Pool Chlorine linked to childhood asthma (drinking water?)

Does this also mean that our chlorinated drinking water may also be causing increased asthma?
-----BumbleBeeBoogie

May 29, 2003
Chlorine in pools linked to childhood asthma
By Oliver Wright and Craig Lord - London Times

CHLORINE used to clean indoor swimming pools is linked to the alarming surge in childhood asthma over the past 30 years, according to research published today. Young children who swim several times a week in highly chlorinated pools could suffer similar lung damage to regular smokers, scientists in Belgium said. They said that much more needed to be done to improve water and air quality controls in public pools despite significant changes in recent years.

In the past 25 years in Britain asthma among adults has risen threefold while asthma among children has risen six-fold. According to a study last year, one in eight British children suffers from asthma while one in five has had the illness diagnosed at some stage in their life.

Sports doping statistics suggest that the condition is more prevalent among swimmers, with more than 40 per cent of elite swimmers registered as asthmatic. The new study claims that the problems have been caused by nitrogen trichloride, an irritant gas released when chlorinated water reacts with urine or sweat on swimmers.

Researchers took blood samples from 226 primary schoolchildren who had swum regularly at indoor pools since early childhood. They also took samples from 29 adults and children both before and after a session in an indoor pool. The samples showed that children who regularly attend indoor pools accumulated proteins that destroyed the cellular barrier protecting the lungs, making it permeable and more prone to the passage of allergens, the substances that unleash an asthma attack.

Protein levels even rose measurably among people who had been sitting at the poolside and had not swum. The effects were the same for children wherever they lived and remained after taking account of other environmental pollutants. They were strongest in the youngest children and in the worst cases were similar to that found in regular smokers.

"The increasing exposure of chlorination products in indoor pools might be an important cause of the rising incidence of childhood asthma and allergic disease in industrialised countries," the study concludes.

Other experts said that the research was important but nitrogen trichloride was likely to be just one factor in causing asthma. Other significant risk factors include obesity, genetic predisposition, smoking, low birthweight, air pollution and allergens, such as exhaust particles and household dust mites. Strong emotions and even the weather can exacerbate the condition.

Professor Martyn Partridge, an asthma specialist at Imperial College, London, said: "The putative association between swimming and the rise in prevalence of asthma is also interesting but great care must be taken in interpreting such associations and it is very unlikely that swimming by itself could be the cause for the increase in asthma. While we welcome research such as this, much more work needs to be done in this field before we can draw any conclusions and take action to turn off the epidemic of asthma."

Warren Lenney, a spokesman for the British Lung Foundation, added: "The causes of asthma are extremely complicated and even now we are only just beginning to understand them."

The new study, led by Alfred Bernard, a toxicologist at the Catholic University of Louvain, Brussels, and published in the Journal of Occupational and Environmental Medicine, is the first specifically to look at the effect of chlorine and nitrogen trichloride on the lungs and its association with asthma. Chlorine has been used in public swimming baths since the start of the last century but over that period water temperatures in public pools have risen, while children have started swimming younger when they are believed to be most at risk.

Dr Bernard said people should not be surprised by the findings. "Children often go swimming together and in large groups and there is therefore more likely to be urine in the water which reacts with the chlorine to produce nitrogen trichloride. Also children learn to swim much younger now than in the past when we think that they are more susceptible to lung damage. Nitrogen trichloride is a known lung irritant which was withdrawn as a bleaching agent because it was too toxic.

"The belief that the swimming pool environment is safe is so deeply rooted in our minds that it is regarded as a healthy practice to send schoolchildren swimming as frequently as possible. As a result the question needs to be raised as to whether it would not be prudent in the future to move towards non-chlorine based disinfectants, or at least to reinforce water and air quality control in indoor pools."

Phil Penny, chairman of the Amateur Swimming Association's health and safety committee, said the majority of pools in Britain now used less chlorine and had introduced ozone-based chemicals that helped to prevent nitrogen trichloride forming.

"As anyone who has been a regular user of pools knows, the treatment of pools has massively improved over the past 25 years," he said. "Yet as the effects of chlorine compounds have been stripped out, the incidence of asthma in the population has massively increased. That would indicate that there is no evidence for the correlation between swimming and asthma that is suggested."

Top swimmers also rejected the idea that their sport may have caused their asthma. Rather they had become swimmers to cure their condition on the advice of doctors. Speaking from a Great Britain team training camp in France, Karen Pickering, the Commonwealth champion and a relay world champion, said: "One of the reasons I started swimming was because of suffering from asthma, so it was something I had before I became a regular in the pool. The sport has helped me tremendously, helping to increase the strength in my lungs."

Adrian Moorhouse, the 1988 Olympic champion for Britain for 100 metres breaststroke, had asthma at seven. He said that swimming had helped to increase his lung capacity.