Aquatic Environmental Microbiology and Chemistry

University of Wisconsin Milwaukee, Zilber School of Public Health    

 

                  

Chronicaling pollution from antimicrobial soap chemicals

In the last decade, the production of persistent antimicrobial compounds, namely triclosan (TCS; 5-chloro-2-[2,4-dichloro-phenoxy]-phenol) and triclocarban (TCC; 3,4,4’-trichlorocarbanilide) added to personal care products, has steadily increased. Environmental inputs of both biocides into the U.S. environment are known to exceed 600,000 kg/yr and may be as high as 1,000,000 kg/yr (1, 2). Only recently it was realized that, following disposal into wastewater, both TCS and TCC persist during municipal sewage treatment and are subsequently distributed into aquatic environments as well as onto agricultural fields as a result of water reclamation and municipal sludge recycling (2, 4-7).

Both TCC and TCS are distributed widely in environmental habitats and co-occur due to similar partitioning behaviors (3). Raw wastewater contains almost equal amounts of both compounds and processing in conventional activated sludge wastewater treatment plants yields low concentrations in effluent due to partitioning and accumulation of the antimicrobials in sludge (3).

The continuous release of TCC and TCS into aquatic ecosystems over extended periods of time (>40 years) has resulted in the accumulation of these compounds in aquatic sediments. Along with my collaborators, I have examined contaminant profiles of TCC, TCS and TCC breakdown products in dated sediment cores taken near wastewater treatment plants in the Chesapeake Bay watershed, Maryland and Jamaica Bay, New York. In this study we found that biocides exceed 1 mg/kg in surface sediments with higher concentrations in lower sediments. In general, concentrations tracked biocide usage as well as changes in wastewater treatment strategies since concentrations of all carbanilide congeners combined were correlated with heavy metals. This study also produced the first evidence for complete sequential dechlorination of TCC. All possible dechlorination products of TCC were observed including di-, mono- and non-chlorinated carbanilide.

 

Depth-time profile of triclocarban and its dechlorination products in estuarine sediment near a wastewater treatment plant

 

Correlation between copper and the sum of all carbanilides in sediment near a wastewater treatment plant in the Chesapeake Bay, MD.

 

 

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