U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5217

Prepared in cooperation with the Michigan Department of Environmental Quality

Antibiotic, Pharmaceutical, and Wastewater-Compound Data 

for Michigan, 1998–2005

Antibiotic, Pharmaceutical, and 

Wastewater-Compound Data for Michigan, 

1998–2005

By Sheridan Kidd Haack

Prepared in cooperation with the Michigan Department of Environmental Quality

Scientific Investigations Report 2009–5217

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2009

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Suggested citation:

Haack, S.K., 2009, Antibiotic, pharmaceutical, and wastewater-compound data for Michigan, 1998–2005: 

U.S. Geological Survey Scientific Investigations Report 2009–5217, 36 p.
iii

Contents

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

Introduction ....................................................................................................................................................1

Purpose And Scope.......................................................................................................................................2

Sampling Procedures....................................................................................................................................2

Analytical Procedures...................................................................................................................................2

Antibiotic Compounds .........................................................................................................................3

Pharmaceutical Compounds...............................................................................................................5

Wastewater Compounds .....................................................................................................................5

Qualitative Identification Criteria and Reporting Levels .......................................................................11

Quality Assurance And Quality Control....................................................................................................12

Antibiotics ............................................................................................................................................12

Pharmaceuticals.................................................................................................................................13

Wastewater Compounds ..................................................................................................................13

Field Blanks.................................................................................................................................13

Replicates....................................................................................................................................13

Patterns Of Emerging Chemical Detections ...........................................................................................16

Antibiotics ............................................................................................................................................16

Pharmaceuticals.................................................................................................................................18

Wastewater Compounds ...................................................................................................................18

Summary........................................................................................................................................................32

References Cited..........................................................................................................................................33

(Appendix A. Antibiotic, Pharmaceutical, and Wastewater Compounds Detected 

in Michigan Waters is available as a separate downloadable Excel file through 

a link on the HTML index page at http://pubs.usgs.gov/sir/2009/5217/)

A–1. Data for antibiotic compounds in filtered water

A–2. Data for pharmaceutical compounds in filtered water

A–3. Data for wastewater compounds in unfiltered water

A–4. Data for wastewater compounds in filtered water

Figures

1. Map showing locations of sampling sites................................................................................3

2–5. Graphs showing:

2. Relation between concentrations of caffeine determined by 

two different methods. .....................................................................................................15

3. Concentrations of veterinary and general use antibiotics at sites where 

antibiotics were detected. ...............................................................................................17

4. Number of detections of wastewater compounds, by chemical category, 

in the River Raisin above and below the city of Adrian, Michigan............................29

5. Number of detections of wastewater compounds, by chemical 

category, in two reaches of the Galien River during low- and 

high-flow conditions..........................................................................................................30
iv

6–7. Maps showing:

6. The Pigeon River and Pinnebog River watersheds in Huron County, 

showing the number of detections of wastewater compounds in four 

chemical categories, by sampling site...........................................................................31

7. Five watersheds in Oakland County, showing the number of detections of 

wastewater compounds in four chemical categories, by sampling site..................32

Tables

1. Names of antibiotic compounds and their current (2009) reporting levels ........................4

2. Names of pharmaceutical compounds, their uses, and their current (2009) 

and 1999 reporting levels. ...........................................................................................................6

3. Names of wastewater-method compounds and their possible 

uses or sources.............................................................................................................................7

4. Names of wastewater-method compounds and their reporting-level 

variations among filtered and unfiltered analyses, over time...............................................9

5. Compounds detected in field and equipment blanks. ........................................................14

6. Concentration of caffeine in samples analyzed by the pesticide-analysis 

method and by the wastewater-analysis method.................................................................15

7. Wastewater compounds detected in unfiltered water samples in order 

of detection frequency...............................................................................................................19

8. Wastewater compounds detected in filtered water samples in order 

of detection frequency...............................................................................................................21

9. Wastewater compounds detected in filtered water, in Michigan, 

grouped by chemical use or typical source...........................................................................23

10. Detections of wastewater compounds in unfiltered water by 

sampling site, sampling date, and chemical category .........................................................24

11. Detections of wastewater compounds in filtered water by 

sampling site, sampling date, and chemical category .........................................................25
v

Conversion Factors and Abbreviated Water-Quality Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

milliliter (mL) 0.03381 ounce, fluid (fl. oz)

microliter ( μL) 1000 milliliter (mL)

micrometer (μm) 1,000,000 centimeter 

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

Abbreviations

AHTN acetyl hexamethyl tetrahydronaphthalene 

APOWCs antibiotics, pharmaceuticals, and organic-wastewater compounds 

CLLE continuous liquid-liquid extraction 

DEET N,N-diethyltoluamide 

GC/MS gas chromatography/mass spectrometry 

HDPE high-density polyethylene 

HHCB hexahydrohexamethylcyclopentabenzopyran 

HPLC/MS high-performance liquid chromatography/mass spectrometry 

LC/MS-ESI(+) liquid chromatography/mass spectrometry positive-ion electrospray 

 analysis 

LRL laboratory reporting level

LT-MDL long-term method detection limit 

MDL method detection limit 

MRL minimum reporting level 

NFM National Field Manual 

NWQL National Water Quality Laboratory 

R2 coefficient of determination 

SIM selected ion monitoring

SPE solid-phase extraction 

USEPA U.S. Environmental Protection Agency 

USGS U.S. Geological Survey 

WWTP wastewater-treatment plant 

Abstract

Beginning in the late 1990’s, the U.S. Geological Survey 

began to develop analytical methods to detect, at concentrations less than 1 microgram per liter (μg/L), emerging water 

contaminants such as pharmaceuticals, personal-care chemicals, and a variety of other chemicals associated with various human and animal sources. During 1998–2005, the U.S. 

Geological Survey analyzed the following Michigan water 

samples: 41 samples for antibiotic compounds, 28 samples for 

pharmaceutical compounds, 46 unfiltered samples for wastewater compounds (dissolved and suspended compounds), and 

113 filtered samples for wastewater compounds (dissolved 

constituents only). The purpose of this report is to summarize the status of emerging contaminants in Michigan waters 

based on data from several different project-specific samplecollection efforts in Michigan during an 8-year period. During 

the course of the 8-year sampling effort, antibiotics were 

determined at 20 surface-water sites and 2 groundwater sites, 

pharmaceuticals were determined at 11 surface-water sites, 

wastewater compounds in unfiltered water were determined at 

31 surface-water sites, and wastewater compounds in filtered 

water were determined at 40 surface-water and 4 groundwater sites. Some sites were visited only once, but others were 

visited multiple times. A variety of quality-assurance samples 

also were collected. This report describes the analytical 

methods used, describes the variations in analytical methods 

and reporting levels during the 8‐year period, and summarizes all data using current (2009) reporting criteria. Very few 

chemicals were detected at concentrations greater than current 

laboratory reporting levels, which currently vary from a low of 

0.005 μg/L for some antibiotics to 5 μg/L for some wastewater 

compounds. Nevertheless, 10 of 51 chemicals in the antibiotics analysis, 9 of 14 chemicals in the pharmaceuticals analysis, 

34 of 67 chemicals in the unfiltered-wastewater analysis, and 

56 of 62 chemicals in the filtered-wastewater analysis were 

detected. Antibiotics were detected at 7 of 20 tested surfacewater sites, but none were detected in 2 groundwater samples. 

Pharmaceuticals were detected at 7 of 11 surface-water sites. 

Wastewater compounds were detected at 25 of 31 sites for 

which unfiltered water samples were analyzed and at least 

once at all 40 surface-water sites and all 4 groundwater sites 

for which filtered water samples were analyzed. 

Overall, the chemicals detected most frequently in 

Michigan waters were similar to those reported frequently 

in other studies nationwide. Patterns of chemical detections 

were site specific and appear to be related to local sources, 

overall land use, and hydrologic conditions at the time of 

sampling. Field-blank results provide important information 

for the design of future sampling programs in Michigan and 

demonstrate the need for careful field-study design. Fieldreplicate results indicated substantial confidence regarding the 

presence or absence of the many chemicals tested. Overall, 

data reported herein indicate that a wide array of antibiotic, 

pharmaceutical, and organic wastewater compounds occur 

in Michigan waters. Patterns of occurrence, with respect to 

hydrologic, land use, and source variables, generally appear to 

be similar for Michigan as for other sampled waters across the 

United States. The data reported herein can serve as a basis for 

future studies in Michigan. 

Introduction 

Manufactured and natural organic compounds such as 

pharmaceuticals, antibiotics, surfactants, flame retardants, 

plasticizers, steroids, and other trace organics that continue 

to be synthesized, used, and disposed of by modern society 

are now widely recognized as environmental contaminants 

(Daughton and Ternes, 1999; Halling-Sørensen, and others, 

2002; Boxall and others, 2003). Detection capabilities for 

antibiotics, pharmaceuticals, and organic wastewater compounds (APOWCs) in the environment continue to be refined, 

and detection levels presently (2009) range from less than 

1 nanogram per liter (ng/L) to a few micrograms per liter 

(μg/L) (Richardson, 2009). Very low detection capability and 

widespread occurrence have led to the documented presence 

of such compounds in water resources around the world. 

These detections have been associated with a variety of human 

and animal sources such as hospitals, septic tanks, wastewater 

effluents from treatment plants, urban runoff, and livestock 

wastes. Human and animal wastewater effluents are among 

the most important source pathways for the majority of these 

compounds into the aquatic environment (Ternes, 1998; 

Boxall and others, 2003; Paxeus, 2004; Glassmeyer and others, 2005; Lindqvist and others, 2005; Miao and others, 2005; 

Antibiotic, Pharmaceutical, and Wastewater-Compound 

Data for Michigan, 1998–2005

By Sheridan Kidd Haack
2 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Conn and others, 2006; Kinney and others, 2006; Reiner and 

others, 2007). Through a variety of environmental-exposure 

pathways, some APOWCs have been found in plant- and 

animal-tissue samples (Guenther and others, 2002; Delépée 

and others, 2004; Kinney and others, 2008; O’Toole and 

Metcalfe, 2006) and also in human-tissue samples (Hutter and 

others, 2005; Kurunthachalam and others, 2005). 

While there is information on the effect some individual 

APOWCs may have on human or ecological health, much 

remains to be learned about the influence of low environmental concentrations of these chemicals, especially when present 

as complex mixtures (Richardson, 2009). In the United States, 

regulatory standards do not exist for the occurrence of most 

of these chemicals in the environment. Sample-collection, 

processing, and analysis methods have only been developed during the past 10 to 15 years, hampering the ability 

to consistently monitor for the presence of these compounds 

on regional or national scales (Focazio and others, 2004). 

Consequently, the occurrence data typically needed by regulators and policymakers to make informed resource-protection 

decisions is only now becoming widely available for many of 

these chemicals. 

Recognizing the need for additional data at regional and 

national scales, the U.S. Geological Survey (USGS) developed 

some of the first analytical methods, continues to develop and 

refine methods for additional compounds, and implemented a 

series of national reconnaissance efforts targeting a broad suite 

of APOWCs with various potential uses and origins (e.g., pesticides, solvents, pharmaceuticals, personal-care products, etc.) 

in an array of environmental and hydrological settings across 

the United States. Some of these samples were collected in 

Michigan (Barnes and others, 2002; Kolpin and others, 2002; 

Focazio and others, 2008; Haack and others, 2009). In addition, the Michigan Department of Environmental Quality has 

supported the collection and analysis, by USGS and USGStrained personnel, of various types of APOWCs in several 

studies described later in this report. This report reviews and 

summarizes all USGS emerging-contaminant data for 

Michigan groundwater and surface water from 1998 to 2005. 

Purpose And Scope

The purpose of this report is to describe the methods and 

results of USGS analyses of APOWCs in Michigan surface 

water and groundwater from 1998 to 2005. From 1998 to 

2005, water samples were collected at 59 surface-water sites 

and 4 groundwater sites (fig. 1), as part of a variety of studies. 

Depending upon study design and purpose, some sites were 

sampled only once; others were sampled multiple times. 

The report summarizes analytical methods and reporting levels 

for antibiotics, pharmaceuticals, and wastewater compounds 

during the 8-year period and summarizes all data using 

current (2009) reporting criteria. The frequency of detection 

of antibiotics, pharmaceuticals, and wastewater compounds, 

and the spatial and temporal patterns of detections of these 

chemicals, are summarized in tables and figures throughout 

this report. Although the data included in this report were 

collected as part of various studies, taken together they 

provide a perspective on the occurrence and distribution of a 

variety of APOWCs in Michigan waters. Their summary here 

provides a basis for future study design and eventual historical 

comparisons.

Sampling Procedures

All water samples were collected by USGS personnel, or 

by USGS-trained personnel, using standard field protocols for 

ultra-clean sampling, preparation, preservation, and transportation to the laboratory. USGS standard sampling methods for 

water samples to be analyzed for the chemicals described in 

this report are documented in the USGS National Field 

Manual (NFM; http://water.usgs.gov/owq/FieldManual/). 

Among other considerations, the sampling methods for wastewater compounds, pharmaceuticals, and antibiotics (Wilde 

and others, 2004) proscribe the use or wearing of any of the 

chemicals to be analyzed; document that only sampling and 

processing equipment made of fluorocarbon polymers, glass, 

aluminum, or stainless steel should be used; specify the types 

of bottles (laboratory baked, brown glass) to be used for sample collection; and provide information on the proper cleaning 

and storing of sampling equipment. Surface-water samples 

were collected using grab-sampling methods, and groundwater samples were collected using standard USGS procedures 

(U.S. Geological Survey, 2006). For filtered water samples, 

standard USGS field-filtration procedures for organic chemicals were used (Wilde and others, 2004). For filtered water 

samples, a whole-water sample aliquot was passed through a 

0.7 micrometer (μm) pore-size, baked, glass-fiber filter in the 

field or office sample-preparatory area. Following collection 

and processing, samples were immediately chilled and shipped 

overnight to the appropriate laboratory. 

