysts’ notes suggested that results 

from SH1433 for this compound were highly variable. Results 

for cholesterol determined by schedule SH2434 are reported 

under parameter code 64514 (LRL 0.20–2.0 μg/L). Results

for cholesterol determined by schedule SH1433 are reported 

under parameter code 62072 (LRL 2.0 μg/L). Cholesterol

concentrations determined by schedule SH2434 (parameter 

code 64514) were preferred over those determined by schedule 

SH1433 (parameter code 62072) because schedule SH2434 

had higher percent recoveries.

Quality Control

Quality-control samples collected in the field consisted 

of blank, replicate, and matrix-spike samples. In addition 

to quality-control samples collected in the field, the NWQL 

and OGRL analyze several types of quality-control samples 

during laboratory analysis, such as blank, replicate, spike, 

and surrogate samples. Data from the NWQL and the OGRL 

internal quality-control samples, such as percent recoveries for 

individual compounds by method that were used to evaluate 

data quality are available in Null and others (2019).
12 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 3. Compounds analyzed by using more than one laboratory method in water samples collected at study sites in or near Dallas, 

Texas, 2009–13.—Continued

[LRL, laboratory reporting level; μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass 

spectrometry antibiotics schedule; SH, USGS National Water Quality Laboratory schedule; USGS, U.S. Geological Survey; OGRL, USGS Organic 

Geochemistry Research Laboratory in Lawrence, Kansas; NWQL, USGS National Water Quality Laboratory in Denver, Colorado; --, not applicable; β, beta]

Compound Parameter 

code Laboratory Laboratory schedule 

Minimum 

LRL

(μg/L)

Total 

number 

of 

samples

Number of 

detections 

equal to or 

greater than 

the LRL

Detections 

equal to or 

greater than 

the LRL

(percent)

Range of 

detected 

values

(μg/L)

Qualitycontrol 

check

(percent)1

Potable water treatment plant

Carbamazepine 62793 OGRL 2LCAB 0.005 42 15 36 0.006–0.024 0

62793 NWQL SH2080 0.06 42 0 0 0.002–0.015

Sulfamethoxazole 62775 OGRL 2LCAB 0.005 42 17 40 0.009–0.217 5

62021 NWQL SH2080 0.1 42 0 0 0.004–0.009

Trimethoprim 62023 NWQL 2SH2080 0.034 42 0 0 0.009–0.009 0

62023 OGRL LCAB 0.005 42 0 0 --

Caffeine 50305 NWQL 2SH1433 0.06 42 3 7 0.015–0.320 2

50305 NWQL SH2080 0.06 42 2 5 0.014–0.153

Cotinine 62005 NWQL 2SH2080 0.026 42 0 0 -- 0

62005 NWQL SH1433 0.4 42 0 0 0.040–0.041

3-β-Coprostanol 64512 NWQL 2SH2434 0.2 42 1 2 0.260–0.260 0

62057 NWQL SH1433 1.8 42 0 0 0.200–0.300

Cholesterol 64514 NWQL 2SH2434 0.2 42 11 26 0.204–0.456 0

62072 NWQL SH1433 2.0 42 0 0 0.200–0.500

Wastewater treatment plant

Carbamazepine 62793 OGRL 2LCAB 0.005 28 28 100 0.034–0.384 79

62793 NWQL SH2080 0.06 28 5 18 0.003–0.104

Sulfamethoxazole 62775 OGRL 2LCAB 0.005 28 22 79 0.008–1.90 46

62021 NWQL SH2080 0.1 28 0 0 0.025–0.07

Trimethoprim 62023 NWQL 2SH2080 0.034 28 13 46 0.043–0.175 0

62023 OGRL LCAB 0.005 28 1 4 0.011–0.815

Caffeine 50305 NWQL 2SH1433 0.06 28 19 68 0.037–64.0 7

50305 NWQL SH2080 0.06 28 17 61 0.019–134

Cotinine 62005 NWQL 2SH2080 0.026 28 15 54 0.043–0.275 0

62005 NWQL SH1433 0.4 28 8 29 0.050–2.40

3-β-Coprostanol 64512 NWQL 2SH2434 0.2 28 26 93 0.223–108 11

62057 NWQL SH1433 1.8 28 13 46 0.300–51.0

Cholesterol 64514 NWQL 2SH2434 0.2 28 16 57 0.216–1120 7

62072 NWQL SH1433 2.0 28 14 50 0.200–70.0

Trinity River stream water

Carbamazepine 62793 OGRL 2LCAB 0.005 35 35 100 0.054–0.219 71

62793 NWQL SH2080 0.06 35 5 14 0.019–0.067

Sulfamethoxazole 62775 OGRL 2LCAB 0.005 35 35 100 0.017–0.754 51

62021 NWQL SH2080 0.1 35 0 0 --

Trimethoprim 62023 NWQL 2SH2080 0.034 35 0 0 -- 0

62023 OGRL LCAB 0.005 35 3 9 0.005–0.036

Caffeine 50305 NWQL 2SH1433 0.06 35 26 74 0.050–0.760 51

50305 NWQL SH2080 0.06 35 4 11 0.012–0.132

Table 3. Compounds analyzed by using more than one laboratory method in water samples collected at study sites in or near Dallas, 

Texas, 2009–13.

[LRL, laboratory reporting level; μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass 

spectrometry antibiotics schedule; SH, USGS National Water Quality Laboratory schedule; USGS, U.S. Geological Survey; OGRL, USGS Organic 

Geochemistry Research Laboratory in Lawrence, Kansas; NWQL, USGS National Water Quality Laboratory in Denver, Colorado; --, not applicable; β, beta]
Methods 13

Table 3. Compounds analyzed by using more than one laboratory method in water samples collected at study sites in or near Dallas, 

Texas, 2009–13.—Continued

[LRL, laboratory reporting level; μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass 

spectrometry antibiotics schedule; SH, USGS National Water Quality Laboratory schedule; USGS, U.S. Geological Survey; OGRL, USGS Organic 

Geochemistry Research Laboratory in Lawrence, Kansas; NWQL, USGS National Water Quality Laboratory in Denver, Colorado; --, not applicable; β, beta]

Compound Parameter 

code Laboratory Laboratory schedule 

Minimum 

LRL

(μg/L)

Total 

number 

of 

samples

Number of 

detections 

equal to or 

greater than 

the LRL

Detections 

equal to or 

greater than 

the LRL

(percent)

Range of 

detected 

values

(μg/L)

Qualitycontrol 

check

(percent)1

Trinity River stream water—Continued

Cotinine 62005 NWQL 2SH2080 0.026 35 1 3 0.012–0.012 0

62005 NWQL SH1433 0.4 35 0 0 0.040–0.600

3-β-Coprostanol 64512 NWQL 2SH2434 0.2 35 11 31 0.294–0.792 0

62057 NWQL SH1433 1.8 35 0 0 0.200–0.700

Cholesterol 64514 NWQL 2SH2434 0.2 35 27 77 0.210–1.350 0

62072 NWQL SH1433 2.0 35 0 0 0.200–0.800

1

Frequency at which a detection reported by the preferred method with a concentration above the LRL of the non-preferred method was not reported as a 

detection by the non-preferred method. 

2

Preferred values.

Blank Samples

Blank samples are used to quantify contamination 

by compounds that could have been introduced into 

environmental samples because of sampling-related activities 

(USGS, variously dated). Blank samples consist of laboratorygrade organic-free water processed through equipment used 

for collecting and processing environmental samples before 

the collection of environmental water samples (Mueller and 

others, 1997). Blank samples used in this assessment were 

subjected to the same aspects of sample collection, field 

processing and preservation, transportation, and laboratory 

handling as the environmental samples. Nine equipment 

blank samples were analyzed for the same CECs that were 

targeted in the water samples collected at the three types 

of sites sampled during the study. Results were compiled 

without regard as to the type of site from which the sample 

was collected. There were no detections of human-health 

pharmaceuticals, antibiotics, steroidal hormones, stanols, or 

sterols in field-blank samples. However, there were detections 

of CECs in some of the blank samples that were analyzed 

with the wastewater compound schedule, SH1433 (table 4). 

Generally, concentrations reported from blank samples were 

very low. For example, the maximum concentrations of 

12 compounds measured in blank samples were less than the 

respective minimum LRLs for the study period.

Detections of compounds in field-blank samples that 

were equal to or greater than the minimum LRL for the 

study period could have possible implications regarding the 

concentrations of these compounds measured in environmental 

samples. For 10 compounds detected in laboratory-grade 

organic-free water, the censoring level was the minimum 

LRL that applied during the study period (table 4). The 

censoring level for six compounds (acetyl-hexamethyltetrahydronaphthalene [AHTN], N,N-diethyl-m-toluamide 

[DEET], isophorone, phenol, tributyl phosphate, and tris(2-

chloroethyl)phosphate) was determined by multiplying the 

maximum concentration detected in a blank sample by five. 

This method of determining the censoring level was generally 

used when the maximum concentration detected in a blank 

sample exceeded the lowest LRL for the compound. The 

censoring level for 4-nonylphenol (sum of all isomers) and 

d-limonene was set to the maximum concentration detected in 

a blank sample.

Replicate Samples

Replicate samples were collected to identify variability 

in the analytical results that could have been introduced 

during sample collection, processing, and analysis. Relative 

percent differences (RPDs) were calculated for each replicate 

pair having detectable concentrations by using the following 

equation:

RPD = [|C1 – C2|/((C1 + C2)/2)] × 100 (1)

where

C1 is the constituent concentration, in 

micrograms per liter, from the 

environmental sample; and

C2 is the constituent concentration, in 

micrograms per liter, from the replicate 

sample. 
14 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 4. Detected compounds and range of concentrations in laboratory-grade organic-free water in nine blank samples analyzed in 

conjunction with water-quality sampling in or near Dallas, Texas, 2009–13.

[LRL, laboratory reporting level; μg/L, micrograms per liter]

Compounds that were detected in more than 30 percent of blanks 

Compound Parameter 

code

Detections 

in blanks

(percent)

LRL range 

during study 

period

(μg/L)

Range of 

detected 

concentrations

(μg/L)

Maximum 

blank 

detection

(μg/L)

Selected 

censor level

(μg/L)

4-Nonylphenol (sum of all isomers) 62085 33 1–2 0.1–2.0 2.00 2.00

Acetyl-hexamethyltetrahydronaphthalene (AHTN)62065 56 0.028–0.500 0.005–0.015 0.015 0.075

Hexahydro-hexamethyl-cyclopentabenzopyran (HHCB) 62075 67 0.052–0.500 0.012–0.041 0.041 0.052

Menthol 62080 44 0.32–0.40 0.02–0.10 0.100 0.320

1,4-Dichlorobenzene 34572 44 0.040–0.080 0.014–0.036 0.036 0.040

N,N-diethyl-meta-toluamide (DEET) 62082 89 0.06–0.14 0.01–0.14 0.140 0.700

Benzophenone 62067 44 0.08–0.12 0.03–0.07 0.070 0.080

Isophorone 34409 56 0.032–0.080 0.015–0.058 0.058 0.290

Compounds that were detected in less than 30 percent of blanks 

Compound Parameter 

code

Detections 

in blanks

(percent)

LRL range 

during study 

period

(μg/L)

Range of 

detected 

concentrations

(μg/L)

Maximum 

blank 

detection

(μg/L)

Selected 

censor level

(μg/L)

4-Nonylphenol diethoxylate 62083 11 5.0 3.0 3.00 5.00

Camphor 62070 11 0.044–0.100 0.014 0.014 0.044

d-Limonene 62073 11 0.08–0.14 0.27 0.270 0.270

Methyl salicylate 62081 11 0.044–0.100 0.009 0.009 0.044

Phenol 34466 22 0.16–1.4 0.15–0.21 0.210 1.05

Phenanthrene 34462 11 0.016–0.080 0.005 0.005 0.016

Tributyl phosphate 62089 22 0.16–0.20 0.02 0.020 0.100

Triphenyl phosphate 62092 11 0.12 0.01 0.010 0.120

Tris(2-chloroethyl)phosphate 62087 22 0.10 0.07–0.12 0.12 0.60

Tris(dichloroisopropyl)phosphate 62088 11 0.10–0.16 0.02 0.020 0.100

All RPDs were rounded to the nearest percent. RPDs 

were reported as zero percent when there was no difference 

between paired replicate concentrations if both values were 

equal to or greater than the LRL. RPDs were not reported 

if either of the paired replicate concentrations was less than 

the LRL or less than the selected censoring level for the 

compound (table 5).

For this study, five sequential replicates were collected 

for finished water, raw water, or treated-effluent water; 

five sequential replicates were collected for stream-water 

samples; and one sequential replicate was collected for 

bed-sediment samples. Replicate samples were collected 

immediately after their associated environmental samples. 

Each environmental and replicate sample was analyzed for 

as many as 120 different compounds. There were 65 pairings 

between compounds for the environmental and replicate 

samples across all study sites and dates (table 5). For 7 of the 

65 paired samples, RPDs were zero; for 30 of the 65 paired 

samples, RPDs were greater than 10. Of the seven compounds 

with at least four calculated RPD values, tribromomethane 

had the lowest mean RPD (6), and sulfamethoxazole had the 

highest mean RPD (35). Sulfamethoxazole and 4-androstene3,17-dione were the only two compounds with two or more 

RPDs greater than 30.
Table 5. Relative percent differences of compounds detected in 11 replicate samples collected at water-quality study sites in or near Dallas, Texas, [--, compound measured in concentration below reporting level or not present; sed, bed-sediment sample; β, beta]

Compound 

PWTP-2 

finished 

water

PWTP-1 

raw 

water

PWTP-1 

raw 

water

PWTP-1 

finished 

water

WWTP-2 

treatedeffluent 

water

Trinity 

River 

below 

Dallas

Trinity 

River 

Wilmer

Trinity 

River 

Wilmer 

(sed)

Tri

Ri

Wi

8/18/2009 11/17/2009 3/2/2010 3/2/2010 8/26/2010 12/11/2009 3/8/2011 3/8/2011 8/30

Human-health pharmaceuticals

Caffeine -- -- -- -- -- 0 8 -- Carbamazepine -- 15 -- -- 6 1 2 -- Dehydronifedipine -- -- -- -- -- -- 0 -- Trimethoprim -- -- -- -- -- 17 77 -- 

Antibiotics

Sulfamethoxazole -- -- 57 -- 94 7 15 -- 

Steroidal hormones and sterols

3-β-Coprostanol -- -- -- -- 9 12 8 17 4-Androstene-3,17-dione 23 -- -- -- 36 -- 45 -- Cholesterol -- -- -- -- -- 8 14 13 Estrone -- -- -- -- -- 5 1 -- 

Wastewater compounds

4-tert-Octylphenol monoethoxylate -- -- -- -- -- 67 -- -- 5-Methyl-1H-benzotriazole -- -- -- -- -- 0 -- -- 2Acetyl-hexamethyl-tetrahydronaphthalene -- -- -- -- 29 -- 10 -- 1,4-Dichlorobenzene -- -- -- -- 17 -- -- -- Cotinine -- -- -- -- -- -- -- -- Hexahydro-hexamethyl-cyclopenta-benzopyran (HHCB) -- -- -- -- 21 11 5 -- Benzophenone -- -- -- -- 22 -- 0 -- Tribromomethane (Bromoform) 6 -- -- -- 9 6 7 -- Tributyl phosphate -- -- -- -- 29 -- 6 -- Triclosan -- -- 50 -- -- -- -- -- Triethyl citrate -- -- -- -- 6 0 0 -- Phenol -- 40 -- -- -- -- -- -- Tris(2-butoxyethyl)phosphate -- -- -- -- -- 40 -- -- Tris(2-chloroethyl)phosphate -- -- -- -- -- 11 -- Tris(dichloroisopropyl)phosphate -- -- -- 170 8 6 1 -- 
16 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Matrix-Spike Samples

Environmental-matrix spikes are environmental 

samples with known concentrations of compounds added in 

the field; one of the uses of environmental-matrix spikes is 

the assessment of any effects that the sample matrix could 

have on the concentration measured for each of the added 

compounds. Other uses include the assessment of possible 

bias associated with analytical methods and the degradation 

of compounds in the sample during sample shipment and 

storage (Mueller and others, 1997). Environmental-matrix 

spikes were analyzed by schedule SH1433 for treated-effluent 

samples collected at WWTPs on November 23, 2009, and 

March 26, 2013. Results from two environmental-matrix 

spikes are likely not representative of all the matrices sampled 

in this project. On November 23, 2009, a split-spike sample 

(one portion of the sample was spiked in the field, and the 

other portion was spiked at the NWQL) was collected to 

determine possible changes in concentration between the time 

that the samples were collected in the field and the time they 

were processed and analyzed at the NWQL. Matrix-spike 

recovery percentages ranged from 67 percent (5-methyl-1Hbenzotriazole) to 109 percent (4-tert-octylphenol diethoxylate) 

for the 18 compounds detected in the environmental sample 

spiked in the field on November 23, 2009 (table 6). In the 

environmental samples collected on November 23, 2009, and 

subsequently spiked at the NWQL, matrix-spike recoveries 

for the 18 detected compounds ranged from 66 percent 

(bromoform) to 125 percent (4-tert-octylphenol diethoxylate). 

RPDs for the 32 detected compounds ranged from zero 

percent (8 compounds) to 33 percent (indole) (table 7). 

