Vincent LaBombardi, the director of microbiology at New York's Mount Sinai Medical Center, tells PM, "you shouldn't be ripping out the pipes over this." LaBombardi says that exposure to Mycobacterium avium--the scapegoat microorganism in the toxic shower head scare prompted by a recent University of Colorado study--is quite common. "You've all been `infected,' so to speak," with the organism LaBombardi refers to by the nickname "mac." A normal individual inhales mac all the time, LaBombardi says. "Mac is just not that big a deal. I'm not going to lose any sleep over shower heads contaminated with mac."
Yet microbiologist Norman Pace, author of the study, calls mac a "lurking iceberg" in our society. His study states that people most at risk are those with compromised immune systems, or, as he put it in a telephone interview, "People with AIDS or opiate drug addicts" (though the population of immuno-compromised people is not quite so narrow and includes the elderly or anyone taking immunosuppressant drugs for diseases such as lupus or rheumatoid arthritis). Pace added that, anecdotally, it appears plastic shower heads harbor more bacteria than shower heads that are made from metal. "I've seen some plastic shower heads that are really bad, just drooling," Pace says.
The remedy suggested by Lars Christensen, senior product manager at Hansgrohe, a company that makes high-end shower heads, sounds a lot like a normal shower. "I think the best thing to do would be to flush the system with hot water," Christensen says. The study describes the highest mac exposure as occurring if you get a face full of water when you first turn the shower on. "Most people turn it on, let it run, then it gets hot," Christensen says. He suggested that by turning on the hot water only, allowing it to fully heat, then turning on the cold valve moments before stepping in, one might minimize the risks.
Hansgrohe notes that virtually all shower heads contain plastic parts, so attempting to avoid them entirely isn't a good solution. Higher-end Hansgrohe models might contain metal casings, but between silicone nozzles and ABS body parts, "the water contact, 95 percent of the time, is against plastic," Christensen says. Kohler's Mirjam Luppuner Konsek adds that older pre-plastic shower heads tend to clog up with calcified deposits, and that all-metal shower heads are "extremely heavy and expensive, and would not enhance the flow experience."
As might be expected, both Kohler and Hansgrohe call the coverage an overreaction, saying that the group affected appears to be marginal. LaBombardi agrees. "If you're immuno-compromised, even in the hospital, you shouldn't be taking a shower, period," he says. "I'm not saying mac will never cause infection, because in certain situations it will. But if you turn on the tap water, you have loads of organisms in there. You drink mac, it doesn't cause problems. We've all been exposed to this. I'm not going to get hysterical about it at all."