Analytical Procedures

Three separate analytical procedures were used to assess 

detections and concentrations of the chemicals described in 

this report. Methods varied during the time covered by this 

report. Early data were provided on a provisional basis, with 

the understanding that method development was an ongoing 

process, and that compounds tested and compound-detection 

limits might change over time. All methods reported herein 

have been routinely evaluated and revised during the past several years as deemed appropriate. These evaluations include 

new information, insights, and focused studies on matrix 

interferences, laboratory and field contamination, and interlaboratory comparisons. Some compounds have been dropped 

from current (2009) versions of methods, owing to poor 

method recovery. Some of these compounds were reported in 

earlier USGS reports and other publications. 
Analytical Procedures 3

Antibiotic Compounds 

Antibiotic compounds and selected antibiotic metabolites analyzed in filtered/unfiltered water samples, as well as 

reporting levels for these compounds, are identified in 

table 1. Antibiotic compounds were analyzed only on filtered 

water samples. Three samples collected in Michigan in 1999 

were analyzed for 21 antibiotic compounds by off-line tandem 

solid-phase extraction (SPE) and single quadrupole, liquid 

chromatography/mass spectrometry positive-ion electrospray 

analysis (LC/MS-ESI(+)) using selected ion monitoring 

(SIM). Additional details on this method are provided elsewhere (Kolpin and others, 2002; Meyer and others, 2007). 

Two samples collected in Michigan in 2001 were analyzed for 

24 antibiotic compounds using an on-line SPE LC/MS-ESI(+) 

method (Meyer and others, 2007). Since 2003, samples collected in Michigan have been analyzed for 39 to 49 antibiotic 

compounds using either the previous method, or an on-line 

SPE LC dual mass spectrometry (SPE LC/MS/MS) method 

modified from the on-line SPE LC/MS-ESI(+) method of 

Meyer and others, 2007.

Figure 1. Map showing locations of sampling sites.
4 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 1. Names of antibiotic compounds and their current (2009) reporting levels.—Continued

[CAS, Chemical Abstract Service; RL, reporting level; NA, not applicable; all values in micrograms per liter]

Name CAS number Current RL

Beta-Lactams

Amoxicillin 26787-78-0 0.01

Ampicillin 69-53-4 .01

Cefotaxime 64485-93-4 .01

Cloxacillin 61-72-3 .01

Oxacillin 7240-38-2 .01

Penicillin G 61-33-6 .01

Penicillin V 87-08-1 .01

Macrolides

Erythromycin 114-07-8 .005

Erythromycin-H2O (Anhydroerythromycin)1 NA .005

Azithromycin 83905-01-5 .005

Roxithromycin 80214-83-1 .005

Tylosin2 1401-69-0 .005

Virginiamycin2 11006-76-1 .005

Quinolones

Ciprofloxacin 85721-33-1 .005

Enrofloxacin2 (no longer analyzed) 93106-60-6

Clinafloxacin 105956-97-6 .005

Flumequine 42835-25-6 .005

Lomefloxacin 98079-51-7 .005

Norfloxacin 70458-96-7 .005

Ofloxacin 83380-47-6 .005

Oxolinic Acid 14698-29-4 .005

Sarafloxacin 98105-99-8 .005

Sulfonamides

Sulfachlorpyridazine2 80-32-0 .005

Sulfadiazine2 68-35-9 .005

Sulfadimethoxine2 122-11-2 .005

Sulfamerazine2 (no longer analyzed) 127-79-7

Sulfamethazine2 57-68-1 .005

Sulfamethizole2 (no longer analyzed) 144-82-1

Sulfamethoxazole 723-46-6 .005

Sulfathiazole2 72-14-0 .005

Tetracyclines

Chlorotetracycline2 57-62-5 .01

Anhydrochlorotetracycline1 13803-65-1 .01

Epi-anhydro-chlorotetracycline1 4497-08-9 .01

Epi-chlorotetracycline1 14297-93-9 .01

Iso-chlorotetracycline1 514-53-4 .01

Epi-iso-chlorotetracycline1 NA .01

Demeclocycline 127-313-0 .01

Doxycycline 564-25-0 .01

Minocycline (no longer analyzed) 10118-90-8
Analytical Procedures 5

Table 1. Names of antibiotic compounds and their current (2009) reporting levels.—Continued

[CAS, Chemical Abstract Service; RL, reporting level; NA, not applicable; all values in micrograms per liter]

Name CAS number Current RL

Oxytetracycline2 79-57-2 0.01

Alpha apo-oxytetracycline1 18695-01-7 .01

Beta apo-oxytetracycline1 18751-99-0 .01

Epi-oxytetracycline1 14206-58-7 .01

Tetracycline 64-75-5 .01

Anhydrotetracycline1 13803-65-1 .01

Epi-anhydro-tetracycline1 4465-65-0 .01

Epi-tetracycline1 23313-80-6 .01

Other

Carbodox2 15630-89-4 .005

Lincomycin2 154-21-2 .005

Ormetoprim2 6981-18-6 .005

Trimethoprim 738-70-5 .005

1

 Degradation product of the parent compound.

2

 Primarily veterinary uses.

Pharmaceutical Compounds

Pharmaceutical compounds and selected pharmaceutical 

metabolites analyzed in filtered/unfiltered water samples, as 

well as reporting levels for these compounds, are identified 

in table 2. In 1999, the Methods Research and Development 

Program of the USGS National Water Quality Laboratory 

(NWQL) began the process of developing a method designed 

to identify and quantify human-health pharmaceuticals in filtered water (Cahill and others, 2004). A variety of compounds 

were evaluated in early methods development, but were 

subsequently dropped from the method for failure to satisfy 

long-term method-performance criteria. These compounds 

are identified in table 2 because previous USGS reports may 

have included data for these compounds. The current method 

identifies 14 compounds (12 pharmaceuticals and metabolites 

plus the antibiotics sulfamethoxazole and trimethoprim) using 

a chemically modified styrene-divinylbenzene resin-based 

SPE cartridge for analyte isolation and concentration and a 

high-performance liquid chromatography/mass spectrometry 

(HPLC/MS) system to separate the pharmaceuticals of interest 

from each other. Immediately following separation, the pharmaceuticals are ionized by electrospray ionization operated in 

the positive mode, and the positive ions produced are detected, 

identified, and quantified using a quadrupole mass spectrometer (Furlong and others, 2008). 

Wastewater Compounds

Wastewater compounds analyzed from 1998 to 2005 are 

identified in table 3. Wastewater compounds were originally 

analyzed on unfiltered water samples, but more recently analyses for both filtered and unfiltered water samples have been 

made available. For water samples filtered in the field, 

disposable, polypropylene SPE cartridges containing a 

polystyrene-divinylbenzene phase are used to extract target 

compounds. Concentrated extracts are analyzed by capillarycolumn gas chromatography/mass spectrometry (GC/MS). 

The SPE method was used at the NWQL as a conditional 

method starting January 1, 2001, and was officially approved 

and implemented at the NWQL on June 27, 2001. Further 

information on this method can be found in Zaugg and 

others (2002). 

A method that uses continuous liquid-liquid extraction 

(CLLE) instead of SPE for sample preparation for unfiltered 

water samples was implemented at the NWQL in October 

1998 on a custom basis. This method was approved for 

unfiltered water samples in June 2006. Further information on 

the method for unfiltered water samples is available in Zaugg 

and others (2006). 

A comparison of results for more than 30 environmental samples between the CLLE and the SPE methods demonstrated that concentrations for hydrophobic (low-water 

solubility) compounds were much less (up to 400 percent) 

when determined by SPE because of sample filtration, whereas 

results for hydrophilic compounds were identical. Therefore, 

detection limits and constituents reported vary between the 

two methods (table 4), and reporting levels for both methods 

have varied over time. Application of the SPE method 

provides data for dissolved wastewater compounds to supplement whole-water CLLE data used to identify wastewater constituents in samples such as sanitary- or storm-sewer waters or 

animal waste. 
6 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 2. Names of pharmaceutical compounds, their uses, and their current (2009) and 1999 reporting levels. 

[CAS, Chemical Abstract Service; RL, reporting level; --, not analyzed; E, concentrations are always qualified as estimated; NA, not available; all values in 

micrograms per liter]

Name CAS number Use Current RL 1999 RL

1,7-Dimethylxanthine 611-59-6 Caffeine metabolite 0.10 0.018

Acetaminophen 103-90-2 Analgesic .08 .009

Caffeine 58-08-2 Stimulant and food component .06 .014

Carbamazepine 298-46-4 Epilepsy treatment .04 --

Cimetidine (no longer analyzed) 51481-61-9 Stomach acid reducer .007

Codeine 76-57-3 Opioid analgesic .04 .024

Cotinine 486-56-6 Degradation product of nicotine .026 .023

Dehydronifedipine 67035-22-7 Metabolite nifedipine, a vasodilator .06 .01

Digoxigenin (no longer analyzed) 1672-46-4 Cardiac regulation .008

Digoxin (no longer analyzed) 20830-75-5 Cardiac regulation .26

Diltiazem 42399-41-7 Angina medication E .04 .012

Diphenhydramine 147-24-0 Allergy relief .05 --

Enalaprilat (no longer analyzed) 76420-72-9 Active metabolite of Enalapril, an 

antihypertensive

.152

Fluoxetine (no longer analyzed) 54910-89-3 Antidepressant .018

Gemfibrozil (no longer analyzed) 25812-30-0 Lipid/cholesterol regulator .015

Ibuprofen (no longer analyzed) 15687-27-1 Analgesic .018

Metformin (no longer analyzed) 657-24-9 Glycemic control .003

Paroxetine metabolite(no longer 

analyzed)

NA Caffeine metabolite .26

Ranitidine (no longer analyzed) 66357-35-5 Stomach acid reducer .01

Albuterol (Salbutamol) 18559-94-9 Bronchodilator .04 .029

Sulfamethoxazole 723-46-6 Antibiotic .10 .023

Thiabendazole 148-79-8 Antibiotic .10 --

Trimethoprim 738-70-5 Antibiotic .04 .014

Warfarin 81-81-2 Anticoagulant for thrombosis and 

pulmonary embolism

E .06 .001
Analytical Procedures 7

Table 3. Names of wastewater-method compounds and their possible uses or sources.—Continued

[CAS, Chemical Abstract Service; NA, not applicable; PAH, polycyclic aromatic hydrocarbon] 

Name Synonym CAS number Possible uses or sources1

1,2-Dichlorobenzene 95-50-1 Wide industrial use

1,3-Dichlorobenzene 541-73-1 Wide industrial use

1,4-Dichlorobenzene 106-46-7 Moth Repellant, fumigant, deodorant

1-Methylnaphthalene 90-12-0 Gasoline, diesel fuel, or crude oil

2 (2-butoxyethoxy) ethyl acetate 124-17-4 Wide industrial use

2,2',4,4'-Tetrabromodiphenyl ether 5436-43-1 Fire retardant manufacture

2,6-Dimethylnaphthalene 581-42-0 Diesel/kerosene (trace in gasoline)

2,6-di-tert-butyl-phenol 128-39-2 Chemical manufacture

2,6-di-tert-p-benzoquinone 719-22-2 Chemical manufacture

2-Methylnaphthalene 91-57-6 Gasoline, diesel fuel or crude oil

3,4-Dichlorophenyl isocyanate 102-36-3 Dye, chemical manufacture

3-Methyl-1(H)-indole Skatole 83-34-1 Fragrance, stench in feces and coal tar

3-tert-Butyl-4-hydroxy anisole BHA 25013-16-5 Antioxidant, general preservative

4-Cumylphenol 599-64-4 Nonionic detergent metabolite

4-n-Octylphenol 1806-26-4 Nonionic detergent metabolite

4-Nonylphenol, total p-Nonylphenol 84852-15-3 Nonionic detergent metabolite

4-Nonylphenol monoethoxylate NP1EO NA Nonionic detergent metabolite

4-Nonylphenol diethoxylate NP2EO NA Nonionic detergent metabolite

4-tert-Octylphenol 140-66-9 Nonionic detergent metabolite

4-tert-Octylphenol diethoxylate OP2EO NA Nonionic detergent metabolite

4-tert-Octylphenol monoethoxylate OP1EO NA Nonionic detergent metabolite

5-Methyl-1H-benzotriazole 136-85-6 Antioxidant in antifreeze and deicers

Acenaphthene 83-32-9 PAH

Acetophenone 98-86-2 Fragrance in detergent and foods

Acetyl hexamethyl tetrahydronaphthalene AHTN 21145-77-7 Musk fragrance

Anthracene 120-12-7 Wood preservative, in tar/crude oil

Anthraquinone 84-65-1 Dye/textiles, bird repellant

Atrazine 1912-24-9 Herbicide

Benzaldehyde 100-52-7 Industrial solvent, flavor

Benzo[a]pyrene Benz[a]pyrene 50-32-8 Regulated PAH

Benzophenone 119-61-9 Fixative for perfumes and soaps

beta-Sitosterol 83-46-5 Plant sterol

beta-Stigmastanol Stigmastanol 19466-47-8 Plant sterol

Bis 2-ethylhexyl adipate 103-23-1 Plasticizer

Bis 2-ethylhexyl phthalate 117-81-7 Plasticizer

Bisphenol A 80-05-7 Polycarbonate resins, antioxidant

Bromacil 314-40-9 Herbicide, noncrop usage

Bromoform Tribromomethane 75-25-2 Ozonation byproduct, explosives

Butylated hydroxy toluene 128-37-0 Antioxidant, food additive

Caffeine 58-08-2 Beverages, diuretic

Camphor 76-22-2 Flavor, odorant, ointments

Carbaryl 63-25-2 Insecticide, crop and garden use

Carbazole 86-74-8 Dyes, explosives and lubricants
8 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 3. Names of wastewater-method compounds and their possible uses or sources.—Continued