There were 26 compounds with RPDs between zero and 

10. There were six compounds with RPDs greater than 10; 

however, RPDs greater than 10 likely were caused by low 

compound concentrations and variability inherent in the 

method rather than a change in measured spike concentrations 

in the environmental sample between the field and the 

laboratory. For example, the RPD for indole was 33 with 

measured concentrations in the field- and laboratory-spiked 

environmental samples differing by only 0.04 μg/L (0.10 and 

0.14 μg/L, respectively). There were 17 compounds with 

spike recoveries ranging from 21 percent (3-beta-coprostanol) 

to 104 percent (menthol) in the environmental field-spiked 

sample collected March 26, 2013 (table 6).

Surrogate Data

The NWQL adds surrogates to each environmental 

sample after filtration or to internal laboratory samples 

before sample processing to monitor sample-specific 

method performance. Each surrogate is closely related to 

a target compound but is not expected to be present in any 

environmental sample. There were 26 surrogates used in the 

study: 2 surrogates added to schedule SH2080; 4 added to 

schedule LCAB; 14 added to schedule SH2434; 3 added to 

schedule SH1433; and 3 added to schedule SH5433 (table 8). 

Surrogate recoveries for the antibiotics schedule (LCAB) were 

grouped together and not separated by sample type (Michael 

Meyer, USGS, written commun., 2015). Not all surrogates 

were added to each sample, and some surrogates were 

substituted during the project.

Generally, compounds in the SH2080 schedule had poor 

surrogate recoveries; however, the median recoveries for 

all compounds analyzed by the NWQL, including those in 

schedule SH2080, ranged from 44 (decafluorobiphenyl) to 

101 percent (4-androstene-3,17-dione-2,2,4,6,6,16,16-d7) for 

PWTP samples (table 8). Median recoveries for compounds 

in the SH2434 and SH1433 schedules collected at WWTPs 

ranged from 47 percent (decafluorobiphenyl) to 115 percent 

(estriol-2,4,17-d3). Median recoveries for samples collected 

at sites on the Trinity River, including compounds in schedule 

SH5433, were generally lower than the other two site 

types (PWTPs and WWTPs) and ranged from 23 percent 

(decafluorobiphenyl) to 90 percent (Caffeine-13C). Median 

recoveries for the four surrogates in the LCAB schedule 

ranged from 83 percent (meclocycline) to 140 percent 

(naxidilic acid).

Statistical Analyses

SigmaPlot version 13 was used for statistical analyses 

(Systat Software, Inc., 2018). The Wilcoxon rank-sum test 

(Helsel and Hirsch, 2002) was used to compare concentrations 

of compounds detected in raw- and finished-water samples 

from PWTPs. At WWTPs, collection times for untreatedinfluent and treated-effluent water samples were based on 

estimated residence times to sample the same volume of 

water, which allows for statistical analyses of paired samples. 

Therefore, the Wilcoxon signed-rank test (Helsel and Hirsch, 

2002) was used to compare concentrations of compounds 

detected in both untreated-influent and treated-effluent 

water samples from WWTPs. One-way analysis of variance 

(ANOVA) on ranks (Helsel and Hirsch, 2002) was used to 

compare detection frequencies and compound concentrations 

for samples collected at Trinity River main-stem sites. Dunn’s 

multiple comparison tests (Systat Software, Inc., 2018) were 

used if ANOVA results were statistically significant. Results 

were considered statistically significant if the probability value 

(p-value) was less than or equal to 0.05 (Helsel and Hirsch, 

2002).
Table 6. Spike report for treated-effluent water samples collected at water-quality study sites in or near Dallas, Texas, 2009–13.—Continued[μg/L, micrograms per liter; NWQL, U.S. Geological Survey National Water Quality Laboratory; <, less than; --, no data/not determined; E, estimated]

Parameter 

code

Compound

November 23, 2009 @ 2221 November 23, 2009 @ 2220 M

(spiked in field) (spiked at NWQL) 

Spike

(μg/L)

Environmental 

sample 

concentration

(μg/L)

Recovery

(percent)

Spike

(μg/L)

Environmental 

sample 

concentration

(μg/L)

Recovery

(percent)

Spike

(μg/L)

34572 1,4-Dichlorobenzene 0.78 0.13 76 0.73 0.13 68 0.47 62054 1-Methylnaphthalene 0.32 <0.022 -- 0.33 <0.022 -- 0.25 62055 2,6-Dimethylnaphthalene 0.28 <0.06 -- 0.28 <0.06 -- 0.23 62056 2-Methylnaphthalene 0.3 <0.036 -- 0.3 <0.036 -- 0.24 62057 3-β-Coprostanol E 2.6 <1.8 -- E 3.2 <1.8 -- E 1.3 62058 3-Methyl-1H-indole (Skatole) 0.33 <0.036 -- 0.36 <0.036 -- 0.22 62060 4-Cumylphenol 0.43 <0.06 -- 0.44 <0.06 -- 0.26 62061 4-n-Octylphenol E 0.15 <0.16 -- E 0.16 <0.16 -- E 0.074 62085 4-Nonylphenol (all isomers) E 3.2 <2.0 -- E 3.4 <2.0 -- E 1.6 62083 4-Nonylphenol diethoxylate E 7.7 E 0.93 98 E 8.4 0.93 106 E 4.7 61705 4-tert-Octylphenol diethoxylate E 0.58 E 0.11 109 E 0.66 0.11 125 E 0.28 61706 4-tert-Octylphenol monoethoxylate E 1.4 E 0.025 89 E 1.5 0.025 95 E 0.78 62062 4-tert-Octylphenol E 0.2 <0.14 -- E 0.21 <0.14 -- E 0.14 62063 5-Methyl-1H-benzotriazole 2.8 E 0.49 67 2.9 0.49 69 1.7 62066 9, 10-Anthraquinone E 0.44 <0.16 -- E 0.46 <0.16 -- E 0.38 62064 Acetophenone 0.88 <0.4 -- 0.94 <0.4 -- 0.84 62065 Acetyl-hexamethyl-tetrahydronaphthalene (AHTN) 0.58 0.15 100 0.6 0.15 103 0.42 34421 Anthracene 0.18 <0.028 -- 0.2 <0.028 -- 0.11 34248 Benzo[a]pyrene 0.094 <0.05 -- 0.15 <0.05 -- 0.081 62067 Benzophenone 0.96 0.12 98 1.0 0.12 100 0.88 62068 β-Sitosterol E 4.7 <4.0 -- E 5.8 <4.0 -- E 1.7 62086 β-Stigmastanol E 1.4 <2.6 -- 1.8 <2.6 -- E 1.4 40290 Bromacil 1.7 <0.36 -- 1.9 <0.36 -- -- 50305 Caffeine 0.87 <0.06 -- 0.94 <0.06 -- 0.8 62070 Camphor 0.81 <0.044 -- 0.86 <0.044 -- 0.77 62071 Carbazole 0.2 <0.03 -- 0.22 <0.03 -- 0.17 38933 Chlorpyrifos 2.8 <0.16 -- 3.0 <0.16 -- 2.6 62072 Cholesterol E 2.5 <2.0 -- E 3 <2.0 -- E 2.1 62005 Cotinine E 0.71 <0.038 -- E 0.84 <0.038 -- E 0.4 

Table 6. Spike report for treated-effluent water samples collected at water-quality study sites in or near Dallas, Texas, 2009–13.[μg/L, micrograms per liter; NWQL, U.S. Geological Survey National Water Quality Laboratory; <, less than; --, no data/not determined; E, estimated]
Table 6. Spike report for treated-effluent water samples collected at water-quality study sites in or near Dallas, Texas, 2009–13.—Continued [μg/L, micrograms per liter; NWQL, U.S. Geological Survey National Water Quality Laboratory; <, less than; --, no data/not determined; E, estimated] Param- eter code Compound November 23, 2009 @ 2221 November 23, 2009 @ 2220 M

(spiked in field) (spiked at NWQL) 

Spike (μg/L) Environmental sample concentration (μg/L) Recovery (percent) Spike (μg/L) Environmental sample concentration (μg/L) Recovery (percent) Spike (μg/L) 

39572 Diazinon 2.6 <0.16 -- 3.5 <0.16 -- 1.2 62073 d-Limonene 1 <0.08 -- 1.1 <0.08 -- 0.46 34377 Fluoranthene 0.2 <0.024 -- 0.21 <0.024 -- 0.16 62075 Hexahydro-hexamethyl-cyclopenta-benzopyran (HHCB) 1.8 1.40 93 1.8 1.4 91 1.4 62076 Indole 0.1 <0.08 -- 0.14 <0.08 -- 0.048 62077 Isoborneol 0.85 <0.18 -- 0.91 <0.18 -- E 0.96 34409 Isophorone 0.48 0.1 88 0.52 0.1 96 0.5 62078 Isopropylbenzene 0.31 <0.3 -- 0.31 <0.3 -- 0.13 62079 Isoquinoline 0.36 <0.046 -- 0.43 <0.046 -- 0.22 62080 Menthol 3.3 E 0.098 93 3.5 0.098 97 E 3.6 50359 Metalaxyl 1.8 <0.12 -- 2.0 <0.12 -- 1.5 62081 Methyl salicylate 0.84 E 0.01 96 0.9 0.01 101 0.76 39415 Metolachlor 0.43 <0.08 -- 0.45 <0.08 -- 0.36 62082 N,N-diethyl-meta-toluamide (DEET) 0.5 0.09 95 0.52 0.09 98 0.39 34443 Naphthalene 0.18 <0.04 -- 0.18 <0.04 -- 0.13 62084 p-Cresol 0.85 <0.08 -- 0.88 <0.08 -- 0.64 34462 Phenanthrene 0.19 <0.032 -- 0.2 <0.032 -- 0.17 34466 Phenol 0.85 <0.16 -- 0.93 <0.16 -- 0.78 40370 Prometon 1.7 <0.12 -- 1.9 <0.12 -- -- 34470 Pyrene 0.2 <0.042 -- 0.21 <0.042 -- 0.16 34476 Tetrachloroethylene E 0.54 <0.12 -- E 0.57 <0.12 -- E 0.38 34288 Tribromomethane (Bromoform) 2 0.84 67 2 0.84 66 1.7 62089 Tributyl phosphate 0.56 E 0.15 95 0.60 E 0.15 103 0.45 62090 Triclosan 3.4 <0.2 -- 3.4 <0.2 -- 2.4 62091 Triethyl citrate 0.59 E 0.14 105 0.63 E 0.14 112 0.54 62092 Triphenyl phosphate 0.84 E 0.059 91 0.9 E 0.059 96 0.8 62093 Tris(2-butoxyethyl)phosphate 6.3 <0.8 -- 6.9 <0.8 -- 5.5 62087 Tris(2-chloroethyl)phosphate 1.8 0.21 92 2.0 0.21 102 1.7 62088 Tris(dichloroisopropyl)phosphate 3.9 0.37 103 4.2 0.37 109 3.6 
Methods 19

Table 7. Relative percent differences for field and laboratory spikes of treated-effluent water samples collected November 23, 2009, at 

WWTP-2 near Dallas, Texas.

[μg/L, micrograms per liter; RPD, relative percent difference; E, estimated value]

Compound

Field 

spike value

(μg/L)

Laboratory 

spike value

(μg/L)

RPD

1-Methylnaphthalene 0.32 0.33 3

2,6-Dimethylnaphthalene 0.28 0.28 0

2-Methylnaphthalene 0.3 0.3 0

3-β-Coprostanol E 2.6 E 3.2 21

4-Cumylphenol 0.43 0.44 2

4-Nonylphenol (sum of all isomers) E 3 E 3 0

4-Nonylphenol diethoxylate E 7.7 E 8.4 9

β-Stigmastanol E 1.4 E 1.8 25

Camphor 0.81 0.86 6

Carbaryl E 0.64 E 0.65 2

Carbazole 0.2 0.22 10

Chlorpyrifos 2.8 3.0 7

Cholesterol E 2.5 E 3 18

Diazinon 2.6 3.5 30

d-Limonene 1 1 10

Fluoranthene 0.2 0.2 5

Hexahydro-hexamethyl-cyclopenta-benzopyran (HHCB) 1.8 1.8 0

Indole 0.1 0.14 33

Isoborneol 0.85 0.91 7

Isophorone 0.48 0.52 8

Isopropylbenzene 0.31 0.31 0

Isoquinoline 0.40 0.40 0

Menthol 3.3 3.5 6

Metalaxyl 1.8 2.0 11

Metolachlor 0.43 0.45 5

N,N-diethyl-meta-toluamide (DEET) 0.5 0.52 4

Naphthalene 0.18 0.18 0

p-Cresol 0.85 0.88 3

Tetrachloroethylene E 0.54 E 0.57 5

Triclosan 3.4 3.4 0

Triethyl citrate 0.59 0.63 7

Tris(dichloroisopropyl)phosphate 3.9 4.2 7
Table 8. Surrogate percent recoveries for environmental samples collected at study sites in or near Dallas, Texas, 2009–13. [pcode, parameter code; SH, U.S. Geological Survey (USGS) National Water Quality Laboratory schedule; LCAB, USGS Organic Geochemistry Research Laboratory liquid chantibiotics schedule; --, no data; N/A, parameter code not assigned for surrogate standard; α, alpha; β, beta] Surrogate (isotope dilution standard) pcode Potable water treatment plants Wastewater treatment plants Trinity R

NumberMini- mum (per- cent) Mean (per- cent) Median (per- cent) Maxi- mum (per- cent)

NumberMini- mum (per- cent) Mean (per- cent) Median (per- cent) Maxi- mum (per- cent)

NumberMini- mum (per- cent) 

Human health and pharmaceuticals (SH2080)

Carbamazepine-d10 90797 42 22 52 53 70 28 9 21 19 39 35 27 Ethyl nicotinate-d4 99571 42 38 69 59 93 28 21 40 40 62 35 44 

Antibiotics (LCAB)

Combined dataset

Meclocycline 62680 137 2 83 83 204Naxidilic acid N/A 149 32 220 140 1,300Oleandomycin 62964 92 52 120 120 26013C6-sulfamethazine N/A 139 4 130 130 270

Steroidal hormones and sterols (SH2434)

16-Epiestriol-2,4-d2 91676 20 63 76 76 87 19 41 76 80 99 25 24 17-α-Ethynylestradiol-2,4,16,16-d4 90813 42 69 84 82 109 28 51 81 84 104 35 32 17-β-Estradiol-13,14,15,16,17,18-13C6 91753 30 69 79 78 94 24 51 79 83 94 30 31 17-β-Estradiol-2,4,16,16-d4 90777 12 78 86 85 94 4 70 82 84 91 5 80 4-Androstene-3,17-dione-2,2,4,6,6,16,16-d7 90815 12 58 99 101 128 4 55 96 102 122 5 49 Bisphenol A-d16 67308 42 65 91 92 123 28 60 95 100 108 35 26 Cholesterol-25,26,26,26,27,27,27-d7 90778 42 62 75 75 90 28 49 72 73 88 35 15 Dihydrotestosterone-1,2,4,5a-d4 90823 12 81 91 90 107 4 59 83 85 105 5 80 Estriol-2,4,17-d3 90819 12 74 95 94 118 4 114 116 115 120 5 76 Estrone-2,4,16,16-d4 90820 12 64 89 94 118 4 60 87 88 110 5 68 Mestranol-2,4,16,16-d4 90821 42 70 80 80 92 28 55 79 82 98 35 30 Progesterone-2,2,4,6,6,17a,21,21,21-d9 90822 12 6 63 72 126 4 22 89 102 128 5 31 Testosterone-2,2,4,6,6-d5 90824 12 70 92 94 109 4 77 99 104 111 5 58 trans-Diethyl-1,1,1’,1’-d4-stilbestrol3,3’,5,5’-d4 90817 42 30 61 61 90 28 57 80 81 100 35 19 

Wastewater compounds in the water column (SH1433)

Caffeine-13C 99584 42 76 91 93 104 28 56 95 94 104 35 75 Fluoranthene-d10 99586 42 74 84 85 98 28 48 87 88 123 35 66 Decafluorobiphenyl 99585 42 24 44 44 70 28 16 48 47 69 35 30 

Wastewater compounds in bed sediments (SH5433)

Fluoranthene-d10 90738 -- -- -- -- -- -- -- -- -- -- 35 48 Bisphenol A-d3 90735 -- -- -- -- -- -- -- -- -- -- 35 2 Decafluorobiphenyl 90737 -- -- -- -- -- -- -- -- -- -- 35 5 

*Data in LCAB section combined from potable water treatment plant, wastewater treatment plant, and Trinity River sample sites.
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 21

Detections, Concentrations, and 

Distributions of Compounds of 

Emerging Concern 

Analytical results were sorted by study site type (PWTPs, 

WWTPs, and Trinity River sites) and are presented in Null 

and others (2019). Results are grouped primarily by compound 

type and subdivided on the basis of the laboratory schedules 

used for analysis; compounds are listed in the following order: 

human-health pharmaceuticals (schedule SH2080); antibiotics 

(schedule LCAB); steroidal hormones, stanols, and sterols 

(schedule SH2434); wastewater compounds in water (schedule 

SH1433); and wastewater compounds in bed sediment at 

Trinity River sites (schedule SH5433).

