Although the smell of chlorine might seem normal to dedicated swimmers, the chemicals in pools make some people feel ill. Swimmers inhale chemicals in the air just above the water, and absorb the chemicals in the water through their skin. Despite some drawbacks, though, chlorine is essential to pool safety. Without it, public swimming pools would quickly become health hazards.
Definition
Chlorine is an element that belongs to the halogen family. Among the most reactive of substances, chlorine has strong disinfecting capabilities, particularly in water. Pool managers commonly use chlorine in swimming pools for this reason. According to Mary Pohlman, M.D., assistant professor of clinical medicine at Southern Illinois University School of Medicine and a member of the U.S. Masters Swimming Sports Medicine Committee, byproducts from the disinfection process sometimes cause distress in some swimmers.
Potential Health Threats
In an article submitted at the November, 2005 conference of the Chartered Institution of Water and Environmental Management, D.M. Bonnick, BSc, MSc, CChem, MRSC, explains that potential health risks in pools come from a variety of sources. Some swimmers excrete contaminants, such as urine, or transport them into the water. Animals, birds and pollution can contaminate outdoor pools. Improperly maintained filters and plumbing infrastructure also might contaminate water, says Bonnick.
According to Bonnick, viruses, bacteria and protozoa in pools represent public health threats. Chlorine breaks down the sheath that protects viruses, given time and adequate levels of concentration. Chlorine also helps to eliminate bacteria and protozoa in water. Inadequate chlorine levels and improper pool maintenance sometimes result in illnesses caused by the adenovirus, bacteria such as E coli, or protozoa, such as giardia.
Chlorine Function
Chlorine functions to disinfect pool water and make it safe for recreational use by the public. The pH level of the water influences chlorine's effectiveness. Maintaining a constant pH level between 7.2 and 7.8 helps to keep water safe, and ensures a comfort level for swimmers, according to the Centers for Disease Control and Prevention. High pH levels hinder chlorine's disinfectant power, and low pH levels are caustic to human skin and membranes.
The level of chlorine in the water is another important factor in maintaining pools. The Centers for Disease Control and Prevention describes safe levels as 1.0 to 3.0 parts per million.
Byproducts
Chlorine disinfects by reacting with contaminants to eliminate potential threats. It interacts with the ammonia from urine contamination to produce chloramines. The different types of chloramine byproducts produced depend on chlorine levels, contaminant levels and the pH of the water. Dichloramine, typically produced from the interaction of chlorine and ammonia, has as pungent odor.
As detailed in "Swimming Pool Disinfection Techniques and Pitfalls," D.M. Bonnick, BSc, MSc, CChem, MRSC, explains that chlorine also interacts with nitrogen in amino acids such as creatinine, to create chloro-creatinine and other by-products. Chloro-creatinine produces a strong odor, and does not break down when chlorine levels rise. The byproducts need ozone treatment or exposure to UV radiation in order to break down. Charcoal filters also help to neutralize the substances. Trihalomethane is another byproduct that results from chlorine's interaction with organic contaminants.
Side Effects
Nitrogen dichloride, one of the byproducts of chlorine's interaction with ammonia, causes lung and nasal membrane irritation, and might also worsen or cause asthma. Proper ventilation in indoor pools helps to minimize side effects from the substance, along with proper pool chemical balance and hygiene control, says Professor Bonnick.
Some swimmers suffer from the chlorine byproducts, and from low pH balance in the pool. Skin rashes in sensitive people and irritation of nasal passages and eyes are common in the presence of chloramines. Some concerns exist about possible connections between trihalomethane and bladder cancer, but claims remain unproved, says an article on the Environmental Health Perspectives website.
Misconceptions
Pools rely on a combination of chemicals and other factors to prevent infection and illness. Bromine, another element from the halogen family, sometimes complements chlorine use. It is more expensive, and breaks down in sunlight, so often-indoor facilities use it to disinfect spas and wading pools. (Ref #2)
Chlorine is a powerful disinfectant, but in dilution levels acceptable for human use, it cannot eliminate every contaminant. Swimmers need to shower before entering pools to minimize bacteria and microorganism counts, and they should not swim when they have diarrhea or any contagious illnesses.
References
- CDC: Your Disinfection Team: Chlorine and pH
- USMSSwimmer: The Health Swimmer: Readers Ask
- ehp: Childhood Asthma and Environmental Exposures at Swimming Pools: State of the Science and Research Recommendations
- Siemens: Swimming Pool Disinfection Techniques & Pitfalls
- USMSSwimmer: The Healthy Swimmer: Coping With Chlorine Reactions
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