[CAS, Chemical Abstract Service; NA, not applicable; PAH, polycyclic aromatic hydrocarbon] 

Name Synonym CAS number Possible uses or sources1

Chlorpyrifos 2921-88-2 Insecticide, termite and pest control 

Cholesterol 57-88-5 Fecal indicator, plant sterol

cis-Chlordane 5103-71-9 Pesticide

Codeine 76-57-3 Human pharmaceutical

3-beta-Coprostanol 360-68-9 Carnivore fecal indicator

Cotinine 486-56-6 Primary nicotine metabolite

Diazinon 333-41-5 Insecticide, ants and flies

Dichlorvos 62-73-7 Insecticide, pets, grains

Dieldrin 60-57-1 Pesticide

Diethyl phthalate 84-66-2 Plasticizer

d-Limonene 5989-27-5 Fungicide, antimicrobial, fragrance

Fluorene 86-73-7 PAH

Fluoranthene 206-44-0 Component of coal tar and asphalt

Hexahydrohexamethylcyclopentabenzopyran HHCB 1222-05-5 Musk fragrance

Indole 120-72-9 Pesticide inert, fragrance in coffee

Isoborneol 124-76-5 Fragrance in perfume

Isophorone 78-59-1 Solvent 

Isopropylbenzene Cumene 98-82-8 Phenol/acetone, fuels and paint thinner

Isoquinoline 119-65-3 Flavors and fragrances

Lindane 58-89-9 Pesticide

Menthol 89-78-1 Flavor in cigarettes, cough drops

Metalaxyl 57837-19-1 Herbicide, fungicide

Methyl parathion 298-00-0 Pesticide

Methyl salicylate 119-36-8 Liniment, food, beverage, sun block

Metolachlor 51218-45-2 Herbicide

N,N-Diethyl-meta-toluamide DEET 134-62-3 Insect repellant

Naphthalene 91-20-3 Fumigant, moth repellent, gasoline

para-Cresol 106-44-5 Wood preservative

Pentachlorophenol 87-86-5 Wood preservative, fungicide

Phenanthrene 85-01-8 Explosives, tar, diesel and crude oil

Phenol 108-95-2 Disinfectant

Phthalic anhydride 85-44-9 Adhesives, resins

Prometon 1610-18-0 Herbicide, noncrop

Pyrene 129-00-0 Component of coal tar and asphalt

Tetrachloroethylene PCE 127-18-4 Solvent, degreaser

Tributyl phosphate 126-73-8 Antifoaming agent, flame retardant

Triclosan 3380-34-5 Disinfectant, antimicrobial

Triethyl citrate Ethyl citrate 77-93-0 Cosmetics and pharmaceuticals

Triphenyl phosphate 115-86-6 Plasticizer, resin wax, roofing paper

Tri(2-butoxyethyl) phosphate 78-51-3 Flame retardant

Tri(2-chloroethyl) phosphate 3380-34-5 Plasticizer, flame retardant

Tri(dichlorisopropyl) phosphate 77-93-0 Flame retardant

1

 From Zaugg and others, 2002.
Analytical Procedures 9

Table 4. Names of wastewater-method compounds and their reporting-level variations among filtered and unfiltered 

analyses, over time.—Continued 

[RL, reporting level; E, concentration is always estimated; all values in micrograms per liter]

Name

Filtered water

current

(2009)

RL

Unfiltered water

Current 

(2009)

RL

1999

RL

2001

RL

1,2-Dichlorobenzene (no longer analyzed) 0.03

1,3-Dichlorobenzene (no longer analyzed) .03

1,4-Dichlorobenzene 0.5 0.2 .03 0.5

17α–ethynyl estradiol (deleted from analysis)

17α–estradiol (deleted from analysis) .5

1-Methylnaphthalene .5 .2 .5

2 (2-butoxyethoxy) ethyl acetate (no longer analyzed) .06

2,2',4,4'-Tetrabromodiphenyl ether .2

2,6-Dimethylnaphthalene .5 .2 .09 .5

2,6-di-tert-butyl-phenol (no longer analyzed) .09

2,6-di-tert-p-benzoquinone (no longer analyzed) .07

2-Methylnaphthalene .5 .2 .5

3,4-Dichlorophenyl isocyanate 2

3-Methyl-1(H)-indole (Skatole) 1 .2 1

3-tert-Butyl-4-hydroxy anisole (BHA) E 5 .2 .12 5

4-Cumylphenol 1 .2 1

4-n-Octylphenol 1 .2 1

4-Nonylphenol (total) (branched) E 5 1.6 .5 5

4-Nonylphenol diethoxylate, (sum of all isomers) E 5 3.2 1.1 5

4-Nonylphenol monoethoxylate, (sum of all isomers) 2 1

4-tert-Octylphenol 1 .2 1

4-tert-Octylphenol diethoxylate E 1 1 .2 1

4-tert-Octylphenol monoethoxylate E 1 .3 .1 1

5-Methyl-1H-benzotriazole 2 1.6 2

Acenaphthene (no longer analyzed) .04

Acetophenone .5 .3 .1 2

Acetyl hexamethyl tetrahydronaphthalene (AHTN) .5 .2 .5

Anthracene .5 .2 .05 .5

Anthraquinone .5 .2 .5

Atrazine .2

Benzaldehyde (no longer analyzed) .10

Benzo[a]pyrene 0.5 .2 .05 .5

Benzophenone .5 .2 .5

beta–Sitosterol E 2 .8 2

beta–Stigmastanol E 2 .8 2

Bis 2-ethylhexyl adipate (no longer analyzed) 1.5

Bis 2-ethylhexyl phthalate 2 2

Bisphenol A 1 .4 .09 1

Bromacil .5 .2 .5

Bromoform E .5 .2
10 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 4. Names of wastewater-method compounds and their reporting-level variations among filtered and unfiltered 

analyses, over time.—Continued 

[RL, reporting level; E, concentration is always estimated; all values in micrograms per liter]

Name

Filtered water

current

(2009)

RL

Unfiltered water

Current 

(2009)

RL

1999

RL

2001

RL

Butylated hydroxy toluene (no longer analyzed) .08

Caffeine .5 .2 .08 .01

Camphor .5 .2 .5

Carbaryl E 1 .2 .06 1

Carbazole .5 .2

Chlorpyrifos .5 .2 .02 .5

Cholesterol E 2 .8 1.5 2

cis-Chlordane (no longer analyzed) .04

Codeine (no longer analyzed) .1

3-beta-Coprostanol E 2 .8 .6 2

Cotinine 1 .8

Diazinon .5 .2 .03 .5

Dichlorvos (deleted from filtered water analysis) .2 1

Dieldrin (no longer analyzed) .08

Diethyl phthalate .2

d-Limonene E .5 .2 .5

Equilenin (deleted from analysis)

Estrone (deleted from analysis)

Fluoranthene .5 .2 .03 .5

Fluorene (no longer analyzed)

Hexahydrohexamethylcyclopentabenzopyran (HHCB) .5 .2 .5

Indole .5 .2 .5

Isoborneol .5 .2 .5

Isophorone .5 .2 .5

Isopropylbenzene E .5 .2 .5

Isoquinoline .5 .2 .5

Lindane (no longer analyzed) .05

Menthol .5 .2 .05 .5

Metalaxyl .5 .2 .5

Methyl parathion (no longer analyzed) .06

Methyl salicylate .5 .2 .5

Metolachlor .5 .2 .5

N,N-diethyl-meta-toluamide (DEET) .5 .2 .5

Naphthalene .5 .2 .03 .5

para-Cresol 1 .2 .03 1

Pentachlorophenol E 2 .8 2

Phenanthrene .5 .2 .06 .5

Phenol .5 .2 .08 2

Phthalic anhydride (no longer analyzed) .15

Prometon .5 .2
Qualitative Identification Criteria and Reporting Levels 11

Qualitative Identification Criteria and 

Reporting Levels

The three analytical methods used in this report share a 

common rationale for compound identification and quantification, despite differences in specific analytical details. All rely 

on the application of mass-spectrometric techniques, which 

provides compound-specific fragments that, when coupled 

with chromatographic-retention characteristics, produce 

unambiguous identification of each compound. In addition, 

the specific criteria for the identification of each compound are 

based upon analysis of authentic standards for all compounds 

(Zaugg and others, 2006; Meyer and others, 2007: Furlong and 

others, 2008). 

For antibiotic compounds, analyzed at the USGS Organic 

Research Laboratory in Lawrence, Kansas, only concentrations equal to or above the minimum reporting level (MRL) 

for each compound are reported. Reporting levels for antibiotic compounds for each method are equal to the limit of 

quantitation (signal-to-noise ratios of 5 to 10 times above 

background) for the method. In this report, all concentrations of antibiotic compounds are reported using the reporting 

criteria appropriate at the time, since the method of determining antibiotic reporting levels has not changed. However, the 

use of different analytical methods for the same compounds 

has resulted in varying compound-reporting levels from 1998 

to 2008. The most recent analytical method offers the lowest 

reporting levels (0.005–0.01 μg/L; table 1); previous reporting 

levels ranged from 0.05 to 0.10 μg/L for analytical methods 

used through 2003. 

Wastewater and pharmaceutical compounds were 

analyzed at the USGS NWQL. Historically, the NWQL used 

MRLs when reporting data. For wastewater compounds, initial 

MRLs were set higher (two to five times for most compounds) 

than initial method detection limits (MDLs) calculated according to the then-current U.S. Environmental Protection Agency 

(USEPA) protocol, (U.S. Environmental Protection Agency 

1997). For pharmaceutical compounds, MDLs were likewise 

calculated using USEPA procedures (U.S. Environmental 

Protection Agency, 1997, 2005). 

The NWQL currently (2009) uses a statistic called the 

long-term method detection limit (LT-MDL; Bonn, 2008), 

which is similar to the current (2009) USEPA MDL 

(U.S. Environmental Protection Agency, 2005), and is determined on an annual basis for each compound. The LT-MDL 

is statistically defined as identical to the USEPA-MDL: the 

smallest measured concentration that can be reported with 

99-percent confidence that the concentration of the compound 

is greater than zero, and there is less than a 1-percent chance 

of a false-positive determination. Like the USEPA-MDL, it 

is obtained from replicate analyses of spiked blank water; 

therefore, it applies to uncomplicated samples. It differs from 

the USEPA-MDL in that it incorporates variability owing to 

different instruments and analysts and is calculated over an 

extended period of time. This means that MDLs, and MRLs 

calculated from MDLs, may change over time. 

In conjunction with the LT-MDL, NWQL currently 

(2009) uses a laboratory reporting level (LRL) that replaces 

the MRL. Similar to the MRL, the LRL is set higher than the 

LT-MDL. Further, LRLs may change over time if LT-MDLs 

are revised after annual reviews. 

Table 4. Names of wastewater-method compounds and their reporting-level variations among filtered and unfiltered 

analyses, over time.—Continued 

[RL, reporting level; E, concentration is always estimated; all values in micrograms per liter]

Name

Filtered water

current

(2009)

RL

Unfiltered water

Current 

(2009)

RL

1999

RL

2001

RL

Pyrene .5 .2 .03 .5

Tetrachloroethylene E .5 .4 .03 .5

Tributyl phosphate .5 .2 .5

Triclosan 1 .2 .04 1

Triethyl citrate (ethyl citrate) .5 .2 .5

Triphenyl phosphate .5 .2 .1 .5

Tris(2-butoxyethyl)phosphate E .5 .2

Tris(2-chloroethyl)phosphate .5 .2 .04 .5

Tris(dichlorisopropyl)phosphate .5 .2 .1 .5
12 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Currently (2009), the NWQL reports without qualification most analytical results greater than the LT-MDL (Bonn, 

2008). These results can be considered detected (different 

from zero with 99‐percent confidence) if the sample matrix 

has no interfering properties. Historically and currently 

(2009), if no LT-MDL (and associated LRL) has been established, the NWQL reports without qualification all analytical 

results greater than the MRL. Analytical results less than the 

LT-MDL, or MRL prior to conversion to the LT-MDL, are 

reported with qualification if the analytical method includes 

compound-specific identification—usually a matching spectral 

signature—such as for the compounds discussed in this report. 

Results less than the LT-MDL or historically, the MRL, are 

reported with a qualifying E (estimated) or M (detected but 

not quantified) code. The E code signifies that the reported 

compound concentration has greater relative uncertainty than 

if the concentration exceeded the LT-MDL or MRL. Results 

less than the LT-MDL or MRL that can be rounded to zero at 

the order of magnitude reported for a given constituent are 

reported with an M code. For example, a concentration of 

0.04 μg/L would receive an M code for a constituent for which 

the LT-MDL or MRL is 0.1 μg/L or an E code for a constituent for which the LT-MDL or MRL is 0.06 μg/L, but would 

receive no qualification for a constituent for which the LTMDL or MRL is 0.01 μg/L. Compounds that are not detected 

are reported as less than the LRL. Concentrations of some 

compounds are always reported as estimated owing to variable 

performance. Pharmaceutical and wastewater compounds for 

which estimated concentrations are always reported are 

indicated in tables 2 and 4. 

