Your Survival Blog
Wednesday, April 14, 2010
So … your shower can kill you?
Pandemic flu. Anthrax. MRSA (the “flesh-eating bacteria"). These are a few of the pathogens well-off Westerners think about when they worry about superbugs that can kill them ... things they can catch from other people, either via contagion on an epidemic level or via bioterrorism.
Now comes the word that another source of superbugs is just as dangerous: the showerhead in your bathroom.
In July of 1976, attendees at an American Legion convention in Philadelphia were stricken by a mysterious illness dubbed by puzzled investigators “Legionnaire’s disease” — a pneumonia caused by a then-unknown bacterium, now known as Legionella — and many died. (Death rates can vary from 1% to 50%, depending on the initial health of those infected and how late antibiotic treatment is begun.)
I was a little too young to pay much attention at the time, but the American Legion illnesses — traced to a cooling tower feeding the hotel’s air-conditioning system — were the first well-known outbreak of a respiratory disease caused by aerosol infection: suspension of pathogens in mist. Other outbreaks have been linked to indoor fountains and whirlpools, hot tubs, hospital drinking-water systems — and showers.
And no, chlorinating the water doesn’t help. Hospitals have been battling Legionella in their plumbing since the bacteria was discovered, and one study of Texas hospitals with free chlorine (as opposed to monochloramine, a newer water-treatment method with less effectiveness against many other pathogens) in their water supplies found that they all had notable amounts of the bacteria. Headlines in the UK’s Daily Mail in 2006 told the story of a 37-year-old man in remission from leukemia, who died the day of his planned discharge from the Royal United Hospital in Bath — from an infected showerhead.
So the latest news (published just last September) is that showerheads in nine US cities contained layers of unexpected microbes, some of them potentially dangerous. The worst offender, identified in a fifth of the samples, was Mycobacterium avium. This is a bacterium linked to serious respiratory illness in people whose immune systems are compromised: chemotherapy patients (like the man who’d beat leukemia), people with AIDS, transplant patients — and elderly people, pregnant women, and anyone fighting off some other illness. If you have someone in one of these categories in your household, it’s a story worth paying attention to. (Healthy people usually don’t fall victim to this particular bug, but it has been known to happen.)
The initial blast of hot water from the showerhead — which many of us stand under, sometimes with face upturned — apparently contains the highest levels of bacteria, so the study authors suggested that anyone concerned might want to run the shower for a minute or two, while standing outside the bathroom, to disperse the bacteria before stepping in.
Most of the news stories I’ve seen (perhaps prodded by manufacturers of plumbing products?) suggest that the simplest things to do for families concerned about infectious showerheads are to swap them out every few months, and to substitute metal showerheads for metal-coated plastic. I’m now curious about their rationale, since one study of “biofilms” (layers of icky microbes) on various metal and plastic piping found the lowest levels on CPVC (a type of plastic) and the highest levels on copper; another found that PVC was better than iron. Perhaps the specific metals and plastics used in showerhead construction are the key.
Also, very little was mentioned about cleaning your showerhead.
Mycobacterium avium, unfortunately, is highly resistant to chemical disinfectants, but there are a few that work. An hour reading the medical journals shows that aldehydes (such as glutaraldehyde or the better-known formaldehyde), phenols, isopropanol, undiluted chlorine bleach, and peracetic acid (a combination of acetic acid — better known as vinegar — and hydrogen peroxide) have all been shown effective. So has boiling, though I’ve seen times as long as 30 minutes given. For me, now, the question is exactly what my showerheads are made of, and how much home chemistry experimentation I’m willing to do to clean them of nasty bugs.
A word of extreme caution: unless you know exactly what you are doing, never never ever mix disinfecting agents with each other. (Bleach + ammonia = deadly gas. Peracetic acid + some other chemicals = explosion. Bad juju!)
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