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Tap Water ‘Increases Risk of Birth Defects’
Chemical by-products in tap water in some Perth suburbs are increasing the risk of birth defects and pregnant women may need to drink bottled water to avoid the danger, health researchers led by the University of WA have warned.
The researchers examined water samples from almost 50 public locations north of the Perth central business district and found that women who lived in areas with high concentrations of trihalomethanes in drinking water had a 22 per cent greater risk of having a baby with a birth defect when compared with women in areas with lower concentrations.
Heart problems were the most likely defect.
Trihalomethanes are by-products formed by the reaction of chemical disinfectants, particularly chlorine, with natural organic matter in water. The researchers found high levels of THM in five water catchment areas stretching 10km north of the CBD.
The researchers defined high levels of THM as 130 micrograms per litre and above.
Australia’s recommended maximum allowable level is set by the National Health and Medical Research Council at 250 micrograms per litre.
The NHMRC reviewing drinking water guidelines but the limit is much higher than in some other industrialised countries such as Canada, which allows just 80 micrograms per litre.
Professor Philip Weinstein, from UWA’s school of population health, said developing foetus was very sensitive to environmental toxins. “This is one possible route of exposure that hasn’t really been considered adequately in the past,” he said.
“If you introduce poisons to the foetus when it’s forming, things go wrong, development is very complex and the slightest toxin can interrupt the normality of that development.”
He said that it was difficult to balance the need to chlorinate water to protect against diarrhoea-causing bacteria and the chemical by-products formed when chlorine was added to water.
“On the one hand you’ve got the bacteria, on the other hand you’ve got the disinfection by-products, to get neither requires pretty heavy duty water engineering,”Professor Weinstein said.
He said more study was needed and if the extra research supported the group’s findings, pregnant women in some suburbs may need to be advised to drink only bottled or filtered water.
“If it’s deemed to be a serious enough problem across a wide enough population then maybe something should be done about removing them (THM), if it’s a minor localised problem maybe bottled water for those people at risk,” he said.
The water samples were collected for 12 months over 2005 and 2006.
The researchers than examined the WA Birth Defects Registry and the number of total births and birth defects from postcodes corresponding to the sample locations between 2000 and 2004.
The Water Corporation referred the issue to the Health Department, the body
that regulates water quality standards and operates the Advisory Committee for the Purity of Water.
Dr Richard Lugg, chairman of the committee and Health Department environmental health consultant, said levels of THM in Perth drinking water were within Australian guidelines but the study warranted further investigation.
“There is no consensus in the scientific literature on the risk of birth defects due to THM levels in drinking water,” he said. “However, the study provides data and raises important issues.”
He said the study had been referred to the NHMRC and would form part of its review into drinking water guidelines.
WA Tap Water May Be Threat To Babies
Perth tap water may pose risk to unborn babies, university researchers have warned after finding that elevated nitrate levels in some suburbs could increade the risk of birth complication that causes a mother’s waters to break before the onset of labour.
Called term pre-labour rupture of membranes (PROM), the condition occurs when pregnancy has reached full term. It can effect up to 10 per cent of pregnancies and can be dangerous because without protective membranes the baby can be exposed to infection.
Led by researchers from the University of WA’s school of population health, a study of more than 16,000 Perth women who gave birth between 2002 and 2004 found that those living in high nitrate areas were almost 50 per cent more likely to have the complication.
This was compared with women in areas the researchers classified as having low nitrate exposure. Women in medium exposure areas had a 23 per cent increased risk of the complication.
Researcher Philip Weinstein said the study showed there were some areas of Perth were the water posed a risk to unborn babies. He said this was backed by previous UWA research published in April which found that chemical by-products in tap water increased the risk of birth defects.
Co-author John Newnham, from UWA’s school of women’s and infants’ health, said while term PROM could be easily managed, it was a significant problem. “It’s not that dangerous because we know how to deal with it but it occupies a lot of resources,” he said. “There‘s always the risk of infection so it’s a big issue for us.”
Even though a link was made between term PROM and nitrate levels, there was no need for pregnant women to swich to bottled water. “We’ve found something very interesting,” he said. “Have we proved it? No, we haven’t proved it, we now need to see it replicated in other populations.”
Published in the American Journal of Epidemiology, the latest study looked at the whole Perth region but did not list specific suburbs classified as high nitrate areas.
But based on its definition of high nitrate levels as greater than 0.35mg/L, suburbs that may be at risk include Neerabup, Two Rocks, Whitfords, Yanchep, Mt Hawthorn and Greenmount.
Richard Lugg, Health Department environmental health consultant and chairman of the advisory committee for the purity of water , said the results were only preliminary and more research was needed.
“The levels of nitrate in Perth drinking water are extremely low compared with the Australian drinking water guidelines and there is no basis for recommending that pregnant women should change their source of drinking water,” he said. “Nevertheless, the Department of Health would support further research in this area.”
Water Corporation spokesman Phil Kneebone said every area in Perth recorded less than 10 per cent of the recommended guideline level for nitrates, with most recording less than 5 per cent.
Professor Weinstein said nitrates found in Perth’s water supply came from various sources, with many a residue of natural processes of plant decay. But it might not be the nitrate itself that was toxic. Instead, the elevated levels could be an indication that other nitrogen-containing toxins known as nitrogenous disinfection by-products could place oxidative stress on the protective membrane, resulting in an inflammatory reaction that could lead to the membrane rupturing. The study also found no link between nitrate levels in water and the risk of the more dangerous pre-term PROM, when a woman’s waters broke before 37 weeks of pregnancy.
The Health Department will submit the study to the National Health and Medical Research Council to be considered as part of a review of drinking water guidelines.
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