Reporting levels for many compounds changed during 1998–2008. In addition, some compounds either were 

removed or added to analysis suites during 1998–2008. 

Tables 2 and 4 show that some previous pharmaceutical and 

wastewater-compound reporting levels were lower than current (2009) levels. Concentrations lower than those currently 

considered reliable for these methods may have been reported 

previously in USGS and other publications. In this report, 

previously reported concentrations less than current (2009) 

reporting levels have been recensored using current reporting 

criteria to provide consistent information. In addition, data for 

compounds removed from analytical methods are not included 

in this report, even though data for such compounds may have 

appeared in previous USGS or other publications.

Quality Assurance And Quality Control

Several quality-control sample types are required to 

properly interpret ambient environmental concentrations of 

pharmaceutical, antibiotic and wastewater compounds in 

aqueous samples. The quality-control sample types include 

field blanks, replicate environmental samples, and matrixspike recovery samples. Matrix-spike materials were not 

generally available prior to 2005; no matrix-spike samples 

were analyzed. 

Field blanks characterize the likelihood of positive bias 

or contamination owing to field and laboratory handling. Field 

blanks consisted of laboratory-grade organic-free water that 

was processed in the field and laboratory in the same manner as environmental samples. Field blanks were submitted 

for about 2 percent (1 for 41 environmental samples) of the 

samples analyzed for antibiotics, 10 percent (3 for 28 environmental samples) of the samples analyzed for pharmaceuticals, 

and 10 percent (12 for 113 environmental samples) of the 

filtered water samples analyzed for wastewater compounds. 

However, no field blanks were collected for the 46 unfiltered 

environmental samples analyzed for wastewater constituents. 

Teflon is the recommended composition of containers for 

collection of APOWC samples. High-density polyethylene 

(HDPE) is a common container composition for collection of 

many other types of water samples. To determine the effect 

of container composition on wastewater analytes, one field 

blank was collected in a high-density polyethylene (HDPE) 

container (HDPE Blank, table A4), whereas all other field 

blanks were collected in Teflon containers. One equipment 

blank (Filter Blank, table A4) was collected in the following manner. Organic-free water was spiked with an artificial 

sample of wastewater compounds at known concentrations. In 

the laboratory, this spiked water was passed through the filtration apparatus as though it was a routine sample. The filtration 

apparatus was then cleaned according to established protocols, 

and a subsequent “sample” of organic-free water was processed through the filter. This sample was sent for analysis for 

the purpose of establishing that the cleaning 

procedure adequately removed any contamination. 

Replicate samples are used to characterize the amount 

of variability associated with sample collection, processing, 

and analysis. Replicate field samples were collected once for 

antibiotic compounds, twice for pharmaceutical compounds, 

and nine times for wastewater compounds. Replicate samples 

identify the variation that may be associated with compound 

concentrations, owing to any step of sample collection or 

analysis. 

Antibiotics

Results of antibiotic analyses for 41 environmental 

samples and 1 field blank are reported in table A1. No 

antibiotics were detected in the field blank sample. On 

August 9, 2006, a field replicate was collected at the Clinton 

River at Auburn Hills, Mich. Five antibiotics were detected in 

the primary environmental sample, but one additional antibiotic—azithromycin—was detected in the replicate sample. 

Otherwise, there was agreement regarding detection of the 

five antibiotics common to both samples. The pharmaceuticals 

method also was performed on three of these environmental 

samples (Boardman River at Traverse City, June 16, 1999; 

Huron River near Ann Arbor, September 10, 2001; and River 

Raisin near Deerfield, September 11, 2001). Therefore, results 

for the two antibiotics (sulfamethoxazole and trimethoprim) 
Quality Assurance And Quality Control 13

analyzed by the pharmaceuticals method can be compared 

with results from the antibiotics method. Sulfamethoxazole 

was not reported for any of these samples by either method. 

Trimethoprim was reported for the Boardman River sample by 

the pharmaceuticals method but not by the antibiotics method. 

This result likely reflects the lower reporting limit for the pharmaceuticals method for this compound. 

Pharmaceuticals

Results of pharmaceutical analyses for 28 environmental samples and 3 field blanks are reported in table A2. No 

pharmaceuticals were detected in any field-blank sample. 

Two field-replicate samples were collected. Only caffeine was 

detected in both the primary environmental sample and the 

associated replicate sample collected on June 15, 2004. For 

the field-replicate sample collected on November 17, 2004, 

carbamazepine and cotinine were detected in both the primary 

environmental sample and the associated replicate sample. 

For three additional samples, laboratory-replicate analyses 

were provided. These replicates exhibited general agreement 

among the primary environmental samples and the associated 

replicate samples regarding compounds detected and concentrations estimated. 

Wastewater Compounds 

The range of compound groups in the wastewater method 

includes potential contaminant sources from chemicals commonly used by field and laboratory personnel in their personal 

as well as professional lives and from the equipment used to 

collect, process, and analyze the samples. Unlike antibiotics 

and pharmaceuticals, several wastewater compounds were 

detected in field blanks. In addition, some wastewater-chemical results were inconsistent among primary environmental 

samples and associated replicate samples. The quality-assurance data for wastewater compounds must be carefully taken 

into account in interpretation of wastewater-chemical occurrence and concentration. Results of wastewater-compound 

analyses for 46 unfiltered water samples are reported in table 

A3 and results for 113 filtered water samples are reported in 

table A4. 

Field Blanks

Although some wastewater compounds were detected 

in field blanks, the majority of the wastewater compounds 

analyzed were not detected in any field blank in this study. 

Table 5 lists all of the wastewater compounds detected in field 

and equipment blanks analyzed in this study. Many of the 

constituents detected in blanks are the same as those detected 

in more than 5 percent of USGS field blanks from across the 

country (Zaugg and Leiker, 2006; table 5). The USGS NWQL 

considers occurrence of compounds in 10 percent or more 

field blanks to be evidence of chronic contamination. Since 

only 13 field and equipment blanks were collected, detection 

of a compound in even 1 blank results in an occurrence level 

near 10 percent; therefore, occurrence results for the compounds in environmental samples, shown in table 5, should be 

viewed with caution. However, there were some differences in 

the probable significance of these compounds as revealed by 

comparing detection frequencies for the compounds in blanks, 

overall environmental samples, and paired environmental 

samples. Paired environmental samples were those samples 

collected on the same date as the field blank and immediately 

preceding or following blank processing. Some of the compounds reported in table 5 occurred in blanks and overall environmental samples with similar frequencies and at equivalent 

concentrations. For example, 1,4-dichlorobenzene occurred 

in the majority of blanks, overall environmental samples, and 

paired environmental samples. Phenol contamination also was 

prevalent. Data for these two constituents indicate pervasive 

contamination at some sample-processing step. However, 

caffeine was detected in only one field blank at an unquantifiable concentration and was never detected in a paired environmental sample, but was present in approximately one-half of 

environmental samples and occasionally at reliably quantified 

concentrations. Caffeine occurrence in blanks may be reflective of random contamination. 

Only two constituents—the ubiquitous field-blank contaminants 1,4-dichlorobenzene and phenol—were detected in 

the equipment blank that was processed using Teflon, glass, 

and stainless-steel containers (Filter Blank, table A4). Other 

than the HDPE Field Blank (HDPE Field Blank, table A4), all 

other field blanks were collected in Teflon containers. Nine 

wastewater constituents were detected in the blank processed in the HDPE container; however, 11 constituents were 

detected in a Field Blank collected on October 28, 2004, and 

8 constituents were detected in 2 additional Field Blanks 

(June 15, 2004 and November 22, 2005). The constituents 

detected in the HDPE Field Blank also were detected in other 

(Teflon container) field blanks. These results do not indicate 

any particular contamination effect arising from use of HDPE 

plastic as opposed to Teflon containers. 

Replicates

Nine replicate pairs of samples were analyzed for 62 

wastewater compounds (table A4). These 9 replicate analyses 

produced 531 consistent results, which indicated the compound was either absent or present in both replicates. There 

were 92 samples for which a given compound was reported as 

present in both the primary sample and the replicate. For 88 

of these instances, the indicated concentration was either M or 

the identical estimated value in both samples. In the remaining 

4 instances, there were two cases where one sample had an 

estimated value and the other was coded “M,” and there were 

two cases where two different estimated values were given. 

In the latter two cases, the estimated values were different by 

only 0.1 μg/L. These results indicate substantial agreement 

between replicate samples; however, there were 27 instances 
14 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

in which replicate analyses did not report the same result for 

a compound. For 26 of these instances, the compound was 

reported as not being present (concentration less than the 

reporting level) in one sample, but present with either an M or 

E qualifier in the replicate sample. For the remaining sample 

pair, phenol was reported as <0.5 μg/L in one sample, but 

present at 0.6 μg/L in the replicate sample. Five compounds 

reported in blanks (acetophenone, benzophenone, caffeine, phenol, and tributyl phosphate) accounted for 9 of the 

25 inconsistent replicate-pair results, leaving 16 inconsistent 

results for compounds that did not occur in field blanks. 

Discrepancies in results for a primary sample and its 

replicate may arise when concentrations are near the LT-MDL. 

Data for caffeine shed some light on how to interpret replicate 

analyses in which one replicate sample indicates a compound 

was not detected, and the other indicates a very low, usually 

estimated concentration of the constituent. There were 

18 environmental samples for which caffeine was analyzed 

by two different methods: the wastewater method and a 

pesticide method providing concentration data for caffeine at 

reporting levels approximately 10 times lower than those of 

the wastewater method. Data for these 18 samples are shown 

in table 6 and figure 2. Of seven samples in which caffeine 

was not detected by the wastewater method, five also indicated no detection by the pesticide method; however, in the 

remaining two samples, caffeine was indeed present at the 

lower concentration detectable by the pesticide method. In 

addition, for the 10 samples in which caffeine was detected by 

the wastewater method, it also was detected by the pesticide 

method. For cases where caffeine was detected by both methods, estimated values obtained by the wastewater method were 

approximately double those obtained by the pesticide method 

(table 6, fig. 2). The coefficient of determination (R2

) for these 

paired values was 0.78. Generally, the higher the concentraTable 5. Compounds detected in field and equipment blanks. 

[μg/L, micrograms per liter; NA, not applicable; E, concentrations are estimated; M, detected but not quantified]

Compound

Number 

of blank 

samples

Detection in 

blanks

(percent)

Detection in 

overall 

environmental 

samples 

(percent)

Detection 

in paireda

samples 

(percent)

Highest 

concentration 

in blanks

(μg/L)

Highest 

concentration 

in samples

(μg/L)

Antibiotics 1 0 variable NA NA variable

Parmaceuticals 3 0 variable NA NA variable

Wastewater compounds

1,4-Dichlorobenzeneb 13 92 72 82 E 0.1 E 0.3

1-Methylnaphthalene 13 23 34 18 M E .1

2-Methylnaphthalene 13 23 38 18 E .1 E .1

Acetophenone 13 8 10 0 E .4 E .2

Benzophenone 13 23 52 9 E .1 E .3

Bisphenol A 9 11 19 0 M M

Caffeine 13 8 52 0 M .7

Isophorone 13 31 42 9 M 3.1

Menthol 13 15 23 9 M E .2

N,N-diethyl-meta-toluamide (DEET) 13 31 69 18 E .1 E .3

Naphthalene 13 31 36 9 E .4 E .1

Nonylphenol diethoxylate 13 8 23 0 E 8 E 8

para-Nonylphenol (total) 13 8 19 0 M E 2

Phenanthrene 13 8 26 9 M M

Phenol 13 54 39 45 1.2 1.6

Tributyl phosphate 13 15 34 9 E .1 E .2

Triphenyl phosphate 13 15 32 9 E .1 E .1

Tris(2-chloroethyl)phosphate 13 15 30 9 E .1 E .1

Tris(dichlorisopropyl)phosphate 13 8 23 0 E .1 E .2

a

Compound occurred in field blank and in environmental sample collected immediately before or after processing of the field blank. 

b

Constituents in bold reported in more than 5 percent of field blanks nationwide since August 2004 (Zaugg and Leiker, 2006).
Quality Assurance And Quality Control 15

0.6

0.0

0.1

0.2

0.3

0.4

0.5

0.00 0.05 0.10 0.15 0.20 0.25 0.30

CONCENTRATION OF CAFFEINE DETECTED BY

WASTEWATER METHOD (MICROGRAMS PER LITER)

CONCENTRATION OF CAFFEINE DETECTED BY PESTICIDE METHOD 

(MICROGRAMS PER LITER)

Only detected by pesticide method (3 points)

Detected by both methods

Not detected by either method (5 points)

Figure 2. Graph showing relation between 

concentrations of caffeine determined by 

two different methods. 

Table 6. Concentration of caffeine in samples analyzed by the pesticide-analysis method and by the wastewater-analysis method.

