SILVER SPRING, MD. — Several decades' worth of clinical data on antibacterial additives in home-use soaps and detergents has shown no benefit over plain soap and water in reducing infection, the Food and Drug Administration's advisory panel on nonprescription drugs found at its recent meeting.
Lacking such clear benefits, compounds such as triclosan and triclocarban pose unacceptable risks of environmental contamination and contribution to the evolution of antibiotic resistance, the panel unanimously concluded.
Evidence on the efficacy of alcohol-based gels and wipes was found to be similar (no more effective in reducing infection than soap and water). However, their utility in situations where water was not available, safe, or convenient—combined with their low risk of contributing to the development of resistant bacteria—was recognized by the panel, which recommended the products' continued use in defined circumstances.
A 1994 FDA decision said that antibacterial consumer products were deemed effective if they could meet the surrogate end point of decreasing bacterial load on the skin. Such a decrease was assumed to be clinically significant, according to the 1994 monograph.
However, subsequent, real-world clinical trials, though imperfect in design, have been unable to demonstrate a corresponding decrease in disease incidence or severity, compared with soap and water, for either respiratory or GI infections.
It was this question of efficacy of consumer antiseptic products that the FDA asked its advisory panel to address.
The panel heard presentations of clinical evidence regarding the benefits of consumer antiseptics from Steven Osborne, M.D., medical officer at FDA's Office of Nonprescription Products, and Allison E. Aiello, Ph.D., of the University of Michigan School of Public Health, Ann Arbor.
In eight studies from the literature, use of plain or unidentified soap and water reduced cases of diarrhea from 30% to 89% (median reduction 53%). In three studies comparing antiseptic soap with no soap in control groups, reductions in diarrhea with antiseptic soap ranged from 29% to 50%.
Furthermore, in five studies comparing antiseptic soaps with plain soap, there was no statistically significant difference shown for all infectious symptoms, the presenters said.
Stuart B. Levy, M.D., a professor at Tufts University, Boston, spoke on the products' contribution to bacterial resistance.
“What are we worried about?” he asked, “We are worried that an antibiotic can select this kind of mutant and make it resistant to biocides…. Or we could be using the biocides and select a mutant which now is resistant to antibiotics. We're not talking about just one [antibiotic]. We're talking about tetracycline, penicillin, fluoroquinalone, chloramphenicol.”
Such resistance can also develop to the biocides themselves, he added. “I'm not saying I don't see the need for biocides—I don't see that they are needed in consumer products.”
The impact of triclosan and triclocarban accumulation in the environment was discussed by Rolf U. Halden, Ph.D., of Johns Hopkins University, Baltimore.
In Baltimore area surface water samples, Dr. Halden and colleagues found triclocarban concentrations of 6,750 ng/L (Environ. Sci. Technol. 2005;39:1420–6).
According to Dr. Halden, his results suggest triclocarban is a previously unrecognized contaminant of U.S. water resources nationwide, probably in the top 10 in occurrence rates and in the top 20 in maximum concentration.
The amount of triclocarban contamination was markedly higher than the non-peer-reviewed numbers (240 ng/L) used by the Environmental Protection Agency to evaluate ecological and human health risks, he said. The predicted half-life of triclocarban ranged from less than a day in air to 540 days in sediment. Cooccurrence of triclosan was observed at all sites.
Dr. Halden questioned why manufacturers were still using vast quantities of chlorinated compounds that could migrate into the environment, given the dubious nature of chlorine chemistry in the previous history of pollutants.
Several presenters highlighted the importance of hand hygiene in preventing the transmission of infectious diseases and the effectiveness of antibacterial products in reducing or eliminating bacteria.
“Every 3 minutes, a child brings his/her hand to nose or mouth; every 60 seconds, a working adult touches as many as 30 objects…. Washing fomites with soap and water is not enough to prevent the spread of pathogens,” said Charles P. Gerba, Ph.D., of the University of Arizona, Tucson.
Handwashing after risk exposure is needed for home infection control, he said, adding that the data show that antiseptic products “decrease bacteria on the skin.”
The utility of antibacterial consumer products was stressed by the Cosmetic, Toiletry, and Fragrance Association (CTFA), which said “the benefits of topical OTC antimicrobial drug products clearly support the current proposed labeling indication (i.e., 'to decrease bacteria on skin') and provide consumers an effective means of controlling the risks of infection.”