Ab Initio and in Situ Comparison of Caffeine, Triclosan, and Triclocarban as Indicators of Sewage-Derived Microbes in Surface Waters

Abstract

Three organic wastewater compounds (OWCs) were evaluated in theory and practice for their potential to trace sewage-derived microbial contaminants in surface waters. The underlying hypothesis was that hydrophobic OWCs outperform caffeine as a chemical tracer, due to their sorptive association with suspended microorganisms representing particulate organic carbon (POC). Modeling from first principles (ab initio) of OWC sorption to POC under environmental conditions suggested an increasing predictive power: caffeine (0.2% sorbed) < triclosan (9-60%; pH 6-9) < triclocarban (76%). Empirical evidence was obtained via analysis of surface water from three watersheds in a rural-to-urban gradient in Baltimore, MD. Mass spectrometric OWC detections were correlated to microbial plate counts for 40 monitoring sites along 14 streams, including multiple chronic sewage release sites and the local wastewater treatment plant. Consistent with ab initio calculations, correlation analyses of 104 observations for fecal coliforms, enterococci, and Escherichia coli in natural surface waters showed that the particle-active antimicrobials triclosan and triclocarban (R2 range, 0.45-0.55) were indeed superior to caffeine (0.16-0.37) for tracking of microbial indicators. It is concluded that chemical monitoring of microbial risks is more effective when using hydrophobic OWCs such as triclosan and triclocarban in place of, or in conjunction with, the traditional marker caffeine.

Seasonal and Spatial Distribution of Caffeine, Atrazine, Atenolol and DEET in Surface and Drinking Waters from the Brazilian Federal District

“…Many studies show that the presence of caffeine in surface waters can be used do indicate the degree of human activities, 15 especially those associated with wastewater inputs. [16][17][18] In Brazil, caffeine was also investigated in previous works as a marker for sewageimpacted aquatic systems. 2,19,20 Atenolol was the second most abundant contaminant with levels varying from 4.7 ± 0.5 to 90 ± 19 ng L -1 .…”

Triclosan as a surrogate for household biocides: An investigation into biocides in aquatic environments of a highly urbanized region

“…To our knowledge, triclosan and triclocarban are the chemical indicators of household sewage contamination as they are widely used in household products such as toothpastes and hand wash (Young et al, 2008). Pearson correlation analysis was used to identify the potential pollution sources for the biocides by the correlations between different biocides and triclosan (or triclocarban) in water and sediment.…”

“…Triclosan has been used as a potential indicator to track household sewage contamination (Young et al, 2008). Halden and Paull predicted the concentrations of triclocarban in US streams by using an empirical correlation between triclosan and triclocarban (Halden and Paull, 2005).…”

Recent Advances in the Use of Chemical Markers for Tracing Wastewater Contamination in Aquatic Environment: A Review

“…To identify contaminant inputs from raw wastewater, various techniques using molecular markers (chemical, microbial, or combination of both) have been widely practiced [14][15][16][17].…”