The University of South Carolina's recently released study contains findings of interest for aquatics professionals. New disinfection byproducts in hot tub and pool water were discovered, as well as some health impacts on people, according to its authors.

The latest study adds knowledge about DBPs to that which has been gained by researchers over the decades. It was published in the American Chemical Society’s magazine, Environmental Science & Technology, and is called “Progressive Increase in Disinfection Byproducts and Mutagenicity from Source to Tap to Swimming Pool and Spa Water: Impact of Human Inputs.”

Susan D. Richardson
Susan D. Richardson

A team led by University of South Carolina chemistry professor Susan D. Richardson analyzed 28 water samples from indoor and outdoor spas and pools, commercial and private, from seven locations in the U.S. where chlorine, bromine, ozone or ozone-chlorine were used. The samples were taken and compared after high usage and low usage of the vessels.

The team, which worked with David DeMarini, a genetic toxicologist at the U.S. Environmental Protection Agency, had several goals in mind. “We wanted to see if there’s an increase in DBPs and mutagenicity from human inputs,” Richardson said. “And we wanted to see the effects from (bodily fluids) and compare different DBPs — chlorinated vs. brominated vs. ozonated, and private vs. public pools and spas. Especially, what’s in the spa water?”

What they found were 100 DBPs, at least 50 of which are new. That includes a new class: bromoimidazoles. Identified in brominated pool and spa water, they are expected to be found toxic. “Bromoimidazoles are not seen in drinking water,” Richardson noted. “It’s pretty likely they may be coming from urine constituents reacting with pool water ... or it could be pharmaceuticals or skin-care products.”

Though studies by others have drawn conclusions about the potential health effects of pool and spa DBPs and their interaction with bodily fluids, this team said its research is the first to examine the mutagenicity — or ability to change one’s DNA — of spa water, and to evaluate source water for comparison. The University of South Carolina team tracked mutagenicity of water from the tap through to interaction with swimmers in pools and spas.

The study compared mutagenicity between pools and spas and among different sanitizers. When brominated pool/spa water samples were studied, they were found to be 1.8 times more mutagenic than chlorinated ones; spa water was 1.7 times more mutagenic than pool water. And pool and spa samples were 2.4 and 4.1 times more mutagenic, respectively, than corresponding tap water.

Over the next three or four months, the team will dig deeper, analyzing the study to see if there are more correlations and impacts from the DBPs. A draft of the findings will be released by DeMarini and Richardson.