Compounds of Emerging Concern in Water 

Samples Collected at Potable Water Treatment 

Plants

Compound Detections

Of the 120 targeted compounds, 16 were detected 

in samples collected at PWTPs; 14 compounds were 

detected in raw-water samples, and 5 compounds were 

detected in finished-water samples (tribromomethane, 

4-androstene-3,17-dione, benzophenone, methyl salicylate, 

and tris(dichloroisopropyl)phosphate) (fig. 2). Eleven CECs 

were detected exclusively in raw-water samples, indicating 

that they were removed or degraded to compounds that 

were not analyzed. Of those 11 CECs, 3 were humanhealth pharmaceutical compounds (carbamazepine, 

sulfamethoxazole, and caffeine); 3 were steroidal 

hormones/stanols/sterols (estrone, 3-beta-coprostanol, and 

cholesterol); a detergent (4-tert-octylphenol); a flavor/

fragrance (hexahydro-hexamethyl-cyclopenta-benzopyran 

[HHCB]); an industrial wastewater compound (p-cresol); 

a PAH (pyrene), and a flame retardant/plasticizer (tributyl 

phosphate). Two of the five CECs detected in finishedwater samples (the androgen, 4-androstene-3,17-dione, and 

tribromomethane, which is a byproduct of water treatment 

processes) were detected exclusively in finished-water 

samples. Tris(dichloroisopropyl)phosphate, benzophenone, 

and methyl salicylate were detected in raw-water and 

finished-water samples; however, benzophenone and methyl 

salicylate were detected in only one finished-water sample. 

Twelve CECs were detected less frequently in finished-water 

samples than in raw-water samples. Tris(dichloroisopropyl)

phosphate, a persistent plasticizer/flame retardant (Hudec 

and others, 1981) and EDC (Wang and others, 2013), was 

detected seven times in each sample type (33 percent of 

samples). Stackelberg and others (2004) detected methyl 

salicylate and tris(dichloroisopropyl)phosphate in finishedwater samples collected at a PWTP. Carbamazepine, 

sulfamethoxazole, and tris(2-butoxyethyl)phosphate were 

detected in finished-water samples by Stackelberg and others 

(2004) but were not detected in finished-water samples in 

this study. Tribromomethane and 4-androstene-3,17-dione

were detected in finished-water samples but not in rawwater samples (fig. 2). Tribromomethane, also known as 

bromoform, is a trihalomethane disinfection byproduct formed 

during the water treatment process by the reaction between 

disinfectants (chlorine or ozone) and organic matter and 

bromide (U.S. Department of Health and Human Services, 

2005). Tribromomethane was detected in 48 percent of 

finished-water samples and in at least one finished-water 

sample from each of the three PWTPs. Three compounds were 

detected in more than 50 percent of the raw-water samples: 

sulfamethoxazole (81 percent of samples), carbamazepine 

(71 percent of samples), and cholesterol (52 percent of 

samples). Reif and others (2012) found sulfamethoxazole, 

carbamazepine, and caffeine to be the most frequently 

detected pharmaceutical compounds in samples collected at 

surface-water sites within 5 miles of PWTP raw-water intakes 

in Pennsylvania. In a nationwide study, Valder and others 

(2014) detected cholesterol in 19 percent of samples. The 

most common personal-use products detected in the Valder 

and others study (2014) was the fragrance compound HHCB, 

which was detected in 30 percent of samples. In this study, 

HHCB was detected in 24 percent of raw-water samples but 

was not detected in any finished-water sample. The study 

by Valder and others (2014) and this study used a similar 

censoring level for HHCB (table 4).

Compound Concentrations

Concentrations of CECs detected in finished-water 

samples at PWTPs were generally very low and less than 

concentrations of CECs detected in raw-water samples. In 

some cases, detected concentrations were in the range of the 

variable LRLs. The treatment processes used by the PWTPs 

could have reduced concentrations (and detections) to levels 

less than the LRL or selected censoring level. In addition, 

CECs could have been transformed during water-treatment 

processes into degradates that were not analyzed. For 

example, the three CECs most prevalent in raw-water samples, 

sulfamethoxazole, carbamazepine, and cholesterol, were 

not detected in finished-water samples (fig. 2). Maximum 

concentrations of sulfamethoxazole, carbamazepine, and 

cholesterol in raw-water samples were 0.22, 0.02, and 

0.46 μg/L, respectively. In a similar study of surface waters 

in the San Antonio River Basin near San Antonio, Texas, 

maximum concentrations of 0.27 and 1.74 μg/L were 

reported for sulfamethoxazole and cholesterol, respectively 

(Opsahl and Lambert, 2013). Eight CECs that were detected 

in less than 25 percent of raw-water samples were not 

detected in any finished-water samples (fig. 2). Although 

five compounds were detected in finished-water samples, 

only three of these five compounds were detected in more 

than 10 percent of finished-water samples: tribromomethane 
22 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

0 10 20 30 40 50 60 70 80 90 100

Detections in raw-water samples, in percent

0

10

20

30

40

50

60

70

80

90

100

Detections in finished-water samples, in percent

Note: One symbol might represent more than one compound

EXPLANATION

Carbamazepine

Sulfamethoxazole

Caffeine

Estrone

4-Androstene-3,17-dione

3-beta-Coprostanol

Cholesterol

4-tert-Octylphenol

Hexahydro-hexamethyl-cyclopenta-benzopyran (HHCB)

Benzophenone

Methyl salicylate

p-Cresol

Tribromomethane (Bromoform)

Pyrene

Tributyl phosphate

Tris(dichloroisopropyl)phosphate

A

B

C

D

E

F

G

F

H

I

J

F

K

F

C

L

I

D C G A B

E

F

L

J

K

H

Figure 2. Detection frequencies of selected compounds in raw- and finished-water 

samples collected at potable water treatment plants in or near Dallas, Texas, 2009–13.
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 23

(48 percent of samples), tris(dichloroisopropyl)phosphate 

(33 percent of samples), and 4-androstene-3,17-dione

(19 percent of samples) (Null and others, 2019). The 

maximum concentration of tribromomethane was 0.50 μg/L, 

which is similar to the maximum concentration (0.67 μg/L) 

reported by Opsahl and Lambert (2013) from river sites 

downstream from treated-effluent discharges from WWTPs. 

The maximum concentration of tris(dichloroisopropyl)

phosphate was 0.35 μg/L. The maximum concentration of 

the male steroidal hormone, 4-androstene-3,17-dione, was 

0.003 μg/L. The maximum concentration for this compound 

was also 0.003 μg/L in the San Antonio study (Opsahl and 

Lambert, 2013). Three compounds were detected in raw- and 

finished-water samples: tris(dichloroisopropyl)phosphate, 

benzophenone, and methyl salicylate. The paired statistical 

analyses of these compounds between raw- and finishedwater samples were not statistically significant (table 9) likely 

because of the high number of values that were less than the 

LRLs.

Compounds of Emerging Concern in Water 

Samples Collected at Wastewater Treatment 

Plants

Generally, detection frequencies for CECs in treatedeffluent samples from WWTPs were substantially lower 

compared to detection frequencies for CECs in untreatedinfluent samples from WWTPs. Of the 120 targeted CECs, 

74 were detected in water samples collected at WWTPs 

(Null and others, 2019). Seventy-three CECs were detected 

in untreated-influent samples, and 31 CECs were detected in 

all 14 untreated-influent samples. Forty-seven compounds 

were detected in at least 70 percent of the untreatedinfluent samples. A total of 30 compounds were detected 

in treated-effluent samples, 5 of which were detected in all 

treated-effluent samples: carbamazepine, AHTN, HHCB, 

1,4-dichlorobenzene, and tris(dichloroisopropyl)phosphate. 

Forty-four CECs were detected exclusively in untreatedinfluent samples, indicating that they were removed or 

degraded to compounds that were not analyzed. Twentynine CECs (including carbamazepine, sulfamethoxazole, 

4-androstene-3,17-dione, 3-beta-coprostanol, AHTN, HHCB, 

1,4-dichlorobenzene, tribromomethane, benzophenone, and 

tris(dichloroisopropyl)phosphate) were detected in untreated 

and treated water, indicating that treatment processes likely 

did not remove or degrade these compounds. Wilcoxon 

signed-rank test results indicated concentrations decreased 

significantly during wastewater treatment processes for 

22 CECs detected in untreated-influent and treated-effluent 

samples collected at WWTPs (8 human-health pharmaceutical 

and antibiotic compounds, 3 steroidal hormones, 2 stanol/

sterol compounds, 2 detergent compounds, and various CECs 

from other classes of compounds, such as HHCB, DEET, 

1,4-dichlorobenzene, p-cresol, benzophenone, triethyl citrate, 

and tributyl phosphate). Concentrations of carbamazepine and 

tribromomethane increased significantly between samples 

types at WWTPs. Tribromomethane was the only compound 

detected substantially more frequently in treated-effluent 

samples (93-percent detection frequency) than untreatedinfluent samples (29-percent detection frequency). The 

estrogen compound equilin was the only compound detected 

in a treated-effluent sample that was not also detected in at 

least one untreated-influent sample. Equilin was detected in 

one treated-effluent sample, which corresponds to a 7-percent 

detection frequency.

Human-Health Pharmaceuticals and Antibiotics

Eighteen of the 44 targeted human-health 

pharmaceuticals and antibiotic compounds were detected 

in untreated-influent samples (fig. 3). Five pharmaceutical 

compounds (carbamazepine, 1,7-dimethylxanthine, 

acetaminophen, caffeine, and cotinine) were detected in all 

untreated-influent samples with maximum concentrations 

of 0.29, 8.8, 56, 64, and 0.32 μg/L, respectively (fig. 3; 

Null and others, 2019). One pharmaceutical compound 

(sulfamethoxazole) and four antibiotic compounds 

(ciprofloxacin, ofloxacin, anhydroerythromycin, and 

trimethoprim) were detected in untreated-influent samples 

at detection frequencies ranging from 78 to 93 percent. The 

maximum concentration of sulfamethoxazole was 2.75 μg/L. 

Ibuprofen, azithromycin, tetracycline, and lincomycin were 

detected in 57 to 72 percent of untreated-influent samples 

(fig. 3; Null and others, 2019).

Table 9. Results of Wilcoxon rank-sum tests for selected compounds detected in water samples 

collected at potable water treatment plants in or near Dallas, Texas, 2009–13.

[μg/L, micrograms per liter; ≤, less than or equal to; <, less than]

Compound Parameter 

code

Rawwater 

median

(μg/L)

Finishedwater 

median

(μg/L)

Statistically 

significant 

at p≤0.05

p-value 

Tris(dichloroisopropyl)phosphate 62088 <0.10 <0.10 No 0.945

Benzophenone 62067 <0.08 <0.08 No 0.750

Methyl salicylate 62081 <0.044 <0.044 No 1
24 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

0 10 20 30 40 50 60 70 80 90 100

Detections in untreated-influent water samples, in percent

0

10

20

30

40

50

60

70

80

90

100

Detections in treated-effluent water samples, in percent

EXPLANATION

Note: One symbol might represent more than one compound

A

B

C

D

E

A

F

G

H

I

J

G

K

L

M

N

O

P

Acetaminophen

Cotinine

Ibuprofen

Sulfamethoxazole

Trimethoprim

1,7-Dimethylxanthine (p-Xanthine)

Doxycycline

Tetracycline

Azithromycin

Carbamazepine

Erythromycin

Lincomycin

Ciprofloxacin

Ofloxacin

Sulfadiazine

Anhydroerythromycin

4-Epitetracycline hydrochloride

Caffeine

I

G A

B

C

D

E

F

L

J

K

O

M

P

H

N

Figure 3. Detection frequencies of human-health pharmaceuticals and antibiotic 

compounds in untreated-influent and treated-effluent water samples collected at 

wastewater treatment plants in or near Dallas, Texas, 2009–13.
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 25

Of the 44 targeted CECs in the human-health 

pharmaceuticals and antibiotics group, 11 were detected in 

treated-effluent samples. Sulfamethoxazole and azithromycin 

were detected in 64 percent of samples. Carbamazepine 

was the only CEC in the human-health pharmaceuticals and 

antibiotic compounds group that was detected in all untreatedinfluent and treated-effluent samples. The occurrence of 

sulfamethoxazole and carbamazepine in untreated-influent 

and treated-effluent samples is consistent with low amount of 

removals reported by Kasprzyk-Hordern and others (2009). 

The maximum concentration of carbamazepine was 0.38 μg/L, 

which was measured in a treated-effluent sample (Null and 

others, 2019). In contrast to the maximum carbamazepine 

concentration of 0.38 μg/L measured in this study, Opsahl 

and Lambert (2013) reported a maximum concentration of 

0.12 μg/L for carbamazepine in stream-water samples in the 

San Antonio River Basin.

Nine CECs were detected in at least 70 percent of 

untreated-influent samples (fig. 3). Eight of these nine 

CECs that were detected in at least 70 percent of untreatedinfluent samples were also detected in more than 10 percent 

of treated-effluent samples (fig. 4). Cotinine is not shown on 

figure 4 because although it was detected in all untreatedinfluent samples, it was detected in less than 10 percent of 

treated-effluent samples. Median concentrations for the nine 

compounds detected in at least 70 percent of untreated-influent 

samples were significantly lower in treated-effluent samples 

than in untreated-influent samples (p-values ranged from 

less than 0.001 to 0.042; table 10). The only exception was 

the difference in carbamazepine concentrations measured in 

untreated-influent and treated-effluent samples. The median 

concentration of carbamazepine was significantly higher in 

treated-effluent samples (0.20 μg/L) than in untreated-influent 

samples (0.18 μg/L) (p-value equals 0.011) (Null and others, 

2019). Increases in concentrations of carbamazepine after 

wastewater treatment processes could be caused by hydrolysis 

of compound conjugates and were also reported by KasprzykHordern and others (2009). The largest difference between 

median concentrations in untreated influent and treated 

effluent was observed for caffeine. A median concentration 

of 30.0 μg/L was measured for caffeine in untreated-influent 

samples compared to a median concentration of less than 

0.08 μg/L in treated-effluent samples. 

Acetaminophen and 1,7-dimethylxanthine (p-xanthine) 

were detected in all untreated-influent samples but were 

not detected in treated-effluent samples. Cotinine was 

also detected in all untreated-influent samples but was 

only detected in one treated-effluent sample. It is likely 

acetaminophen, 1,7-dimethylxanthine (p-xanthine), and 

cotinine were removed or degraded by the wastewater 

treatment processes. The effectiveness of a WWTP in 

removing or degrading CECs in untreated influent arriving 

U T U T U T U T U T U T U T U T

Concentration, in micrograms per liter

0.001

0.01

0.1

1

10

100

Carbamazepine 

Caffeine 

Ciprofloxacin 

Ofloxacin 

Anhydroerythromycin 

Azithromycin 

Sulfamethoxazole 

Trimethoprim

14 14 14 5 13 4 13 2 11 6 10 9 13 9 11 2

EXPLANATION

Range of laboratory reporting levels

Concentration in untreated-influent water

Concentration in treated-effluent water

Number of values

Untreated influent

Treated effluent

14

U

T

Figure 4. Concentrations of selected human-health pharmaceuticals and antibiotics in untreated-influent and treated-effluent water 

samples collected at wastewater treatment plants in or near Dallas, Texas, 2009−13.
26 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 10. Results of Wilcoxon signed-rank tests for selected human-health pharmaceuticals and antibiotic compounds detected in 

water samples collected at wastewater treatment plants in or near Dallas, Texas, 2009–13.

[μg/L, micrograms per liter; ≤, less than or equal to; <, less than]

Compound Parameter 

code

Untreatedinfluent median

(μg/L)

Treatedeffluent median

(μg/L)

Increase or 

decrease from 

untreated- to 

treated-water

Statistically 

significant at 

p≤0.05

p-value 

Carbamazepine 62793 0.183 0.201 Increase Yes 0.011

Sulfamethoxazole 62775 1.15 0.011 Decrease Yes <0.001

Caffeine 50305 30.0 <0.08 Decrease Yes <0.001

Cotinine 62005 0.211 <0.038 Decrease Yes <0.001

Ciprofloxacin 62898 0.494 <0.005 Decrease Yes <0.001

Ofloxacin 62899 0.234 <0.005 Decrease Yes 0.002

Anhydroerythromycin 63674 0.046 <0.008 Decrease Yes 0.003

Azithromycin 62792 0.236 0.019 Decrease Yes 0.042

Trimethoprim 62023 0.053 <0.034 Decrease Yes 0.010

at the plant depends on several factors including which 

compounds are present in the source water, type and mode 

of operation of each treatment process, and physiochemical 

characteristics of the compounds themselves, some of which 

change over time (Stackelberg and others, 2007).

Steroidal Hormones, Stanols, and Sterols

Fifteen of the 21 targeted steroidal hormone/stanol/

sterol compounds were detected in untreated-influent samples 

(fig. 5). Thirteen of these 15 detected compounds were in 

more than 70 percent of the untreated-influent samples. Two 

steroidal hormone compounds were detected in more than 

10 percent of the treated-effluent samples—the androgen 

compound 4-androstene-3,17-dione (detected in 93 percent of 

the samples) and the estrogen compound estrone (detected in 

29 percent of the samples). Maximum concentrations for these 

androgen and estrogen compounds were 0.10 and 0.08 μg/L 

in untreated-influent samples and 0.003 and 0.03 μg/L in 

treated-effluent samples, respectively (Null and others, 

2019). The naturally occurring steroidal hormone compound 

4-androstene-3-17-dione has been identified as the androgen 

most commonly present in treated wastewater effluent samples 

(Phillips and others, 2012). Opsahl and Lambert (2013) 

reported maximum concentrations of 0.003 and 0.005 μg/L 

for these androgen and estrogen compounds, respectively, 

in stream-water samples from locations downstream from 

WWTP discharges. Concentrations reported by Opsahl 

and Lambert (2013) were likely lower than those reported 

in this study because samples were collected at the point 

of treated-effluent discharge in this study rather than at a 

downstream stream-water site.