[μg/L, micrograms per liter; MI, Michigan; <, less than; E, estimated]

Site Sampling date

Concentration of caffeine 

by pesticide-analysis 

method

 (μg/L)

Concentration of caffeine 

by wastewater-analysis 

method

 (μg/L)

Pigeon River at Maxwell Road near Rescue, MI 5/17/2004 < 0.010 < 0.5

Pigeon River at Maxwell Road near Rescue, MI 8/25/2004 .017 E .1

Pigeon River near Pigeon, MI 5/17/2004 .023 E .1

Pigeon River near Pigeon, MI 8/25/2004 .022 < .5

Pigeon River near Caseville, MI 5/17/2004 .028 E .1

Pigeon River near Caseville, MI 8/25/2004 .023 < .5

Pinnebog River at Limerick Rd near Pinnebog, MI 5/20/2004 .017 E .1

Pinnebog River at Limerick Rd near Pinnebog, MI 8/26/2004 .031 E .1

Pinnebog River near Port Crescent, MI 5/20/2004 .047 E .11

Pinnebog River near Port Crescent, MI 8/26/2004 .019 < .5

Pigeon River at Caseville, MI 5/20/2004 .091 E .2

Pigeon River at Caseville, MI 8/26/2004 .278 E .2

Pinnebog River at Moore Road near Elkton, MI 5/17/2004 .027 E .1

Pinnebog River at Moore Road near Elkton, MI 8/25/2004 < .014 < .5

Pinnebog River at Richardson Road near Elkton, MI 5/17/2004 .023 E .1

Pinnebog River at Richardson Road near Elkton, MI 8/25/2004 < .019 < .5

16N 11E 13Aadd01 Huron County (Oliver Twp H-14) 8/26/2004 < .010 < .5

17N 11E 16Dddd Huron County (Chandler Twp H-20) 8/27/2004 < .010 < .5
16 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

tion determined by both methods, the greater the agreement 

between the two values. These results indicate two considerations for interpretation of detections and concentrations near 

the limits of detection for the wastewater method. First, even 

though a compound is reported as not detected, it may indeed 

be present. Second, when the compound is reported with an 

estimated concentration, there is confidence that it is indeed 

present in the sample, but more uncertainty regarding the 

actual concentration (as indicated by the E code). Based on 

these considerations, and assuming other compounds behave 

as caffeine, compounds detected by the wastewater method in 

either a primary environmental sample or an associated replicate, but not both, should be considered present in the sample.

In general, field-blank samples indicate that some wastewater compounds, but no pharmaceuticals or antibiotics, may 

be present owing to contamination of sampling equipment or 

ambient environmental contamination. Field-blank results provide important information for the design of future sampling 

programs and may demonstrate the ubiquitous nature of some 

organic wastewater compounds. Field-replicate results indicate 

substantial confidence regarding the presence or absence of the 

many chemicals tested. 

Patterns Of Emerging Chemical 

Detections 

Among the factors known to affect AOPWC occurrence 

in water at any sampling time are type, proximity, and intensity of source; environmental degradation or dilution of the 

chemical; and hydrologic variables. Each of these factors may 

have affected patterns of chemical detections reported herein. 

Land use may affect the types and concentrations of chemicals 

detected (Barber and others, 2006). For wastewater-treatmentplant (WWTP) effluents, detections of wastewater chemicals 

and pharmaceuticals become more frequent and concentrations 

become greater with increasing size of population served 

(Kolpin and others, 2004; Spongberg and Witter, 2008). Therefore, the occurrence of a WWTP effluent above a sampling 

point has a profound effect on the number and concentration 

of chemicals detected (Kolpin and others, 2004; Glassmeyer 

and others, 2005; Barber and others, 2006). The effect of 

WWTP effluents is modified by proximity to the sampling 

point and by the degree to which river flow dilutes the effluent 

(Kolpin and others, 2004). Since river flow varies throughout 

the year, chemical detections also may exhibit seasonal variability. In rural settings, septic systems and agricultural practices (including manure or biosolids application) may affect 

chemical detections. Detections of antibiotics or pharmaceuticals (both human and veterinary) will be affected by use in the 

population and by transport pathways, such as rainfall runoff. 

Therefore, variability in chemical detections and concentrations might be expected. Antibiotics, pharmaceuticals, and 

wastewater compounds were detected in Michigan at locations and times generally consistent with probable sources and 

hydrologic conditions. 

Antibiotics

Ten of the 51 antibiotics analyzed were detected at least 

once. No beta-lactam or tetracycline antibiotics were detected 

in any sample. The beta-lactam antibiotics degrade rapidly 

under environmental conditions and are rarely detected in 

environmental samples (Zuccato and others, 2004). The 

tetracycline antibiotics exhibit a high affinity for calciumcontaining minerals and bind readily to solids in the environment (Hamscher and others, 2004); therefore, the lack of 

detection of such compounds is reasonable. In a recent study 

of untreated surface-water and groundwater drinking-water 

sources, Focazio and others (2008) reported erythromycinH2

O, trimethoprim, and enrofloxacin to be the most frequently 

detected antibiotics. Only four additional antibiotics were 

detected at all: azithromycin, ciprofloxacin, sarafloxacin, and 

sulfamethoxazole. Similarly, in a study of low-flow samples at 

selected Iowa streams, the most frequently detected antibiotics were sulfamethoxazole (20 percent), trimethoprim (16.7 

percent), and erythromycin-H2O (10 percent). Antibioticdetection frequencies for Michigan are similar, as shown in 

figure 3. 

No antibiotics were detected in two groundwater samples. 

Antibiotics were detected at 7 of 20 tested surface-water sites. 

Antibiotics used only for veterinary purposes were detected 

at two locations: Pinnebog River in Huron County, and Paint 

Creek near Rochester in Oakland County (fig. 3). These sites 

are characterized by rural settings, where animals may be 

prevalent in the watershed. Even the Paint Creek watershed, 

although located in a generally urban county, has only 

11 percent residential and commercial land use and greater 

than 35 percent agricultural land use above the sampling point. 

All detections were at very low concentrations and occurred in 

August, when discharge in Michigan rivers is generally low. 

Kolpin and others (2004) reported that for selected streams in 

Iowa, antibiotics and other prescription drugs were frequently 

detected only during low-flow conditions. Therefore, one 

possible reason for the lack of detections at other times of the 

year may be dilution of a small local source by greater river 

discharge.

General-use antibiotics (fig. 3) were detected at one 

site in Oakland County (Clinton River at Auburn Hills), but 

at several sites in Huron County. The Clinton River site is 

downstream of the discharge point for the Pontiac WWTP, and 

detections likely reflect this source. The Pinnebog River at 

Richardson Road receives discharge from a wastewater-treatment lagoon; the lagoon was discharging in April 2004 at the 

time of sampling. The detections of four antibiotics at the Pinnebog River at Richardson Road, as well as the detection of 

sulfamethoxazole at downstream locations at Limerick Road 

and near Port Crescent in April 2004, may reflect this source.
Patterns Of Emerging Chemical Detections 17

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

CONCENTRATION (MICROGRAMS PER LITER)

Veterinary Antibiotics

Sulfadimethoxine

Sulfamethazine

Tylosin

0.000

0.050

0.100

0.150

0.200

0.250

0.300

CONCENTRATION (MICROGRAMS PER LITER)

General Use Antibiotics

Azithromycin

Erythromycin

Erythromycin-H2O/ Anhydroerythromycin

Sulfamethoxazole

Trimethoprim

Ciprofloxacin

Ofloxacin

Figure 3. Graphs showing concentrations of veterinary and general use antibiotics at sites where antibiotics were detected.
18 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Pharmaceuticals

Five compounds in the pharmaceuticals method (the 

pharmaceuticals albuterol, dehydronifedipine, thiabendazole, 

and warfarin, and the antibiotic sulfamethoxazole) were not 

detected in any sample. Nine of the 14 chemicals analyzed 

were detected at least once. Of 11 sites sampled for pharmaceuticals (table A2), 4 sites had none detected; however, each 

of those four sites was sampled only once. In contrast, the 

Kalamazoo River at New Richmond and the Grand River at 

Eastmanville were sampled on multiple dates over 3 years. 

Those two sites accounted for most of the pharmaceutical 

detections. Diltiazem, diphenhydramine, and trimethoprim 

were detected at the Grand River site, but never at the Kalamazoo River site. These three chemicals also were detected in the 

Boardman River at sites within the Traverse City area downstream of the WWTP effluent. Only at the Kalamazoo River 

site were any chemicals (acetaminophen and caffeine) detected 

at concentrations substantially above reporting levels. 

Patterns of pharmaceutical-compound detections were 

similar to those reported in other studies. The most frequently 

detected pharmaceuticals were carbamazepine and caffeine 

(14 detections in 28 environmental analyses for each of the 

compounds). Carbamazepine was reported from 100 percent 

of 11 WWTP effluents at concentrations appreciably above 

those of background samples (Glassmeyer and others, 2005). 

That same study indicated carbamazepine was recalcitrant to 

environmental degradation, which may explain its frequency 

of detection in Michigan waters. Other pharmaceuticals 

detected frequently were cotinine (11 detections), acetaminophen (9 detections), and trimethoprim (7 detections). All 

five of these chemicals were among the 35 most commonly 

detected chemicals in the study by Glassmeyer and others 

(2005). However, of these latter four chemicals, only trimethoprim occurred in WWTP effluents more frequently than 

at locations upstream of the effluent outfalls (Glassmeyer 

and others, 2005). Caffeine may enter surface waters through 

stormwater runoff or septic systems, and in some geographic 

settings, plants may produce caffeine naturally (Peeler and 

others, 2006). Other pharmaceutical compounds may be associated with septic wastes or possibly biosolids applications 

(Conn and others, 2006; Kinney and others, 2006). In a recent 

study of untreated surface-water and groundwater drinkingwater sources, Focazio and others (2008) reported cotinine 

(51 percent of samples), 1,7‐dimethyxanthine (27 percent), 

and carbamazepine (21.6 percent) to be the most frequently 

detected pharmaceuticals. Similarly, in a study of low-flow 

samples at selected Iowa streams (Kolpin and others, 2004), 

the most frequently detected pharmaceuticals were carbamazepine (70 percent), caffeine (56.7 percent), 1,7-dimethylxanthine (53.3 percent), and cotinine (53.3 percent). As Kolpin 

and others (2004) reported for antibiotics, pharmaceuticals 

also were most prevalent in low-flow samples in their study. 

Wastewater Compounds

Results of wastewater-compound analyses for 46 unfiltered water samples are summarized by detection frequency 

in table 7 and similarly for 113 filtered water samples in 

table 8. Of 67 chemicals analyzed on unfiltered water, 

34 were detected. Of 62 chemicals analyzed on filtered water, 

56 were detected. The most frequently detected compound in 

unfiltered water samples was N,N-diethyltoluamide (DEET), 

a commonly used insect repellant. This chemical also was 

the second most frequently detected compound in filtered 

water samples. The most frequently detected compound in 

filtered water samples was 1,4-dichlorobenzene; DEET and 

1,4-dichlorobenzene were detected in field blanks at 31 and 

92-percent frequency, respectively, and at concentrations close 

to those reported in environmental samples (table 5). These 

two constituents and others detected in field blanks are marked 

with bold-face lettering in table 8. There were no field blanks 

collected for unfiltered water samples, but consideration of 

field-blank occurrence is recommended when examining 

table 7 as well as table 8. 

Wastewater compounds detected in Michigan waters are 

grouped by chemical use or typical source (hereafter referred 

to as chemical category) in table 9. Among the chemicals 

detected in Michigan waters and not detected in field blanks 

were the musk fragrances hexahydrohexa-methylcyclopentabenzopyran (HHCB) and acetyl hexamethyl tetrahydronaphthlaene (AHTN); triclosan, an antimicrobial ingredient added 

to many household products; and some detergent metabolites (4-tert-octylphenol and its mono- and di-ethoxylates). 

