Still haven't read the original source articles, so with that in mind:
It isn't just 3 studies. Chlorinated DBPs (disinfection by-products) were first detected decades ago. Look in almost any textbook on water treatment (drinking, sewage) and you'll find a section on it. Many of the chemical listed have been identified as potential or probable human carcinogens. Nothing controversial about any of that. Heck, non-swimmers' greatest exposure level to volatile chlorinated DBPs like chloroform probably happens in the shower (hot water will increase the vapor pressure of volatile chemicals).
What is controversial is the degree to which environmental carcinogens actually contribute to incidences of human cancer. Some dismiss it as negligible, others do not. Due to the long lag period for cancer, it is hard to assign "blame," so to speak, from epidemiological studies. I suspect the paper is aimed at investigating this aspect of swimming pool chlorination.
Focusing on cancer is pretty understandable: it is a scary disease and, from a regulatory standpoint, there is no threshold level for carcinogens. That implies that guarding against cancer will guard against other health effects.
But with respect to pools, personally I am much more concerned about those other effects. I'm with Kirk: if you are having trouble breathing, it isn't good, and not just because of cancer. Most people know (or they should) that repeated high-intensity exercise in the outdoors during ozone-alert days will reduce lung function permanently; it isn't hard to imagine the same thing happening in swimming pools due to chlorination DBPs with long-term exposure. People in sensitive populations (eg asthmatics, people with COPD) will be even more at risk.
I had to smile at the phrase about "investigating alternative methods of disinfection." They've been known and used for years. In some -- maybe most -- cases they are more expensive. I'll have to ask my coach (who is also the facilities manager at the pools where I usually swim) about the economics of the uv and ozone treatments that he uses, and any other info about it.
Still haven't read the original source articles, so with that in mind:
It isn't just 3 studies. Chlorinated DBPs (disinfection by-products) were first detected decades ago. Look in almost any textbook on water treatment (drinking, sewage) and you'll find a section on it. Many of the chemical listed have been identified as potential or probable human carcinogens. Nothing controversial about any of that. Heck, non-swimmers' greatest exposure level to volatile chlorinated DBPs like chloroform probably happens in the shower (hot water will increase the vapor pressure of volatile chemicals).
What is controversial is the degree to which environmental carcinogens actually contribute to incidences of human cancer. Some dismiss it as negligible, others do not. Due to the long lag period for cancer, it is hard to assign "blame," so to speak, from epidemiological studies. I suspect the paper is aimed at investigating this aspect of swimming pool chlorination.
Focusing on cancer is pretty understandable: it is a scary disease and, from a regulatory standpoint, there is no threshold level for carcinogens. That implies that guarding against cancer will guard against other health effects.
But with respect to pools, personally I am much more concerned about those other effects. I'm with Kirk: if you are having trouble breathing, it isn't good, and not just because of cancer. Most people know (or they should) that repeated high-intensity exercise in the outdoors during ozone-alert days will reduce lung function permanently; it isn't hard to imagine the same thing happening in swimming pools due to chlorination DBPs with long-term exposure. People in sensitive populations (eg asthmatics, people with COPD) will be even more at risk.
I had to smile at the phrase about "investigating alternative methods of disinfection." They've been known and used for years. In some -- maybe most -- cases they are more expensive. I'll have to ask my coach (who is also the facilities manager at the pools where I usually swim) about the economics of the uv and ozone treatments that he uses, and any other info about it.