Fewer steroidal hormone compounds were detected in 

treated-effluent samples (4 detections) than in untreatedinfluent samples (11 detections), which indicates that the 

wastewater treatment processes effectively removed most 

steroidal hormone compounds or transformed them into 

degradates that were not analyzed. Three of the 11 CECs 

detected in untreated-influent water were also detected in 

treated-effluent water, indicating that 73 percent of detected 

compounds in this group were removed or degraded by 

wastewater treatment processes. Statistical comparisons of 

steroidal hormone compound concentrations for untreatedinfluent and treated-effluent samples show a significant 

decrease in concentrations between sample types for 

three steroidal hormones (17-beta-estradiol, estrone, and 

4-androstene-3,17-dione) (p-value less than 0.001, Wilcoxon 

signed-rank test; table 11). Median concentrations of 

4-androstene-3,17-dione in untreated-influent and treatedeffluent water samples were 0.07 and 0.002 μg/L, respectively. 

Median concentrations of estrone in untreated-influent 

and treated-effluent water samples were 0.04 and less than 

0.0008 μg/L, respectively. Concentrations of 4-androstene3,17-dione and estrone in untreated-influent samples were 

generally 10 or more times higher than those in the treatedeffluent samples, and median concentrations of both steroidal 

hormones and of the estrogen compound 17-beta-estradiol 

decreased significantly after the wastewater was treated 

(p-value less than 0.001, Wilcoxon signed-rank test; table 11).
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 27

0 10 20 30 40 50 60 70 80 90 100

Detections in untreated-influent water samples, in percent

0

10

20

30

40

50

60

70

80

90

100

Detections in treated-effluent water samples, in percent

17-beta-Estradiol 

Equilenin 

Estriol 

Estrone 

Equilin 

4-Androstene-3,17-dione 

cis-Androsterone

Epitestosterone 

Testosterone

11-Ketotestosterone 

Dihydrotestosterone

Progesterone

3-beta-Coprostanol 

Cholesterol

beta-Stigmastanol 

beta-Sitosterol

Note: One symbol might represent more than one compound

A

B

C

D

E

F

C

G

C

C

C

H

I

J

K

H

EXPLANATION

J

B K H G C

A

I

F

E

D

Figure 5. Detection frequencies of steroidal hormones, stanols, sterols, and other 

wastewater compounds measured in untreated-influent and treated-effluent water 

samples collected at wastewater treatment plants in or near Dallas, Texas, 2009–13.
28 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 11. Results of Wilcoxon signed-rank tests for selected hormones, stanols, sterols, and wastewater compounds detected in 

water samples collected at wastewater treatment plants in or near Dallas, Texas, 2009–13.

[μg/L, micrograms per liter; ≤, less than or equal to; <, less than; β, beta]

Compound Parameter 

code

Untreated-influent 

median

Treated-effluent 

median 

Increase or 

decrease 

from 

untreated 

to treated 

water

Statistically 

significant 

at p≤0.05

p-value 

Steroidal hormones

17-β-Estradiol 64510 0.01 μg/L <0.0008 μg/L Decrease Yes <0.001

Estrone 64521 0.04 μg/L <0.0008 μg/L Decrease Yes <0.001

4-Androstene-3,17-dione 64513 0.07 μg/L 0.002 μg/L Decrease Yes <0.001

Stanols and sterols

3-β-Coprostanol 64512 42 μg/L 0.70 μg/L Decrease Yes <0.001

Cholesterol 64514 77 μg/L <2.0 μg/L Decrease Yes <0.001

Detergents and detergent metabolites 

4-Nonylphenol (sum of all isomers) 62085 5.0 μg/L <2.0 μg/L Decrease Yes <0.001

4-tert-Octylphenol monoethoxylate 61706 1.25 μg/L <1.0 μg/L Decrease Yes 0.002

Personal-use products (flavors and fragrances)

Acetyl-hexamethyltetrahydronaphthalene (AHTN) 62065 0.18 μg/L 0.14 μg/L Decrease No 0.094

Hexahydro-hexamethyl-cyclopentabenzopyran (HHCB) 62075 1.90 μg/L 1.25 μg/L Decrease Yes 0.005

Pesticides and repellents

N,N-diethyl-meta-toluamide (DEET) 62082 0.93 μg/L <0.70 μg/L Decrease Yes 0.008

1,4-Dichlorobenzene 34572 0.90 μg/L 0.12 μg/L Decrease Yes <0.001

Industrial wastewater compounds

p-Cresol 62084 27.0 μg/L <0.08 μg/L Decrease Yes <0.001

Tribromomethane (Bromoform) 34288 <0.10 μg/L 0.86 μg/L Increase Yes <0.001

Benzophenone 62067 0.95 μg/L 0.16 μg/L Decrease Yes <0.001

Triethyl citrate (ethyl citrate) 62091 0.76 μg/L 0.25 μg/L Decrease Yes <0.001

Flame retardants and plasticizers

Tris(dichloroisopropyl)phosphate 62088 0.44 μg/L 0.49 μg/L Increase No 0.626

Tributyl phosphate 62089 0.28 μg/L 0.15 μg/L Decrease Yes <0.001

Two of the four stanol/sterol compounds (3-betacoprostanol and cholesterol) were detected in all untreatedinfluent samples (fig. 5). The compounds 3-beta-coprostanol 

and cholesterol were also detected frequently in a nationwide 

study where they were found in 31 and 77 percent of streamwater samples, respectively (Valder and others, 2014). In this 

study, 3-beta-coprostanol and cholesterol were detected in 

86 and 14 percent of treated-effluent samples with maximum 

concentrations of 7.94 and 9.41 μg/L, respectively (Null 

and others, 2019). Maximum concentrations of 3-betacoprostanol and cholesterol in the San Antonio River Basin 

were 0.42 and 1.74 μg/L, respectively (Opsahl and Lambert, 

2013). Treatment processes of the WWTPs could have had 

a pronounced effect on concentrations of the four stanols/

sterols. The other two targeted stanols/sterols, beta-sitosterol 

and beta-stigmastanol, were detected in 71 and 36 percent 

of untreated-influent samples, respectively, and were not 

detected in treated-effluent samples. Median concentrations of 

3-beta-coprostanol in untreated-influent and treated-effluent 

samples were 42 and 0.70 μg/L, respectively (fig. 6; table 11). 

Median concentrations of cholesterol in untreated-influent and 

treated-effluent samples were 77 μg/L and less than 2.0 μg/L, 

respectively (table 11). Differences in median concentrations 

of 3-beta-coprostanol and cholesterol in untreated-influent 

samples compared to the median concentrations of these 

compounds in treated-effluent samples were statistically 

significant (p-value less than 0.001, Wilcoxon signed-rank 

test; table 11).
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 29

U T U T U T U T U T U T

U T U T U T U T U T U T

Concentration, in micrograms per liter

0.001

0.01

0.1

1

10

100

Concentration, in micrograms per liter

0.001

0.01

0.1

1

10

100

3-beta-Coprostanol

4-Androstene-3,17-dione

Estrone 

Acetyl-hexamethyl-tetrahydronaphthalene (AHTN)

Hexahydro-hexamethyl-cyclopenta-benzopyran (HHCB)

1,4-Dichlorobenzene

Tribromomethane (Bromoform)

Benzophenone 

Triethyl citrate 

Tris(dichloroisopropyl)phosphate Tributyl phosphate 

p-Cresol

14 12 14

13

14

4

12 14 14 14 14 14

4 13 14 13 14 13 14 14 14 12 14 3

EXPLANATION

Range of laboratory reporting levels

Concentration in untreated-influent water

Concentration in treated-effluent water

Number of values

Untreated influent

Treated effluent

14

U

T

Figure 6. Concentrations of steroidal hormones, stanols, sterols, and wastewater compounds 

detected in untreated-influent and treated-effluent water samples collected at wastewater treatment 

plants in or near Dallas, Texas, 2009−13.
30 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Detergents, Personal-Use Products, and 

Pesticides

Eighteen of the 27 detergents, personal-use products 

(flavors and fragrances), and pesticide compounds were 

detected at least once in an untreated-influent sample (fig. 7). 

Of these 18 compounds, 11 were detected in at least 70 percent 

of samples. HHCB, AHTN, and 1,4-dichlorobenzene were 

detected in all treated-effluent samples, with maximum 

concentrations of 1.7, 0.29, and 0.26 μg/L, respectively 

(Null and others, 2019). Opsahl and Lambert (2013) reported 

a maximum concentration for HHCB in the San Antonio 

River Basin of 1.9 μg/L. Five of the seven compounds in 

the detergents group were detected in untreated-influent 

samples (fig. 7). Three compounds from the detergents group 

(4-tert-octylphenol monoethoxylate, 4-nonylphenol (sum 

of all isomers), and 4-tert-octylphenol) were detected in at 

least 70 percent of the untreated-influent samples; 4-tertoctylphenol, a non-ionic detergent metabolite (Morace, 

2012), was detected in each untreated-influent sample. 

No compounds from the detergents group were detected 

in samples from treated-effluent discharge, indicating that 

they were removed or degraded by the wastewater treatment 

processes.

Nine of the 10 compounds categorized as personaluse products were detected in at least 1 untreated-influent 

sample (fig. 7). Eight of the nine detected personal-use 

compounds were detected in at least 64 percent of the 

untreated-influent samples. The compounds HHCB, menthol, 

3-methyl-1H-indole (skatole), camphor, d-limonene, and 

isoborneol were detected in each untreated-influent sample. 

Only two of the nine compounds detected in untreatedinfluent samples (HHCB and AHTN) were also detected in 

treated-effluent samples, indicating that 78 percent of the 

personal-use products were removed or degraded. AHTN 

was detected in 86 percent of untreated-influent samples 

and in 100 percent of treated-effluent samples. The higher 

number of detections in treated-effluent samples could be 

an artifact of laboratory uncertainty associated with the 

analyses and could be attributed to the similar concentrations 

of this compound between the two sample types. Median 

concentrations of AHTN were similar between untreatedinfluent and treated-effluent samples (0.18 and 0.14 μg/L, 

respectively; fig. 6; table 11), indicating that the wastewater 

treatment process likely does not affect this compound 

(p-value equals 0.094, Wilcoxon signed-rank test; table 11). 

This pattern is consistent with findings by Phillips and others 

(2012). Median concentrations of HHCB in untreated-influent 

and treated-effluent samples were 1.90 and 1.25 μg/L, 

respectively. The reduction of median concentrations of 

HHCB between untreated-influent and treated-effluent water 

samples was statistically significant (p-value equals 0.005, 

Wilcoxon signed-rank test; table 11); however, another study 

(Stackelberg and others, 2004) found consistent HHCB 

concentrations throughout the treatment process, indicating 

little or no removal of HHCB was likely through conventional 

water treatment processes.

Four of the 10 targeted pesticide/repellent compounds 

(prometon, bromacil, DEET, and 1,4-dichlorobenzene) 

were detected in untreated-influent samples (fig. 7). 

1,4-Dichlorobenzene was detected in all untreated-influent 

and treated-effluent samples—1,4-dichlorobenzene was 

the only pesticide compound detected in at least 60 percent 

of untreated-influent samples (maximum concentration of 

1.8 μg/L) and was the only pesticide compound detected in 

treated-effluent samples (75 percent of pesticide compounds 

removed/degraded) (Null and others, 2019). DEET, a 

common insect repellent, has been found in many other 

studies at high frequencies and was detected in 57 percent 

of the untreated-influent water samples at concentrations 

greater than or equal to 0.70 μg/L. Although the LRL for 

DEET in this study was 0.06 μg/L, concentrations of less than 

0.700 μg/L were censored (reported as not detected) based on 

DEET concentrations measured in blank samples (table 4). 

The maximum concentration of DEET in untreated-influent 

samples was 5.7 μg/L (Null and others, 2019). DEET was not 

detected at concentrations greater than or equal to 0.70 μg/L 

in any of the treated-effluent samples (fig. 7). Although 

1,4-dichlorobenzene was detected in all untreated-influent 

and treated-effluent samples, the median concentration of 

0.12 μg/L in treated-effluent samples was significantly less 

than the median concentration of 0.90 μg/L in untreatedinfluent samples (p-value less than 0.001, Wilcoxon signedrank test; table 11; fig. 6). The herbicides prometon and 

bromacil were detected in 14 and 7 percent of untreatedinfluent samples, respectively, but were not detected in 

treated-effluent samples (fig. 7).
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 31

0 10 20 30 40 50 60 70 80 90 100

Detections in untreated-influent water samples, in percent

0

10

20

30

40

50

60

70

80

90

100

Detections in treated-effluent water samples, in percent

Detergents and detergent metabolites

4-Nonylphenol (sum of all isomers)

4-Nonylphenol diethoxylate

4-tert-Octylphenol diethoxylate

4-tert-Octylphenol monoethoxylate

4-tert-Octylphenol

Personal-use products (flavors and fragrances)

Camphor

3-Methyl-1H-indole (Skatole)

Acetophenone

Acetyl-hexamethyl-tetrahydronaphthalene (AHTN)

Hexahydro-hexamethyl-cyclopenta-benzopyran (HHCB)

Indole

Isoborneol

d-Limonene

Menthol

Pesticides and repellents

N,N-diethyl-meta-toluamide (DEET)

1,4-Dichlorobenzene

Bromacil

Prometon

EXPLANATION

Note: One symbol might represent more than one compound

A

B

C

D

E

B

H

J

C

E

E

F

G

H

I

E

E

E

J C I B F D A E

G H

Figure 7. Detection frequencies of detergents and detergent metabolites, personaluse products (flavors and fragrances), and pesticides and repellents in untreatedinfluent and treated-effluent water samples collected at wastewater treatment plants 

in or near Dallas, Texas, 2009–13.
32 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Industrial Wastewater and Disinfection 

Compounds and Polycyclic Aromatic 

Hydrocarbons

Sixteen of the 22 industrial wastewater, disinfection, 

and PAHs compounds were detected in untreated-influent 

samples (fig. 8). Of these 16 compounds, 8 were detected in 

at least 75 percent of the untreated-influent samples. Nine 

of the 10 industrial wastewater compounds were detected in 

untreated-influent samples. Four of these nine compounds—

benzophenone, triethyl citrate, p-cresol, and methyl 

salicylate—were detected in all untreated-influent samples. 

Three compounds (tribromomethane, benzophenone, and 

triethyl citrate) were detected in 93 percent of treated-effluent 

samples. A statistically significant decrease in the median 

concentration of benzophenone from 0.95 μg/L in untreatedinfluent samples to 0.16 μg/L in treated-effluent samples 

was observed (p-value less than 0.001, Wilcoxon signedrank test; table 11). A statistically significant decrease in the 

median concentration of triethyl citrate was also observed, 

from 0.76 μg/L in untreated-influent samples to 0.25 μg/L in 

treated-effluent samples (p-value less than 0.001, Wilcoxon 

signed-rank test; table 11). The median concentration of 

the disinfection byproduct tribromomethane increased in a 

statistically significant manner from less than 0.10 μg/L in 

untreated-influent samples to 0.86 μg/L in treated-effluent 

samples (p-value less than 0.001, Wilcoxon signed-rank test; 

table 11; fig. 6). Detection frequencies of tribromomethane 

also increased between untreated-influent samples and 

treated-effluent samples. Increases in detection frequencies 

and concentrations of tribromomethane are likely a result of 

wastewater treatment processes, specifically, chlorination.

The disinfection compounds triclosan and phenol were 

detected in 100 and 93 percent of untreated-influent samples, 

respectively (fig. 8). Neither disinfection compound was 

detected in any of the treated-effluent samples, indicating that 

the compounds were removed or degraded. In all samples, 

concentrations of triclosan and phenol ranged from less than 

0.20 to 5.6 μg/L and less than 0.16 to 19 μg/L, respectively 

(Null and others, 2019).

Five of the 10 PAHs were detected in untreatedinfluent samples (fig. 8). Two PAHs, naphthalene and 

1-methylnaphthalene, were detected in at least 75 percent of 

untreated-influent samples, with maximum concentrations 

of 1.00 and 0.16 μg/L, respectively (Null and others, 2019). 

There were no detections of PAHs in treated-effluent samples. 

The wastewater treatment process possibly degraded or 

removed these compounds.

Flame Retardants and Plasticizers

All six flame retardant and plasticizer compounds were 

detected in untreated-influent samples (fig. 9), and three of 

these compounds—the flame retardants tris(2-butoxyethyl)

phosphate and tris(dichloroisopropyl)phosphate and the 

plasticizer tributyl phosphate—were detected in 100 percent of 

untreated-influent samples (50 percent of all flame retardants 

and plasticizers removed/degraded). Maximum concentrations 

of tributyl phosphate, tris(2-butoxyethyl)phosphate, and 

tris(dichloroisopropyl)phosphate in untreated-influent 

samples were 0.99, 51.0, and 1.3 μg/L, respectively (Null 

and others, 2019). BPA, a common plasticizer (Ferrell, 2009), 

was detected in 93 percent of untreated-influent samples 

but was not detected in treated-effluent samples. Maximum 

concentrations of BPA were 1.01 and less than 0.20 μg/L 

(less than the LRL), in untreated-influent and treated-effluent 

samples, respectively (Null and others, 2019). KasprzykHordern and others (2009) detected BPA in all untreatedinfluent samples and 75 percent of treated-effluent samples. 

