Miscarriage risk from swimming pools

Experts have called for levels of chemical by-products in public swimming pools to be fully investigated and cut as far as possible amid fears that they are linked to health problems including cancer.

Pregnant women are encouraged to exercise in swimming pools because the water supports their body weight and improves joint mobility and muscle tone.

But new research published yesterday shows that levels of the by-products of chlorine are relatively high in the UK’s indoor swimming pools.

There is rising concern over a possible link between such chemicals and miscarriage, according to the scientists.

Dr Mark Nieuwenhuijsen, of the Imperial College of Science and Technology and Medicine, London, explained that when chlorine is added to water it reacts with organic matter, such as skin cells and body care products, to form disinfection by-products or DBPs. The most common of these are trihalomethanes (THMs), volatile compounds that can vaporise from water into the atmosphere.

Adverse reproductive outcomes such as miscarriage, low birthweight and some birth defects have been associated with THMs, but current evidence appears to be inconsistent , the researchers said.

Dr Nieuwenhuijsen said: "For many decades, chlorination has been used as a major disinfectant process for public drinking and swimming pool water in many countries.

"However, there has been rising concern over the possible link between DBPs and adverse reproductive outcomes.

"As a precautionary measure, THM levels should be reduced as far as possible in swimming pools while maintaining effective control against waterborne microbiological disease".

The research, published in the journal Occupational and Environmental Medicine, was based on 44 water samples from eight indoor swimming pools in London which were taken at different times over three weeks during the summer of 2000.

Researchers took the samples and compared them with tap water. The total amount of organic matter was three times higher in swimming pool water than tap water and chloroform, the most commonly occurring trihalomethane, was more than 20 times higher.

Chloroform has been classed as a potential cancer-causing agent.

Higher levels of THM were associated with higher water temperature and higher numbers of people in the pool.

Levels varied from day to day, according to the numbers of swimmers, but they were higher, overall, than the levels reported by studies of other European sites.

The researchers did not measure uptake of THMs, but they wrote that previous research had indicated that a one-hour swim would provide a chloroform dose about 141 times higher than a ten-minute shower.

They suggest that there are several routes of entry for swimmers - through the skin, swallowing water and breathing it in off the surface of the water as it evaporates.

Belinda Phipps, the chief executive of the National Childbirth Trust, said: "For a vast number of pregnant women in the UK, swimming and aqua exercise programmes are a very enjoyable and beneficial part of their pregnancy."

She added that the paper highlights an area of potential risk to pregnant women and offers a simple solution to limit chemical levels in swimming pool water by reducing the amount of chlorine used - a measure which the NCT would strongly support.

Ms Phipps said: "All too often in this kind of situation it is the mother that is made to feel guilty and change her practices. The burden of responsibility here lies with appropriate regulatory bodies and not with pregnant women to restrict their habits and lifestyle because of preventable and unnecessary factors such as this."

Ralph Riley, the chairman of the Institute of Sport and Recreation Management, insisted that British swimming pools were monitored regularly and were within safe limits.

He said: "This is something we have known about for some time. We need to disinfect water to stop cross-infection between bathers. Chlorine levels are monitored continuously in pools. Levels of the chlorine by-products are way below levels that would cause any harm to pregnant women."

CHLORINE A MOTHER’S CONCERN

FIONNUALA Munro is expecting her second child in May.

She swims every week at her local pool to keep in shape because she believes it is one of the best forms of exercise.

However, the 35-year-old, who lives in Edinburgh with her husband, Craig, admits she is concerned that the levels of chlorine by-product in the water may be putting her unborn child at risk.

She is determined to carry on swimming while she is pregnant because she is enjoying the benefits of the exercise.

But she feels she needs to know more about the levels of chemicals in swimming pools before she can make an informed decision about whether swimming while pregnant is the safest form of exercise.

She said: "I usually go swimming twice a week but recently I have not been going as often because I am so tired with the pregnancy.

"I have always looked upon swimming as a good form of exercise and I would recommend it to any expectant mother. But I have to say that the safety of the water I swim in has never been something I considered worrying about before. I think people just assume it is safe," she added.

"I went swimming a lot when I was pregnant with my daughter, Ciara, who is now nearly two, and everything was fine with her, thank goodness. But I would certainly take this research on board.

"I would not stop swimming now because I would not want to do anything too drastic."

However, she added: "I would try and find out as much as I could about this possible link between chlorine by-products and miscarriage or birth defects and I will keep my eye out for any further developments.

"I would also want to know what the levels of chlorine by-products are in swimming pools in Scotland and whether they are as high as the levels in the pools that were studied.

"I certainly wouldn’t ignore research like this."