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Response to Comment On “Co-Occurrence of Triclocarban and Triclosan in U.S. Water Resources” We thank Sanderson (1) and the Soap and Detergent Association (SDA (2)) for their interest in our paper (3), reporting the co-occurrence of triclocarban (TCC) and triclosan (TCS) in 42 grab samples from the Greater Baltimore region, and predicting nationwide contamination of U.S. streams with TCC, based on TCS concentrations reported in 2002 (4). Before addressing Sanderson’s concerns (1), we would like to correct a false quote attributed to our 2004 paper (5). The correct quote should read: “Nine of 26 urban stream samples tested negative for TCC at an estimated detection limit of 25-30 ng/L. Seventeen river samples, obtained from various locations along six urban streams, tested positive for TCC.” Thus, the actual percentage of stream samples with detectable TCC concentrations was 65% and not 23%, as stated by Sanderson. Furthermore, Sanderson (1) suggests that wesand the reviewers of Environmental Science & Technologysshould have been aware of a more recent study which, if included in our paper, would have resulted in the prediction of lower TCC concentrations in the environment. These new data (6) could not be considered at the time because they were published five weeks after submission of our manuscript. It is important to note that, when our predictive model is applied to this new data set (6), it yields additional predictions of TCC occurrences in the environment. These neither falsify nor contradict the values predicted for a different set of streams included in our paper (4). Sanderson (1) questions the validity of our predictions on the grounds that, during development of our predictive model, we included data from nonrepresentative, contaminated stream locations. We believe this assertion to be unfounded. The empirical model was derived based on TCS and TCC measurements obtained for various environmental matrixes, including drinking water, river water, wastewater, and municipal sludge. We neither stated nor intended these samples to be reflective of U.S. streams. Any bias inherent to these data would be reflected in the concentrations of both TCS and TCC, according to the specific modeling assumptions stated in our paper (3). We feel that measured concentrations are more important than predictions. Therefore, we disagree with Sanderson’s notion (1) that values obtained by risk assessment modeling are more descriptive of the environmental status quo than the concentrations actually measured in these locales and reported by us (TCC concentrations in U.S. streams of up to 6750 ng/L). In addition, whereas nutrients and certain pathogens may rapidly attenuate following sewage spills, TCC likely will exhibit an unfavorably long environmental halflife, as stated in our paper (3). Sanderson questions whether raw wastewater frequently enters the U.S. environment (1). Unfortunately, the answer is yes, it does. Many surface waters in the United States are significantly impacted by raw sewage. A recent Report to Congress (7) estimates the annual volume of sewer overflows (CSOs) and sanitary sewer overflows (SSOs) at a combined total of about 860 billion gallons. This implies that at least 7% of the total volume of U.S. wastewater enters the environment untreated. This phenomenon is discussed in our paper, and mass estimates of the resultant TCC loadings 10.1021/es058014y CCC: $30.25 Published on Web 07/06/2005
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from CSOs and SSOs are presented (3). This volumetric estimate does not include sewage spills from leaky pipes and improper engineering that triggered the concentrations reported in our studies (3, 5). Contrary to the suggestion of Sanderson (1), the severity of contamination of the urban stream, Gwynns Run in Baltimore, MD, was disclosed openly and repeatedly. Figure 5A of our 2004 paper (5) shows a TCC concentration of 5600 ng/L side-by-side with values of 6650 and 6750 ng/L for raw wastewater. These values indicated a similarity to raw sewage of about 83%. In Figure 4A of our 2005 paper (3), we reported additional measurements for Gwynns Run that essentially were indistinguishable from those obtained for wastewater treatment plant influent. The concept of normalizing the data to raw sewage was introduced after submission of our paper. [Sanderson (1) failed to realize that the publication date of the Baltimore Sanitary Sewer Oversight Coalition Annual Report for the year 2003 actually was September 2004 (8).] Our paper (3) leaves open the question of whether the estimated data are true, as is the nature of a prediction. However, in a follow-up study that is currently under review, Sapkota et al. confirm the suspected phenomenon of nationwide contamination of U.S. streams with TCC (9). Interestingly, the experimentally determined detection frequency (9) actually turned out to be higher than that predicted in our 2005 study (3). Sanderson (1) emphasizes the extremely low effluent concentrations of TCC (110 ( 10 ng/L) detected at the wastewater treatment plant we examined. However, much higher TCC concentrations of up to 6000 ng/L have been reported previously for effluent of less efficient plants (10)sa fact omitted from both Sanderson’s comment (1) and the robust summary report (11) provided by the TCC Consortium to the U.S. Environmental Protection Agency (EPA). With his comments (1), Sanderson initiates the important process of scientific discussion. For this process to be most beneficial and productive, we would like to renew our request to the industrysas stated earlier this year in our invited presentation to Sanderson and other industry representatives at the SDA headquarters in Washington (2)sto make available to the public all reports, studies, and data that were cited in the robust summary report (11). A fair and competent assessment of the safety profile of TCC is impossible unless the sampling strategies and analytical methods that form the basis of the data contained in the report (11) are available in their entirety to reviewers within and outside of industry and government.