They reported that mean concentrations of BPA decreased 

79 percent between the two sample types. Tris(2-butoxyethyl)

phosphate was detected in 1 of 15 treated-effluent samples, 

a detection frequency of about 7 percent. Two compounds, 

tributyl phosphate and tris(dichloroisopropyl)phosphate, were 

detected in more than 87 percent of treated-effluent samples, 

with detections of tris(dichloroisopropyl)phosphate observed 

in all treated-effluent samples. Median concentrations of 

tributyl phosphate decreased significantly between untreatedinfluent (0.28 μg/L) and treated-effluent (0.15 μg/L) samples 

(p-value less than 0.001, Wilcoxon signed-rank test; table 11), 

which is similar to the pattern observed by Phillips and others 

(2012). The wastewater treatment process did not appear to 

affect the concentrations of tris(dichloroisopropyl)phosphate 

appreciably; the median concentration for this compound 

increased slightly from 0.44 μg/L in untreated-influent 

samples to 0.49 μg/L in treated-effluent samples, an increase 

that was not statistically significant (p-value equals 0.626, 

Wilcoxon signed-rank test; table 11).

Observations Regarding Compounds of 

Emerging Concern Detected in Water Samples 

Collected at Potable Water and Wastewater 

Treatment Plants

The analytical results for water samples collected at 

PWTPs and WWTPs indicate a decrease in the frequency 

of detections of most CECs in treated samples compared 

to untreated samples. At PWTPs, 11 CECs were reduced 

to concentrations less than their respective LRLs by the 

treatment process or were transformed into degradates that 

were not analyzed. Compounds most commonly detected 

in raw-water samples at PWTPs include sulfamethoxazole, 

carbamazepine, cholesterol, tris(dichloroisopropyl)

phosphate, and HHCB (fig. 2). Of these compounds, only 

tris(dichloroisopropyl)phosphate was detected in finishedwater samples. At WWTPs, 44 CECs were removed or 

degraded during water-treatment processes—acetaminophen, 

testosterone, isoborneol, and triclosan are a few of the 

compounds that were each detected in every untreatedinfluent sample but were not detected in any treated-effluent 
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 33

0 10 20 30 40 50 60 70 80 90 100

Detections in untreated-influent water samples, in percent

0

10

20

30

40

50

60

70

80

90

100

Detections in treated-effluent water samples, in percent

Note: One symbol might represent more than one compound

EXPLANATION

A

B

B

C

D

E

F

L

M

J

K

C

C

G

H

I

Industrial wastewater compounds

Tribromomethane (Bromoform)

Triethyl citrate (ethyl citrate)

Benzophenone

Isopropylbenzene

5-Methyl-1H-benzotriazole

Isophorone

Tetrachloroethene

Methyl salicylate

p-Cresol

Disinfection compounds

Phenol

Triclosan

Polycyclic aromatic hydrocarbons

Phenanthrene

2,6-Dimethylnaphthalene

2-Methylnaphthalene

1-Methylnaphthalene

Naphthalene

F G H I J K

L

M

A B

C

D E

Figure 8. Detection frequencies of industrial wastewater and disinfection 

compounds and polycyclic aromatic hydrocarbons in untreated-influent and treatedeffluent water samples collected at wastewater treatment plants in or near Dallas, 

Texas, 2009–13.
34 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

0 10 20 30 40 50 60 70 80 90 100

Detections in untreated-influent water samples, in percent

0

10

20

30

40

50

60

70

80

90

100

Detections in treated-effluent water samples, in percent

A

B

C

D

E

F

EXPLANATION

Bisphenol A (BPA) 

Tributyl phosphate 

Triphenyl phosphate 

Tris(2-butoxyethyl)phosphate

Tris(2-chloroethyl)phosphate

Tris(dichloroisopropyl)phosphate

D

C A

B

F

E

Figure 9. Detection frequencies of flame retardants and plasticizers in untreatedinfluent and treated-effluent water samples collected at wastewater treatment plants 

in or near Dallas, Texas, 2009–13.

samples. Some compounds, however, were not affected by 

water treatment processes. For example, methyl salicylate 

(PWTPs) (fig. 2) and erythromycin, carbamazepine, HHCB, 

and 1,4-dichlorobenzene (WWTPs) were detected at the 

same frequency in untreated samples as they were in treated 

samples (figs. 3 and 7). At a given type of treatment plant, 

the detection frequency in untreated and treated samples 

of the flame retardant/plasticizer tris(dichloroisopropyl)

phosphate was similar; tris(dichloroisopropyl)phosphate was 

detected in 100 percent of the untreated-influent and treatedeffluent samples at WWTPs, and in about 30 percent of the 

raw-water and finished-water samples collected at PWTPs 

(Null and others, 2019). At PWTPs, 4-androstene-3,17-

dione and tribromomethane were detected more frequently 

in finished-water samples than in raw-water samples; at 

WWTPs, equilin, AHTN, and tribromomethane were detected 

more frequently in treated-effluent samples than in untreatedinfluent samples. Of these four compounds (4-androstene3,17-dione, tribromomethane, equilin, and AHTN), only 

tribromomethane was detected in substantially more treatedeffluent samples than in untreated-influent samples, likely 

because it is a byproduct of the treatment process at each type 

of water treatment plant.

Statistically significant differences were not observed in 

the median concentrations of CECs measured in raw-water 

and finished-water samples collected at PWTPs (table 9). A 

statistically significant decrease in the median concentration 

was measured for 22 compounds in treated-effluent 
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 35

samples compared to the median concentration measured in 

untreated-influent samples collected at WWTPs (tables 10 

and 11). Median concentrations of carbamazepine and 

tribromomethane increased significantly between untreatedinfluent and treated-effluent samples (tables 10 and 11).

Compounds of Emerging Concern in StreamWater and Bed-Sediment Samples Collected at 

Study Sites on the Trinity River

Results for stream-water samples and bed-sediment 

samples collected at the five USGS water-quality monitoring 

stations on the Trinity River are presented in Null and others 

(2019). Comparisons of compounds detected in stream-water 

samples to compounds detected in bed-sediment samples were 

limited to selected stanols/sterols and wastewater compounds 

listed in laboratory schedules SH1433 and SH5433 (Null and 

others, 2019).

Compounds of Emerging Concern in StreamWater Samples

Twenty-three of the 120 targeted CECs were detected 

in stream-water samples collected at the 5 study sites on 

the main stem of the Trinity River (Null and others, 2019). 

Ten of the 23 CECs were detected in samples collected at 

all 5 sites—carbamazepine, sulfamethoxazole, caffeine, 

3-beta-coprostanol, cholesterol, HHCB, benzophenone,

triethyl citrate, tributyl phosphate, and tris(dichloroisopropyl)

phosphate—indicating their persistence in the environment.

Tris(dichloroisopropyl)phosphate, a flame retardant

(Stackelberg and others, 2004), was the only compound

detected in all stream-water samples. Carbamazepine and

sulfamethoxazole were detected in 97 percent of stream-water

samples, and HHCB was detected in 94 percent of streamwater samples. Nine compounds were detected in more

than half of the stream-water samples. In general, detection

frequencies decreased with distance downstream; however, the

decrease was not statistically significant (p-value equals 0.314,

one-way ANOVA on ranks). Median concentrations of nine

compounds detected at all five Trinity River sites decreased

between the most upstream main-stem site closest to where

WWTP effluent is discharged and the farthest downstream site

on the Trinity River, Trinity River Trinidad; the concentration

of tributyl phosphate was similar at the most upstream and

farthest downstream main-stem sites.

Nine of the 44 human-health pharmaceutical and 

antibiotic compounds were detected in stream-water samples 

(fig. 10). All nine of the human-health pharmaceutical and 

antibiotic compounds detected in stream-water samples 

collected at Trinity River sites were also detected in 

treated-effluent samples at WWTPs, and four of these 

nine compounds were detected in more than 40 percent of 

treated-effluent samples at WWTPs (fig. 3). Carbamazepine, 

caffeine, and sulfamethoxazole were among the most 

frequently detected human-health pharmaceutical and antibiotic 

compounds in samples collected at main-stem sites on the 

Trinity River (fig. 10). In a similar study by Reif and others 

(2012), these three compounds were also detected frequently. 

Median concentrations of these three compounds did not 

change significantly between Trinity River main-stem sites 

(p-value greater than 0.596 for each compound, one-way 

ANOVA on ranks; Null and others, 2019). Carbamazepine and 

sulfamethoxazole, which were frequently detected in raw-water 

samples at PWTPs and in both sample types at WWTPs, were 

each detected in 34 of 35 stream-water samples (97 percent 

of samples). Caffeine was detected in 25 of 35 stream-water 

samples (71 percent of samples) and was detected in at least 

4 of 7 samples at each study site. Five antibiotic compounds 

(ciprofloxacin, ofloxacin, anhydroerythromycin, azithromycin, 

and sulfamethoxazole) were detected in samples collected at the 

upstream site on the Trinity River (Trinity River Highway 310 

site). In addition to sulfamethoxazole, anhydroerythromycin 

was the only other antibiotic compound detected in more than 

15 percent of all stream-water samples (Null and others, 2019).

Two of the 17 steroidal hormone CECs were detected in 

stream-water samples—estrone and 4-androstene-3,17-dione 

(fig. 10), and these two compounds were detected in less than 

15 percent of all stream-water samples that were collected (Null 

and others, 2019). Estrone and 4-androstene-3,17-dione were 

detected in all untreated-influent samples and in 28 percent 

or more of treated-effluent samples collected at WWTPs 

(fig. 5). Estrone was detected in 5 of the 35 stream-water 

samples (about 14 percent of samples); all stream-water samples 

in which estrone was detected were collected at the three most 

upstream sites on the Trinity River. 4-Androstene-3,17-dione, 

which was detected in 93 percent of treated-effluent samples at 

WWTPs, was not detected in samples collected at the two most 

upstream sites (Trinity River Highway 310 and Trinity River 

Dallas) or in samples collected at the most downstream site 

(Trinity River Trinidad) but was detected in samples collected 

at the Trinity River Wilmer and Trinity River Rosser sites. 

Detected concentrations, 0.001 and 0.0008 μg/L, respectively, 

were slightly greater than or equal to the LRL of 0.0008 μg/L 

used for most analyses of the compound.

Of the four stanol/sterol compounds analyzed, two 

compounds (3-beta-coprostanol and cholesterol) were detected 

in stream-water samples collected at each main-stem site on the 

Trinity River. The frequency at which 3-beta-coprostanol was 

detected (31 percent of stream-water samples) was lower than 

the frequency at which cholesterol was detected (77 percent of 

the stream-water samples). 3-beta-Coprostanol and cholesterol 

were detected in all untreated-influent samples at WWTPs 

(fig. 5) and were detected in 86 and 14percent of treated-effluent

samples, respectively. Generally, concentrations of 3-betacoprostanol and cholesterol measured in samples collected

at the main-stem sites on the Trinity River decreased from

upstream to downstream (Null and others, 2019); however, the

decreases were not statistically significant (p-value greater than

0.370 for each compound, one-way ANOVA on ranks).
EXPLANATION Trinity River site, identified by short name (table 1) Trinity River Highway 310 Trinity River below Dallas Trinity River Wilmer Trinity River Rosser

Trinity River Trinidad

Detections, in percent

0

102030405060708090

100

CarbamazepineCaffeine Cotinine CiprofloxacinOfloxacin

Anhydroerthromycin Azithromycin Trimethoprim Estrone 

3-beta-Cop

Sulfamethoxazole 4-Androstene-3,17-dione

Compound

Human-health Antibiotics

pharmaceuticals

Steroidal hormones, s

Figure 10. Detection frequencies of human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, and sterols in seven stream-watestudy sites on the Trinity River in or near Dallas, Texas, 2009–13.
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 37

In stream-water samples collected at main-stem sites 

on the Trinity River, there were no detected concentrations 

of detergent compounds that were equal to or greater than 

the LRL. The lack of detections of detergent compounds 

in samples collected at main-stem river sites is consistent 

with results from WWTPs; some of these compounds were 

detected in untreated-influent samples, but none was detected 

in treated-effluent samples, representative of discharge to the 

Trinity River (fig. 7).

Two personal-use product compounds (the fragrances 

AHTN and HHCB) were detected in stream-water samples 

collected at main-stem sites on the Trinity River; AHTN was 

detected in samples collected at two of the five main-stem 

sites, whereas HHCB was detected at all five sites (fig. 11). 

AHTN and HHCB were detected in each treated-effluent 

sample collected at the WWTPs (fig. 7). Compared to the 

frequency of detection of AHTN in the WWTP samples, the 

frequency of detection of AHTN in samples collected at the 

main-stem site closest to where a WWTP discharges (Trinity 

River Highway 310) was substantially less (14 percent of 

samples). AHTN has been reported at greater detection 

frequencies in samples collected at stream sites in other 

studies. For example, AHTN was detected in all samples 

analyzed in a study by Stackelberg and others (2004). For the 

analyses in this report, HHCB was detected in every sample 

collected at the four most upstream sites on the Trinity River 

and in about 94 percent of all stream-water samples (fig. 11; 

Null and others, 2019). Stackelberg and others (2004) reported 

a similar detection frequency for HHCB; HHCB was detected 

in 92 percent of the samples that represented streamflow and 

raw water for municipal supply. Median concentrations of 

HHCB in samples collected at main-stem Trinity River sites 

were greatest at the Trinity River Wilmer site (0.44 μg/L), 

and the median concentration decreased substantially at 

the downstream Trinity River Rosser and Trinity River 

Trinidad sites (0.22 and 0.17 μg/L, respectively; Null and 

others, 2019). HHCB was the only compound for which a 

statistically significant change in concentrations was measured 

between upstream and downstream main-stem sites. Median 

concentrations of HHCB were statistically significantly lower 

at the most distant main-stem site, the Trinity River Trinidad 

site, than at the other sites (p-value equals 0.001, one-way 

ANOVA on ranks with Dunn’s multiple comparison test).

Two of the 10 pesticide compounds (1,4-dichlorobenzene 

and metolachlor) were detected in stream-water samples 

collected at main-stem Trinity River sites (fig. 11). The 

compound 1,4-dichlorobenzene was detected in 86 percent 

of samples at the two most upstream main-stem sites (Null 

and others, 2019). At the three remaining main-stem sites, 

detection frequencies decreased with distance downstream to 

57, 14, and zero percent, respectively. Median concentrations 

of 1,4-dichlorobenzene also decreased with distance 

downstream, but the change was not statistically significant 

(p-value greater than 0.05, one-way ANOVA on ranks). 

Metolachlor was detected in only one sample collected at 

one of the five main-stem sites (the Trinity River Rosser 

site). Although the insect repellent DEET was detected in 

concentrations equal to or greater than the LRL (0.06 μg/L) at 

all five main-stem sites, none of the concentrations was equal 

to or greater than the censoring level of 0.700 μg/L used for 

DEET (table 4).

Three of the 10 industrial wastewater compounds were 

detected in water samples collected at the main-stem sites on 

the Trinity River (fig. 11). Benzophenone, tribromomethane, 

and triethyl citrate were detected in samples collected at 

each main-stem site, except for tribromomethane, which was 

not detected at the farthest downstream site, Trinity River 

Trinidad. All three of these compounds were detected in 

at least 93 percent of treated-effluent samples at WWTPs 

(fig. 8). Benzophenone was detected in 86 percent of water 

samples collected at each main-stem Trinity River site. 

Tribromomethane was detected in each water sample collected 

at the three upstream sites on the Trinity River. Detection 

frequency of values greater than or equal to the LRL decreased 

to 43 percent at the Trinity River Rosser site, and there were 

no detections at the Trinity River Trinidad site. Median 

concentrations of benzophenone decreased with distance 

downstream, but the changes were slightly outside the range 

considered statistically significant at the 95-percent confidence 

level (p-value equals 0.059, one-way ANOVA on ranks). 

Median concentrations of triethyl citrate also decreased with 

distance downstream, but the changes were not statistically 

significant (p-value equals 0.323, one-way ANOVA on ranks). 

Median concentrations of tribromomethane were greatest 

at the three upstream sites Trinity River Highway 310, 

Trinity River Dallas, and Trinity River Wilmer (0.40, 0.41, 

and 0.43 μg/L, respectively) then decreased substantially to 

0.17 μg/L at the Trinity River Rosser site (Null and others, 

2019).

The two disinfection compounds phenol and triclosan 

were not detected in concentrations equal to or greater than 

the LRL in stream-water samples collected at the main-stem 

Trinity River sites. This agrees with results from the WWTPs, 

where these compounds were detected in untreated-influent 

samples but not in treated-effluent samples (fig. 8).

The 10 PAH compounds were not detected in 

concentrations equal to or greater than the LRL in streamwater samples collected at main-stem Trinity River sites. This 

agrees with results from the WWTPs, where these compounds 

were not detected in the treated-effluent samples (fig. 8).

