Marketing appears to trump science on antibacterials

antibacterial soapStore shelves these days sag under the weight of antibacterial soaps, cosmetics, socks, toys and even garbage bags. There’s no question that “antibacterial” on a label increases sales, but there are plenty of questions about the wisdom of impregnating everything in sight with compounds that kill bacteria indiscriminately.

Triclosan has been the hot antibacterial ingredient in household products for about four decades. But it is now itself feeling the heat, due to concern about endocrine disruption, the promotion of antibiotic resistance and effects on aquatic ecosystems.

The state of Minnesota has already passed legislation to phase out triclosan except in a medical setting such as a hospital, and regulatory agencies around the world are considering doing the same. Companies such as Johnson & Johnson, Avon and Colgate-Palmolive are all planning to remove triclosan from their formulations. This raises the question of whether triclosan is to be replaced by some other antibacterial. “Quaternary ammonium compounds” are likely candidates, but they also come with baggage. Exposure has been linked to respiratory irritation, and more specifically the triggering or exacerbation of asthma.

It stands to reason that the use of any chemical should be based on a proper evaluation of risk vs. benefit, but such an evaluation is often problematic.

Triclosan was first registered as a pesticide in 1969 and it quickly found its way into the operating room as a surgical scrub to replace hexachlorophene. It was less toxic, more effective and more biodegradable; so the risks greatly outweighed the benefits. Triclosan also proved to be useful in protecting adhesives, plastics, caulking compounds, carpets, sealants and fabrics from attack by bacteria, fungi and mildew. There is no great issue here because any leaching from these products is minimal. However, the story is different when it comes to soaps, deodorants, shaving creams, cosmetics, dishwashing liquids and toothpaste, residues of which go down the drain. Here the risk-benefit ratio has been the subject of some bitter controversy.

A fear of bacteria is legitimate, although not of all bacteria. Most live happily in our body and on our skin without causing any harm. But indeed there are the pathogenic varieties that can cause a great deal of misery. Salmonella, listeria, campylobacter, streptococci, E. coli, staphylococci, botulinum clostridium and mycobacterium tuberculosis are worthy of dread, as they are responsible for hundreds of thousands of cases of illness every year — as well as a significant number of deaths.

Aside from toothpaste, while there is actual evidence that 0.3% triclosan can help reduce cavities, plaque formation and gum inflammation, there is no compelling evidence that the addition of triclosan to household products reduces bacterial illness. True, antibacterial soaps can be shown to reduce bacterial counts more than regular soap, but that is not the same as demonstrating a reduction in infections. Marketing seems to have trumped science here.

Another point is that many of the diseases germophobes worry about are caused by viruses unaffected by antibacterials. The viruses that cause the common cold, hepatitis and many gastro problems scoff at antibacterials. Triclosan may even cause mutations in some viruses, possibly enhancing the risk of viral infection. More importantly, ordinary soap works as well as antibacterial soaps in getting rid of bacteria as long as hands are properly washed, 15 seconds on each side.

The development of bacteria that are immune to antibiotics is a significant concern. Whether or not bacteria can become resistant to triclosan, and whether triclosan can induce resistance to other antibiotics, are hotly debated topics, as is the issue is what happens to all the triclosan that enters the environment from our array of antibacterial consumer products.

Waste water treatment does not eliminate triclosan. About four per cent is discharged into natural water systems, including those that supply our drinking water. And the rest remains in sewage sludge that often ends up being used as fertilizer. Here residual triclosan may interfere with the action of bacteria that help fix nitrogen, and it may even affect earthworms.

Some studies have shown that triclosan can react with the chlorine used to disinfect drinking water to form chloroform, an established carcinogen, and that under the influence of sunlight it can even form small amounts of the notorious dioxins. Then there is the matter of endocrine disruption, with concern being raised about triclosan’s chemical similarity to thyroid hormones and its potential disruption of hormone activity by binding to thyroid hormone receptor sites. This merits further investigation given that triclosan has been found in breast milk, meaning that it finds its way into the body.

Indeed the chemical is so widespread in the environment that it turns up in the urine of the majority of the North American population. Of course, detecting triclosan in the urine does not necessarily mean that we are at risk, although studies on mice and fish have shown a hindrance of heart-muscle contraction at doses that are not far from human exposure.

Finally, there is the hypothesis that our overuse of cleaning agents and antimicrobials may be disrupting the human biome, that collection of 100 trillion bacteria that inhabit our body, outnumbering human cells 10 to one. Some researchers believe that the increase being noted in the incidence of allergies, celiac disease, Crohn’s disease, diabetes, mood disorders, obesity and even autism is linked to a shift in the body’s microbial environment.

The industry line is that triclosan is a “thoroughly researched chemical that has been safely used for decades.”

That is actually a hollow argument because the “thorough” research did not focus on the kinds of subtle effects that are raising eyebrows, and “safe use” is based on lack of acute effects.

Indeed triclosan has no acute toxicity since its biological effect is based on the compound’s ability to block a key bacterial enzyme that humans do not possess. While no specific health or environmental consequence has been linked to the widespread use of triclosan, it is unlikely that we would be worse off if it were removed from products where its claimed effectiveness to reduce bacterial disease has not been backed up by evidence.

Our microbiome may even thank us.

 

Joe Schwarcz

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