Public Release: 

Engineers Find Potential Health Risks From Water-Saving Shower Nozzles

University of Cincinnati

Cincinnati -- Environmental researchers in the University of Cincinnati College of Engineering have found that the same technology which lowers homeowner's water bills could potentially increase their risk of lung trouble.

Professor Pratim Biswas and his colleagues at the U.S. Environmental Protection Agency will present their findings about water-saving shower nozzles Thursday, Oct. 17 during the annual meeting of the American Association for Aerosol Research in Orlando, Florida. Biswas is also serving as the conference chairman. He said the nozzles do a good job at reducing water consumption, but there is a potential drawback.

"The way these nozzles are designed, the openings are smaller. As a result, the water comes out at a faster velocity, and the spray created is very different," said Biswas.

The makeup of the spray is important, because the size of the water droplets determines whether the spray particles can be inhaled deep into the lungs. The finer the particles, the greater the risk.

The risk can come from a number of factors. Chlorinated water typically contains many "volatile organic compounds" or VOCs. Many VOCs are potentially carcinogenic. The spray can stir up contaminants in the area, such as mildew spores. There is also a risk of contamination from microbes growing inside the water lines and especially inside the shower nozzle itself. The microbes grow in thin layers known as biofilms.

"Sometimes, the nozzles grow biofilms because they're always wet and the water is lukewarm," noted Biswas. "So, when you turn on the shower, the spray comes out and breaks pieces of the biofilm off." If the pieces are small enough to be inhaled, Biswas says there is a real health risk, especially for those with existing breathing problems such as asthma.

Biswas reports that there were significant differences among the three models of shower nozzles tested. One water-saver design produced a large number of inhalable particles. A second water- saver model and a conventional shower head did not. That means there is a good chance that design changes could solve the problem.

The overall goal of the UC-EPA research effort is to identify and reduce the risk from indoor air pollution. "It's not only showers. It's restrooms with toilets. There are a lot of indoor air problems. Buildings are typically closed circulation, so a bathroom down the hall might cause a problem in my office."

The collaborators on the project include University of Cincinnati alumnus Virenda Sethi, John Cicmanec and Robert Clark. All three are with the U.S. EPA's National Risk Management Laboratory in Cincinnati.

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