Beware of the pool…
B-52's, "Private Idaho"
In saltwater swimming pool treatment systems, sanitation is not achieved through high salinity. Rather, salt (sodium chloride) is simply used to make chlorine.1
The chlorine level in a saltwater pool like the one at the Biltmore Athletic Club in Asheville is kept at at 2-3 ppm.2 This is the same amount as is recommended for a regular pool.3 Why then do saltwater pools smell less and feel better? It's not, as some would have you believe, because the chlorine in public pools is kept at higher levels (3-10 ppm).4 It's actually because in conventional pools, the chlorine level often falls too low.
Most people can't smell chlorine at levels under 3.5 ppm.5 What smells in a pool and irritates your eyes, skin, and lungs is "used" chlorine, i.e., compounds created when chlorine combines with organic compounds in the water (skin, hair, sweat, and yes, pee). A "chlorine level" of 2-3 ppm only refers to pure or fresh (i.e., "free") chlorine. If free chlorine levels are kept at 1 ppm or more, these compounds do not build up. If levels drop, however, it takes a mega chlorine "shock treatment" to correct the problem.6
Since shock treatment brings the pool to an unsafe chlorine level (i.e., 5+ ppm), making you have to wait for it to come back down through evaporation, people often don't use a strong enough dose. People routinely add too little chlorine to the shock treatment, and this actually makes the problem worse.7
The undesirable compounds that result are called chloramines. You've probably heard not to mix chlorine and ammonia (which is what stale urine turns into) because it creates a poisonous gas. Chloramines (such as chloroform) are the poison that's created.8
Chloramines are part of a class of compounds (organochlorines) that include the most toxic substances ever made. Dioxin, for example, the active ingredient in Agent Orange, is 300,000 times more toxic than DDT.9 One gram can kill over 10,000 people.10
Chlorination does not create dioxin but it does create other organochlorines. These mimic human hormones and can cause "lower IQ, reduced fertility, genital deformities, breast cancer, prostate cancer, testicular cancer, dramatic reductions in human sperm counts, and abnormalities within the immune system."11 Chloromines specifically are known to cause or exacerbate asthma and emphysema12 and have other adverse health effects.13
Apparently with saltwater treatment there is less of these compounds because chlorine levels never fall low enough to allow them to form.14 There are other advantages to saltwater filtration as well: the pH is kept near neutral, the water is softer (less calcium), and additional chemicals are not needed.15
Still, though not as easily noticed, the free chlorine in pools is a considerable problem. Chlorine is extremely reactive. That's why it's useful as bleach.16 And if it's going to combine with organic compounds in the water, it's certainly going to combine with stuff on/in you! That's why drinking chlorinated water is such a problem.
The chemistry and conditions for treating swimming pools and drinking water are almost identical, so many of the same compounds - and therefore, many of the same effects - can be expected in both.17
And there's at least as much chlorine in a pool as in tap water.18
The amount of chloramines in chlorinated water is bad enough,19 yet you absorb more of these from immersion than you do from drinking.
If you don't drink unfiltered tap water, you will certainly want to avoid swimming in pools as you can absorb more chlorine after one hour in a pool than you will from a week of drinking tap water.20
The same goes for bathing or showering in chlorinated water.21
House holders can receive 6 to 100 times more of the chemical by breathing the air around showers and bath than they would by drinking the water.22
For these reasons, I recommend sink and shower filters (see box). By the way, unless you have a whole-house chlorine filter, you also get a lot of chlorine in the air when you open the dishwasher. The same problem applies to swimming pools and even more to spas, particularly when the pool area is poorly ventilated.23
In conclusion, 2-3 ppm free chlorine in a pool, even a saltwater one, is an unacceptable level for me. I'll do some other kind of exercise until summer, when I'll swim in a relatively clean lake or the ocean.24
For more info
These pages have good basic information on pool chlorination:
A pool maintenance glossary can be found at:
For a detailed explanation
of chlorination, see
CHLORINE, STAINLESS STEEL TANKS AND CORROSION at
To see the particular system the Biltmore Athletic Club uses (I'm not positive on the exact model), see:
Healthier pool water-treatment alternatives may include silver
UV treatment
and ionization
For high quality sink and shower filters, see
Reader comment:
Thanks for the info. I guess one thing that is a pet peeve for me is information like organochlorines causing all kinds of diseases (implying swimming in a pool will do this) without any information on exposure levels. For instance in the case of someone who has arthritis and has no access to a salt water pool. If the only way they get aerobic exercise or maintain healthy range of motion is water aerobics or therapy (as is the case for many of the people in YWCA classes), is the risk of swimming in organochlorines worse than frozen joints, or weight gain, or CV disease? Is there a relatively "safe" exposure?
