Harmful bacteria from the genus Mycobacterium have been shown to linger in showerheads and lead to lung infections through inhalation of steam. University of Colorado researchers analyzed 656 biofilms coating the inside of showerheads sent to them by volunteers throughout the U.S. and Europe, and found twice as much mycobacterium in showerheads from households receiving municipal water than in those receiving well water. Chlorine disinfection methods were suspected by the researchers. Plastic showerheads had levels that were, on average, two times lower than showerheads made of metal or metal and plastic components. “Hot spots” with high levels of mycobacteria—such as Hawaii, southern California, Florida, the upper Midwest and the mid-Atlantic states—generally overlapped regions where mycobacterium-related lung diseases are most prevalent.

This article appears in the February 2019 issue of Natural Awakenings.