Three of the six flame retardant and plasticizer 

compounds (tributyl phosphate, tris(2-butoxyethyl)

phosphate, and tris(dichloroisopropyl)phosphate) were 

detected in stream-water samples collected at mainstem sites (fig. 11). Two of these compounds, tributyl 

phosphate and tris(dichloroisopropyl)phosphate, were 

detected in at least 86 percent of treated-effluent samples 

at WWTPs (fig. 9), and both were detected at all mainstem sites (fig. 11). Tris(dichloroisopropyl)phosphate 

was the only compound detected in all 35 main-stem 

samples in this study. Median concentrations of tributyl 

phosphate and tris(dichloroisopropyl)phosphate did not 
EXPLANATION Trinity River site, identified by short name (table 1) Trinity River Highway 310 Trinity River below Dallas Trinity River Wilmer Trinity River Rosser

Trinity River Trinidad

Detections, in percent

0

102030405060708090

100

1,4-DichlorobenzeneMetolachlor Benzophenone Tribromomethane (Bromoform) Triethyl citrate Tris(2-butoxyethyl)phosphate Tris(dichloroisopropyl)phosphate 

Compound

Hexahydro-hexamethyl- cyclopenta-benzopyran (HHCB) Acetyl-hexamethyl- tetrahydronapthalene (AHTN)

Fragrances Pesticides Flame retardants

and plasticizers

Industrial wastewater

compounds

Fragrances Pesticides Flame retardants

and plasticizers

Industrial wastewater

compounds

Figure 11. Detection frequencies of personal-use products (fragrances), pesticides, industrial wastewater compounds, and flame retardants aseven stream-water samples collected at study sites on the Trinity River in or near Dallas, Texas, 2009–13.
Detections, Concentrations, and Distributions of Compounds of Emerging Concern 39

change significantly between sites, possibly because of 

their resistance to degradation in the environment (p-values 

equal 0.355 and 0.570, respectively, one-way ANOVA on 

ranks). Median concentrations of tributyl phosphate and 

tris(dichloroisopropyl)phosphate measured in stream-water 

samples collected at the five main-stem sites ranged from 0.14 

to 0.18 μg/L and 0.51 to 0.63 μg/L, respectively.

Compounds of Emerging Concern in BedSediment Samples

Eleven of the 57 CECs analyzed in bed-sediment samples 

were detected (fig. 12). Two compounds (beta-sitosterol and 

cholesterol) were detected in bed-sediment samples collected 

at all five main-stem sites. Nine other CECs were detected 

in bed-sediment samples, including 3-beta-coprostanol (also 

detected in stream-water samples at all five main-stem sites), 

phenol, fluoranthene, pyrene, and bis(2-ethylhexyl) phthalate. 

Of the 11 CECs detected in bed-sediment samples, 9 were not 

detected in any stream-water sample (cholesterol and 3-betacoprostanol were the exceptions) likely because of the strong 

hydrophobic characteristics of these compounds. At the two 

farthest downstream sites on the Trinity River, the detection 

of compounds other than beta-sitosterol or cholesterol was 

rare—phenol was detected in one bed-sediment sample 

collected at the Rosser site, and bis(2-ethylhexyl) phthalate 

was detected in one bed-sediment sample collected at the 

Trinity River Trinidad site (fig. 12; Null and others, 2019). 

This indicates that most compounds analyzed were not 

subjected to substantial downstream transport. Overall, 

detection frequencies of CECs decreased with distance 

downstream; however, the decrease was not statistically 

significant (p-value equals 0.205, one-way ANOVA on ranks). 

Concentrations of five CECs in bed-sediment samples were 

highest at the most distant downstream site at which they were 

detected: cholesterol, phenol, fluoranthene, pyrene, and bis(2-

ethylhexyl) phthalate, indicating that these CECs are resistant 

to degradation during downstream transport. It is important to 

note that variable LRLs for some compounds complicate data 

interpretation.

All four stanol/sterol compounds were detected in 

bed-sediment samples (fig. 12). Two of these compounds, 

beta-sitosterol and cholesterol, were detected in 54 and 57 

percent of bed-sediment samples, respectively (Null and 

others, 2019). These two compounds were the most frequently 

detected CECs in bed-sediment samples in this study. 

Cholesterol and 3-beta-coprostanol were the only two CECs 

detected in stream-water and bed-sediment samples (figs. 10 

and 12). Cholesterol and 3-beta-coprostanol were detected 

in every untreated-influent sample collected at WWTPs and 

in 14 and 86 percent of treated-effluent samples collected at 

WWTPs, respectively (fig. 5). At the farthest upstream site 

(Trinity River Highway 310), 3-beta-coprostanol and betastigmastanol were each detected in one of the seven samples 

collected, which corresponds to a 14-percent detection 

frequency (fig. 12); 3-beta-coprostanol was also detected 

in one sample collected at the second farthest upstream site 

on the Trinity River (Trinity River Dallas). Neither 3-betacoprostanol nor beta-stigmastanol was detected in any samples 

collected at the three most downstream sites on the Trinity 

River. Beta-sitosterol was not detected in treated-effluent 

samples at WWTPs or in stream-water samples collected at 

any of the main-stem sites on the Trinity River. The maximum 

concentrations for beta-sitosterol (4,310 micrograms per 

kilogram [μg/kg]) and cholesterol (3,550 μg/kg), however, 

were measured in samples collected at the most upstream site 

on the Trinity River (Trinity River Highway 310) (Null and 

others, 2019). Downstream from the Trinity River Highway 

310 site, beta-sitosterol and cholesterol concentrations 

decreased in bed-sediment samples collected at the Trinity 

River Dallas and Trinity River Wilmer sites, and then 

increased at the two sites farthest downstream (Trinity River 

Rosser and Trinity River Trinidad). Concentrations were not 

significantly different between sites for either beta-sitosterol 

or cholesterol (p-values equal 0.896 and 0.226, respectively, 

one-way ANOVA on ranks).

Two of the 10 compounds in the personal-use product 

group were detected in bed-sediment samples collected 

at main-stem sites (fig. 12). Indole was detected in one 

sample collected at the Trinity River Highway 310 site, and 

d-limonene was detected in one sample collected at the Trinity 

River Dallas site. The compound d-limonene was detected 

in every untreated-influent sample collected at the WWTPs, 

whereas indole was detected in only 50 percent of untreatedinfluent samples (fig. 7). Neither indole nor d-limonene

was detected in any treated-effluent samples collected at the 

WWTP sites or in stream-water samples collected at the mainstem Trinity River sites (Null and others, 2019).

Phenol was the only disinfection compound detected in 

bed-sediment samples (fig. 12). Phenol was detected in one 

sample collected at the Trinity River Highway 310 site and in 

one sample collected at the Trinity River Rosser site. Phenol 

was not detected in treated-effluent samples collected at the 

WWTPs (fig. 8) or in main-stem Trinity River stream-water 

samples (Null and others, 2019).

Three of the 10 PAH compounds were detected in 

bed-sediment samples (benzo[a]pyrene, fluoranthene, and 

pyrene); however, none of these three compounds was 

detected in more than 50 percent of the samples collected 

at a given site (fig. 12). PAHs were not detected in treatedeffluent samples at WWTPs (fig. 8) or stream-water samples 

(Null and others, 2019), likely because of their strong 

hydrophobic characteristics (Abdel-Shafy and Mansour, 

2015). Fluoranthene and pyrene were detected in bedsediment samples collected at the three sites farthest upstream 

on the Trinity River. Overall, the detection frequency for 

fluoranthene and pyrene was low at the five Trinity River 

main-stem sites (detected in 23 percent of all bed-sediment 

samples) and was very low for benzo[a]pyrene (detected in 

3 percent of all bed-sediment samples); however, each of 

these three PAHs was detected in at least one bed-sediment 

sample collected at the Trinity River Wilmer site (fig. 12). 
EXPLANATION Trinity River site, identified by short name (table 1) Trinity River Highway 310 Trinity River below Dallas Trinity River Wilmer Trinity River Rosser Trinity River Trinidad

Detections, in percent

0

102030405060708090

100

3-beta-Coprostanol beta-Sitosterol beta-StigmastanolCholesterol d-Limonene Indole Phenol Fluoranthene Pyren

Benzo[a]pyrene 

Compound

Stanols and sterols Personal-use products

and fragrances

Stanols and sterols Personal-use products Disinfectants Polycyclic aromatic hydrocarbons (

and fragrances

Disinfectants Polycyclic aromatic hydrocarbons (

Figure 12. Detection frequencies of stanols and sterols, personal-use products and fragrances, disinfectants, polycyclic aromatic hydrocarbonseven bed-sediment samples collected at study sites on the Trinity River in or near Dallas, Texas, 2009–13.
Summary 41

Concentrations of fluoranthene and pyrene increased with 

distance downstream and were greatest at the Trinity River 

Wilmer site (116 and 112 μg/kg, respectively; Null and 

others, 2019). None of the PAHs was detected at the two most 

downstream sites on the Trinity River.

One of the nine flame retardant and plasticizer 

compounds, bis(2-ethylhexyl) phthalate, was detected in bedsediment samples (fig. 12). The plasticizer compound bis(2-

ethylhexyl) phthalate was detected in one sample collected 

at each of three different sites. The maximum concentration 

of bis(2-ethylhexyl) phthalate (1,030 μg/kg) was detected 

in a sample collected at the most downstream site, Trinity 

River Trinidad (Null and others, 2019). Because of its strong 

hydrophobic characteristics (U.S. Department of Health and 

Human Services, 2002), this compound was not targeted in 

water samples collected at PWTP, WWTP, or Trinity River 

main-stem sites.

Summary

The U.S. Geological Survey, in cooperation with the City 

of Dallas, Dallas Water Utilities, evaluated the occurrence and 

concentrations of selected compounds of emerging concern 

(CECs) in samples collected at potable water treatment 

plants (PWTPs) and wastewater treatment plants (WWTPs) 

in Dallas, and downstream in the Trinity River, Texas, 

from August 2009 to December 2013. CECs are synthetic 

or naturally occurring chemicals that are not commonly 

monitored in the environment but can enter the environment 

and cause known or suspected adverse ecological or human 

health effects. Targeted CECs (120 total) included humanhealth pharmaceuticals (prescription and nonprescription), 

antibiotics, steroidal hormones, stanols, sterols, detergents and 

detergent metabolites (hereinafter referred to as “detergents”), 

personal-use products (flavors and fragrances), pesticides and 

repellents, industrial wastewater compounds, disinfection 

compounds, polycyclic aromatic hydrocarbons (PAHs), flame 

retardants, and plasticizers. Water samples were collected at 

three PWTPs, two WWTPs, and five main-stem sites on the 

Trinity River in and near Dallas. Additionally, bed-sediment 

samples were collected at each of the Trinity River sites. Bedsediment samples were analyzed only for stanols, sterols, and 

organic compounds typically found in domestic and industrial 

wastewater (57 compounds). Quality-control samples 

collected during the study period included equipment blanks, 

replicates, matrix spikes, and surrogates. During the study, 

129 samples were analyzed; of these 129 samples, 105 were 

environmental samples, and 24 were quality-control samples.

Generally, CECs were detected more frequently in 

samples collected at WWTPs than in samples collected at 

PWTPs. Water treatment processes at PWTPs and WWTPs 

were effective at reducing concentrations of most CECs 

to undetectable levels or transforming the compounds into 

degradates that were not analyzed.

At PWTPs, 16 out of 120 targeted CECs were detected. 

Only four compounds were detected in more than 30 percent 

of raw-water samples: sulfamethoxazole (81 percent of 

samples), carbamazepine (71 percent of samples), cholesterol 

(52 percent of samples), and tris(dichloroisopropyl)

phosphate (33 percent of samples). Only two compounds 

were detected in more than 20 percent of finished-water 

samples: tribromomethane (48 percent of samples) and 

tris(dichloroisopropyl)phosphate (33 percent of samples). 

Eleven compounds were detected in raw-water samples 

but were not detected in finished-water samples (that is, 

compounds were removed or degraded to compounds that 

were not analyzed): three human-health pharmaceutical 

compounds (carbamazepine, sulfamethoxazole, and 

caffeine), three steroidal hormones/stanols/sterols (estrone, 

3-beta-coprostanol, and cholesterol), a detergent (4-tertoctylphenol), a flavor/fragrance (hexahydro-hexamethylcyclopenta-benzopyran [HHCB]), an industrial wastewater 

compound (p-cresol), a PAH (pyrene), and a flame retardant/

plasticizer (tributyl phosphate). Only three compounds 

were detected in raw water and finished water, indicating 

that treatment processes likely did not remove or degrade 

these compounds: the industrial wastewater compounds 

benzophenone and methyl salicylate and the flame retardant/

plasticizer tris(dichloroisopropyl)phosphate, which is a 

suspected endocrine disrupting compound. Benzophenone 

and methyl salicylate, however, were detected in only one 

finished-water sample. Tris(dichloroisopropyl)phosphate, a 

persistent plasticizer/flame retardant, was detected at the same 

frequency (33 percent of samples) in raw and finished water. 

Two compounds that were detected in finished water but not 

in raw water were an androgen (4-androstene-3,17-dione) and 

tribromomethane, which is a byproduct of water treatment 

processes.

At WWTPs, 74 of 120 targeted CECs were detected. 

Of these 74 CECs, 73 were detected in untreated-influent 

samples. Thirty-one CECs were detected in all untreatedinfluent samples; however, only 5 CECs were detected in all 

treated-effluent samples: carbamazepine, acetyl-hexamethyltetrahydronaphthalene (AHTN), HHCB, 1,4-dichlorobenzene, 

and tris(dichloroisopropyl)phosphate. Forty-four CECs were 

detected in untreated-influent samples but not in treatedeffluent samples, indicating removal or degradation of 

these compounds. Twenty-nine compounds were detected 

in untreated-influent water and treated-effluent water, 

indicating that treatment processes likely did not remove or 

degrade these compounds, which included carbamazepine, 

sulfamethoxazole, caffeine, anhydroerythromycin, 

azithromycin, trimethoprim, 4-androstene-3,17-dione, 3-betacoprostanol, AHTN, HHCB, benzophenone, tribromomethane, 

triethyl citrate, tributyl phosphate, and tris(dichloroisopropyl)

phosphate. Equilin, an estrogen, was the only compound that 

was detected in treated-effluent water but not in untreatedinfluent water; however, it was detected in only one treatedeffluent sample.
42 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Detection frequencies decreased substantially for 

most groups of CECs between untreated-influent samples 

at WWTPs and treated-effluent samples at WWTPs. 

For example, 11 steroidal hormones were detected in 

untreated-influent water, and, of these, only 3 were 

detected in treated-effluent water, indicating that 73 percent 

of detected compounds in this group were removed or 

degraded by wastewater treatment processes. All detergents 

(five compounds), disinfectants (two compounds), and PAHs 

(five compounds) were removed or degraded. Of the nine 

flavor/fragrance compounds detected in untreated-influent 

water, only two (AHTN and HHCB) were detected in treatedeffluent water, indicating that 78 percent of the detected 

compounds in this group were removed or degraded. Four 

pesticide compounds were detected in untreated-influent 

water, and only one of these (1,4-dichlorobenzene) was 

detected in treated-effluent water, indicating that 75 percent of 

pesticide compounds were removed or degraded. In addition, 

of the six flame retardant/plasticizer compounds detected 

in untreated-influent water, three were detected in treatedeffluent water, indicating a 50-percent removal or degradation 

of these types of compounds.

Wilcoxon signed-rank test results indicated 

concentrations decreased significantly during wastewater 

treatment processes for 22 CECs detected in untreated-influent 

and treated-effluent samples collected at WWTPs (8 humanhealth pharmaceutical and antibiotic compounds, 3 steroidal 

hormones, 2 stanol/sterol compounds, 2 detergent compounds, 

and various CECs from other classes of compounds, 

such as HHCB, N,N-diethyl-m-toluamide (DEET), 

1,4-dichlorobenzene, p-cresol, benzophenone, triethyl 

citrate, and tributyl phosphate. However, concentrations of 

carbamazepine and tribromomethane increased significantly 

between samples types at WWTPs.

Twenty-three CECs were detected in stream-water 

samples collected at the 5 Trinity River main-stem sites. 

Ten of these 23 CECs were detected in samples collected 

at all 5 sites—carbamazepine, sulfamethoxazole, caffeine, 

3-beta-coprostanol, cholesterol, HHCB, benzophenone, 

triethyl citrate, tributyl phosphate, and tris(dichloroisopropyl)

phosphate—indicating their persistence in the environment. 

Median concentrations of nine of these persistent compounds 

decreased between the most upstream main-stem site closest 

to where WWTP effluent is discharged and the farthest 

downstream site on the Trinity River, Trinity River Trinidad. 

The concentration of tributyl phosphate was similar at the 

most upstream and farthest downstream main-stem sites. 

HHCB was the only compound with a statistically significant 

change in concentration; the median concentration of HHCB 

was statistically significantly lower at the most distant mainstem site compared with the median HHCB concentration 

measured at the other four main-stem sites.

Eleven of the 57 targeted compounds were detected in 

bed-sediment samples. Of these 11 compounds, only betasitosterol and cholesterol were detected in bed-sediment 

samples at all 5 study sites on the Trinity River, an indication 

that these 2 compounds were ubiquitous throughout the 

study reach. Nine other CECs were detected in bed-sediment 

samples, including 3-beta-coprostanol (also detected in 

stream-water samples at all five main-stem sites), phenol, 

fluoranthene, pyrene, and bis(2-ethylhexyl) phthalate. 

Concentrations of five CECs in bed-sediment samples were 

highest at the most distant downstream site at which they were 

detected—cholesterol, phenol, fluoranthene, pyrene, and bis(2-

ethylhexyl) phthalate—indicating that these CECs are resistant 

to degradation during downstream transport. Of the 11 CECs 

detected in bed-sediment samples, 9 were not detected in any 

stream-water sample, likely because of the strong hydrophobic 

characteristics of these compounds; cholesterol and 3-betacoprostanol were the exceptions.

Results from water treatment plants indicate that the 

water treatment process is effective at removing or degrading 

most CECs. Water treatment processes, however, are less 

effective for compounds that are engineered to be resistant 

to degradation (for example, flame retardants). Results from 

Trinity River main-stem sites, including bed-sediment data, 

indicate that some compounds are naturally attenuated during 

transport, but a few are persistent throughout the study reach. 

