USGS Scientific Investigations Report 2007-5054

Prepared in cooperation with the Triangle Area Water Supply Monitoring Project Steering Committee

Occurrence of Organic Wastewater Compounds in Selected Surface-Water Supplies, Triangle Area of North Carolina, 2002–2005

This report is only available online in pdf format (1.65 MB): SIR 2007-5054 (Opens the PDF file in a new window. )

By M.J. Giorgino, R.B. Rasmussen, and C.A. Pfeifle

U.S. Geological Survey Scientific Investigations Report 2007-5054, 28 pages (Published June 2007)

Cover thumbnailSelected organic wastewater compounds, such as household, industrial, and agricultural-use compounds, sterols, pharmaceuticals, and antibiotics, were measured at eight sites classified as drinking-water supplies in the Triangle Area of North Carolina. From October 2002 through July 2005, seven of the sites were sampled twice, and one site was sampled 28 times, for a total of 42 sets of environmental samples.

Samples were analyzed for as many as 126 compounds using three laboratory analytical methods. These methods were developed by the U.S. Geological Survey to detect low levels (generally less than or equal to 1.0 microgram per liter) of the target compounds in filtered water. Because analyses were conducted on filtered samples, the results presented in this report may not reflect the total concentration of organic wastewater compounds in the waters that were sampled. Various quality-control samples were used to quality assure the results in terms of method performance and possible laboratory or field contamination.

Of the 108 organic wastewater compounds that met method performance criteria, 24 were detected in at least one sample during the study. These 24 compounds included 3 pharmaceutical compounds, 6 fire retardants and plasticizers, 3 antibiotics, 3 pesticides, 6 fragrances and flavorants, 1 disinfectant, and 2 miscellaneous-use compounds, all of which likely originated from a variety of domestic, industrial, and agricultural sources. The 10 most frequently detected compounds included acetyl-hexamethyl tetrahydronaphthalene and hexahydro-hexamethyl cyclopentabenzopyran (synthetic musks that are widely used in personal-care products and are known endocrine disruptors); tri(2-chloroethyl) phosphate, tri(dichloroisopropyl) phosphate, and tributyl phosphate (fire retardants); metolachlor (herbicide); caffeine (nonprescription stimulant); cotinine (metabolite of nicotine); acetaminophen (nonprescription analgesic); and sulfamethoxazole (prescription antibiotic).

The occurrence and distribution of organic wastewater compounds varied considerably among sampling sites, but at least one compound was detected at every location. The most organic wastewater compounds (19) were detected at the Neuse River above U.S. 70 at Smithfield, where two-thirds of the total number of samples were collected. The fewest organic wastewater compounds (1) were detected at the Eno River at Hillsborough. The detection of multiple organic wastewater compounds was common, with a median of 3.5 and as many as 12 compounds observed in individual samples. Some compounds, including acetaminophen, cotinine, tri(2-chloroethyl) phosphate, and metolachlor, were detected at numerous sites and in numerous samples, indicating that they are widely distributed in the environment. Other organic wastewater compounds, including acetyl-hexamethyl tetrahydronaphthalene and hexahydro-hexamethyl cyclopentabenzopyran, were detected in numerous samples but at only one location, indicating that sources of these compounds are more site specific. Results indicate that municipal wastewater may be a source of antibiotics and synthetic musks; however, the three sites in this study that are located downstream from wastewater discharges also receive runoff from agricultural, urban, and rural residential lands. Source identification was not an objective of this study.

Concentrations of individual compounds generally were less than 0.5 microgram per liter. No concentrations exceeded Federal drinking-water standards or health advisories, nor water-quality criteria established by the State of North Carolina; however, such criteria are available for only a few of the compounds that were studied.

Compared with other surface waters that have been sampled across the United States, the Triangle Area water-supply sites had fewer detections of organic wastewater compounds; however, differences in study design and analytical methods used among studies must be considered when making comparisons. In general, concentrations of organic wastewater compounds detected in the Triangle Area were within ranges of concentrations reported for other areas. Maximum concentrations of pharmaceuticals, antibiotics, pesticides, fragrances, and disinfectants observed in the Triangle Area--even at sites downstream from major municipal wastewater discharges--generally were lower than those reported for other surface-water sites in the United States. In contrast, maximum concentrations of fire retardants that were detected in this study were consistent with concentrations observed elsewhere.


This report is available online in pdf format (1.65 MB): USGS SIR 2007-5054 (Opens the PDF file in a new window. )
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Suggested citation: Giorgino, M.J., Rasmussen, R.B., and Pfeifle, C.M., 2007, Occurrence of organic wastewater compounds in selected surface-water supplies, Triangle Area of North Carolina, 2002–2005: U.S. Geological Survey Scientific Investigations Report 2007–5054, 28 p., available online at

For more information, please contact M.J. Giorgino.

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