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Showerheads Are Spraying Harmful Bacteria

September 15, 2009

A disturbing new study has found that the showers people enjoy everyday are actually spraying them with bacteria.

This news should not necessarily strike fear in those with normal immune systems, but such microbes could be a problem for those suffering from cystic fibrosis or AIDS, people who are undergoing cancer treatment or those who have had a recent organ transplant.

Researchers at the University of Colorado tested 45 showers in five different states as part of a larger study of the microbiology of air and water in homes, schools and public facilities. They found that about 30 percent of the devices harbored significant levels of the dangerous bacteria.

The team reported that some of the bacteria and related pathogens were grouping together in slimy “biofilms” that stuck to the inside of showerheads at more than 100 times the “background” levels of municipal water.

“If you are getting a face full of water when you first turn your shower on, that means you are probably getting a particularly high load…which may not be too healthy,” said lead author Norman R. Pace.

Their findings were published in Tuesday’s edition of Proceedings of the National Academy of Sciences.

When asked if showers should be considered dangerous, Pace said, “Probably not, if your immune system is not compromised in some way.”

“But it’s like anything else “” there is a risk associated with it.”

For those who are still not comforted, the researchers suggest getting all-metal showerheads, which make it more difficult for microbes to cling to it.

Even so, showerheads are full of hiding places for the bacteria and are difficult to clean. The researchers say that the microbes return even after being cleaned with bleach.

Those with filtered showerheads could replace the filter weekly, added co-author Laura K. Baumgartner. She added that baths do not splash microbes into the air like showers, which spray them into breathable aerosol form.

The bacteria that the researchers were finding are Mycobacterium avium, which have been linked to lung disease in some people.

Studies by the National Jewish Hospital in Denver indicate increases in pulmonary infections in the United States within recent decades resulting from species like M. avium might have something to do with people taking more showers and fewer baths, according to Pace.

He said that symptoms of infection can include tiredness, a persistent, dry cough, shortness of breath, weakness and “generally feeling bad.”

The researchers took samples from showerheads in houses, apartment buildings and public places in New York, Illinois, Colorado, Tennessee and North Dakota.

They sampled water flowing from the showerheads, then removed them and swabbed the inside of the devices and even separately sampled the water flowing from the pipes without the showerheads.

They were then able to determine which bacteria were living there by examining the DNA of the individual samples.

They discovered that the bacteria had built up in the showerhead, where they were much more common than in the incoming feed water.

The majority of the samples were taken from municipal water systems in cities such as New York and Denver, but the team also looked at showerheads in four rural homes supplied by private wells. Though they found other kinds of bacteria in those showerheads, there were no M. avium present.

The same research team has found M. avium in soap scum on vinyl shower curtains and above the water surface of warm therapy pools in previous studies.

Funding for the research came from the Alfred P. Sloan Foundation and the National Institute of Occupational Safety and Health.

The discovery was well received by Virginia Tech microbiologist Joseph O. Falkinham, who said M. avium can be dangerous considering the fact that it is aerosolized and therefore can be inhaled.

The bacteria could pose problems for more than just those with compromised immune systems, according to Falkinham, who cited studies showing increased M. avium infections in slender, elderly people who have a single gene for cystic fibrosis, without having the actual disease.

“There are lessons to be learned here in terms of how we handle and monitor water,” said Pace. “Water monitoring in this country is frankly archaic. The tools now exist to monitor it far more accurately and far less expensively that what is routinely being done today.”

The National Academy of Sciences awarded Pace the Selman Waxman Award in 2001, considered the nations highest award in microbiology, for pioneering the molecular genetic techniques he now uses to quickly detect, identify and classify microbe species by using nucleic acid technology without the need for lab cultivation. He was also awarded a MacArthur Foundation “genius grant” for his work that same year.

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