J.M., RN
1 "Many people refer to saltwater pools as non-chlorinated, but it's actually a misnomer... The difference between saltwater pools and so-called chlorine pools is the way the water is treated. In conventional chlorinated systems, you must add chlorine via a carrier mineral to the water in either tablet or liquid form. In saltwater systems, a salt-chlorine generator is added to the filtration system to automatically convert salt to the natural form of chlorine." http://www.faqfarm.com/Home/Pool/11361
2 Josh [Vandergrift, the owner?], personal communication, 1/25/05; ppm is parts per million.
3 "You should... maintain between 1 - 3 ppm free available chlorine..." (http://www.poolforum.com/dcforum/DCForumID21/94.html - page no longer available (2008)); "an ideal chlorine level [for any pool] is 1-3 PPM" (http://www.acquanita.com/faq.htm - page no longer available (2008)); "...keep FAC [free available chlorine] levels between 1.0 and 3.0 ppm" (http://c3.org/chlorine_knowledge_center/POOLTREATMENT101.html).
4 see e.g., http://www.poolplaza.com/pool-school/salt_differences.shtml
5 http://www.biophysica.com/chlorine.html
http://www.co.san-bernardino.ca.us/dehs/RECHEALTH/faqsrechealth.htm#8anchor and
http://c3.org/chlorine_knowledge_center/POOLTREATMENT101.html
7 http://www.poolspa.com/publications/sin/stories/shocktrt.htm
8 http://www.kintera.org/site/pp.asp?c=coIHKTMHF&b=84419
9 http://www.kintera.org/site/pp.asp?c=coIHKTMHF&b=83945
10 http://www.smartyhealth.com/detox.html (for more on dioxin see http://science.howstuffworks.com/question220.htm)
11 http://www.kintera.org/site/pp.asp?c=coIHKTMHF&b=83945
12 http://www.abc.net.au/worldtoday/content/2003/s867621.htm and http://www.drgreene.com/21_1599.html
13 http://www.gjne.com/fluoride/chlorine.htm and http://www.mercola.com/2002/apr/17/chlorine.htm
14 in the case of saltwater bromine-treated pools, on the other hand, there may be more "disinfection byproducts" (http://www.who.int/entity/water_sanitation_health/bathing/en/recreaII-ch4.pdf).
15 "There is no real difference in the chlorine produced by the salt water generator compared to liquid chlorine added directly to the pool. There are some differences if you add chlorine in the form of tabs, as there are some other ingredients incorporated with them, such as calcium and cyanuric acid, used for keeping the chlorine in solution until it is needed" (http://www.poolforum.com/dcforum/DCForumID21/364.html - page no longer available (2008)). Specifically, "if you are using chlorine tablets, you are adding 1 lb. of stabilizer for every 2 lbs. of tablets you put into your pool" (http://www.poolplaza.com/pool-school/salt_differences.shtml).
16 It brings the staining compounds into solution. For exactly how that works, see http://science.howstuffworks.com/question189.htm.
17 previously at http://www.hidrion.pt/english/eng_imp_dados.html - page no longer available
18 "Typically, a pool is treated at a rate of 3 PPM, and drinking water is treated at anywhere from 0.2 PPM to 3 PPM depending on the level of contamination and the contact time" (http://science.howstuffworks.com/question189.htm). See also http://www.epa.gov/safewater/mdbp/dbp1.html and http://www.gjne.com/fluoride/chlorine.htm. The chlorine level at a given location partly depends on its distance– along the water line– from the water treatment facility.
19 http://www.mercola.com/1997/archive/cancer_risk.htm
20 http://www.mercola.com/2002/apr/17/chlorine.htm. I'm assuming this applies to saltwater pools as well.
21 http://www.gjne.com/fluoride/chlorine.htm
22 "Showers pose a risk to health," Ian Anderson, New Scientist, September 18th, 1986.
23 Even Biltmore Athletic Club's owner admits that in their basement where the pool is located, "there's not a lot of ventilation down here." http://orig.citizen-times.com/cache/article/fitness/73875.shtml - page no longer available (2008)
24 unfortunately, chemical run off from paper mills, other industries, and home use of chlorinated detergents, along with high natural levels of organic matter in lakes has rendered most of them unsafe as well.