By Ashley Yeager
As a long-time swimmer, I was a bit disturbed when EPA scientist David DeMarini said he had scientific evidence showing that extra time in the water could damage my DNA or even raise my risk for bladder cancer.
The damage, he said, comes from leftover chemicals from the treatment process in which bromine and chlorine are used to kill E. coli and other bacteria in drinking, bath and swimming water.
There are at least 600 of these chemicals, called disinfection byproducts or DPBs, released into the water after treatment, and DeMarini has spent more than a decade identifying them and how they interact with the molecules in our bodies.
Through his research, he has shown that many of the DPBs, whether ingested, inhaled or absorbed through our skin, can change our DNA. Yet, only 11 DPBs, all from drinking water, are regulated in the U.S., and none are regulated in any of the other developed countries, DeMarini said during a Nov. 11 Integrated Toxicology & Environmental Health seminar at Duke.
No one really thought about pool water until about five years ago because “people always thought swimmers weren’t at risk for anything. They thought, ‘swimmers are healthy, so why waste our time studying them,’ ” DeMarini said.
That assumption changed in 2007. Researchers in Spain found, based on interviews, that swimmers had a 1.6-fold increase for bladder cancer. Then, in 2010, DeMarini and his colleagues showed that after a 40-minute workout, swimmers’ cells created micronuclei, suggesting damage was done to the DNA so that another nuclei formed as the cell began to divide.
Together, the teams were able to identify a specific gene that makes some individuals more susceptible to DNA damage from DPBs, further increasing their cancer risks. About 28 percent individuals in the U.S. have this gene.
That doesn’t mean we should stop swimming, bathing or drinking municipal water though, DeMarini stressed. He said that the known benefits of drinking, bathing with or swimming in chlorinated water are still much greater than the potential health risks from DPBs.
“You’re naïve, though, if you think that the environment you live in is pristine,” he said. “It’s not.”
But to keep pools a little cleaner and reduce the burden of disinfection byproducts, he suggested not peeing in the water and showering before taking a dip. Drinking pool water is not a good idea either.