Swimming Pool Secret #70

What's the REAL Danger from Chlorine in my Swimming Pool?

Pick up a newspaper, watch CNN, read a women's magazine: every where you turn, there are reports of studies about the danger of chlorine in our water. People are concerned . . . and maybe they should be!

The dangers of chlorine gas are real. So are risks of fire or even explosions from common chlorine based swimming pool chemicals. And the risk of cancer from ingesting trihalomethanes (THM's) and other disinfection by-products (DPB's) is real, if small. The problems with asthma my own son has when competing in certain indoor swimming pools is one I'm personally affected by. These are complex issues, and ones I'm continually investigating, out of both professional and personal interest.

A serious assessement of these risks, and in particular, the US EPA's analysis of these risks caused Peruvian health officials to take action, while US authorities hesitated. They discontinued use of chlorine to treat wells and other small water systems, thus eliminating the risk from THM's and DPB's.

The result?

According to the EPA's current analysis of cancer risks from drinking chlorinated water, among Peru's 18,000,000, 180 cases of cancer each year have been avoided. (1)

Not too shabby!

But why hasn't the US followed Peru's lead? Especially, since it was US data that persuaded Peruvian officials to act in the first place? (2)

Unfortunately, as a result of US emphasis on the risk of cancers, Peruvian health officials forgot why they began chlorinating in the first place. And as a result of lapse of memory, more than 600,000 Peruvians have suffered brutal cholera infections . . . and over 4,000 have died.(3)

The dangers from chlorination are real, but really small. The dangers from not chlorinating are also real, but not so small.

(1) EPA Guide to Environmental Risk (local copy)
(2) Cholera Epidemic in U.S. Courtesy of EPA Science (local copy)
(3) Risks Misjudged in Cholera Epidemic (local copy)
(4) PAHO News Release on Cholera (local copy)

Note: the original links are all down. You may be able to search the sites (EPA.gov, junkscience.com, health.org, or PAHO.org) to find their archival copy of those articles. Or, you can just look at the copies I archived on my server.

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