Probably the same people who use all kinds of "anti-bacterial" agents all over their houses. 
(joke)
(joke)
Which may be causing some (potential) problems with their widespread use in hand soaps, etc.
http://pubs.acs.org/subscribe/journals/esthag-w/2006/apr/science/lt_soap.html
Their work is the first peer-reviewed field study of triclocarban in sewage sludge and one of the few reports of the compound’s fate during wastewater treatment. The findings suggest that—given the high rate of sewage sludge reuse as fertilizer—a single WWTP can return more than 1 metric ton of triclocarban to the environment. The authors agree that their findings also raise the question of whether triclocarban could be promoting antibiotic resistance in bacteria in the sludge or elsewhere in the environment.
Halden suggests that triclocarban’s antimicrobial properties give additional cause for concern, noting that the related compound triclosan has faced scrutiny since the late 1990s, when researchers first found that it could promote growth of resistant strains of bacteria. The conditions under which microbes encounter topical antiseptics like triclosan and triclocarban—at low concentrations, for extended periods of time—are considered the most likely to encourage resistance. But Stuart Levy, a professor at Tufts University and the president of the Alliance for the Prudent Use of Antibiotics, cautions: “With triclocarban, we don’t have any data of its relation to antibiotic resistance. So that makes this paper more speculative as to what [the residue might] do in the microbial world.”
The authors plan to continue their investigations into triclocarban, and they emphasize that many unanswered questions remain. “It’s kind of a detective story,” Halden says. “We noticed [triclocarban] in the streams, and we followed it to the wastewater treatment plant and see it’s not being degraded. We’re not at the end of the story.”
