If you long for those summers of youth spent splashing in pools, here’s something to deflate your nostalgia. A new study has found a powerful link between time children spend in outdoor chlorinated pools and the development of asthma. The study, out of Catholic University of Louvain in Belgium, tested 847 teenagers. The researchers found that even after controlling for other factors such as exposure to smoking and pollution, the subjects who had spent the most time in outdoor pools as children had by far the highest incidence of asthma. In fact, those who swam once a week over a ten-year period had five times the rate of asthma compared to those who had stayed out of pools. The more time kids spent in pools, the greater the chance that they would develop asthma. The researchers also found that swimming in pools before the age of seven led to an increased rate of cat and dust allergies.
The link between asthma and chlorine has been known for some time, but until now, scientists thought that outdoor pools were relatively safe. They had assumed that chlorine evaporated when exposed to the air, as compared to indoor pools, where chlorine fumes would be trapped. And so, earlier studies focused on indoor pools. The same research team found, in 2006, that chlorine in indoor pools raised asthma risk by two to three times, and that exposure to chlorine damaged the lung epithelium in children. In fact, the lung damage sustained by children who spent an average of 1.8 hours weekly in pools was equivalent to that experienced by heavy smokers. And the kids in the study averaged age 10!
Now this new study shows that outdoor pools offer no safe harbor and that chlorine vapors actually remain on the water’s surface instead of evaporating. According to study director Alfred Bernard, “We see that the risk of the outdoor pool is equal and even higher than indoor pools because children tend to spend longer in outdoor pools and they are more chlorinated.”
Certainly concerns about the chlorine-asthma connection should carry weight, given that the rate of asthma has increased by more than 50 percent in developed countries in the last 25 years, with about 150 million people in the world suffering from the condition. But chlorine causes more health problems than asthma alone. A study earlier this year found that chlorine in drinking water doubles the risk of birth defects. Chlorine can cause skin and sinus irritations, and it can lead to loss of weight in body organs. But most significant of all, it’s one of the most vicious carcinogens out there.
As I wrote way back in 1999, in Lessons from the Miracle Doctors, “According to the U.S. Council on Environmental Quality, the cancer risk among people drinking chlorinated water is 93% higher than among those whose water does not contain chlorine. There is a higher incidence of cancer of the esophagus, rectum, breast, and larynx and a higher incidence of Hodgkin’s disease among those drinking chlorinated water.”
Basically, while chlorine may work as a disinfectant — its benefits are at least somewhat compromised by the fact that it’s simultaneously a potent poison. (Check this page on how to treat chlorine poisoning.) And unfortunately, it’s a poison that’s omnipresent in our environment. At least you can choose to stay out of swimming pools — but chlorine is still added to 98 percent of the US public drinking water supply. Most of us get a daily dose of chlorine through drinking tap water or hot beverages made with tap water, through showering (we absorb more chlorine into our bodies from taking a 15-minute shower than we do from drinking eight glasses of chlorinated water), and from using cleaning products containing chlorine bleach.
Look, chlorine is here to stay. It prevents the spread of diseases such as cholera. But that doesn’t mean you should drink or bathe in that water as it comes from the tap. You absolutely want to remove the chlorine from the water that you drink and bathe in. Minimize your exposure to chlorine-based cleaning products and toilet disinfectants, and if you love to swim in pools, find one that uses an alternative to chlorine. The alternatives are out there — including ozone and ultraviolet technologies; oxygen, copper, zinc and silver purification systems; natural salt (which converts to chlorine, but in much lower concentrations); safer biguanide chemicals, and moss (yes, moss!).
I wouldn’t put too much stock into this study. I mean, sure, if you inhaled the fumes directly from chlorine you might face some risks, but if you swam in a pool without chlorine you’d run the risk of contracting all kinds of nasty diseases and infections.
Actually, I would put a whole lot of stock into this study. As I said in the blog “Chlorine is here to stay. It prevents the spread of diseases such as cholera. But that doesn’t mean you should drink or bathe in that water as it comes from the tap.” There are alternatives. You can absolutely prevent the spread of disease without increasing your risk of asthma and cancer. You’d have to be an ostrich with your head in the sand not to do so. As Geena Davis said in The Fly, “Be afraid. Be very afraid.”
Ha, Joe, a little dramatic, don’t you think? I do some work with the American Chemistry Council and I’ll be the first to admit that if you handle chlorine improperly, like any chemical, it can carry risks. But if you use it properly, I think you’re going to be OK. I think Michael Phelps is a shining example of this point.
As far as I know, pools at the Olympic games have been treated with ozone and UV for the past 12 years or so. As a matter of fact Europeans are so accustomed to the pristine environment of swimming pools without chlorine, that a group of European swimmers at the Atlanta Olympics refused to enter a chlorinated pool. The pool was subsequently switched to an Ozone treatment system.
Why take the risks if we have alternatives like ozone ? Knowledge empowers us.People perish because of lack of knowledge.Thanks for all the information posted.
Thank you Jon and everyone who agrees chlorine
is not good for us humans. Let’s keep trying to educate those who believe otherwise. Not only about chlorine but a lot of toxic chemicals and products.
Hi. I know this is a bit out of the topic but……may I ask if chlorine in chlorinated swimming pools can actually cause our skin to get darken? Thanks a lot.=)
There are certainly many conflicting opinions on this issue all over the net. But the fact is that it is highly unlikely that chlorine darkens your skin. As a matter of fact, if you swim enough it may strip any tan you may have. Skin darkens as a result of the production of melanin due to exposure to the ultraviolet radiation in sunlight! And we’re exposed to more sunlight in the summer because we wear fewer clothes that expose more of our skin. Beyond that, the darkening you speak of is probably caused from sunlight if you are swimming in an outdoor pool, especially since water relfects the light and therefore magnifies its tanning effect.
Great post, even if swimming could be good for Asthmatic people, you’re right, precautionary measures should still be taken.
There are ozone generators
There are ozone generators that reduce the need for chlorine but they don’t eliminate it entirely. They also have UV systems that help but again they only reduce the need not eliminate the need for chlorine. Salt systems still create chlorine gas.
Let’s face it. Chlorine is the most popular because it’s the most economical and the most effective.
However, this study does make one think twice about swimming or drinking tap water.
Phoenix Pool Replastering
It's quite ironic because
It’s quite ironic because chlorine is used to purify drinking water. Chlorine can trigger asthma but not always; some people with asthma can deal with it. Some pool owners would switch to salt water and use pool chlorine generator to convert salt to chlorine and clean the pool water. I would suggest a natural pool but it’s expensive to have.