AHTN and HHCB, as well as nonyl- and octyl-phenol and 

their metabolities and several other emerging chemicals often 

detected in water, have been cited for potential or recognized 

endocrine-disruption effects (Benotti and others, 2009; 

Richardson, 2009). AHTN and HHCB have been detected in 

Great Lakes water and fish (O’Toole and Metcalfe, 2006; 

Peck and Hornbuckle, 2004; Peck and others, 2006). Triclosan 

has been cited along with other antimicrobial compounds for 

the potential to encourage antimicrobial resistance in environmental microorganisms. AHTN, HHCB, and triclosan were 

persistently detected in WWTP effluents by Glassmeyer and 

others (2005). Alkylphenols, such as nonylphenol, have been 

detected in sewage entering the Great Lakes (Barber and 

others, 2000). In Michigan, HHCB and AHTN were detected 

in 24 and 25 percent, respectively, of unfiltered water samples 

and in 27 and 32 percent, respectively, of filtered water 

samples; triclosan was detected in 7 percent of filtered water 

samples. Other chemicals detected in more than 10 percent of 

either filtered or unfiltered water samples, and not detected in 

field blanks, include pesticides or herbicides (metolachlor and 

prometon), the flame retardant tri(2‐butoxyethyl) phosphate, 

and several chemicals used in cleaning agents or as fragrances. 
Patterns Of Emerging Chemical Detections 19

Table 7. Wastewater compounds detected in unfiltered water samples in order of detection frequency. —Continued

Compound

Number 

of 

Analyses

Detected 

but not 

quantified 

(number of 

results)

Concentration 

estimated 

(number of 

results)

Concentration 

greater than 

reporting level 

(number of 

results)

Not 

detected 

(number 

of results)

Detection 

frequency 

(percent)

N,N-diethyl-meta-toluamide (DEET) 17 4 11 0 2 88

4-tert-Octylphenol 17 7 0 0 10 41

Benzophenone 17 5 1 0 11 35

Anthraquinone 17 0 5 0 12 29

Tris(2-chloroethyl)phosphate 45 5 6 0 34 24

Caffeine 46 8 3 0 35 24

1,4-Dichlorobenzene 46 10 1 0 35 24

Tris(2-butoxyethyl)phosphate 46 0 10 1 35 24

Acetyl hexamethyl tetrahydronaphthalene (AHTN) 17 3 1 0 13 24

Hexahydrohexamethylcyclopentabenzopyran HHCB) 17 0 3 1 13 24

Phenanthrene 46 9 0 0 37 20

Triethyl citrate (ethyl citrate) 17 2 1 0 14 18

Prometon 17 0 3 0 14 18

Fluoranthene 46 5 3 0 38 17

Tris(dichlorisopropyl)phosphate 46 5 2 0 39 15

Cholesterol 46 2 5 0 39 15

Pyrene 46 7 0 0 39 15

Phenol 46 4 2 0 40 13

Tributyl phosphate 40 3 2 0 35 13

Tetrachloroethylene 46 3 1 0 42 9

Bromoform 14 1 0 0 13 7

Bis 2-ethylhexyl phthalate 29 0 0 2 27 7

para-Cresol 46 3 0 0 43 7

Triphenyl phosphate 46 3 0 0 43 7

beta-Sitosterol 17 1 0 0 16 6

Camphor 17 0 1 0 16 6

Anthracene 46 2 0 0 44 4

Bisphenol A 23 1 0 0 22 4

d-Limonene 40 1 0 0 39 3

1-Methylnaphthalene 40 1 0 0 39 3

2-Methylnaphthalene 40 1 0 0 39 3

Metolachlor 40 1 0 0 39 3

Acetophenone 46 1 0 0 45 2

Naphthalene 46 1 0 0 45 2

2,6-Dimethylnaphthalene 23 0 0 0 23 0

3-Methyl-1(H)-indole (Skatole) 17 0 0 0 17 0

3-tert-Butyl-4-hydroxy anisole (BHA) 46 0 0 0 46 0

4-Cumylphenol 17 0 0 0 17 0
20 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 7. Wastewater compounds detected in unfiltered water samples in order of detection frequency. —Continued

Compound

Number 

of 

Analyses

Detected 

but not 

quantified 

(number of 

results)

Concentration 

estimated 

(number of 

results)

Concentration 

greater than 

reporting level 

(number of 

results)

Not 

detected 

(number 

of results)

Detection 

frequency 

(percent)

4-n-Octylphenol 17 0 0 0 17 0

4-nonyl phenol 46 0 0 0 46 0

4-Nonylphenol diethoxylate, (sum of all isomers) 46 0 0 0 46 0

4-Nonylphenol monoethoxylate, (sum of all isomers) 29 0 0 0 29 0

4-tert-Octylphenol diethoxylate 23 0 0 0 23 0

4-tert-Octylphenol monoethoxylate 23 0 0 0 23 0

5-Methyl-1H-benzotriazole 17 0 0 0 17 0

Atrazine 23 0 0 0 23 0

Benzo[a]pyrene 46 0 0 0 46 0

beta–Stigmastanol 17 0 0 0 17 0

Bromacil 17 0 0 0 17 0

Carbaryl 46 0 0 0 46 0

Carbazole 14 0 0 0 14 0

Chlorpyrifos 46 0 0 0 46 0

3-beta-Coprostanol 46 0 0 0 46 0

Cotinine 17 0 0 0 17 0

Dichlorvos 16 0 0 0 16 0

Diazinon 46 0 0 0 46 0

Diethyl phthalate 6 0 0 0 6 0

Indole 17 0 0 0 17 0

Isoborneol 17 0 0 0 17 0

Isophorone 17 0 0 0 17 0

Isopropylbenzene 17 0 0 0 17 0

Isoquinoline 17 0 0 0 17 0

Menthol 23 0 0 0 23 0

Metalaxyl 17 0 0 0 17 0

Methyl salicylate 17 0 0 0 17 0

Pentachlorophenol 17 0 0 0 17 0

Triclosan 23 0 0 0 23 0
Patterns Of Emerging Chemical Detections 21

Table 8. Wastewater compounds detected in filtered water samples in order of detection frequency.—Continued

[Constituents in bold were detected in field blanks]

Compound

Number 

of 

Analyses

Detected 

but not 

quantified 

(number 

of results)

Concentration 

estimated 

(number of 

results)

Concentration 

greater than 

reporting level 

(number of 

results)

Not 

detected 

(number 

of results)

Detection 

frequency 

(percent)

1,4-Dichlorobenzene 113 36 45 0 32 72

N,N-diethyl-meta-toluamide (DEET) 113 20 58 0 35 69

Benzophenone 113 15 45 0 53 53

Caffeine 113 22 37 1 53 53

Metolachlor 113 17 28 8 60 47

Phenol 113 0 40 12 61 46

Isophorone 113 41 6 1 65 42

2-Methylnaphthalene 113 30 14 0 69 39

Naphthalene 113 21 20 0 72 36

1-Methylnaphthalene 113 37 2 0 74 35

Tributyl phosphate 113 16 22 0 75 34

Camphor 113 37 0 0 76 33

Triphenyl phosphate 113 23 14 0 76 33

Tris(2-butoxyethyl)phosphate 113 1 36 0 76 33

Fluoranthene 113 24 12 0 77 32

Hexahydrohexamethylcyclopentabenzopyran (HHCB) 113 16 20 0 77 32

Pyrene 113 26 8 0 79 30

Tris(2-chloroethyl)phosphate 113 12 22 0 79 30

Acetyl hexamethyl tetrahydronaphthalene (AHTN) 113 12 19 0 82 27

Cholesterol 113 20 10 0 83 27

Phenanthrene 113 30 0 0 83 27

Tris(dichlorisopropyl)phosphate 113 9 18 0 86 24

Nonylphenol diethoxylate 113 3 23 0 87 23

Menthol 113 8 17 0 88 22

Methyl salicylate 113 20 4 0 89 21

para-Nonylphenol (total) 113 12 10 0 91 19

Bisphenol A 88 17 0 0 71 19

Triethyl citrate (ethyl citrate) 113 9 12 0 92 19

beta-Sitosterol 113 11 7 0 95 16

Anthraquinone 113 4 13 0 96 15

p-Cresol 113 17 0 0 96 15

4-tert-Octylphenol diethoxylate 113 16 0 0 97 14

3-beta-Coprostanol 113 12 3 0 98 13

Bromoform 113 12 0 0 101 11

Acetophenone 113 0 11 0 102 10

beta-Stigmastanol 113 5 6 0 102 10

Cotinine 112 0 10 0 102 9

4-tert-Octylphenol monoethoxylate 113 10 0 0 103 9

Carbazole 113 8 2 0 103 9

4-tert-Octylphenol 113 9 0 0 104 8
22 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

In a recent study of untreated surface-water and groundwater 

drinking-water sources, Focazio and others (2008) reported 

cholesterol (59 percent of samples), metolachlor (53 percent 

of samples), and beta-sitosterol (37 percent of samples) to be 

the most frequently detected wastewater compounds in surface 

waters. Similarly, in a study of low-flow samples at selected 

Iowa streams (Kolpin and others, 2004), the most frequently 

detected wastewater compounds were metolachlor (80 percent), cholesterol (76.7 percent), beta-sitosterol (73.3 percent), 

and AHTN (36.7 percent). Again, as Kolpin and others (2004) 

reported for antibiotics and pharmaceuticals, wastewater 

compounds also were most prevalent in low-flow samples in 

their study. It is interesting that Michigan waters do not appear 

to have the frequency of detection of the steroid compounds 

(cholesterol, beta-sitosterol) as do these other studies. These 

compounds are naturally occurring and can be derived from 

many plant and animal sources; however, as with the antibiotic 

Table 8. Wastewater compounds detected in filtered water samples in order of detection frequency.—Continued

[Constituents in bold were detected in field blanks]

Compound

Number 

of 

Analyses

Detected 

but not 

quantified 

(number 

of results)

Concentration 

estimated 

(number of 

results)

Concentration 

greater than 

reporting level 

(number of 

results)

Not 

detected 

(number 

of results)

Detection 

frequency 

(percent)

Prometon 113 2 6 0 105 7

Triclosan 113 8 0 0 105 7

Indole 113 6 1 0 106 6

Tetrachloroethylene 113 7 0 0 106 6

3-Methyl-1(H)-indole (Skatole) 113 6 0 0 107 5

d-Limonene 113 4 2 0 107 5

Isopropylbenzene 113 4 2 0 107 5

2,6-Dimethylnaphthalene 113 4 0 0 109 4

Anthracene 113 4 0 0 109 4

Carbaryl 113 3 1 0 109 4

Diazinon 113 1 3 0 109 4

Isoborneol 113 4 0 0 109 4

Metalaxyl 113 0 4 0 109 4

Benzo[a]pyrene 113 2 0 0 111 2

Bromacil 113 0 1 1 111 2

5-Methyl-1H-benzotriazole 113 1 0 0 112 1

3-tert-Butyl-4-hydroxy anisole (BHA) 113 0 0 0 113 0

4-Cumylphenol 113 0 0 0 113 0

4-n-Octylphenol 113 0 0 0 113 0

Chlorpyrifos 113 0 0 0 113 0

Isoquinoline 113 0 0 0 113 0

Pentachlorophenol 85 0 0 0 85 0

and pharmaceutical data, it is difficult to compare detection 

frequencies among studies without being able to take into 

account river flow conditions and proximity to sources at the 

sampling location. Detections of wastewater compounds for 

unfiltered water samples are summarized by sampling site and 

chemical category in table 10 and similarly for filtered water 

samples in table 11. There were 34 compounds detected at 

least once in unfiltered water samples (table 7). Of 31 sites for 

which unfiltered water samples were analyzed, 6 were sampled 

only once and had no detections. Seven sites were sampled 

more than once and had no detections of any chemical on at 

least one date. The maximum number of chemicals detected at 

any site was 20 (Clinton River at Auburn Hills), followed by 

18 detections (Evans Ditch at Southfield), and finally 17 detections (Clinton River at Yates). At these sites and others with 

large numbers of overall detections, industrial chemicals and 

human wastewater chemicals (as defined in table 9) accounted 
Patterns Of Emerging Chemical Detections 23

for the majority of detections. These detections are consistent 

with the locations of these sites in highly urban settings and in 

the case of the Clinton River at Auburn Hills, downstream of 

the City of Pontiac WWTP effluent. Only two herbicides were 

detected in unfiltered water samples (table 10). Metolachlor, 

an agricultural-use herbicide, was detected at a location within 

an agricultural setting. Prometon, an urban-use herbicide, was 

detected only in urban settings.

There were 56 compounds detected at least once in 

filtered water samples (table 8). There were 40 surface-water 

sites and 4 groundwater sites for which filtered water samples 

were analyzed. Two groundwater sites had no detections of 

any chemical on at least one date. The maximum number of 

chemicals detected at any groundwater site was 13 (or 11 if the 

frequently detected blank contaminants 1,4-dichlorobenzene 

and phenol are not included). The one reported industrialchemical occurrence—Ionia County (Portland Well #6 on 

11/9/2004)—was of phenol. If this detection was discounted as 

contamination, there would have been no chemicals detected 

for that well on that date (table 11). No sterols, herbicides or 

pesticides, or cotinine were detected in groundwater; however, industrial chemicals, human wastewater chemicals, 

and other chemicals (as defined in table 9) were detected in 

groundwater (table 11, appendix A4). The two wells in Huron 

County are monitoring wells not used for water supply, but 

the Kalamazoo and Ionia County wells are used for supply of 

drinking water. Although several of the compounds detected in 

the Kalamazoo and Ionia County wells also were detected in 

field blanks at least once, at least six chemicals were detected 

that never occurred in blanks, including AHTN and HHCB 

(appendix A4). Previous studies have reported differences in 

the occurrence of wastewater compounds and lower frequency 

of occurrence of these chemicals in groundwater as compared 

to surface water (Barnes and others, 2008). 

Table 9. Wastewater compounds detected in filtered water, in Michigan, grouped by chemical use or typical source.

