Before its health risks were known, asbestos was widely used in cement water pipe manufacturing to increase the cement’s tensile strength. So popular did this product become that by 1988, 12 million people were receiving their water supply through 23,000 miles of asbestos cement pipes.
Asbestos cement water pipe is no longer installed but much of the old pipework is still in use. Most of this is also approaching the end of its estimated 50 to 70-year lifespan and starting to deteriorate. Does this potentially present a health risk?
How does asbestos cement pipe deteriorate?
As water flows through asbestos cement pipes, calcium seeping from the concrete into the water softens the pipe wall, causing the cement to corrode. This exposes the asbestos fibres and eventually releases them into the water supply.
What do scientists think about asbestos cement water pipe health risks?
While asbestos can enter the water supply from natural sources, the deterioration of asbestos cement pipes creates another source of exposure. Some scientists believe that while the risk isn’t high, there is no such thing as a safe level of asbestos exposure.
Asbestos has long been recognised as being capable of causing cancer in humans through inhalation. When its small airborne fibres are breathed in, they attach themselves to the lining of the respiratory system and cause scarring, inflammation, asbestosis and an incurable cancer called mesothelioma.
For many years, the general opinion has been that asbestos presents only a small risk through ingestion, as it was believed that most of the fibres would pass through the gut and be expelled in faeces. This stance is now being questioned.
Italian researchers published a scientific review in 2023, stating that large numbers of asbestos fibres appear to accumulate in the colon. Other studies have linked exposure to high levels of industrial asbestos to incidents of colorectal cancer, although other factors mean that these are inconclusive. There is also some speculative scientific concern that high levels of asbestos fibre in turbulent water could release fibres into the air.
The evidence is contradictory; while some epidemiological studies show a relationship between exposure to asbestos in drinking water and occurrences of stomach and gut cancers, others have failed to find such a link.
How much asbestos is present in drinking water?
Although the World Health Organisation currently sets no exposure limit to asbestos in drinking water, its next four-year drinking water quality guidelines are due to be updated in 2026. The 2022 guidelines also called for "investigative monitoring" to establish the quantity, size and shape of fibres present in water from older asbestos cement pipes, noting it was "appropriate to minimise the concentrations of asbestos fibres in drinking water as far as practical".
In 2012, the International Agency for Research in Cancer (IARC) stated that in some locations there can be as many as 10-300 million asbestos fibres per litre of water.
What precautions are being taken to minimise the risk?
While the jury is still out on whether asbestos in drinking water is a potential health risk, some countries are taking precautionary measures.
In the United States, the Environmental Protection Agency placed a maximum safe limit of seven million fibres per litre back in 1974. This only applies to fibres exceeding 10 microns in length, as longer fibres have been found to present a higher risk of respiratory disease. However, the Centres for Disease Control and Prevention states evidence of five micron-long fibres causing injury. On average, asbestos fibres used in US cement pipes are four microns long.
In the UK, the Drinking Water Inspectorate (DWI) doesn’t require water companies to monitor asbestos levels in water, in line with the WHO guidelines.
The European Parliament adopted a resolution in 2021 that would require member states to regularly monitor asbestos levels in drinking water and take preventive measures "in case there is a risk to human health". However, this was excluded from the Asbestos Work Directive which became law across the EU in 2023.
In Australia, 70% of the nation’s asbestos cement water pipes are to be found in the state of Victoria. The state is adopting strong measures to prevent harm by replacing the pipes with safer, modern alternatives and leaving the old pipes buried to eventually decompose in the soil.
Should asbestos cement water pipes be replaced in the UK?
As many of these pipes are now approaching the end of their lifespan, deterioration will naturally require their replacement. It’s a question of whether this should be done as and when the pipework reaches that stage or before deterioration commences.
There is not yet sufficient evidence to definitively confirm a health risk, and with an estimated cost of £5-8 billion to replace all asbestos cement water mains currently used in the UK and Ireland a nationwide upgrade is highly unlikely.
How should asbestos cement pipes be safely replaced?
If old asbestos cement water pipes are damaged or deteriorating and need to be replaced, great care should be taken to prevent harm to human health. The ideal solution would be to follow the lead of Victoria and simply bypass the old pipework with plastic pipe, as asbestos presents little risk if it’s buried and will eventually decompose.
If that option isn’t viable, appropriate disposable PPE should be worn while handling asbestos, particularly if it is damaged or needs to be broken or cut. The working area and any tools or equipment should be enclosed to capture any airborne asbestos fibres and air monitoring equipment may be required. the old pipework and contaminated workwear should be properly disposed of and all tools and equipment decontaminated.
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