Literature Cited (1) Sanderson, H. Environ. Sci. Technol. 2005, 39, xxxx. (2) Halden, R. U. Fate of Polychlorinated Antimicrobials in the U.S. Environment. Invited presentation delivered to the Soap and Detergent Association at the SDA Headquarters in Washington, DC, March 29, 2005. (3) Halden, R. U.; Paull, D. H. Co-Occurrence of Triclocarban and Triclosan in U.S. Water Resources. Environ. Sci. Technol. 2005, 39 (6), 1420-1426. (4) Kolpin, D. W.; Furlong, E. T.; Meyer, M. T.; Thurman, E. M.; Zaugg, S. D.; Barber, L. B.; Buxton, H. T. Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999-2000: A National Reconnaissance. Environ. Sci. Technol. 2002, 36, 1202-1211. (5) Halden, R. U.; Paull, D. H. Analysis of Triclocarban in Aquatic Samples by Liquid Chromatography Electrospray Ionization Mass Spectrometry. Environ. Sci. Technol. 2004, 38, 48494855. VOL. 39, NO. 16, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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(6) Kolpin, D. W.; Skopec, M.; Meyer, M. T.; Furlong, E. T.; Zaugg, S. D., Urban contribution of pharmaceuticals and other organic wastewater contaminants to streams during differing flow conditions. Sci. Total Environ. 2004, 328, 119-130. (7) U.S. Environmental Protection Agency. Impacts and Control of CSOs and SSOs; Report No. EPA 833-R-04-001; U.S. EPA, Office of Water: Washington, DC, 2004. (8) Hollyday, G.; Cothran, C. Sewage in Baltimore. Baltimore Sanitary Sewer Oversight Coalition, 2004. http://www. jhsph.edu/Dept/EHS/Faculty/Halden/Full_BSSOC_Report_ 2003.pdf (accessed June 7, 2005.) (9) Sapkota, A.; Heidler, J.; Halden, R. U. Isotope Dilution Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric Detection of Triclocarban and Discovery of Additional Contaminants in U.S. Water Resources; submitted for publication, 2005. (10) Clark, L. B.; Rosen, R. T.; Hartman, T. G.; Louis, J. B.; Rosen, J. D., Application of particle beam LC/MS for the analysis of water from publicly owned treatment works. Int. J. Environ. Anal. Chem. 1991, 45, 169-178. (11) TCC Consortium. High Production Volume (HPV) Chemical Challenge Program Data Availability and Screening Level
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Assessment for Triclocarban, CAS# 101-20-2; report no. 20114186A, December 27, 2002. http://www.epa.gov/chemrtk/ tricloca/c14186tp.pdf (accessed June 7, 2005).
Rolf U. Halden Johns Hopkins Bloomberg School of Public Health Center for Water and Health 615 N. Wolfe Street BSPH Building, E6618 Baltimore, Maryland 21205
Daniel H. Paull Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore, Maryland 21218 ES058014Y
