LONDON - Scientists warned yesterday that high levels of a chemical compound found in indoor swimming pools might pose a risk to pregnant women and their unborn babies.
Researchers at Imperial College London said they found levels of trihalomethanes (THMs), a by-product of chlorine, in London swimming pools that were higher than amounts found in tap water which had been associated with health problems. "There have been some previous studies carried out with tap water where they found some effects like spontaneous abortion, stillbirths and congenital malformations at lower levels of these byproducts," said Dr Mark Nieuwenhuijsen, who led the study reported in Occupational and Environmental Medicine.
He added that the by-product levels are relatively high but scientists do not know what effects THMs in swimming pools might have on pregnant women and unborn babies.
THMs are formed when chlorine, which is added to swimming pools to keep them clean, reacts with organic matter such as skin or hair.
Nieuwenhuijsen said more information is needed about THMs, which can be swallowed or inhaled, and their impact on pregnant women. In the meantime efforts should be made to reduce the levels, he said.
"The owners of swimming pools have to make sure they reduce the by-product levels because there might be a risk if they stay at this level," Nieuwenhuijsen said.
Chlorine is necessary to disinfectant swimming pools but the scientists said levels of THMs can be reduced by making sure people clean themselves before swimming. Filtering the water can also help to keep organic matter at low levels.
The scientists examined 44 water samples from eight indoor pools in London and compared the levels of THMs found in the pools and in tap water. Although the amount of THMs varied according to the water temperature and the number of people in the pool, it was higher than levels found in tap water.:
