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April 15, 2005

Researchers & Industry Argue Over Safety of Antibacterial Agent Triclosan

I've strongly supported handwashing with regular soap, and simple disinfectants like chlorine bleach to kill household germs. However, the escape of antibiotic-resistant superbugs like MRSA from hospitals into the general community is making a case for greater use of antibacterial products in daily life (more on this below).

Of course, as there are profits to be made from the sale of such products, we will begin to see more such products come to market in order to meet a real or perceived need for protection against harmful microbes. And there will be powerful advocacy of these products' use in as many situations as possible, and strong statements made about their usefulness and safety. (Update 16 Apr 05: Here's an amusing article on this very point from the Washington Post.)

Case in point: a kerfuffle has arisen over the use of triclosan, an antibacterial agent found in many products (from household soaps to Brian Bennett's MRSA-killing hand cream).

A research team from Virginia Tech, led by Peter Vikesland, has published findings that triclosan-containing products reacts with chlorine in ordinary tap water, releasing chloroform. This led to a press release from Virginia Tech, provocatively titled, "Being too clean could be hazardous to your health and the environment." The release contains the following:
Vikesland and his associates have conducted research closely mimicking conditions found when washing dishes in the home. The results show that it is possible that the chloroform produced when the antimicrobial soap containing triclosan mixes with chlorinated water could be absorbed through your skin or inhaled. Vikesland's research is funded by the American Water Works Association Research Foundation (AWWARF) and by a National Science Foundation (NSF) graduate research fellowship to Krista Rule, the lead student on the project.

Most of the consumer products that contain triclosan eventually end up being discharged down residential drains. It has previously been shown by researchers from the University of Minnesota that the photochemical reactions of triclosan could be producing dioxins in the presence of sunlight. Dioxins do not degrade over time and they can accumulate in body tissues to cause a greater effect. Even low levels of dioxin are a problem because of their tendency to accumulate along the food chain.

This news generated articles in the consumer-health media, with titles like "Antimicrobial Soaps May Harm Your Health."

Now the cleaning-products industry, under the leadership of The Soap and Detergent Association, is fighting back, with their own press release titled "Antibacterial Research Should Be Focused on Facts, Not Fear." The SDA says the media followup to Vikesland's findings "are more about hype and headlines than real-world science," and make some good points (my summaries and analysis):

1. the amount of chlorine in city water supplies is so far below the concentrations used in Vikesland's research, that it's unlikely any chloroform would be released.

2. Regarding the issue of chlorine-containing cleaning products, their labels already instruct the user not to mix them with other types of cleaners (which might release deadly chlorine gas).

3. Triclosan has been used for over 30 years around the world, under regulation by health authorities.

4. The seriousness of MRSA-related infections argues for the use of antibacterial soaps.

As I noted above, I'm beginning to see some merit in this final point. If MRSA does become a daily-life hazard in the coming years, it seems to me the argument against using antibacterial soaps (that bacteria will eventually develop resistance to the antibacterial compounds) is less important than avoiding a life-threatening infection.

The problem, though, is the tendency for industry to put chemicals like triclosan in everything possible, rather than restricting them to more sensible applications. For instance, do we need triclosan in soaps that we use for everyday hand- and body-washing? Or imbedded in the fibers of sports towels? Probably not. But if I've been digging in the garden, gotten a deep cut on my hand or foot, or just visited a busy gym or the doctor's office, I would definitely want to use a germ-killing soap to clean up afterward. Even a year ago, I wouldn't have thought such a step was necessary, but with the breakout of MRSA into the general community, it appears the rules are changing quickly.

Even for general household cleanup, however, I think it's overkill to use triclosan in dishwashing soap or bathroom cleaners. The simple, diluted-bleach solution (not mixed with other cleaners, of course!) is cheap and effective against bacteria.

3 Comments:

At 6/01/2005 11:54 AM, Blogger Paul said...

The big concern among microbiologists has been, and still is, the possibility of resistance. Chlorine resistance has been well documented (and responsible for a few deaths, by way of fecal coliform contamination of chlorinated pools). A pubmed search on "triclosan resistance" yields results indicating Salmonella (GI pathogen) and Pseudomonas (resp. pathogen) that have demonstrated resistance to this agent (in the laboratory). If we look back at the literature from the early 1950s, we can see similar results for methicillin resistance in Staph, a prelude to our current situation.

What's the solution? Sadly, I have no idea. Overuse accelerates the decline of chemical antibacterials, but "perfect" use only delays the inevitable rise of resistance.

As for MRSA, the scary thing, imho, is the arrival of MRSA that cause necrotizing fasciitis (flesh eating bacteria, previously almost always Group A Strep, susceptible to most antibiotics).

 
At 6/01/2005 10:25 PM, Anonymous BZ MD said...

To see just how involved this can get, see the document published by the Center For Disease Control and Prevention (CDC) at www.cdc.gov/mmwr/preview/mmwrhtml/rr5116a1.htm. This is an extensive review with recommendations about how to wash your hands; seemingly a simple subject, but actually complex. The best recommendation is to...wash your hands. What you wash with is less important. Even simple soap will solve most of the problems by just removing visible soil and contamination. For actual decontamination (germ-killing), the simplest solution is something containing at least 60% ethanol (grain alcohol; not isopropyl rubbing alcohol). Commecial preparations include Dial and Purell "hand sanitizers." Many hospitals in the US are moving away from antimicrobial soaps and towards ethanol-based solutions for hand cleansing. The most important thing is...WASH!

 
At 6/03/2005 9:23 AM, Blogger Don said...

BZ MD, I can't agree more with your call for handwashing and the use of alcohol-based hand rubs.

Paul, resistance to antibacterial compounds is already developing in MRSA: see this article summarized at MRSA Watch:
http://tahilla.typepad.com/mrsawatch/2005/06/some_mrsa_strai.html

 

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