The European Commission and the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) launched a consultation process on the preliminary opinion concerning the antibiotic resistance effects of biocides. The consultation is running until 30 November 2008.
Role of biocides evidenced
The worldwide increase of antibiotic resistance in bacterial pathogens and the accompanying treatment failures in human and animal infectious diseases are generating concerns. Therefore, in order to preserve the role of biocides in infection control and hygiene it is paramount to prevent the emergence of bacterial resistance and cross-resistance through their appropriate and prudent use. As a result, the European Commission asked the SCENIHR to assess the role of biocides in the occurrence of antibiotic-resistant bacteria.
In their answer, EU experts said there is evidence that biocides can trigger bacterial resistance, but add that more research needs to be done to see how extensive a problem this might be.
Widely used compounds
Biocides are used to control the growth of bacteria in a huge range of applications, from cosmetics and personal care products to laundry detergents, cleaning fluids, food and feed preservatives, and building materials. “However, the regular use of personal hygiene products (e.g. cosmetics, wipes), cleaning products, laundry detergents, pet disinfectants and general disinfectants are the major sources of exposure to biocides in home settings,” experts explain.
Triclosan in cosmetics
EU Directive 76/768/EEC (the so-called "Cosmetics Directive") lists 57 chemicals in Annex VI that are permitted, with the restrictions laid down in the Annex, for the use as preservatives (i.e. antimicrobial substances with biocidal functions) in cosmetic products. Triclosan is among the most commonly used. The largest amount of triclosan in cosmetics was found in products for dental hygiene, including toothpaste. Besides cosmetics, Triclosan is also used in cleaning products, paint, textiles and plastic products. However, according to a Danish study, cosmetics would be the largest contributor to the amount of triclosan on the market, as they constituted 99% of the totally reported amount in the survey.
Some mechanisms of resistance are common to both biocides and antibiotics. The selective pressure exerted by biocides may favour the expression and dissemination of these mechanisms of resistance.
“The most studied biocides, triclosan and quaternary ammonium compounds, are likely to contribute to maintaining selective pressure allowing the presence of mobile genetic elements harbouring specific genes involved in the resistance to biocides and antibiotics,” EU experts say. However, the lack of data on the other biocidal compounds prevents reaching a definitive answer as to their role in selecting for or maintaining bacterial antibiotic resistance. The existence of horizontal gene transfer, particularly associated with mobile genetic elements, is the most likely mechanism for selecting and increasing antibiotic resistance.
Further research needs
However, the SCENIHR notes that biocides are "invaluable compounds that provide society with numerous benefits", and that in order to preserve their role in infection control and hygiene, it is important to ensure their "appropriate and prudent use".
SCENIHR therefore recommends developing standard protocols for assessing antimicrobial resistance induced or selected by biocides with the aim to provide useful data for the development and use of biocidal products and for regulatory bodies
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