Industrial chemicals Human wastewatera Other chemicals

1,4-dichlorobenzene AHTN 4-tert-octylphenol

1-methylnaphthalene benzophenone 4-tert-octylphenol diethoxylate

2,6-dimethylnaphthalene HHCB 4-tert-octylphenol monoethoxylate

2-methylnaphthalene tri(2-chloroethyl)phosphate acetophenone

5-methyl-1H-benzotriazole tributyl phosphate caffeine

3-methyl-1H-indole triclosan camphor

anthracene tri(dichlorisopropyl)phosphate carbazole

anthraquinone triethyl citrate (ethyl citrate) d-limonene

benzo[a]pyrene Human pharmaceutical metabolite menthol

bisphenol-A cotinine methyl salicylate

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

fluoranthene 3-beta-coprostanol nonylphenol diethoxylate

indole beta-sitosterol octylphenol diethoxylate

isoborneol beta-stigmastanol para-nonylphenol

isophorone cholesterol

isopropyl benzene Urban herbicides and pesticides

naphthalene bromacil

p-cresol diazinon

phenanthrene prometon

phenol Agricultural herbicides and pesticides

pyrene carbaryl

tetrachloroethylene metalaxyl

triphenyl phosphate metolachlor

tris (2-butoxyethyl) phosphate

a

Compounds detected in 100 percent of wastewater-treatment-plant effluents (Glassmeyer and others, 2005).
24 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 10. Detections of wastewater compounds in unfiltered water by sampling site, sampling date, and chemical category.—

Continued

[MI, Michigan]

Site name

Number of detections

Sampling 

date

Industrial 

chemicals

Humanwastewater 

chemicals

Other 

chemicals Sterols Metolachlor Prometon Total

South Branch Boardman River near 

South Boardman, MI

12/24/1998 0 1 0 0 0 0 1

North Branch Boardman River near 

South Boardman, MI

10/13/1998 0 0 0 0 0 0 0

Boardman River above Brown Bridge 

Road near Mayfield, MI

 

5/12/1998 0 0 2 1 0 0 3

10/13/1998 0 0 0 0 0 0 0

12/24/1998 0 0 0 0 0 0 0

8/13/2002 1 0 0 0 0 0 1

Boardman River near Mayfield, MI 10/13/1998 0 0 0 1 0 0 1

12/24/1998 0 0 0 0 0 0 0

Boardman River at Traverse City, MI 5/12/1998 0 0 0 0 0 0 0

10/13/1998 2 0 1 0 0 0 3

12/24/1998 2 0 0 0 0 0 2

6/16/1999 1 1 0 0 0 0 2

Hospital Creek at Traverse City, MI 10/13/1998 1 0 1 0 0 0 2

12/24/1998 0 0 0 0 0 0 0

Mitchell Creek at Hammond Road 

near Traverse City, MI

12/24/1998 1 0 0 0 0 0 1

Mitchell Creek at Town Line Road at 

Traverse City, MI

12/24/1998 0 0 0 0 0 0 0

Tributary to Fourmile Creek near 

Traverse City, MI

12/24/1998 0 0 0 0 0 0 0

Mitchell Creek at Traverse City, MI 10/13/1998 3 0 0 0 0 0 3

12/24/1998 1 0 0 0 0 0 1

Acme Creek at U.S. Highway 31 at 

Acme, MI

5/12/1998 0 0 0 0 0 0 0

10/13/1998 1 0 0 0 0 0 1

12/24/1998 1 0 0 0 0 0 1

Yuba Creek near Acme, MI 5/12/1998 0 0 1 0 0 0 1

10/13/1998 0 0 0 1 0 0 1

12/24/1998 1 0 0 0 0 0 1

Shiawassee River at Holly, MI 9/9/2003 3 7 2 0 0 0 12

Kearsley Creek at Mill Street 

at Ortonville, MI

9/9/2003 2 0 1 0 0 0 3

Sashabaw Creek near

 Drayton Plains, MI

9/9/2003 3 0 2 0 0 0 5

Clinton River near 

Drayton Plains, MI

9/8/2003 1 0 2 0 0 0 3

Clinton River at Auburn Hills, MI 9/8/2003 9 7 4 0 0 0 20

Paint Creek at Rochester, MI 9/9/2003 3 0 2 0 0 0 5

Stony Creek near Romeo, MI 9/9/2003 1 0 1 0 0 0 2

Clinton River at Yates, MI 9/9/2003 7 7 3 0 0 0 17

River Rouge at Birmingham, MI 9/8/2003 6 2 2 1 0 1 12
Patterns Of Emerging Chemical Detections 25

Table 10. Detections of wastewater compounds in unfiltered water by sampling site, sampling date, and chemical category.—

Continued

[MI, Michigan]

Site name

Number of detections

Sampling 

date

Industrial 

chemicals

Humanwastewater 

chemicals

Other 

chemicals Sterols Metolachlor Prometon Total

River Rouge at Southfield, MI 9/8/2003 8 1 2 1 0 1 13

Evans Ditch at Southfield, MI 9/8/2003 9 4 3 1 0 1 18

Upper River Rouge at 

Clarenceville, MI

9/8/2003 2 2 1 0 0 0 5

Huron River at Milford, MI 9/8/2003 4 5 4 0 0 0 13

Huron River near New Hudson, MI 9/8/2003 3 1 1 0 0 0 5

Huron River near Ann Arbor, MI 12/19/1999 0 0 0 0 0 0 0

9/10/2001 0 1 1 2 0 0 4

Wolf Creek at Adrian, MI 1/1/2000 0 0 0 0 0 0 0

River Raisin at Blissfield, MI 12/19/1999 0 0 0 0 0 0 0

River Raisin near Deerfield, MI 

(2nd site)

1/1/2000 0 0 0 0 0 0 0

9/11/2001 0 1 0 0 1 0 2

River Raisin near Loyd Road at 

Dundee, MI

1/1/2000 0 0 0 0 0 0 0

Table 11. Detections of wastewater compounds in filtered water by sampling site, sampling date, and chemical category.—Continued

[MI, Michigan; data in bold print include either 1,4-dichlorobenzene or phenol; data in bold and italic print include both 1,4-dichlorobenzene and phenol]

Site name

Number of detections

Sampling 

date

Industrial 

chemicals

Human 

wastewater 

chemicals

Other 

chemicals Sterols Cotinine

Agricultural 

herbicides 

and pesticides

Urban herbicides and 

pesticides Total

Shiawassee River at 

Holly, MI

8/21/2002 9 6 1 0 0 0 0 16

Kearsley Creek at Mill 

Street at Ortonville, MI

8/21/2002 10 2 1 0 0 0 0 13

Sashabaw Creek near 

Drayton Plains, MI

8/20/2002 8 2 4 2 0 0 0 16

Clinton River near 

Drayton Plains, MI

8/20/2002 9 2 2 2 0 0 0 15

Clinton River at 

Auburn Hills, MI

8/28/2002 2 7 2 0 0 0 0 11

Paint Creek at 

Rochester, MI

8/28/2002 3 1 1 2 0 0 0 7

Clinton River at Avon 

Road at Yates, MI

8/21/2002 11 7 3 0 1 1 0 23

River Rouge at 

Birmingham, MI

9/3/2002 6 5 5 1 0 0 0 17

River Rouge at Southfield, MI8/20/2002 3 3 2 2 0 0 0 10
26 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 11. Detections of wastewater compounds in filtered water by sampling site, sampling date, and chemical category.—Continued

[MI, Michigan; data in bold print include either 1,4-dichlorobenzene or phenol; data in bold and italic print include both 1,4-dichlorobenzene and phenol]

Site name

Number of detections

Sampling 

date

Industrial 

chemicals

Human 

wastewater 

chemicals

Other 

chemicals Sterols Cotinine

Agricultural 

herbicides 

and pesticides

Urban herbicides and 

pesticides Total

Huron River at 

Milford, MI

8/20/2002 10 5 5 2 0 0 0 22

Huron River near 

New Hudson, MI

8/28/2002 1 3 1 0 0 0 0 5

East Branch Galien River 

at Gardner Road near 

Glendora, MI 

8/19/2003 6 1 6 2 0 1 0 16

9/2/2003 4 1 4 1 0 1 0 11

Galien River near 

Sawyer, MI

8/18/2003 6 1 7 1 0 1 0 16

9/2/2003 5 1 4 3 0 2 0 15

South Branch River 

Raisin at Carleton Rd 

near Adrian

8/13/2003 8 3 6 4 0 1 0 22

South Branch River 

Raisin near Adrian, MI

8/13/2003 13 7 8 4 1 1 2 36

Osborn Drain near 

Glenwood, MI

10/13/2004 1 0 0 0 0 1 0 2

Butternut Creek near 

South Haven, MI

9/8/2004 4 1 3 0 0 1 0 9

Little Libhart Creek near 

Lyons, MI

9/13/2004 4 0 3 0 0 0 1 8

Bellamy Creek near 

Ionia, MI

9/14/2004 4 0 3 2 0 1 0 10

Little Thornapple River 

near Gresham, MI

10/12/2004 2 0 2 4 0 0 0 8

Cedar Creek near 

Quimby, MI

9/23/2004 1 0 1 0 0 0 0 2

South Branch White 

Creek near Deford, MI

9/29/2004 3 0 3 2 0 0 0 8

Laird Creek near 

Waldron, MI

9/15/2004 6 0 6 1 0 1 0 14

Crystal River Below Dam 

near Glen Arbor, MI

5/5/2004 7 4 6 0 0 0 0 17

10/6/2004 1 0 1 4 0 0 0 6

Crystal River near 

Glen Arbor, MI

10/6/2004 1 0 0 4 0 0 0 5

Pigeon River at Maxwell 

Road near Rescue, MI

5/17/2004 2 1 0 0 0 1 0 4

8/25/2004 2 0 2 0 0 1 0 5

Pigeon River near 

Pigeon, MI

5/17/2004 6 1 3 0 0 1 0 11

8/25/2004 1 0 2 0 0 2 0 5

Pigeon River near 

Caseville, MI

5/17/2004 6 0 3 0 0 1 0 10

8/25/2004 3 0 3 0 0 1 0 7
Patterns Of Emerging Chemical Detections 27

Table 11. Detections of wastewater compounds in filtered water by sampling site, sampling date, and chemical category.—Continued

[MI, Michigan; data in bold print include either 1,4-dichlorobenzene or phenol; data in bold and italic print include both 1,4-dichlorobenzene and phenol]

Site name

Number of detections

Sampling 

date

Industrial 

chemicals

Human 

wastewater 

chemicals

Other 

chemicals Sterols Cotinine

Agricultural 

herbicides 

and pesticides

Urban herbicides and 

pesticides Total

Pinnebog River at 

Limerick Rd near 

Pinnebog, MI

5/20/2004 6 1 3 0 0 1 1 12

8/26/2004 2 3 4 0 0 1 1 11

Pinnebog River near Port 

Crescent, MI

5/20/2004 6 1 3 0 0 1 1 12

8/26/2004 1 0 2 0 0 1 0 4

Pigeon River at 

Caseville, MI

5/20/2004 5 0 3 0 0 1 0 9

8/26/2004 5 0 3 0 0 1 0 9

Pinnebog River at Moore 

Road near Elkton, MI

5/17/2004 2 0 1 0 0 1 0 4

8/25/2004 4 0 2 0 0 1 0 7

Pinnebog River at 

Richardson Road near 

Elkton, MI

5/17/2004 5 0 1 0 0 1 0 7

8/25/2004 5 0 2 0 0 1 0 8

16N 11E 13Aadd01 

Huron County (Oliver 

Twp, Well H-14)

8/26/2004 1 1 1 0 0 0 0 3

17N 11E 16Dddd 

Huron County (Chandler Twp, Well H-20) 

8/27/2004 1 1 1 0 0 0 0 3

01S 11W 34Aa01 

Kalamazoo County 

(Parchment Well #3)

6/28/2004 1 0 1 0 0 0 0 2

6/29/2005 5 2 2 0 0 0 0 9

8/25/2005 4 0 0 0 0 0 0 4

8/31/2004 0 0 0 0 0 0 0 0

11/9/2004 0 0 0 0 0 0 0 0

3/29/2005 1 1 2 0 0 0 0 4

11/23/2005 7 1 5 0 0 0 0 13

3/22/2006 3 0 0 0 0 0 0 3

06N 05W 28Db01

 Ionia County 

(Portland Well #6)

6/28/2004 2 0 0 0 0 0 0 2

8/31/2004 0 0 0 0 0 0 0 0

11/9/2004 1 0 0 0 0 0 0 1

3/29/2005 1 0 1 0 0 0 0 2

6/16/2005 3 4 4 0 0 0 0 11

8/18/2005 4 1 3 0 0 0 0 8

11/23/2005 7 1 5 0 0 0 0 13

3/23/2006 3 0 0 0 0 0 0 3

Clinton River at Gratiot 

Avenue at Mt. Clemens, MI

6/24/2004 13 6 5 0 0 2 0 26

8/24/2004 4 5 2 0 1 0 0 12

11/3/2004 4 1 4 2 0 0 0 11

3/14/2005 16 7 8 2 1 0 0 34

6/14/2005 19 8 11 4 1 2 1 46

8/15/2005 12 6 10 4 1 2 2 37

11/22/2005 5 2 2 0 0 0 0 9

3/14/2006 15 2 7 0 0 1 0 25
28 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Table 11. Detections of wastewater compounds in filtered water by sampling site, sampling date, and chemical category.—Continued

[MI, Michigan; data in bold print include either 1,4-dichlorobenzene or phenol; data in bold and italic print include both 1,4-dichlorobenzene and phenol]

