September 16, 2009
Weekly News UpdateUniversity of Colorado-Boulder Study Finds Some Showers Deliver a Blast of Pathogens
Research led by Dr. Norman Pace, a Distinguished Professor in the Department of Molecular, Cellular and Developmental Biology at the University of Colorado at Boulder, indicates that showerheads are home to a soupy mix (also called a "bio-film") of pathogenic bacteria. In their study, the scientists analyzed the bacterial content of 50 showerheads located in apartment buildings, homes, and public places. The research was conducted across the United States in nine different cities located in seven different states, including Colorado, North Dakota, Illinois, and New York. In their analysis, the researchers found that 30 percent of the tested showerheads contained a significant quantity of the pathogen Mycobacterium avium, a bacteria implicated in certain types of lung disease.
M. avium subspecies (rod-shaped bacteria stained red). (Photo credit: CDC/ Dr. Edwin P. Ewing, Jr.)
To determine the identities of bacteria living in the showerheads, the scientists collected bacterial samples, isolated DNA from the samples, and used the polymerase chain reaction (PCR) method to identify bacterial species. In addition, the scientists took apart some of the showerheads and used a scanning electron microscope to analyze the showerhead's surface in detail.
According to the researchers, the presence of M. avium and other pathogens in shower water should not be a major cause for concern for most people. Only those with compromised immune systems, such as the elderly, pregnant women, or those with chronic diseases, are particularly vulnerable to M. avium. Common symptoms related to an M. avium infection include shortness of breath, weakness, tiredness, and a dry cough that does not go away.
However, the scientists did provide two suggestions as to how to decrease your exposure to pathogens that may live in your showerhead. First, they suggest allowing the water to run for a few seconds before entering the shower, as the first blast of water from the showerhead typically contains the most pathogens. Also, the scientists suggest switching from a plastic showerhead to a metal showerhead, as they found that metal showerheads commonly harbor fewer bacteria than those made of plastic.
The results of the scientists' research was published online in the September 14, 2009 edition of the journal Proceedings of the National Academy of Sciences. In addition to Dr. Pace, other researchers who contributed to the study included Leah Feazel, Laura Baumgartner, and Kristin Peterson of CU-Boulder and Kirk Harris of the University of Colorado at Denver.