Swim for Your Life

The official start of summer is right around the corner — and chances are the long hot days will find you and your family at the pool as often as possible.

A new study, however, offers a vivid reminder of why health officials request you shower before you dive in.

Pool and hot tub samples were 2.4 and 4.1 times more mutagenic, respectively, than the original tap water used to fill them.

Scientists have found that the more pools and hot tubs are used, the more they contain potentially harmful compounds that could cause health problems for you and your family.

Disinfectants such as chlorine, bromine, and ozone kill pathogens in hot tubs and swimming pools, whether the facilities are personal or public. The problem is, these disinfectants also react with sweat, lotions, urine, and other substances that almost every single pool user adds to the water — resulting in what are called disinfection byproducts (DBPs).

Testing has shown that these DBPs can cause genetic damage to cells in lab settings.

“It’s not the disinfectants themselves that are the problem. It’s the disinfection byproducts that are formed when they react with organic matter. No one has ever looked at this progression from source, to tap, to pool, to spas — seeing the impacts of human precursors,” Susan Richardson, an environmental chemist and professor of chemistry with the University of South Carolina, told LifeZette.

Richardson’s team sampled water from public and private hot tubs and pools from tap to basin, after both normal and intense use. They identified more than 100 DBPs in the water and tested extracts of the samples for their potential to cause genetic damage to cells in the lab.

On average, pool and hot tub samples were 2.4 and 4.1 times more mutagenic, respectively, than the original tap water used to fill them. Mutagenicity is often a predictor of carcinogenicity, Richardson said.

“Everything in moderation. I would say your casual swimmer probably isn’t going to have any trouble.”

“In a public swimming pool, studies show that each swimmer contributes about 70 ml of urine on average. Urine has shown to react very easily with chlorine to form something called trichloramine. Trichloramine is the suspected chemical in the cases of asthma observed in swimmers. There is the potential for bladder cancer as well, but we don’t yet know which DBPs are responsible,” she said.

Richardson said she hopes the new research published this week in Environmental Science & Technology creates an awareness there are potential risks.

“I think swimming is great exercise. My sense on this is, everything in moderation. I would say your casual swimmer probably isn’t going to have any trouble. They don’t see asthma in casual swimmers. They see it in swimmers who spend hours every day, especially Olympic swimmers from different countries, the people who spend a lot of time in the pool — that’s where my concern would be.”

Pool and hot tub operators, meanwhile, can reduce the risk for DBPs by cleaning facilities and changing water more frequently. Where hot tubs are concerned, Richardson said ozone and chlorine appear to be better options than bromine.

“With private spas, bromine is what people usually use because it doesn’t give off the bad fumes that chlorine does. But the brominated DBPs are much more mutagenic, and more carcinogenic, so it may not be the best choice because of that,” Richardson said.

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“I don’t want to ruin it for everybody. Getting in the hot tub occasionally is just fine. But if I had one at my house, I’d probably get one of these silver impregnated filters, which don’t produce DBPs, or use chlorine — that won’t give you as many fumes and you’ll still get the disinfection. There may just be safer ways of doing it.”