Study: UV and Ozone in Swimming Pool Treatment Expected to Grow

Chlorination is still the most widely used method of water disinfection for swimming pools, principally thanks to its cost, the ease of use and the huge range of products that are available.

However, many believe it would be desirable if chlorination of water could be phased out because of the known health and environmental risks. Chlorination byproducts have been linked in some studies to cancer risks, and chlorine might be corrosive to some types of swimming pools. 

High THM levels

Recently, researchers at Imperial College London said they found levels of trihalomethanes (THMs), a byproduct of chlorine, in London swimming pools that were higher than amounts found in tap water which had been associated with health problems.

Studies from the United States have suggested a correlation between the number of glasses of chlorinated tap water drunk daily by pregnant women and the risk of spontaneous abortion, stillbirths and congenital malformations.

The presence of chloroform and other THMs in water has been blamed by some experts. The Imperial College team reported that the chloroform content of water in eight pools in London was on average 20 times higher than that of drinking water.

THMs are formed when chlorine, which is added to swimming pools to keep them clean, reacts with organic matter such as skin or hair. THMs can be absorbed through the skin, swallowed or inhaled.

To reduce THM formation, scientists recommended making sure people clean themselves before swimming and filtering the water.

Additional links

September 2001 also saw high levels of THMs linked to lung damage. Children who swim in a chlorinated pool once a week scored the same on one measure of lung damage as adult smokers, announced Belgian researchers.

The team took blood samples to measure levels of three surface proteins that indicate lung damage resulting from exposure to a high level of oxidants. They found the level of the proteins increased with higher exposure to chlorinated water.

This oxidative damage also increases the amount of 'surfactant' proteins, which the team measured after the children had been swimming. The highest levels detected were similar to those seen in adult smokers.

Other researchers have found an increased incidence of asthma in lifeguards who work in indoor pools, although further research will be carried out.