Shower heads 'harbour dangerous bacteria'

In what may be the scariest shower news since Alfred Hitchcock's "Psycho," a study says shower heads can harbor tiny bacteria that come spraying into your face when you wash.

People with normal immune systems have little to fear, but these microbes could be a concern for folks with 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 states as part of a larger study of the microbiology of air and water in homes, schools and public buildings. They report their shower findings in Tuesday's edition of Proceedings of the National Academy of Sciences.

In general, is it dangerous to take showers? "Probably not, if your immune system is not compromised in some way," lead author Norman R. Pace says. "But it's like anything else — there is a risk associated with it."

The researchers offer suggestions for the wary, such as getting all-metal shower heads, which microbes have a harder time clinging to.

Still, shower heads are full of nooks and crannies, making them hard to clean, the researchers note, and the microbes come back even after treatment with bleach.

People who have filtered shower heads could replace the filter weekly, added co-author Laura K. Baumgartner. And, she said, baths don't splash microbes into the air as much as showers, which blast them into easily inhaled aerosol form.

It doesn't seem as frightening as the famous murder-in-the-shower scene in Hitchcock's classic 1960 movie. But it's something to be reckoned with all the same.

The bugs in question are Mycobacterium avium, which have been linked to lung disease in some people.

Indeed, studies by the National Jewish Hospital in Denver suggest increases in pulmonary infections in the United States in recent decades from species like M. avium may be linked to people taking more showers and fewer baths, according to Pace.

Symptoms of infection can include tiredness, a persistent, dry cough, shortness of breath, weakness and "generally feeling bad," he said.

Shower heads were sampled at houses, apartment buildings and public places in New York, Illinois, Colorado, Tennessee and North Dakota.

The researchers sampled water flowing from the shower heads, then removed them, swabbed the interiors of the devices and separately sampled water flowing from the pipes without the shower heads.

By studying the DNA of the samples they were able to determine which bacteria were present.

They found that the bacteria tended to build up in the shower head, where they were much more common than in the incoming feed water.

Most of the water samples came from municipal water systems in cities such as New York and Denver, but the team also looked at shower heads in four rural homes supplied by private wells. No M. avium were found in those shower heads, though some other bacteria were.

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

And stay tuned. Other studies under way by Pace's team include analyses of air in New York subways, hospital waiting rooms, office buildings and homeless shelters.

The research was funded by the Alfred P. Sloan Foundation and the National Institute of Occupational Safety and Health.

Virginia Tech microbiologist Joseph O. Falkinham welcomed the findings, saying M. avium can be a danger because in a shower "the organism is aerosolized where you can inhale it."

In addition to people with weakened immune systems, Falkinham also cited studies showing increased M. avium infections in slender, elderly people who have a single gene for cystic fibrosis, but not the disease itself.

Two copies of the gene are needed to get cystic fibrosis, but having just one copy may result in increased vulnerability to M. avium infection as people age, said Falkinham, who was not part of Pace's research team

Killer sandwich: ham linked to cancer

Killer sandwich: ham linked to cancer

They might seem a harmless lunchtime filler but ham, salami and devon are on the World Cancer Research Fund's hit list.

The cancer charity says eating processed meat is linked to bowel cancer in adults and it is now calling on parents to teach healthy food habits early.

The charity's Lisa Cooney says it is recommending parents do not give their children more than 70 grams of processed meat a week.

That is the equivalent of two ham sandwiches, or three thin rashes of bacon.

"There's convincing scientific evidence linking the consumption of processed meats like ham, salami and bacon to an increase in bowel cancer risk," Ms Cooney said.

"And we also know that the habits we develop during childhood can follow us through to adulthood. So parents have a really wonderful opportunity to help promote really healthy habits in their children."

Ms Cooney says the dangers may lie in the processing stage.

"Researchers aren't yet entirely sure themselves and are still trying to figure out the actual mechanisms, but ... what we think is the process of processing and the things that are added to typically red meat, say for example when things are cured or salted or with the addition of chemical preservatives, lead to the development of cancer," she said.

"But what we are clear on is that people who consume processed meat are at a greater risk of developing bowel cancer."

Meating the addiction

Nutritionist Dr Rosemary Stanton says processed meats can become addictive.

"If you are going to start looking at what you put on sandwiches, most people put about 35 grams or so on a sandwich," she said.

"So two ham sandwiches a week, if you didn't have any other processed meat, wouldn't be such a big problem.

"But if your kids or anyone else gets addicted to ham sandwiches every day they're going to go way over that by the end of the week."

Dr Stanton says there does appear to be a link between bowel cancer and increased consumption of processed meat.

"The link is actually convincing and it comes from lots of studies on lots of people," she said.

"The link is also there for fresh meat.

"These are big important studies. This is not somebody looking at 200 people, these are millions of people when you add up all of the studies and they're all showing the same thing."

But Meat and Livestock Australia general manager David Thomason says other studies refute such findings.

"There are some studies that show that there is a slight, and I emphasise the word slight, increase in cancer risk associated with that, but then other studies don't' support that," he said.

"The most recent work which has been done by a research in the United States, Dr Dominic Alexander, has found in fact there is no statistical association between the two."

He says it is important to take the World Cancer Fund's warning in context.

"This report, which came out of the United Kingdom, is based on European food consumption patterns," he said.

"Australians eat meat and processed meat very differently and in very different quantities to people in Europe.

"Most meat consumption in mainland Europe is based around preserved pork products. In Australia we do consume ham and bacon and what have you, but it's in far more modest quantities."

Defending devon

Consumers are not so sure about the latest warnings.

"I'm not sure about kids but I know that I like more than two serves a week, so I'm going to have to think about that," one woman said.

"You know, protecting the children from meats isn't really going to stop anything happening to them," another customer said.

"We all grew up eating processed meats, microwave food."

Another consumer maintains eating processed meats, which she has eaten since she was young, has never harmed her.

"I mean pigs in blankets, is that right? Where they had the mash potato in the middle? Fantastic!"

"You know you don't see people dropping dead all over the place in Italy. They're going for the salami, there's no national crisis there," another said.