As a quick reminder, triclosan works by binding to the enoyl-acyl carrier protein reductase (ENR) and increasing its affinity for a co-enzyme. When ENR is clogged up, the bacteria is unable to create cell membranes. Since cell membranes are kinda important, the bacteria subsequently dies.
However, the fact that there is a mechanism by which triclosan is capable of killing bacteria does not indicate that triclosan provides a meaningful benefit over safe, environmentally-friendly alternatives. According to the FDA website, "For... consumer products [other than toothpaste, the] FDA has not received evidence that the triclosan provides an extra benefit to health. At this time, the agency does not have evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water."
The new rule would also require that manufacturers to provide additional safety data in order for triclosan to be considered "generally recognized as safe for use". Most concerning is the possibility that antibacterial agents like triclosan will contribute to bacterial resistance. When subpopulations of a larger bacterial population survive a dose of antibiotics, the remaining organisms are more likely to have antibacterial-resistant genes. Since these genes are highly likely to exist on plasmids, small DNA molecules that are separate from the cell's chromosomal DNA, these genes can actually be passed from bacteria to bacteria in a process called horizontal gene transfer. This means that if a single bacterial species develops antibacterial resistance, it can actually be passed from species to species.
As antibacterial agents become more commonly used, there is increased selective pressure on bacterial species. Thus, resistance evolves to become more and more common. If your hospital is relying on antibacterials like triclosan to keep patients safe, but every Tom, Dick, and Harry is using triclosan in their hand soap, this is a big concern. (The proposed rule would exempt hand sanitizers, hand wipes, and antibacterial soaps that are used in health care settings.)
The FDA is currently waiting as both consumers and experts weigh in on their triclosan-related opinions. In the meantime, don't forget to wash your hands.