For example, tris(dichloroisopropyl)phosphate, a flame 

retardant and plasticizer, was resistant to water treatment 

processes at PWTPs and WWTPs and was ubiquitous 

in receiving waters of the Trinity River. Many CECs are 

hydrophobic and were only detected in bed sediment, 

indicating multiple pathways through which CECs can persist 

in the environment. CECs in highly urbanized areas could 

negatively affect the health of aquatic organisms; however, 

more research is needed to determine specific effects of CECs 

on aquatic and terrestrial organisms.

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Table 2 47

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Human-health prescription pharmaceuticals (SH2080, except as noted)

Carbamazepine† 62793 298-46-4 0.005 μg/L Anticonvulsant and antimanic (preferred values by 

LCAB).

1, 2, 3

Carbamazepine 62793 298-46-4 0.060 μg/L Anticonvulsant and antimanic. 1, 2, 3

Diltiazem 62008 42399-41-7 0.04 μg/L Antihypertensive. 2, 3

Diphenhydramine 62796 147-24-0 0.036 Antihistamine, antiemetic (anti-nausea), sleep aid, 

and sedative.

1

Sulfamethoxazole 62021 723-46-6 0.1 μg/L Human antibiotic used to treat urinary tract 

infections, often used in combination with 

trimethoprim.

2, 3

Sulfamethoxazole† 62775 723-46-6 0.005 μg/L Human antibiotic used to treat urinary tract 

infections, often used in combination with 

trimethoprim (preferred values by LCAB 

method).

1, 2, 3

Thiabendazole 62801 148-79-8 0.060 μg/L Anthelmintics (used to treat worm infections). 1, 2, 3

Warfarin 62024 81-81-2 0.080–0.100 μg/L Anticoagulant. In large concentrations used as a 

rodenticide for controlling rats and house mice 

in and around homes, animal and agricultural 

premises, and commercial and industrial sites.

1, 2, 3

Human-health nonprescription pharmaceuticals (SH2080, except as noted)

1,7-Dimethylxanthine 

(p-Xanthine) 

62030 611-59-6 0.100–0.120 μg/L Caffeine metabolite. 1, 2, 3

Acetaminophen 62000 103-90-2 0.080–0.120 μg/L Analgesic. 2, 3

Albuterol (Salbutamol) 62020 18559-94-9 0.060–0.080 μg/L Antiasthmatic. 1, 2, 3

Caffeine 50305 58-08-2 0.060–0.200 μg/L Stimulant. 1

Caffeine† 50305 58-08-2 0.060–0.100 μg/L Stimulant (preferred values by SH1433). 1

Codeine 62003 76-57-3 0.040–0.046 μg/L Analgesic. 1, 2, 3

Cotinine 62005 486-56-6 0.4–0.8 μg/L Nicotine metabolite (SH1433). 6

Cotinine† 62005 486-56-6 0.026–0.038 μg/L Nicotine metabolite (preferred values by SH2080). 6

Dehydronifedipine 62004 67035-22-7 0.080–0.160 μg/L Antianginal. 1

Human-health nonprescription pharmaceuticals (LCAB)

Ibuprofen 62014 15687-27-1 0.05 μg/L Nonsteroidal anti-inflammatory drug. 1

Antibiotics - Quinolones (LCAB)

Ciprofloxacin 62898 85721-33-1 0.005 μg/L Broad spectrum antimicrobial agent, treats 

urinary tract infections and gastrointestinal and 

abdominal infections.

2, 3

Enrofloxacin 66495 93106-60-6 0.005 μg/L Used to treat pets and domestic animals. 2, 3

Lomefloxacin 62900 98079-51-7 0.005 μg/L Used to treat bacterial infections, bronchitis, and 

urinary tract infections.

2, 3

Norfloxacin 62757 70458-96-7 0.005 μg/L Chemotherapeutic antibacterial agent, occasionally 

used to treat urinary tract infections.

2, 3

Ofloxacin 62899 82419-36-1 0.005 μg/L Used in eye and ear drops. 2, 3

Sarafloxacin 62771 98105-99-8 0.005 μg/L Used to treat poultry and fish. 2, 3

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Table 2
48 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Antibiotics - Macrolides (LCAB)

Anhydroerythromycin 63674 114–07–8 0.008 μg/L Macrolide antibiotic used in erythromycin 

degradate.

11

Azithromycin 62792 117772-70-0 0.005 μg/L Used to treat bacterial infections, bronchitis, 

pneumonia, sexually transmitted diseases, 

infections in the ears, lungs, sinuses, skin, throat, 

and reproductive organs.

2, 3

Erythromycin 62797 114-07-8 0.008 μg/L Used to treat infections, bronchitis, diptheria, 

Legionnaires disease, pertussis, pneumonia, 

rheumatic fever, venereal disease, ear, intestine, 

lung, and urinary tract infections.

2, 3

Roxithromycin 62895 80214-83-1 0.005 μg/L Used to treat respiratory tract, urinary, and soft 

tissue infections.

2, 3

Tylosin 62896 1401-69-0 0.005 μg/L Bacteriostatic food additive used in veterinary 

medicine.

2, 3

Virginiamycin 62897 11006-76-1 0.005 μg/L Used in the fuel ethanol industry to prevent 

microbial contamination.

2, 3

Antibiotics - Sulfonamides (LCAB)

Sulfathiazole 62778 72-14-0 0.005–0.050 μg/L Oral and topical antimicrobial agent. 2, 3

Sulfachloropyridazine 62774 80-32-0 0.005 μg/L Used to treat acute urinary tract infections in 

pediatric patients.

2, 3

Sulfadiazine 62963 68-35-9 0.005–0.100 μg/L Used to treat urinary tract infections. 2, 3

Sulfadimethoxine 62776 122-11-2 0.005 μg/L Used to treat respiratory, urinary tract, enteric, and 

soft tissue infections.

2, 3

Sulfamethazine 61762 57-68-1 0.005 μg/L Antibiotic commonly added to animal feed (swine 

and poultry) in subtherapeutic doses as growthpromoting agents.

2, 3

Antibiotics - Tetracyclines (LCAB)

4-Epichlortetracycline 

hydrochloride

63731 14297-93-9 0.010 μg/L Degradation product of chlorotetracycline. 2, 3

4-Epioxytetracycline 63729 35259-39-3 0.010 μg/L Degradation product of oxytetracycline. 2, 3

4-Epitetracycline 

hydrochloride

63727 79-85-6 0.010 μg/L Degradation product of oxytetracycline. 2, 3

Chlortetracycline 61744 64-72-2 0.010 μg/L Broad-spectrum antibiotic commonly given to 

poultry, swine, and livestock. May lead to the 

development of antibiotic resistance.

2, 3

Doxycycline 62694 564-25-0 0.010 μg/L Used to treat pneumonia, respiratory tract 

infections, Lyme disease, acne, infections of the 

skin and urinary systems, and anthrax. Also used 

to help prevent malaria.

2, 3

iso-Chlortetracycline 64175 514-53-4 0.010 μg/L Degradation product of tetracycline. 2, 3

epi-iso-Chlortetracycline 64047 N/A 0.010 μg/L Degradation product of chlorotetracycline. 2, 3

Oxytetracycline 61759 6153-64-6 0.010 μg/L Broad-spectrum antibiotic, used to treat infections 

caused by chlamydia, acne, and chronic 

bronchitis.

2, 3

Tetracycline 62781 60-54-8 0.010 μg/L Used to treat urinary tract infections, chlamydia, 

gonorrhea, acne, and chronic bronchitis.

2, 3
Table 2 49

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Antibiotics - other (LCAB)

Chloramphenicol 65194 56-75-7 0.100 μg/L Human antibiotic. 1

Lincomycin 62894 154-21-2 0.005 μg/L Human antibiotic. 11

Ormetoprim 62962 6981-18-6 0.005 μg/L Veterinary antibiotic. 1

Trimethoprim† 62023 738-70-5 0.020–0.034 μg/L Human antibiotic often used in combination with 

sulfamethoxazole (preferred values by SH2080).

1, 2, 3

Trimethoprim 62023 738-70-5 0.005 μg/L Human antibiotic often used in combination with 

sulfamethoxazole.

1, 2, 3

Steroidal hormones, stanols, and sterols (SH2434)

Natural estrogens (SH2434)

17-α-Estradiol 64508 57-91-0 0.0008 μg/L Low occurrence in humans, common in other 

species.

1, 2, 3

17-β-Estradiol 64510 50-28-2 0.0008 μg/L Principal estrogen in humans, strong estrogen. 1

Equilenin 64518 517-09-9 0.002 μg/L Equine estrogen used in hormone replacement 

therapy.

1, 2, 3

Estriol 64520 50-27-1 0.002 μg/L Metabolite of 17-β-Estradiol. 1, 2, 3

Estrone 64521 53-16-7 0.0008 μg/L Metabolite of 17-β-Estradiol. 1, 2, 3

Synthetic estrogens (SH2434)

17-α-Ethynyl estradiol 64509 57-63-6 0.0008 μg/L Used in oral contraceptives, very strong estrogen. 2, 3

Equilin 64519 474-86-2 0.004–0.008 μg/L Equine estrogen used in hormone replacement 

therapy.

1, 2, 3

Mestranol 64522 72-33-3 0.0008 μg/L Used in oral contraceptives, metabolized to 

17-α-ethynyl estradiol prior to excretion.

1, 2, 3

trans-Diethylstilbestrol 64516 56-53-1 0.0008 μg/L Used in pharmaceuticals. 1, 2, 3

Natural androgen (SH2434)

4-Androstene-3,17-dione 64513 63-05-8 0.0008 μg/L Testosterone precursor. 1, 2, 3

cis-Androsterone 64515 53-41-8 0.0008 μg/L Testosterone metabolite, commonly used in deer 

repellent.

1

Epitestosterone 64517 481-30-1 0.002–0.004 μg/L Human androgen. 1, 2, 3

Testosterone 64525 58-22-0 0.0008–0.0016 μg/L Principal human androgen, strong androgen. 1, 2, 3

Synthetic androgen (SH2434)

11-Ketotestosterone 64507 564-35-2 0.002 μg/L Very strong androgen. 1, 2, 3

Dihydrotestosterone 

(DHT)

64524 521-18-6 0.0008 μg/L Also known as Stanolone. Testosterone 

metabolites; very strong androgen.

1, 2, 3

Natural progestin (SH2434)

Progesterone 64523 57-83-0 0.0008–0.0016 μg/L Principal human progestational hormone. 1, 2, 3

Synthetic progestin (SH2434)

Norethindrone 64511 68-22-4 0.0008 μg/L Used in oral contraceptives. 1
50 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Stanols and sterols (animal) (SH2434, except as noted)

3-β-Coprostanol 62057 360-68-9 1.8–2.0 μg/L Animal fecal indicator, useful sewage tracer 

(values by SH1433).

1

3-β-Coprostanol† 64512 360-68-9 0.20–2.0 μg/L Animal fecal indicator, useful sewage tracer 

(preferred values by SH2434).

1, 2, 3

Cholesterol 62072 57-88-5 2.0 μg/L An important structural molecule of animal cell 

membranes, precursor for steroid hormones, bile 

acids, and vitamin D (by SH1433).

1

Cholesterol† 64514 57-88-5 0.20–2.0 μg/L An important structural molecule of animal cell 

membranes, precursor for steroid hormones, 

bile acids, and vitamin D (preferred values by 

SH2434).

2, 3

Stanols and sterols (plant) (SH1433)

β-Stigmastanol 62086 19466-47-8 2.0–2.6 μg/L Herbivore fecal indicator (digestion of sitosterol). 1

β-Sitosterol 62068 83-46-5 4 μg/L Plant sterol. 1

Wastewater compounds (SH1433)

Detergents and detergent metabolites (SH1433)

4-Cumylphenol 62060 599-64-4 0.060–0.100 μg/L Nonionic detergent metabolite. 1

4-n-Octylphenol 62061 1806-26-4 0.06–0.16 μg/L Nonionic detergent metabolite. 1

4-Nonylphenol (sum of 

all isomers)

62085 84852-15-3 2 μg/L Nonionic detergent. 10

4-Nonylphenol 

diethoxylate, (sum of 

all isomers) also known 

as NP2EO 

62083 N/A 5 μg/L Nonionic detergent metabolite; surfactant 

metabolite.

9

4-tert-Octylphenol 62062 140-66-9 0.14–1.40 μg/L Nonionic detergent metabolite. 5

4-tert-Octylphenol 

diethoxylate, (sum of 

all isomers) also known 

as OP2EO 

61705 N/A 1 μg/L Nonionic detergent. 9

4-tert-Octylphenol 

monoethoxylate, (sum 

of all isomers) also 

known as OP1EO 

61706 N/A 1 μg/L Nonionic detergent or metabolite. 9

Personal-use products (flavors and fragrances) (SH1433)

3-Methyl-1H-indole 

(Skatole)

62058 83-34-1 0.036–0.040 μg/L Fragrance, stench in feces and coal tar. 1

Acetophenone 62064 98-86-2 0.4 μg/L Fragrance in detergent and tobacco, flavor in 

beverages.

1

Acetyl-hexamethyltetrahydronaphthalene 

(AHTN) 

62065 21145-77-7 0.028–0.075 μg/L Used in cosmetics (except oral products). 1

Camphor 62070 76-22-2 0.044–0.060 μg/L Flavor, odorant, ointments. 1

d-Limonene 62073 5989-27-5 0.08–0.14 μg/L Fragrance in aerosols, antimicrobial, antiviral, and 

fungicide.

1, 2, 3
Table 2 51

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Personal-use products (flavors and fragrances) (SH1433)—Continued

Hexahydro-hexamethylcyclopenta-benzopyran 

(HHCB) 

62075 1222-05-5 0.052 μg/L Musk fragrance, persistent and widespread, in 

groundwater.

1, 2, 3

Indole 62076 120-72-9 0.08 μg/L Inert pesticide ingredient, fragrance, in coffee. 1, 2, 3

Isoborneol 62077 124-76-5 0.08–0.18 μg/L Fragrance in perfumery, in disinfectants. 1, 2, 3

Isoquinoline 62079 119-65-3 0.046–0.400 μg/L Flavors and fragrances. 1, 2, 3

Menthol 62080 89-78-1 0.32–0.40 μg/L Cigarettes, cough drops, liniment, mouthwash. 1, 2, 3

Pesticides (SH1433)

1,4-Dichlorobenzene 34572 106-46-7 0.04 μg/L Used as an ingredient in urinal cakes, deodorant, 

disinfectant and chemical intermediate in 

addition to uses as a general insecticide, moth 

repellent, fumigant, and germicide.

1

Bromacil 04029 314-40-9 0.36–1.00 μg/L Uracil compound used as a herbicide for brush 

control on noncropland areas. Greater than 

80 percent noncrop usage on grass.

4

Carbaryl 82680 63-25-2 0.16–1.00 μg/L Broad-spectrum carbamate insecticide used to 

control over 100 species of insects on citrus 

trees, fruit trees, nut trees, cotton, vegetables, 

forests, lawns, ornamentals, shade trees, and 

other crops, as well as poultry, livestock, and 

pets.

8

Carbazole 62071 86-74-8 0.030–0.040 μg/L Insecticide, manufacturing of dyes, explosives, and 

lubricants.

2, 3

Chlorpyrifos 38933 2921-88-2 0.12–0.16 μg/L Broad-spectrum, chlorinated organophosphate 

(OP) insecticide, acaricide, and nematicide 

used on grain, cotton, field, fruit, nut, and 

vegetable crops, as well as on lawns, ornamental 

plants, and golf course turf. Also registered for 

direct use on sheep and turkeys, for horse site 

treatment, dog kennels, domestic dwellings, 

farm buildings, storage bins, and commercial 

establishments as well as nonstructural wood 

treatments including processed wood products, 

fenceposts, and utility poles. Can lead to 

neurotoxicity.

2, 3

Diazinon 39572 333-41-5 0.08–0.16 μg/L Nonsystemic organophosphate Restricted Use 

Pesticide (RUP) for professional pest control 

operator use only. Greater than 40 percent 

nonagricultural usage on a wide variety of trees, 

fruit, row crops, and vegetables. No longer used 

on golf courses/sod farms because of die-offs 

of birds that often congregated in these areas. 

Classified as moderately toxic.

1, 2, 3
52 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Pesticides (SH1433)—Continued

Metalaxyl 50359 57837-19-1 0.12 μg/L Systemic benzenoid compound used as a pesticide, 

herbicide, and fungicide. Applied as either a 

foliar spray, soil treatment, or a seed treatment to 

control downy mildews. Used on many different 

food crops, including tobacco, ornamentals, 

conifer, and golf course/turf applications.

1, 2, 3

Metolachlor 39415 51218-45-2 0.028–0.080 μg/L Pre-emergent herbicide used to control certain 

broadleaf and annual grassy weeds in row crops, 

fruit and nut trees, highway rights-of-way and 

woody ornamentals. General-use pesticide that is 

an indicator of agricultural drainage.

1, 2, 3

N,N-diethyl-metatoluamide (DEET) 

62082 134-62-3 0.06 μg/L Insecticide, urban uses, mosquito repellent. 1, 2, 3

Prometon 04037 1610-18-0 0.12–0.20 μg/L Herbicide, noncrop only, applied prior to blacktop. 1, 2, 3

Industrial wastewater compounds (SH1433)

3-tert-Butyl-4-

hydroxyanisole (BHA)

62059 25013-16-5 0.60–8.0 μg/L Used as an antioxidant and preservative in food, 

animal feed, and rubber.