Site name

Number of detections

Sampling 

date

Industrial 

chemicals

Human 

wastewater 

chemicals

Other 

chemicals Sterols Cotinine

Agricultural 

herbicides 

and pesticides

Urban herbicides and 

pesticides Total

Grand River near Eastmanville, MI6/15/2004 9 7 3 0 0 1 1 21

8/18/2004 7 6 5 1 0 1 1 21

11/17/2004 1 1 0 0 0 0 0 2

3/22/2005 10 8 9 1 1 1 0 30

6/27/2005 12 7 4 1 0 1 1 26

8/23/2005 6 6 3 2 1 1 0 19

11/21/2005 9 4 2 0 1 0 0 16

3/13/2006 13 3 3 0 0 1 0 20

Kalamazoo River at New 

Richmond, MI

6/15/2004 8 4 2 0 0 1 0 15

8/18/2004 8 3 5 0 0 1 0 17

11/17/2004 1 0 0 0 0 0 0 1

3/21/2005 7 5 5 0 0 1 0 18

6/28/2005 6 4 4 0 0 1 0 15

8/24/2005 7 1 3 0 0 0 0 11

11/22/2005 4 0 0 0 0 0 0 4

3/13/2006 8 3 2 0 0 1 0 14

Muskegon River near 

Bridgeton, MI

3/13/2004 6 0 2 0 0 1 0 9

6/16/2004 7 2 3 0 0 1 0 13

8/19/2004 0 1 2 0 0 0 0 3

10/27/2004 2 1 3 0 0 0 0 6

3/22/2005 5 3 4 0 0 0 0 12

6/27/2005 7 3 5 0 0 1 0 16

8/23/2005 5 0 1 0 0 0 0 6

11/21/2005 4 0 2 0 0 0 0 6

Saginaw River at 

Weadock Road at Essexville, MI

6/23/2004 13 6 6 0 0 1 0 26

8/24/2004 2 4 2 0 0 1 0 9

11/4/2004 1 0 1 0 0 0 0 2

3/14/2005 11 8 9 3 1 1 0 33

6/15/2005 9 8 6 0 0 1 0 24

8/16/2005 6 6 6 4 0 1 0 23

11/29/2005 9 3 2 0 0 0 0 14

3/14/2006 14 2 3 0 0 1 0 20

South Branch 

Kalamazoo River near 

Moscow, MI

8/17/2005 6 0 0 0 0 0 0 6
Patterns Of Emerging Chemical Detections 29

0

5

10

15

20

25

30

35

40

Above Adrian, MI

Below Adrian, MI

Agricultural Total

herbicides

and pesticides

Other Sterols

chemicals

Human

wastewater

chemicals

Industrial

chemicals

Cotinine Urban

herbicides

and pesticides

NUMBER OF DETECTIONS

MICHIGAN

Adrian

 Every surface-water site had at least one chemical detected on at least one date. The maximum number of 

chemicals detected in a single sample at any site was 46 (44 

detections if 1,4‐dichlorobenzene and phenol are discounted) 

at the Clinton River at Gratiot Avenue at Mt. Clemens, in June 

2005. The second highest site in terms of number of detections in a single sample (37) also was at the Clinton River at 

Gratiot Avenue at Mt. Clemens, followed by 36 detections 

at the South Branch of the River Raisin downstream from 

Adrian. At these sites and others with large numbers of overall 

detections, industrial chemicals, human wastewater chemicals, 

and other chemicals (as defined in table 9) accounted for the 

majority of detections. These detections are again consistent 

with the locations of these sites downstream of urban areas or 

known wastewater-effluent discharge points. These patterns 

are exemplified by the results (table 11, fig. 4) for the two 

River Raisin sites sampled on August 13, 2003. The Carleton 

Road site is located on the river before it passes through the 

city of Adrian, and the second site is located on the river after 

it passes through the city. The city of Adrian is one of very 

few in Michigan that draws its drinking-water supply from a 

river. Figure 4 shows that the number of detections for most 

categories of chemicals were greater downstream of Adrian; 

only sterols and agricultural herbicides and pesticides were 

similar at both locations. These constituents may reflect the 

overall agricultural land use in the area. Sterols could arise 

from runoff of animal wastes, as well as from human wastes. 

Coprostanol has been reported to be associated with rural 

land use (Isobe and others, 2004). Kolpin and others (2004) 

also reported the greatest number of detections of chemicals 

downstream of urban centers and Barber and others (2006) 

related increasing detections to increasing population size 

as they sampled more downstream locations in their study 

watershed. 

Figure 4. Graph showing number of detections of wastewater compounds, by chemical category, in the River Raisin above and 

below the city of Adrian, Michigan.
30 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Five surface-water sites were sampled on multiple dates. 

For these sites, the number of detections varied with sampling 

date. In general, for these five sites, the number of detections was lower during October or November than in March 

or June. No particular chemical category accounted for this 

pattern. Hydrologic condition is among many factors that may 

affect the detections of wastewater chemicals in water. The 

affect of hydrologic condition on wastewater-chemical detections in two branches of the Galien River is shown in figure 5. 

These rivers were sampled first following a 2‐week period of 

no rainfall, then following the first subsequent rainfall event. 

In general, higher flow conditions resulted in fewer detections 

in each chemical category. This is consistent with dilution of 

wastewater effluent with rainfall runoff. However, as noted 

previously for the River Raisin, sterols and agricultural herbicide and pesticide detections increased with higher flow at 

the Galien River site (fig. 5), possibly as a result of surface 

runoff from agricultural fields. Similar patterns of dilution or 

concentrations of chemicals in different categories were noted 

by Kolpin and others, 2004.

0

2

4

6

8

10

12

14

16

18

East Branch Galien River

NUMBER OF DETECTIONS

Galien River

Low flow

High flow

Agricultural Total

herbicides

and pesticides

Other Sterols

chemicals

Human

wastewater

chemicals

Industrial

chemicals

Other Sterols Total

chemicals

Human

wastewater

chemicals

Industrial

chemicals

Agricultural

herbicides

and pesticides

 

NUMBER OF DETECTIONS

Low flow

High flow

0

2

4

6

8

10

12

14

16

18

Figure 5. Graphs showing number of detections of wastewater compounds, by chemical category, 

in two reaches of the Galien River during low- and high-flow conditions.
Patterns Of Emerging Chemical Detections 31

Several sites in both Huron and Oakland Counties were 

analyzed for wastewater chemicals. These counties vary substantially in land use, with Oakland County being highly urban 

overall and Huron County highly agricultural. Figures 6 and 7 

show site-specific detections of wastewater chemicals in four 

categories as described in table 9: industrial chemicals, human 

wastewater chemicals, sterols, and other chemicals. Human 

wastewater chemicals were rarely detected in Huron County, 

and sterols were never detected (fig. 6). The two Huron 

County sites with the greatest number of industrial chemicals 

detected were Pigeon River at Caseville (downstream of the 

Caseville WWTP) and Pinnebog River at Richardson Road 

(downstream of intermittent discharge from a sewage lagoon). 

However, signature human wastewater chemicals (as defined 

in table 9) were not detected at either of these sites. In contrast, at least one signature human wastewater chemical was 

detected at each Oakland County site (fig. 7), and industrial 

chemicals also were generally more prevalent than in Huron 

County. Patterns in Oakland County likely reflect proximity 

to known WWTP discharges, as well as other potential urban 

inputs such as septic systems or inadvertent connections of 

sewer lines to storm drains. Several recent reports have argued 

that various frequently-detected antibiotics, pharmaceuticals, 

or wastewater chemicals may be useful as indicators of waste 

effluents and of the potential occurrence of other untested 

chemicals common to those wastes (Glassmeyer and others, 

2005; Benotti and others, 2009). 

Figures 6 and 7 demonstrate the potential for multiple 

APOWCs to be present in various water samples. However, 

these are not necessarily the only chemicals present. Pesticides and herbicides also were detected (by other analytical 

methods) in Huron County samples along with the wastewater 

chemicals reported herein (Duris and Haack, 2005). Pollutants such as industrial chemicals, urban-use pesticides, and 

nutrients have been commonly detected in the Clinton River 

(Francis and Haas, 2006). 

Figure 6. Map of the Pigeon River and Pinnebog River watersheds in Huron County, showing the number of detections of 

wastewater compounds in four chemical categories, by sampling site.
32 Antibiotic, Pharmaceutical, and Wastewater-Compound Data for Michigan, 1998–2005

Figure 7. Map of five watersheds in Oakland County, showing the number of detections of wastewater compounds in 

four chemical categories, by sampling site.

Summary

Beginning in the late 1990’s, the U.S. Geological Survey 

(USGS) began to develop analytical methods to detect, at 

concentrations less than 1 microgram per liter (μg/L), emerging water contaminants such as pharmaceuticals, personal-care 

chemicals, and a variety of other chemicals associated with 

various human and animal sources. Three separate analytical 

procedures were used to assess detections and concentrations of the chemicals described in this report. Early data 

were provided on a provisional basis, with the understanding that method development was an ongoing process and 

that compounds tested and compound-detection limits might 

change over time. Reporting levels for many compounds have 

changed from 1998 to present (2009). In addition, some compounds were removed from, or added to, analysis suites from 

1998 to present. In this report, previously reported concentrations less than current reporting levels have been recensored 

using current reporting criteria to provide consistent information. In addition, data for compounds removed from analytical 

methods are not included in this report, even though data for 

such compounds may have appeared in previous USGS or 

other publications.

 During 1998–2005, the USGS analyzed the following Michigan water samples: 41 samples for antibiotic 

compounds, 28 samples for pharmaceutical compounds, 46 

unfiltered samples for wastewater compounds (dissolved and 

suspended compounds), and 113 filtered samples for wastewater compounds (dissolved constituents only). Very few 

chemicals were detected at concentrations greater than current 

(2009) laboratory reporting levels, which currently vary from 

a low of 0.005 μg/L for some antibiotics to 5 μg/L for some 

wastewater compounds. Nevertheless, 10 of 51 chemicals in 

the antibiotics analysis, 9 of 14 chemicals in the pharmaceuti-
References Cited 33

cals analysis, 34 of 67 chemicals in the unfiltered-wastewater 

analysis, and 56 of 62 chemicals in the filtered-wastewater 

analysis were detected. Analysis of caffeine by two different 

methods, one providing concentration data at reporting levels 

approximately 10 times lower than those of the wastewater 

method, helps with interpretation of estimated concentrations. 

Caffeine results showed an overall agreement between the 

two methods, both in assigning presence or absence of caffeine and in terms of concentrations determined. In general, 

field-blank samples indicate that some wastewater compounds, 

but no pharmaceuticals or antibiotics, may be present owing 

to contamination of sampling equipment or ambient environmental contamination. Field-blank results provide important 

information for the design of future sampling programs and 

may demonstrate the ubiquitous nature of some organic wastewater compounds. Field-replicate results indicate substantial 

confidence regarding the presence or absence of the many 

chemicals tested. 

 Antibiotics, pharmaceuticals, and wastewater compounds 

were detected at the majority of analyzed sites. Antibiotics 

were detected at 7 of 20 tested surface-water sites, but none 

were detected in 2 groundwater samples. Pharmaceuticals 

were detected at 7 of 11 surface-water sites. Wastewater 

compounds were detected at 25 of 31 sites for which unfiltered water samples were analyzed and at least once at all 

40 surface-water sites and all 4 groundwater sites for which 

filtered water samples were analyzed. Surface-water sites with 

the largest numbers of detections of chemicals for each analysis method tended to be in urban areas. For example, 46 of 62 

wastewater chemicals analyzed for filtered water samples were 

detected at the Clinton River at Gratiot Avenue at Mt. Clemens 

in June 2005. In contrast, the maximum number of detected 

wastewater chemicals in groundwater was 13. Overall, the 

chemicals detected most frequently in Michigan waters are 

similar to those reported frequently in other studies nationwide. 

Patterns of chemical detections were site specific, and 

appeared to be related to local sources, overall land use, and 

hydrologic conditions at the time of sampling. Sites located 

on the River Raisin before and after it passes through the city 

of Adrian were sampled on August 13, 2003. The numbers of 

detections for most categories of chemicals were greater at the 

downstream site, which is located after the wastewater-treatment-plant (WWTP) effluent enters the river. Several sites in 

both Huron and Oakland Counties were analyzed for wastewater chemicals. The two Huron County sites with the greatest 

number of industrial chemicals detected were Pigeon River at 

Caseville (downstream of the Caseville WWTP) and Pinnebog River at Richardson Road (downstream of intermittent 

discharge from a sewage lagoon). However, signature human 

wastewater chemicals were not detected at either of these sites. 

In contrast, at least one signature human wastewater chemical 

was detected at each Oakland County site and industrial chemicals also were prevalent. Patterns in Oakland County likely 

reflect proximity to known WWTP discharges, as well as other 

potential urban inputs such as septic systems or connections of 

sewer lines to storm drains. Patterns of detections with regard 

to location above or below WWTP effluents, or with respect to 

general land use, were similar in Michigan to those reported in 

other studies nationwide.

Hydrologic conditions may affect the numbers and types 

of chemicals detected. Wastewater effluent may be diluted by 

rainfall runoff or concentrated at times of low river flow. Two 

branches of the Galien River were sampled first following a 

2-week period of no rainfall, then following the first subsequent rainfall event. In general, higher flow conditions resulted 

in fewer detections in each chemical category. Five surfacewater sites were sampled for wastewater on multiple dates 

over 3 years. For these sites, the number of detections varied 

with sampling date. In general, for these five sites, the number 

of detections was lower during October or November than in 

March or June. These patterns could be related to hydrologic 

conditions at the time of sampling, as has been shown in other 

studies. 

Quality-assurance samples indicated that some wastewater compounds, but no pharmaceuticals or antibiotics, may 

have been owing to contamination of sampling equipment or 

ambient environmental contamination. Field-blank results provide important information for the design of future sampling 

programs in Michigan and demonstrate the need for careful 

field-study design to avoid some of these ubiquitous organic 

wastewater compounds. Field-replicate results indicated substantial confidence regarding the presence or absence of the 

many chemicals tested. Analysis of caffeine by two methods 

with differing detection levels demonstrated confidence that 

compounds reported with an estimated concentration are 

indeed present in the sample, but also demonstrated the degree 

of uncertainty regarding the actual concentration. Overall, 

data reported herein indicate that a wide array of antibiotic, 

pharmaceutical, and organic wastewater compounds occur 

in Michigan waters. Patterns of occurrence, with respect to 

hydrologic, land use, and source variables generally appear to 

be similar for Michigan as for other sampled waters across the 

United States. The data reported herein can serve as a basis for 

future studies in Michigan. 

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