Over the weekend I had a demo of a whole house water filter/softener (made by Ecowater). The sales guy (also our oil burner repair guy, so we’re familiar with him) claimed a link between chlorine and cancer, and demonstrated how the chlorine in our water is absorbed through our skin.
I had never heard of this link before, so I did a web search this morning and found several websites (with possible bias) espousing a link. The CDC website says
So I figure we’ve got a collection of some of the greatest minds on the planet here, so let me put the question out there.
If there is, every swimming pool and anyone who’s used them is in trouble. Not to mention people who use chlorine bleach to wash their whites. And that’s not even touching the issue of chlorinated drinking water.
If there was serious concern, I think we would’ve heard about it before this, like about the mercury in dental fillings thing.
If the real question is: do I need a filter to remove chlorine? The answer is no, probably not.
If you’re asking : is chlorine in water dangerous?
The answer is depends on what you mean. Chlorine gas (Cl2) is dangerous to breathe, though the physical damage would much more of a concern than cancer; similarly, concentrated bleach solutions (NaClO) are can do so much immediate damage (either from drinking or breathing concentrated fumes) that cancer is a remote concern. Already reacted Chloride ions (Cl-) are as harmless as table salt (our friend sodium chloride). However, a huge variety of organic molecules containing chlorine are known to be carcinogenic (examples include trihalomethanes, PCBs and dioxins).
If your water is coming from a treatment plant that chlorinates the water, there will in fact be traces of trihalomethanes and other disinfection by-products. But unless there’s a problem at the plant, not enough to worry much about (and much better to have those traces than to be drinking live cholera or typhoid bugs). And a simple filter probably won’t remove trihalomethanes much anyway.
Seriously, if you’re getting water from a treatment plant, it’s being constantly tested six ways from Sunday. Health-wise there are far better things to spend your dollars and energy on than water filters (if you want to soften the water, go for it. But it’s not a health concern).
If you’re getting water from a well, then you should be regularly testing it anyway, and dealing with whatever shows up; but no need to deal with things that aren’t there.
I will say that swimming pools are less well controlled, so the chlorination by-products might be an argument against planning a lifetime of getting all of one’s drinking water from swimming pools, but I don’t think occasional swallows of pool water should be cause for serious alarm.