1

5-Methyl-1Hbenzotriazole62063 136-85-6 0.08 μg/L Antioxidant in antifreeze and deicers. 1

Benzophenone 62067 119-61-9 0.08 μg/L Fixative for perfumes and soap. 1

Isophorone 34409 78-59-1 0.032–0.11 μg/L Used as solvent for paints, tin coatings, agricultural 

chemicals, and synthetic resins; excellent 

solvent for vinyl resins, cellulose esters, and 

ethers, pesticides, storing lacquers; pesticide 

manufacturing. Solvent for lacquer, plastic, oil, 

silicon, resin.

1, 2, 3

Isopropylbenzene 62078 98-82-8 0.20–0.30 μg/L Manufacturing phenol/acetone, fuels and paint 

thinner.

1, 2, 3

Methyl salicylate 62081 119-36-8 0.044–0.100 μg/L Liniment, food, beverage, UV-absorbing lotion. 1, 2, 3

p-Cresol 62084 106-44-5 0.08–0.18 μg/L Wood preservative. 1, 2, 3

Tetrachloroethylene 34476 127-18-4 0.12 μg/L Used in dry cleaning of fabrics. 1, 2, 3

Tribromomethane 

(Bromoform)

34288 75-25-2 0.10 μg/L Was used as a solvent, sedative, and flame 

retardant, today mainly used as a laboratory 

reagent.

7

Triethyl citrate (ethyl 

citrate) 

62091 77-93-0 0.16–0.40 μg/L Cosmetics, pharmaceuticals. 1, 2, 3

Disinfection compounds (SH1433)

Phenol 34466 108-95-2 0.16–1.40 μg/L Antiseptic and disinfectant. Used in 

pharmaceuticals, germicidal paints, dyes, 

indicators, slimicide, laboratory reagents; 

phenolic resins; epoxy resins (Bisphenol A 

[BPA]), nylon-6, 2,4-D. Also used as a solvent 

for refining lubricating oils, preparation of acids 

and other compounds.

1, 2, 3

Triclosan 62090 3380-34-5 0.20 μg/L Disinfectants, antimicrobial (concern for aquired 

microbial resistance).

1, 2, 3
Table 2 53

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Polycyclic aromatic hydrocarbons (SH1433)

1-Methylnaphthalene 62054 90-12-0 0.022–0.040 μg/L 2–5 percent of gasoline, diesel fuel, or crude oil. 1

2,6-Dimethylnaphthalene 62055 581-42-0 0.06–0.12 μg/L Present in diesel/kerosene (trace in gasoline). 1

2-Methylnaphthalene 62056 91-57-6 0.036–0.040 μg/L 2–5 percent of gasoline, diesel fuel, and crude oil. 

Used in organic synthesis and insecticides.

1

9,10-Anthraquinone 62066 84-65-1 0.16 μg/L Used to make dyes, used to bleach pulp for paper 

making.

4

Anthracene 34221 120-12-7 0.010–0.040 μg/L Wood preservative, component of coal tar pitch 

volatiles, diesel, or crude oil; used in dyes, 

preparation of phenanthrene, carbazole, 

anthraquinone, and insecticides, organic 

semiconductor research.

1

Benzo[a]pyrene 34248 50-32-8 0.05–0.08 μg/L Regulated PAH and combustion byproduct, 

component of coal tar pitch volatiles, and used 

in cancer research.

4

Fluoranthene 34377 206-44-0 0.024–0.040 μg/L Component of coal tar and asphalt (only traces 

in gasoline or diesel fuels); used as a research 

chemical. Combustion product.

2, 3

Naphthalene 34443 91-20-3 0.040 μg/L PAH also known as ‘camphor tar’ and derived 

from coal tar or crude oil. Used as a fumigant 

and moth repellent, in preparation of pesticides, 

fungicides, dyes, detergents, wetting agents, 

synthetic resins, celluloids, preservatives, and 

lubricants. Major component (about 10 percent) 

of gasoline.

1, 2, 3

Phenanthrene 34462 85-01-8 0.016–0.040 μg/L Used in explosives, dyes, biochemical research, 

synthesis of drugs, and organic synthesis; 

combustion product.

1, 2, 3

Pyrene 34470 129-00-0 0.040–0.042 μg/L Research chemical derived from industrial and 

experimental coal gasification operations. 

Component of coal tar and asphalt (only traces 

in gasoline or diesel fuel).

1, 2, 3

Flame retardants and plasticizers (SH1433)

Bisphenol A (BPA) 67304 80-05-7 0.10–0.20 μg/L Plasticizer. 2, 3

Tributyl phosphate 62089 126-73-8 0.16 μg/L Used as an extractant and a plasticizer. 1, 2, 3

Triphenyl phosphate 62092 115-86-6 0.12 μg/L Plasticizer, resin, wax, finish, roofing paper. 1, 2, 3

Tris(2-butoxyethyl)-

phosphate 

62093 78-51-3 0.8 μg/L Flame retardant. 1, 2, 3

Tris(2-chloroethyl)-

phosphate 

62087 115-96-8 0.10 μg/L Plasticizer, flame retardant. 1, 2, 3

Tris(dichloroisopropyl)-

phosphate 

62088 13674-87-8 0.10–0.16 μg/L Flame retardant. 2, 3
54 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Wastewater compounds in bed sediments (SH5433)

Stanols and sterols (animal) in bed sediments (SH5433)

3-β-Coprostanol 63170 360-68-9 500–2,000 μg/Kg Compound found in human and carnivorous animal 

feces.

1

β-Stigmastanol 63186 19466-47-8 500–1,760 μg/Kg Herbivore fecal indicator (digestion of sitosterol). 1

Cholesterol 63196 57-88-5 250–860 μg/Kg An important structural molecule of animal cell 

membranes, precursor for steroid hormones, bile 

acids, and vitamin D.

1

Sterols (plant) in bed sediments (SH5433)

β-Sitosterol 63185 83-46-5 500–1,060 μg/Kg Plant sterol. 1

Detergents and detergent metabolites (SH5433)

4-Cumylphenol 63173 599-64-4 22–176 μg/Kg Nonionic detergent metabolite. 1

4-n-Octylphenol 63174 1806-26-4 22–176 μg/Kg Nonionic detergent metabolite. 1

4-Nonylphenol (sum of 

all isomers)

63175 84852-15-3 350–2,640 μg/Kg Nonionic detergent. 10

4-Nonylphenol 

diethoxylate (sum of all 

isomers) also known as 

NP2EO 

63200 N/A 400–3,500 μg/Kg Nonionic detergent metabolite; surfactant 

metabolite.

9

4-Nonylphenol 

monoethoxylate (sum 

of isomers)

63221 N/A 220–1,760 μg/Kg Nonionic detergent or metabolite. 5

4-tert-Octylphenol 

diethoxylate

63201 N/A 22–176 μg/Kg Nonionic detergent. 9

4-tert-Octylphenol 

monoethoxylate

63206 N/A 120–880 μg/Kg Nonionic detergent. 9

4-tert-Octylphenol 63176 140-66-9 24–1,760 μg/Kg Nonionic detergent metabolite. 5

Personal-use products (flavors and fragrances) (SH5433)

Acetophenone 63178 98-86-2 70–530 μg/Kg Fragrance in detergent and tobacco, flavor in 

beverages.

1

3-Methyl-1H-indole 

(Skatole) 

63171 83-34-1 36–86 μg/Kg Fragrance, stench in feces, and coal tar. 1

Acetyl-hexamethyltetrahydronaphthalene 

(AHTN) 

63179 21145-77-7 22–171 μg/Kg Used in cosmetics (except oral products). 1

Benzophenone 63184 119-61-9 22–176 μg/Kg Fixative for perfumes and soap. 1

Camphor 63192 76-22-2 22–176 μg/Kg Flavor, odorant, ointments. 1

d-Limonene 63203 5989-27-5 22–176 μg/Kg Fragrance in aerosols, antimicrobials, antivirals, 

and fungicides.

1, 2, 3

Hexahydro-hexamethylcyclopenta-benzopyran 

(HHCB) 

63209 1222-05-5 46–171 μg/Kg Musk fragrance, persistent and widespread, in 

groundwater.

1, 2, 3

Indole 63210 120-72-9 70–170 μg/Kg Inert pesticide ingredient, fragrance, in coffee. 1, 2, 3

Isoborneol 63211 124-76-5 24–176 μg/Kg Fragrance in perfumery, in disinfectants. 1, 2, 3

Isoquinoline 63214 119-65-3 70–350 μg/Kg Flavors and fragrances. 1, 2, 3
Table 2 55

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Pesticides (SH5433)

1,4-Dichlorobenzene 63163 106-46-7 24–176 μg/Kg Used as an ingredient in urinal cakes, deodorant, 

disinfectant and chemical intermediate in 

addition to uses as a general insecticide, moth 

repellent, fumigant, and germicide.

1

Atrazine 63182 1912–24–9 40–350 μg/Kg Selective triazine herbicide. 5

Bromacil 63189 314-40-9 220–1,760 μg/Kg Uracil compound used as a herbicide for brush 

control on noncropland areas. Greater than 

80 percent noncrop usage on grass.

4

Carbazole 63194 86-74-8 63–104 μg/Kg Insecticide, manufacturing of dyes, explosives, and 

lubricants.

2, 3

Chlorpyrifos 63195 2921-88-2 22–176 μg/Kg Broad-spectrum, chlorinated organophosphate 

(OP) insecticide, acaricide, and nematicide 

used on grain, cotton, field, fruit, nut, and 

vegetable crops, as well as on lawns, ornamental 

plants, and golf course turf. Also registered for 

direct use on sheep and turkeys, for horse site 

treatment, dog kennels, domestic dwellings, 

farm buildings, storage bins, and commercial 

establishments as well as nonstructural wood 

treatments including processed wood products, 

fenceposts, and utility poles. Can lead to 

neurotoxicity.

2, 3

Diazinon 63198 333-41-5 22–176 μg/Kg Nonsystemic organophosphate Restricted Use 

Pesticide (RUP) for professional pest control 

operator use only. Greater than 40 percent 

nonagricultural usage on a wide variety of trees, 

fruit, row crops, and vegetables. No longer used 

on golf courses/sod farms because of die-offs 

of birds that often congregated in these areas. 

Classified as moderately toxic.

1, 2, 3

Menthol 63215 57837-19-1 22–176 μg/Kg Cigarettes, cough drops, liniment, mouthwash. 1, 2, 3

Metolachlor 63218 51218-45-2 22–176 μg/Kg Pre-emergent herbicide used to control certain 

broadleaf and annual grassy weeds in row crops, 

fruit and nut trees, highway rights-of-way and 

woody ornamentals. General-use pesticide that is 

an indicator of agricultural drainage.

1, 2, 3

N,N-diethyl-metatoluamide (DEET) 

63219 134-62-3 50–350 μg/Kg Insecticide, urban uses, mosquito repellent. 1, 2, 3

Prometon 63226 1610-18-0 22–176 μg/Kg Herbicide, noncrop only, applied prior to blacktop. 1, 2, 3

Industrial wastewater compounds (SH5433)

3-tert-Butyl-4-

hydroxyanisole (BHA)

63172 25013-16-5 70–510 μg/Kg Used as an antioxidant and preservative in food, 

animal feed, and rubber.

1

Isophorone 63212 78-59-1 22–171 μg/Kg Used as solvent for paints, tin coatings, agricultural 

chemicals, and synthetic resins; excellent 

solvent for vinyl resins, cellulose esters, and 

ethers, pesticides, storing lacquers; pesticide 

manufacturing. Solvent for lacquer, plastic, oil, 

silicon, resin.

1, 2, 3
56 Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Industrial wastewater compounds (SH5433)—Continued

Isopropylbenzene 63213 98-82-8 40–350 μg/Kg Manufacturing phenol/acetone, fuels and paint 

thinner.

1, 2, 3

p-Cresol 63222 106-44-5 180–860 μg/Kg Wood preservative. 1, 2, 3

Disinfection compounds (SH5433)

Phenol 63225 108-95-2 50–313 μg/Kg Antiseptic and disinfectant. Used in 

pharmaceuticals, germicidal paints, dyes, 

indicators, slimicide, laboratory reagents; 

phenolic resins; epoxy resins (Bisphenol A 

[BPA]), nylon-6, 2,4-D. Also used as a solvent 

for refining lubricating oils, preparation of acids 

and other compounds.

1, 2, 3

Triclosan 63232 3380-34-5 50–176 μg/Kg Disinfectants, antimicrobial (concern for aquired 

microbial resistance).

1, 2, 3

Polycyclic aromatic hydrocarbons (SH5433)

1-Methylnaphthalene 63165 90-12-0 24–176 μg/Kg 2–5 percent of gasoline, diesel fuel, or crude oil. 1

2,6-Dimethylnaphthalene 63167 581-42-0 36–90 μg/Kg Present in diesel/kerosene (trace in gasoline). 1

2-Methylnaphthalene 63168 91-57-6 24–176 μg/Kg 2–5 percent of gasoline, diesel fuel, and crude oil. 

Used in organic synthesis and insecticides.

1

9,10-Anthraquinone 63181 84-65-1 34–86 μg/Kg Used to make dyes, used to bleach pulp for paper 

making.

4

Anthracene 63180 120-12-7 32–86 μg/Kg Wood preservative, component of coal tar pitch 

volatiles, diesel, or crude oil; used in dyes, 

preparation of phenanthrene, carbazole, 

anthraquinone, and insecticides, organic 

semiconductor research.

1

Benzo[a]pyrene 63183 50-32-8 32–171 μg/Kg Regulated PAH and combustion byproduct, 

component of coal tar pitch volatiles and used in 

cancer research.

4

Fluoranthene 63208 206-44-0 32–79 μg/Kg Component of coal tar and asphalt (only traces 

in gasoline or diesel fuels); used as a research 

chemical. Combustion product.

2, 3

Naphthalene 63220 91-20-3 24–176 μg/Kg PAH also known as “camphor tar” and derived 

from coal tar or crude oil. Used as a fumigant 

and moth repellent, in preparation of pesticides, 

fungicides, dyes, detergents, wetting agents, 

synthetic resins, celluloids, preservatives, and 

lubricants. Major component (about 10 percent) 

of gasoline.

1, 2, 3

Phenanthrene 63224 85-01-8 41–171 μg/Kg Used in explosives, dyes, biochemical research, 

synthesis of drugs, and organic synthesis; 

combustion product.

1, 2, 3

Pyrene 63227 129-00-0 50–100 μg/Kg Research chemical derived from industrial and 

experimental coal gasification operations. 

Component of coal tar and asphalt (only traces 

in gasoline or diesel fuel).

1, 2, 3
Table 2 57

Table 2. Human-health pharmaceuticals, antibiotics, steroidal hormones, stanols, sterols, and wastewater compounds analyzed in 

water and bed-sediment samples collected at study sites in or near Dallas, Texas, 2009–13.—Continued

[CAS, Chemical Abstracts Service; LRL, laboratory reporting level; USGS, U.S. Geological Survey; SH, USGS National Water Quality Laboratory schedule; 

μg/L, micrograms per liter; LCAB, USGS Organic Geochemistry Research Laboratory liquid chromatography/mass spectrometry antibiotics schedule; N/A, not 

available or not applicable; pct, percent; μg/kg, micrograms per kilogram; α, alpha; β, beta; UV, ultraviolet]

Compounds Parameter 

code

CAS 

number LRL Description and (or) source Reference

Flame retardants and platicizers (SH5433)

2,2’,4,4’-

Tetrabromodiphenyl 

ether

63166 5436-43-1 22–176 μg/Kg Textile and electronic flame retardant. 5

Bis(2-ethylhexyl) 

phthalate

63187 117-81-7 110–860 μg/Kg Plasticizer. 5

Bisphenol A (BPA) 63188 80-05-7 22–176 μg/Kg Plasticizer. 5

Diethyl phthalate 63202 84-66-2 40–350 μg/Kg Plasticizer for polymers and resins. 5

Tributyl phosphate 63231 126-73-8 22–176 μg/Kg Used as an extractant and a plasticizer. 1, 2, 3

Triphenyl phosphate 63234 115-86-6 22–176 μg/Kg Plasticizer, resin, wax, finish roofing paper. 1, 2, 3

Tris(2-butoxyethyl)

phosphate

63229 78-51-3 70–530 μg/Kg Flame retardant. 1, 2, 3

Tris(2-chloroethyl)

phosphate

63230 115-96-8 40–350 μg/Kg Plasticizer, flame retardant. 1, 2, 3

Tris(dichloroisopropyl)

phosphate

63235 13674-87-8 40–350 μg/Kg Flame retardant. 2, 3

†

Constituent preferred concentration determined by schedule as noted in description. 

1

Reif and others, 2012.

2

Foreman and others, 2012.

3

Furlong and others, 2008.

4

Zaugg and others, 2007.

5

Morace, 2012. 

6

Glassmeyer and others, 2005.

7

Bender and others, 1999.

8

Kelly and others, 2012.

9

Jobling and Sumpter, 1993.

10Kolpin and others, 2002.

11Erickson and others, 2014.

For more information about this publication, contact

Director, Oklahoma-Texas Water Science Center

U.S. Geological Survey

1505 Ferguson Lane

Austin, TX 78754–4501 

For additional information, visit

https://www.usgs.gov/centers/tx-water

Publishing support provided by 

Lafayette Publishing Service Center

Churchill and others—Compounds of Emerging Concern Detected in Water and Sediment Samples, Trinity River, Dallas, Texas—Scientific Investigations Report 2019–5019

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20195019