CBS News medical correspondent Dr. Jennifer Ashton said on "The Early Show" Tuesday bacteria is all around us, and most don't harm us. But, in a University of Colorado at Boulder study released this week, researchers analyzed the different kinds of bacteria found growing inside shower heads, and they were surprised at what they found.
Dr. Norman Pace of the University of Colorado at Boulder, said, "The yuck factor is pretty high because so many of us are exposed to this."
Researchers at the University of Colorado at Boulder examined shower heads taken from nine different cities, they discovered that many contained a form of bacteria that can be dangerous.
Pace said the shower heads contained mycobacterium avium. He said 30 to 40 percent of the shower heads tested had high levels and 80 percent had detectible levels of the bacteria.
Mycobacterium avium, Ashton said, isn't considered to be harmful to most people, but researchers say exposure can be risky for anyone with a weakened immune system, including the elderly and some pregnant women.
Small amounts of mycobacterium avium are often found in tap water, Ashton said, adding the danger comes when it builds up in a shower head and then becomes airborne when the shower is turned on.
Dr. Charles Daley, of National Jewish Hospital in Denver, said the bacteria can cause lung disease.
Referring to the bacteria, he said, "It has certainly caused a lot of lung disease here in the United States."
Daley, who treats pulmonary diseases, said he once traced the source of a bacterial infection back to patient's home.
"We detected the same strain of mycobacterium in a patient as we found in their bathroom," he said, "including their shower head."
Ashton reported that experts say at the moment there's no effective way to prevent bacteria build up in shower heads and that more research is needed.
But Daley said, "Most people are not going to get sick from this organism. We're often asked, "Should I stop taking showers"' And the answer to that to date is really unknown."
Ashton added researchers interviewed by CBS News said they still take showers, but some change their showerheads once or twice a year.
Ashton says metal shower heads are thought to be more effective at reducing the buildup of so-called "bio-film." Also, she said people should run the water a couple of minutes before getting in, because some of the water washes out some of the bacteria. A low pressure spray is also a good idea, she said, because the bacteria won't be sprayed all over the shower. Bleach may not completely eradicate the bacteria, she said, and water that's too hot may pose a scalding risk.