title: Transformation products and human metabolites of triclocarban and triclosan in sewage sludge across the United States.
abstract: Removal of triclocarban (TCC) and triclosan (TCS) from wastewater is a function of adsorption, abiotic degradation, and microbial mineralization or transformation, reactions that are not currently controlled or optimized in the pollution control infrastructure of standard wastewater treatment. Here, we report on the levels of eight transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in raw and treated sewage sludge. Two sample sets were studied: samples collected once from 14 wastewater treatment plants (WWTPs) representing nine states, and multiple samples collected from one WWTP monitored for 12 months. Time-course analysis of significant mass fluxes (α=0.01) indicate that transformation of TCC (dechlorination) and TCS (methylation) occurred during sewage conveyance and treatment. Strong linear correlations were found between TCC and the human metabolite 2'-hydroxy-TCC (r=0.84), and between the TCC-dechlorination products dichlorocarbanilide (DCC) and monochlorocarbanilide (r=0.99). Mass ratios of DCC-to-TCC and of methyl-triclosan (MeTCS)-to-TCS, serving as indicators of transformation activity, revealed that transformation was widespread under different treatment regimes across the WWTPs sampled, though the degree of transformation varied significantly among study sites (α=0.01). The analysis of sludge sampled before and after different unit operation steps (i.e., anaerobic digestion, sludge heat treatment, and sludge drying) yielded insights into the extent and location of TCC and TCS transformation. Results showed anaerobic digestion to be important for MeTCS transformation (37-74%), whereas its contribution to partial TCC dechlorination was limited (0.4-2.1%). This longitudinal and nationwide survey is the first to report the occurrence of transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in sewage sludge.
authors.affiliation: Center for Environmental Security, Biodesign Institute, Security and Defense Systems Initiative, Arizona State University , 781 East Terrace Road, Tempe, Arizona 85287, United States.
authors.forename: Benny F G
authors.initials: BF
authors.lastname: Pycke
authors.forename: Isaac B
authors.initials: IB
authors.lastname: Roll
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Brownawell
authors.forename: Chad A
authors.initials: CA
authors.lastname: Kinney
authors.forename: Edward T
authors.initials: ET
authors.lastname: Furlong
authors.forename: Dana W
authors.initials: DW
authors.lastname: Kolpin
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D001711:Biotransformation; D002224:Carbanilides / Q000302:isolation & purification / Q000378:metabolism*; D004784:Environmental Monitoring; D006801:Humans; D012722:Sewage / Q000737:chemistry*; D013997:Time Factors; D014260:Triclosan / Q000302:isolation & purification / Q000378:metabolism*; D014481:United States; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism*; D018508:Water Purification
chemical_list: D002224:Carbanilides; D012722:Sewage; D014260:Triclosan; D062065:Wastewater; D014874:Water Pollutants, Chemical; C009540:triclocarban