Re: Hello and CYA @ 240-300
Yes. Not "perfectly safe", because nothing is "perfectly safe" -- but the primary risk to your children in the pool, by a VERY large margin, is overexposure to dihydrogen oxide*, rather than overexposure to chlorine.Originally Posted by han78216
We'd been reluctant to say yes, for a number of years, even though many of us have swum in pools at 12 ppm or higher. But, this spring, in researching some claims of "chlorine allergies", I found that dermatologists have for years been recommending "bleach baths" at 50 - 100 ppm chlorine with NO stabilizer for patients, including pediatric patients, with eczema and other skin conditions.
Here's that data we have at present:
+ Bleach bath use at 50 - 100 ppm, as a dermatological treatment for both adult and pediatric patients. (Please note: these were naked bleach baths. 100 ppm of chlorine, in the absence of stabilizer, will do serious damage to most women's swimsuits!)
+ Pool Chlor of Arizona and other pool service companies have used chlorine gas to treat 10,000's of home pools since the 1960s in a process that involves stabilizer levels around 150 ppm and chlorine levels that are 15 - 20 ppm at the end of each weekly chlorine injection treatment, but fall to 5 - 10 ppm by the end of the weekly treatment interval.
+ Personal observation #1: In the late 1990's I was servicing a pool in the subdivision where US Congressman Zach Wamp was living. One of the pool staff made unauthorized changes to the feed system resulting in kiddie pool chlorine levels that had been falling, but were in excess of 100 ppm when I arrived, and found the problem. The feed system had been turned off, so levels would have been falling. My best estimate, from talking to the head guard and trying to determine what had happened, was that the changes had been made 3 days before, and corrected 24 hours later. The kiddie pool had been in HEAVY use during this entire period.
What was done was done, so I drained most of the pool into the main pool, and then refilled it, lowering chlorine and stabilizer levels to more typical values. I asked the head guard specifically, but she had had ZERO complaints, even though many infants had used the pool. We'd both seen how simply hearing about a problem would generate complaints ( I did this as an experiment on one pool, years ago, announcing a fictitious problem) and so we said nothing. But I asked to let me know immediately of any complaints that did arise. There were none.
+ Personal observation #2: Around 1998, the Chattanooga Warner Park 50m pool was being used by several USS teams for long course training. I knew a number of the elite swimmers, since many of them worked as guards I serviced, and because my son was a fairly elite younger swimmer at that time. During a one month interval, the pool had some 'control' issues, resulting in OTO 'orange' chlorine levels (20 - 50 ppm) (I wasn't servicing the pool so I couldn't check too closely). Stabilizer levels were very low during this period. The results of swimming in this pool with 20<FC<50 ppm and 0<CYA<20 ppm for 2-3 hours per day, 6 days per week were:
a. loss of all fine body hair
b. dry skin
c. destruction of multiple swimsuits (both guys and girls wore Lycra swim suits)
d. the guys who did NOT wear swim caps had ash-colored hair, with 'goggle-stripes' where the goggle straps protected the hair underneath, which retained it's original color.
+ Personal observation #3: Around 2000, my son was swimming at the McCallie School indoor pool, which experienced similar control problems. I did test this water, but only by dilution, since I did not have the DPD-FAS test at that time. Levels were 15<FC<30 ppm and CYA=0 ppm. This continued for 3 - 4 weeks, until I called the health department. My son, who had moderate to severe asthma, had had NO breathing problem beyond normal, did lose a suit, and did get the stiff, ash-colored hair, but experienced no other ill effects.
+ Analytical observation: Beginning around 2005 (I'll let him comment on this) Chem_Geek took earlier laboratory research and distilled it into an analytical spread sheet that allows calculation of actual HOCl, and -OCl levels, given DPD chlorine levels, pH and CYA levels. Over the past 8 years, both here and at TroubleFreePools, an increasing body of empirical evidence has validated his analytical conclusion that the EFFECTS of chlorine in water are primarily a function of the HOCl and -OCl components. Stabilized chlorine compounds in the water constitute an effective and instantaneously available chlorine RESERVE, but are not themselves active, until the HOCL levels are reduced, allowing the stabilized chlorine compounds to release their 'reserve'.
+ Bureaucratic observation: The US EPA regulates the treatment of potable water by public utilities. Until recently (maybe 12 years ago?) there was NO upper limit on chlorine levels in drinking water. Even today, the upper limit of 4 ppm FC is an ACTION limit. What this means is that the utility is not in trouble, does not have to report a violation to the EPA OR to its customers, but rather simply has to begin to take "ACTION" to lower the chlorine levels. The fact remains, public utilities ROUTINELY provide DRINKING water to some customers that is at or near FC=4ppm, and occasionally provides water at 10 ppm FC . . . and this has not caused any reported problems I am aware of.
+ Literature: I have collected over 8 Gigabytes of peer-reviewed articles on water treatment (and will be publicly indexing them at SwimmingPoolResearch.com, beginning this fall) and have no articles reporting ill health effects on swimmers as a result of chlorine levels that are 10ppm<FC<100ppm. (Those levels do trash hair and swimsuits, as noted above, in the absence of high CYA levels, though I don't have reports on that, either.)
This is probably more than you wanted -- but it's a question that's going to come up as a result of changes in what I'm suggesting. So I took the opportunity to answer your question somewhat more fully than you might have desired.
I'm going to put a copy of this thread in the China Shop, so those that want to continue the technical "Is high chlorine bad for you?" discussion, can do so there, and leave this thread for your personal questions.
*dihydrogen oxide = H2O = water. Overexposure to dihydrogen oxide is more commonly called "drowning". But the observation that H2O is the most dangerous chemical in your pool by far, is absolutely dead on.
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