DBPs form from reactions between disinfectants and organic matter. Previous studies have found an association between DBPs in drinking water and bladder cancer.
The new study looked at close to 50 healthy adults after they swam for 40 minutes in the chlorinated pool. The researchers found increases in two genotoxicity biomarkers associated with cancer risk.
“… the authors identified more than 100 DBPs in the pool waters, some never reported previously in swimming pool water and/or chlorinated drinking water. In vitro assays showed that the swimming pool water was mutagenic at levels similar to that of drinking water but was more cytotoxic (can kill cells at a lower concentration) than drinking water.”
Swimming is an incredible form of exercise and recreation, but if you perform it in a chlorinated swimming pool, especially one that’s indoors, you could be putting your future health at risk.
The risk comes from disinfection byproducts (DBPs), which are formed when organic materials like hair, skin, sweat, dirt and urine react with the large amounts of chlorine used to sanitize the pool water.
DBPs are over 1,000 times more toxic than the chlorine itself, and in the first study of its kind to examine exactly what kind of damage these toxins are doing to swimmers, the results were alarming.
Swimming for Just 40 Minutes May Result in Cancer-Causing DNA Damage
Researchers measured evidence of genotoxic (DNA damage that may lead to cancer) and respiratory effects on swimmers who swam in a chlorinated pool for 40 minutes. They found:
- Increased micronuclei in blood lymphocytes, which are associated with cancer risk
- Urine mutagenicity, a biomarker of exposure to genotoxic agents
- An increase in serum CC16, which suggests an increase in lung epithelium permeability
In all, more than 100 DBPs were identified in the pool water, and the researchers noted that tests showed the levels was similarly mutagenic to drinking water but able to kill cells at a lower concentration.
The results may make you think twice if you’re a frequent indoor swimmer, as this could be a source of toxin exposure that could significantly increase your risk of cancer.
Already, it’s known that trihalomethanes (THMs), one of the most common DBPs, are Cancer Group B carcinogens, meaning they’ve been shown to cause cancer in laboratory animals. They’ve also been linked to reproductive problems in both animals and humans, such as spontaneous abortion, stillbirths, and congenital malformations, even at lower levels.
These types of DBPs can also:
- Weaken your immune system
- Disrupt your central nervous system
- Damage your cardiovascular system
- Disrupt your renal system
- Cause respiratory problems
Again, this is a serious issue if you swim in chlorinated pools on a regular basis, as your body absorbs higher levels of DBPs by swimming in a chlorinated pool once than you would by drinking tap water for one week!
How Chlorinated Pools May Cause Cancer and Other Health Problems
DBPs are extremely toxic, and when you swim in a chlorinated pool you’re exposed on multiple levels.
According to one study published in the Journal of Environmental Sciences, the cancer risk of THMs from various routes in descending order was:
- Skin exposure while swimming
- Gastro-intestinal exposure from tap water intake
- Skin exposure to tap water
- Gastro-intestinal exposure while swimming
The cancer risk from skin exposure while swimming comprised over 94 percent of the total cancer risk resulting from being exposed to THMs!
The authors even went so far as to conclude that swimming in a chlorinated pool presents “an unacceptable cancer risk.”
As an aside, DBPs are also the likely culprits for the increased incidence of sinusitis and sore throats among swimming instructors, as well as the negative impact of chlorinated pools on the respiratory health of children and adolescents. In fact, one study found that in children with allergic sensitivities, swimming in chlorinated pools significantly increased the likelihood of asthma and respiratory allergies.
How to Avoid DBPs
The most obvious option is to avoid swimming in chlorinated swimming pools, as this will greatly cut down on your exposure.
This doesn’t necessarily mean you have to give up swimming. Swimming in an ocean is an excellent alternative, as is swimming in a lake or other natural body of water. You can also find a way to keep your pool clean from bacteria, algae, and other organisms without the use of dangerous chemicals.
One of the best solutions is NOT to chlorinate your pool and just use a maintenance “shock” treatment every five or six days, which will kill the algae buildup. The shock treatment volatilizes in about 24-48 hours and gives you a several day window in which you can safely use your pool.
You can also reduce the amount of organic material you bring into the pool, and thereby the amount of DBPs created, by showering prior to entering and teaching your children not to urinate in the water.
Beyond your swimming pool, you’ll also need to address other sources of DBPs, such as your tap water, including the water you use to shower and bathe.
Out of all the other toxins and contaminations present in your water, such as fluoride and miscellaneous pharmaceutical drugs, DBPs may be the absolute worst of the bunch.
But, not all water filtration systems are capable of filtering out DBPs. In fact, there is currently no point-of-entry, whole-house water filtration system that is certified to filter out these toxins.
So you’ll need separate filters to cover both your shower and your kitchen tap, and you must look for those that remove chlorine along with other contaminants. Do not settle for anything less, as filters that do not remove chlorine are actually NOT protecting you and your family from DBPs.
It’s important to filter both sources, but if you’re only going to choose one, most people will mistakenly choose to filter their drinking water. Again, it’s important to filter your drinking water for a number of reasons, but in terms of DBPs the biggest risk comes from your shower (or your pool).
You can easily absorb as many toxins in one shower (or swim) as you would by drinking tap water all week long, so be sure you recognize this common source of exposure.